Aquaculture Magazine Volume 49 Number 6 December-January 2024 by Aquaculture Magazine

Disease resistance and improved growth from one dynamic ingredient. Motiv represents a unique new approach for shrimp diets. Instead of relying on additives for functional benefits, it simplifies the diet with one functional macro ingredient. Using a unique fermentation process, Motiv promotes a healthy gut environment. It results in better growth and higher survival rate due to improved nutrient utilization and disease resistance through an improved immune response and stress resistance. The force for growth and vitality. motivshrimp.com

DECEMBER 2023 - JANUARY 2024

INDEX

Aquaculture Magazine Volume 49 Number 6 December 2023 - January 2024

on the

4 EDITOR´S COMMENTS

cover

6 INDUSTRY NEWS

Feed-food competition in global aquaculture: Current trends and prospects

12 GREENHOUSES AND POND LINERS

Oxygen consumption of Litopenaeus vannamei in intensive ponds based on the Dynamic Modeling System.

Feed-food competition is a current but unsustainable practice in aquaculture, where resources are allocated to feed humans to animal feed instead.

20 Volume 49 Number 6 December 2023 - January 2024

16 ARTICLE

Metabolic turnover rate, digestive enzyme activities, and bacterial communities in the white shrimp Litopenaeus vannamei under compensatory growth.

Editor and Publisher Salvador Meza info@dpinternationalinc.com Contributing Editor Marco Linné Unzueta Editorial Coordinator Karelys Osta edicion@dpinternationalinc.com Editorial Design Perla Neri design@design-publications.com Sales & Marketing Coordinator crm@dpinternationalinc.com Sales Support Expert sse@dpinternationalinc.com

ARTICLE Health-promoting additives supplemented in inert microdiets for whiteleg shrimp (Penaeus vannamei) post-larvae: Effects on growth, survival, and health status.

Operations Coordination Johana Freire opm@dpinternationalinc.com Business Operations Manager Adriana Zayas administracion@design-publications.com

Subscriptions: iwantasubscription@dpinternationalinc.com

30 ARTICLE

Practical low-fishmeal diets for rainbow trout (Oncorhynchus mykiss) reared in RAS: Effects of protein meals on fish growth, nutrient digestibility, feed physical quality, and fecal particle size

2 »

Design Publications International Inc. 401 E Sonterra Blvd. Sté. 375 San Antonio, TX. 78258 info@dpintertnatinonalinc.com Office: +210 5043642 Office in Mexico: (+52) (33) 8000 0578 - Ext: 8578 Aquaculture Magazine (ISSN 0199-1388) is published bimontly, by Design Publications International Inc. All rights reserved. www.aquaculturemag.com

DECEMBER 2023 - JANUARY 2024

COLUMNS

34 CARPE DIEM

The importance of scientific method. By Antonio Garza de Yta, Ph.D.*

36 THE GOOD, THE BAD AND THE UGLY EHP update-mitigation of the impact. By: Ph.D. Stephen G. Newman*

40 THE FISHMONGER

Social responsibility in aquaculture. By: The Fishmonger*

DECEMBER 2023 - JANUARY 2024

Organizational transformation: Marco Linné Unzueta Associate Editor

n 2024, a new cycle begins for aquaculture, which has undergone numerous changes. This is an opportune moment to establish and implement various production schemes. It is important to prioritize organizational performance and its impact by monitoring and managing the organization’s effects on aquaculture, as well as identifying high-priority areas for development. However, it is necessary to use cost-effective tools to demonstrate compliance with sustainable production objectives. Organizational transformation is a complex task that requires a change in mentality and the adoption of certain habits. It is influenced by both internal and external factors, particularly the changing environment that affects the organization’s activities. Production activities are intrinsically linked to the objectives of good production practices, aimed at economic, social, and environmental sustainability. The following should be identified as agents of change based on the above: 1) objectives, 2) personnel, 3) target population, 4) public policies, and 5) available resources. Additionally, staff involvement is crucial in implementing proposed changes. Effective communication of organizational transformation management 4 »

Aquaculture is confronting the challenges and paradigms of R&D&I is necessary to define the reasons for change, align with the organization’s principles and care objectives, establish change needs, and promote planning and implementation while considering the current care environment. Bidirectional communication is a valuable tool for organizational transformation. It helps establish commitment, clarity, and coherence in defining, resizing, and achieving objectives from beginning to end. Additionally, it positions the organization to understand and interpret what the transformation means for staff, the organization, and the target population. This approach supports continuous improvement by identifying and addressing areas of opportunity that arise during the transformation process. To achieve sustainability and competitiveness, an organization must overcome various obstacles related to research, development, and innovation (R&D&I). While technological innovation and measurement needs are major challenges, the enabling environment, including regulatory simplification and stability, availability of investment capital, and overall political environment, must also be considered for successful sustainable production development. To achieve this goal, it is crucial to identify areas for improving aquacul-

ture production. This will help to address critical gaps and enhance competitiveness and development. Effective communication with staff is essential in this process. Communication should focus on the organization’s objectives, both in general and on a personal level. It is important to consider: 1) excellent interpersonal relationships, 2) authentic participative conversations, 3) generating accountability and 4) promoting personal, team, and organizational growth and development, recognizing people’s unique talents, and rewarding achievements. Finally, a new approach to managing organizations, projects, and programs is required to optimize investment. The traditional projectcentric approach is no longer adequate. To maximize the budget, it is important to pay closer attention to what needs to be done differently. This is especially important given the presence of issues such as high capital expenditure, rising costs, competitive pressure, and high risk due to long lead times, which can be constant. Therefore, it is necessary to increase the diligence and involvement of the organization’s members in the processes, supervising the scope, selection, and execution of the projects. DECEMBER 2023 - JANUARY 2024

Freedom to formulate. Empyreal 75 creates more space in the aquaculture diet by reducing the need for other, more costly forms of protein, such as fish meal or other protein concentrates. This gives you expanded flexibility to be more creative with your formulations and diet design—so you can deliver higher-value products to your customers. Empyreal75.com

INDUSTRY NEWS

Skretting partners with Norwegian company Zooca Calanus to develop innovative and sustainable nutritional solutions The global company also announces partnership with Thailand’s I&V Bio for artemia enrichment

Leading global company Skretting has announced its brand new partnership with Zooca Calanus, a leading innovator in sustainable marine ingredients. The goal of the partnership is to provide innovative and sustainable nutritional solutions by leveraging Zooca Calanus’ expertise in harvesting and processing Calanus finmarchicus, a small marine copepod rich in essential nutrients. “We are excited to embark on this journey with Zooca Calanus,” said Hassan Skoien, Skretting’s director of 6 »

shrimp innovation. “This partnership represents an important step in our mission to provide innovative and sustainable solutions to the aquaculture industry. By combining Skretting’s expertise in aquafeed formulation with Zooca Calanus’ unique marine ingredients, we aim to set new standards for nutrition, health and sustainability. in aquaculture.” With more than 10 years of previous collaboration, Skretting and Zooca Calanus will now work together to develop nutritionally optimized, high-

quality feeds using Calanus-based ingredients and fresh canned whole canned copepods. These solutions will improve the health and growth of cultured aquatic species while promoting sustainable practices within the aquaculture sector.

Mutual commitment By harnessing the natural benefits of Calanus finmarchicus, both companies are committed to improving the performance of LifeStart species in a sustainable and responsible manner. DECEMBER 2023 - JANUARY 2024

“This partnership represents an important step forward in our mission to provide innovative and sustainable solutions to the aquaculture industry. By combining Skretting’s expertise in aquafeed formulation with Zooca Calanus’ unique marine ingredients, we aim to set new standards for nutrition, health and sustainability,” Skoien added. For his part, Hogne Abrahamsen, CSO of Zooca Calanus Group, expressed his enthusiasm for the collaboration and said, “We are proud to partner with Skretting, a company known for its commitment to quality and sustainability. Together, we will harness the power of Calanus finmarchicus ‘natural baby food’ to create diets that not only improve aquatic health, but also contribute to the preservation of our oceans and marine ecosystems.” According to Skretting, this partnership aligns with both companies’ dedication to driving positive change in the aquaculture industry and underscores their shared vision for a more sustainable future. “Skretting and Zooca Calanus look forward to bringing these innovative products to market and generating a lasting impact on the global aquaculture landscape,” they said. “Calanus is an abundant resource. Incorporating it into our diet allows us to diversify marine ingredients and provides employment opportunities for local fishing communities during the off-season,” said Eamonn O’Brien, global product manager for LifeStart.

Revolution in Artemia enrichment Shortly after the news was released, Skretting announced another strategic partnership in which it has high expectations: its union with the Thai company I&V Bio, a leader in biotechnology, with which it aims to revolutionize artemia enrichment. As explained in a press release, the union will leverage I&V Bio’s innovative prowess and Skretting’s industry expertise with the aim of redefining aquaculture nutrition standards through the application of ORI-N3, Skretting’s cutting-edge nutritional supplement for artemia enrichment. Artemia serves as a vital component in the early stages of the life cycle of various aquatic species, so ensuring its optimal nutrition is essential for the healthy growth and development of shrimp in aquaculture systems. I&V Bio and Skretting claim to recognize the importance of this foundation and have joined forces to improve the nutritional value of artemia using ORI-N3. Developed by Skretting, ORI-N3 is a revolutionary nutritional supplement enriched with proteins, lipids and essential micronutrients. This advanced formula is specifically designed to increase the nutritional content of artemia, providing a balanced and comprehensive diet for early-stage aquatic species. With its unique composition, ORI-N3 ensures optimal growth rates, increased disease resistance and better overall health of shrimp.

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The Center for Aquaculture Technologies and C4U brings CRISPR-CAS3 to aquaculture The United States-Canada operation joint effort with the Japanese developer and proprietary of gene-editing techniques to promote genome editing in major commercial fish species

The joint United States-Canada operation Center for Aquaculture Technologies (CAT), leading provider of genetics solutions in aquaculture, announced a collaboration with the Japanese C4U Corporation. Their joint effort aims to apply CRISPRCas3 technology to promote genome editing in major commercial fish species and drive technological advancements within the industry. CRISPR-Cas3 technology was developed from the research work of Professor Tomoji Mashimo, currently at the Institute of Medical Science, University of Tokyo, who is also a co-founder of C4U, along with other contributions. According to them, the CRISPR-Cas3 platform provides unique advantages, such as increased safety through a reduction in unintended mutations and the capability for broad gene alterations near the target site. It stands out as an attractive option for genome editing, unencumbered by the intricate patents associated with CRISPR-Cas9, offering a practical substitute. Akimitsu Hirai, President & CEO of C4U, commented on the ethos behind the formation of C4U, “our commitment through C4U—CRISPR for you—is to democratize this advanced 8 »

technology, ensuring it is accessible for improving health outcomes and sustainable food production”. “The name C4U encapsulates our vision of bringing the benefits of CRISPR technology directly to the industries that need it most, from medical therapies to enhancing aquaculture’s growth, aligning with CAT’s mission to meet the global food demand responsibly,” he added.

Innovative and accessible technologies The Center for Aquaculture Technologies is committed to delivering technologies that are not only innovative but also accessible to the aquaculture industry. This research initiative with C4U represents a stride towards fulfilling that commitment. At CAT, they explain, there’s a firm belief that genome editing (GE) presents the most feasible and sustainable pathway to meet the world’s increasing food requirements and contribute to the economic vitality of the aquaculture sector. John Buchanan, CEO of CAT, underscores this approach: “Our collaboration with C4U is a key part of our mission to introduce advanced genome editing technologies to aquaculture. We are invested in pursuing relationships that propel the industry forward, addressing the global food demand sustainably and responsibly.” The CAT is at the leading edge of genetic innovation within the aquaculture industry. Employing strategies that are both result-oriented and designed for maximum value, CAT provides advanced genetic services

that enhance profitability while upholding sustainable practices. The organization’s expertise spans genotyping, genomics, breeding, and genome editing, catering to an extensive range of aquatic species. The company’s integrated services support businesses of all sizes, accelerating growth, promoting environmental stewardship, and advancing the industry.

Privately held biotech company C4U Corporation (C4U) is a privately held biotech company based in Osaka, Japan, and focused on the development of safe and efficient gene therapies for rare diseases, including pediatric, and industrial applications based on its proprietary next generation CRISPR-Cas3 gene editing platform. The CRISPR-Cas3 technology platform is similar to CRISPR-Cas9 in terms of its engineering, efficiency, and delivery methods and has already been validated both in vitro and in vivo. It presents the distinct benefits of: no off-target deletions (improved safety); efficient knockouts of large, programmable gene sequences; and entirely independent patent portfolio, which has been exclusively licensed worldwide to C4U by Osaka University for use in eukaryotic cells, thus simplifying sublicensing transactions in sharp contrast with the complex and heavily litigated CRISPR-Cas9 patent landscape.

DECEMBER 2023 - JANUARY 2024

Billund builds in Mexico the first large-scale RAS nursery for striped bass

Mexican company Pacifico Aquaculture has commissioned the international Billund Aquaculture to design and implement a Recirculation Aquaculture Systems (RAS) project for its new land-based hatchery and nursery, which will be the first in the world to produce striped bass (Morone saxatilis) at scale. Billund Aquaculture is set to begin construction of the facility in Ensenada, Baja California, Mexico, the next month with a production capacity of 8 million fish per year. Pacifico Aquaculture CEO, Per-Roar Gjerde, commented: “We are thrilled to have with us Billund as a main supplier to build the first Striped Bass RAS facility in the world. This is the before and after for Pacifico Aquaculture in its growth as a company and in a start of creating a new industry in Baja California Mexico. This project will allow us to build a state-of-the-art hatchery and nursery facility and unlock 20,000 metric tons of annual production capacity to meet the world’s growing demand for healthy, nutritious seafood.” The facility will be built in the Ensenada Bay area of Baja California, Mexico and produce 80 g juveniles that will subsequently be transferred to the company’s grow-out sites, located nearby, about 20 km from the coast of the Pacific Ocean. This new site will include 17 independent intensive-RAS units, based on fix-bed DECEMBER 2023 - JANUARY 2024

biofilter technology, and contain 10 broodstock systems, two larval systems, two weaning systems and three nursery systems. Although there have been several experiences worldwide of farming hybrid striped bass (Morone chrysops + M. saxatilis) in freshwater RAS, this will be a first for striped bass. Moreover, with operations in over 30 countries worldwide, this is Billund Aquaculture’s first RAS design project in Mexico.

8 million 80 g fish per year The project consists of the first RAS hatchery for striped bass anywhere in the world, with a production capacity of 8 million 80 g fish per year. With a total surface area of 9,250 m2 (~2.29 acres), the land-based farm is expected to start construction in January 2024 and be in full operation by the end of 2025. Speaking about the project, Marcelo Varela, CEO of Billund Aquaculture Chile, said, “This is a very important contract for Billund Aquaculture because it represents a major step towards diversifying the number of species farmed using RAS. Also, Mexico is a completely new market for us with huge potential, due to the diversity of new species that can be farmed, and due to its proximity to such an important market as the United States. This whole area holds

enormous possibilities for farming different high-value species that are suitable for RAS and we are thrilled to explore these new opportunities.” Bjarne Hald Olsen, CSO in Billund Aquaculture added, “We are very excited that this RAS facility is finally about to become a reality after a very long time working with Pacifico. We have been discussing the conceptual and design details for a long time, trying to make it as efficient as possible through the best solutions and technology. With the combined knowledge of Pacifico’s specialists in striped bass production and Billund´s experienced RAS engineers, this is the perfect match for designing the most optimal facility for this species. We feel confident that the project will be a success and are eager to get started with this partnership.”

Great for sushi and sashimi Striped bass is a versatile fish and is well known on the east coast of the US as both a sport fish and for seasonal wild commercial fishing from Virginia to Maine. Pacifico’s striped bass, because of the controlled environment it’s raised in, is particularly great for sushi and sashimi. Pacifico Aquaculture is the only dedicated pure breed striped bass fish farmer in the world and the first marine finfish company in Mexico to obtain four-star certification for Best Aquaculture Practices. With a long career in salmon farming, Per-Roar Gjerde said that Pacifico Aquaculture started working with striped bass in 2010 because “This fish is perfect for cooking because of its fat content, which is apt for different methods of preparation, including whole, raw, grilling, poaching, and braising. As sashimi, it’s the best I have ever tasted in my seafood life and cooked, it has a flaky texture with skin that crisps beautifully. It’s a great and healthy choice, however you prepare it.” »

INDUSTRY NEWS

Mowi produces first eggs from Scottish broodstock in 20 years The company, recognized as the world’s most sustainable aquaculture company for the fifth year in a row. brings this all together to make it happen. This milestone is an important time for us as we secure future generations of top-quality salmon that contribute to the country’s most valuable food export. It’s important to report that Mowi Scotland will soon be accepting applications for careers at its new broodstock facility at Ardessie.

Thanks to obtaining the appropriate approvals for Mowi Scotland’s breeding and egg production facilities at Ardessie, the company has already collected the first eggs from its specially selected broodstock. They envisage the new farm will produce up to 50 million eyed eggs to supply the Mowi production hatcheries. For the past several years, the company in Scotland has been reliant on external egg supply since the export ban of ova from Norway restricted the supply of high-quality eggs available to Scotland. Recent approvals to produce broodstock and eggs in Scotland will help secure high-quality egg supply to the company by enabling it to select parent fish whose offspring will be most robust to the specific challenges faced locally and providing significant advances in survival and performance. John Richmond, Broodstock and Post-Smolt Development Manager, explains: “The egg stripping has gone very well this season, considering this is only a temporary solution as we move to securing quality egg supply to Mowi Scotland with a bespoke facility.” And adds, that “this facility should be complete in spring of 2025 in time for the next generation of broodstock.” 10 »

Next generation salmon To prepare for a made-in-Scotland broodstock program, the next generation salmon were taken in 2021 from Mowi nucleus in Ireland and raised at seawater farms in Scotland. After a few weeks held in freshwater this autumn, Mowi breeding experts began checking the salmon for readiness to spawn and the first fish were identified as ripe and stripped of their eggs last month. The broodstock facility at Ardessie will use the latest recirculating aquaculture system (RAS) technology to enable use of temperature and photoperiod regimes to produce early and late season eggs, a key element of Mowi’s freshwater smolt production plan. DNA analysis was undertaken during spawning and all the male fish were ranked by the Mowi geneticists according to their breeding index. The geneticists are considering DNA markers that indicate high growth and robustness towards disease challenges, as well as flesh pigment quality. Ben Hadfield, COO Farming Scotland, says: “Congratulations to the team in Mowi Scotland for their resilience and farming know-how that

At the forefront of sustainable food production In the other hand, Coller FAIRR Protein Producer Index has ranked again Mowi as the world’s most sustainable livestock and aquaculture company for the fifth year in a row. This index is the most detailed sustainability index for major companies in the world’s meat, dairy, and aquaculture industries. The 60 companies will be evaluated on environmental, social, and governance considerations, including greenhouse gas emissions, deforestation, and food safety. “This shows once again that Mowi is at the forefront of sustainable food production. I am both proud and humbled to be in charge of managing such a company. Mowi is responsible. We have strict policies regarding procurement, animal welfare, environmental protection, etc., and are consistently ranked highly in this index,” commented Ivan Vindheim, Mowi CEO. For her part, Chief Sustainability Officer, Catarina Martins, said: “We need to produce more food for the world’s ever-growing population in a way that is kind to the planet. That is our ultimate goal, which is why we are so proud to be recognized once again for our efforts by being named the World’s Most Sustainable Aquaculture Company.” DECEMBER 2023 - JANUARY 2024

National Fisheries Institute partners with Global Shrimp Council to promote consumption of the species in the United States

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Committed to sustainable management According to them, for more than 75 years, NFI has been the leading trade association for the seafood industry whose members represent all aspects of the value chain from water to the table. The National Fisheries Institute is a non-profit organization dedicated to education about seafood safety, sustainability, and nutrition. NFI promotes the US Dietary Guidelines that suggest Americans include fish and shellfish in their diets twice per week for longer, healthier lives. NFI and its members are committed to sustainable management of the oceans and being stewards of the environment by endorsing the United Nations Principles for Responsible Fisheries. Their assure that their investment “in the oceans today will provide our children and

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Work begins on planned promotion coalition “We are excited to get started on this work,” said Brandon Phillips, NFI’s Vice President of External Affairs and Councils. “Creating a structure for the group, collecting funding, and instituting a management structure aren’t quite as sexy as live-fire promotion and marketing. But it’s these foundational things that need to be done first. And they are getting underway,” he added. “In the Netherlands we received initial funding commitments from some of the biggest shrimp producers in the world,” commented Castro for his part. “They see the need for this type of promotion and will be the driving force behind it. We are excited to work with them.”

future generations the health benefits of a plentiful supply of fish and seafood tomorrow.” From responsible aquaculture, to a marketplace supporting free trade, to ensuring the media and consumers have the facts about the health benefits of fish and shellfish, NFI and its members support and promote sound public policy based on ground truth science. In the other hand, and as Castro commented in Netherlands, “the Global Shrimp Council is an initiative with the intention to harmonize the interests of participants in this significant industry through a systemic vision. One of these interests is to introduce the global consumer to the benefits of consuming the finest sustainably produced protein sources, such as shrimp. Shrimp is a flavorful, healthy and nutritious protein, that is accessible, easy to prepare, has low carbon emissions in production and uses minimal consumption of freshwater. I am greatly look forward to seeing the outcome of our discussions and where this could take the industry.”

The American National Fisheries Institute (NFI) has announced it will be home to the Global Shrimp Council as the group begins work to create a precompetitive partnership designed to promote United States (US) shrimp consumption. Co-founders David Castro, from Manta Bay Seafood, and Gabriel Luna, from Gluna Shrimp, announced in September plans for the group during the Global Shrimp Forum Foundation meeting in the Netherlands. The goal in September was to be organized before the end of the year with a leadership team and funding arrangement in place. NFI already manages collaborative work as part of its council system for Tuna, Crab, Shrimp, Mexican Shrimp, Sushi, and Salmon. There has already been nearly a year’s worth of preliminary work done on the effort guided by one of the architects of the Avocados from Mexico strategy. Governance, finance, and membership composition will be the first tenets addressed by NFI and the new group’s leadership.

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GREENHOUSES AND POND LINERS

Oxygen consumption of Litopenaeus vannamei in intensive ponds based on the Dynamic Modeling System In intensive shrimp culture, oxygen consumption of shrimp is an important indicator that greatly affects the physiological condition of shrimp as a reared organism. Here the results of a research that aimed to dynamically determine the oxygen consumption of shrimp in intensive culture as well as the variables of water quality and shrimp growth based on the Dynamic Modeling System. By: Aquaculture Magazine Editorial Team*

issolved oxygen is the most crucial and dynamic water quality parameter in the culture system because aerobic organisms in the waters need oxygen rates that are sufficient for biochemical processes. The oxygen solubility in intensive ponds is mainly influenced by conditions of pH, temperature, salinity, turbulence and air pressure parameters. Dynamically, the dissolved oxygen concentration will fluctuate due to biological, physical and chemical processes. In intensive cultivation, shrimp is an aquatic biota that requires oxygen for the process of bioenergy balance in its metabolic system. The rate of oxygen consumption greatly affects the condition of the shrimp metabolic system when it grows and has activities. The following results derived from a study that aimed to measure the dynamics of oxygen consumption by shrimp in intensive ponds and its relationship with variables of water quality and shrimp growth. 12 »

Methodology This research was conducted in April-June 2019 or during the cultivation period of Litopenaeus vannamei in the intensive aquaculture area of Bayeman Village, Tongas District, Probolinggo Regency with the concept of ex-post-facto causal research design. Data collection in the form

of oxygen consumption, biological growth and water quality were carried out every 10 days from the beginning of stocking to harvest. The cultivation of L. vannamei was carried out in 2 ponds of 400 m2 of HDPE (high-density polyethylene) pond liners with a stocking density of 112 fish/m2 and the use of 4 DECEMBER 2023 - JANUARY 2024

hp waterwheels for each cultivation pond. The data of shrimp oxygen consumption rate were collected by random sampling, after which experimental trials were carried out using a 20 L aquarium and DO meter (AZ 8402, China). The data of oxygen consumption rate of shrimp were collected experimentally, by randomly taking

DECEMBER 2023 - JANUARY 2024

4 shrimp from each pond, and the shrimp taken were the ones with complete body organs, active motion and full intestines. The observation of water quality parameters such as pH, temperature, dissolved oxygen, and salinity was carried out in situ, while the observation of phosphate, nitrite, nitrate, total ammonia nitrogen (TAN), and

total organic matter (TOM) has measured ex-situ at the BBPAP laboratory Situbondo every 10 days.

Results and discussion The rate of oxygen consumption by shrimp during the growth period has a downward trend with the regression model Y = 9.444-0.047x. The highest rate of oxygen consumption is obtained at 0.450 mgO2/L, and the lowest was at 0.002 mgO2/L (Figure 1). This means that the heavier the shrimp weight, the lower the rate of oxygen demand needed. This is because small shrimp need a higher energy for their metabolic system. In addition, the rate of oxygen consumption of shrimp is also influenced by environmental conditions such as temperature and salinity (Bett and Vinatea, 2009). The results of other studies stated that the minimum rate of oxygen consumption for shrimp in the juvenile phase is of 0.65 mg/L with an average weight of juvenile shrimp of 4.1 g (Vinatea et al., 2009). » 13

GREENHOUSES AND POND LINERS

The rate of oxygen consumption greatly

affects the condition of the shrimp metabolic system when it grows and has activities.

In the graph of the weight and average daily gain of shrimp (Figure 2), it can be seen that the body weight

14 »

of shrimp continues to increase from the initial period of cultivation to the harvesting. However, the average daily gain of shrimp appears to experience a decrease at the age of 50 days of cultivation, and after that it remains stagnant. The growth stagnation at the age of 50 days is due to the high stocking density and biomass of shrimp in the ponds and the low levels of water salinity, which affect the biological growth conditions and the balance of osmoregulation system of the shrimp (Bray et al., 1994; Sookying et al., 2011; Chand et al., 2015). These conditions genetically will also affect the level of molt-inhibiting hor-

mone (MIH) expression at each phase of shrimp growth (Gao et al., 2016). The rate of shrimp growth is exponential at the age of 30-50 days. By knowing the period of exponential growth rate of shrimp, it is expected that certain strategies or manipulation can be carried out to spur shrimp growth in that period. Engineering that might be done is to manipulate feeding habits and add supplements to the feed (Jayesh et al., 2015). Based on the simulation analysis with the dynamic modeling concept, it is shown that oxygen consumption was linear to the dynamics of average daily gain and inversely proportional with the increasing rate of shrimp biomass in the ponds (Figure 3). It means that the rate of shrimp consumption will experience a fluctuation in accordance with the growth rate of shrimp because during the process of shrimp growth, physiologically it is necessary to have sufficient oxygen levels to fulfill their metabolic activity. The dissolved oxygen rate required for the metabolic process of adult shrimp at a stable temperature of 280-33°C is 1.49 mg/L (Niu et al., 2003). The increase in shrimp biomass, which is described as having a sigmoidal growth curve, during the cultivation period, will have an impact on the increasing level of nutrient accumulation. The increase in nutrient accumulation will create over-enrichment of excess in the pond water environment (Wu et al., 2014). The waters that are rich in excess nutrients will cause plankton blooms in the ponds and an imbalance of the habitat ecosystem (Muendo et al., 2014). In addition, plankton blooms will also affect the grazing activities of plankton in the food chain in the ponds. In addition, the oxygen consumption rate of shrimp in intensive ponds had a close relationship with water salinity and total organic matter. Based on data on the water quality variable, the rate of oxygen consumption has a negative correlaDECEMBER 2023 - JANUARY 2024

The oxygen consumption rate of shrimp in

intensive ponds had a close relationship with water salinity and total organic matter. tion to salinity and TOM parameters. Also, it does not correlate with other water quality parameters. The negative relationship to the water salinity parameter indicates that the fluctuation of mineral ions in the ponds greatly affects the rate of oxygen consumption by shrimp metabolism for the osmoregulation mechanism (Re and Diaz, 2011). The increased rate of oxygen consumption is a physiological response of shrimp to maintain their body condition to remain in a homeostatic condition due to fluctuations in water salinity levels (Hernandez et al., 2005). Meanwhile, the increasing levels of organic matDECEMBER 2023 - JANUARY 2024

ter due to the increase in shrimp biomass will affect the level of increased oxygen demand in the sediment and water column for the respiration process of organisms (Luong et al., 2016; Leduc and Pilditch, 2017). For the variable of the biological growth of shrimp, the rate of oxygen consumption has a close relationship to the average body weight of shrimp but does not have a close relationship with the average daily gain. This is because, during their life, the rate of oxygen consumption of shrimp at each growth phase or each body weight has different oxygen demand ratios (Budiardi et al., 2005). Small shrimp have a higher probability of oxygen consumption for their metabolic activity (Djawad and Jompa, 2002). Different rates of oxygen consumption in the metabolic system at each stage of organisms’ growth are also predicted as a form of physiological and behavioral adaptation responses (Kieffer and Wakefield, 2009; Bouyoucos et al., 2018).

Conclusion Based on the results of the study, it can be concluded that dynamically fluctuations in oxygen consumption and average daily gain of shrimp in intensive culture are closely influenced by the stability of water quality conditions in the shrimp habitat. This article is sponsored by: REEF INDUSTRIES INC.

This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “OXYGEN CONSUMPTION OF LITOPENAEUS VANNAMEI IN INTENSIVE PONDS BASED ON THE DYNAMIC MODELING SYSTEM” developed by: WAFI, A. Universitas Ibrahimy, ARIADI, H. - Universitas Pekalongan, MUQSITH, A. - Universitas Ibrahimy, MAHMUDI, M. and FADJAR, M. - Universitas Brawijaya. The original article, including tables and figures, was published on FEBRUARY, 2021, through JOURNAL OF AQUACULTURE AND FISH HEALTH. The full version can be accessed online through this DOI: 10.20473/jafh.v10i1.18102

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Metabolic turnover rate, digestive enzyme activities, and bacterial communities in the white shrimp Litopenaeus vannamei under compensatory growth One of the main challenges for the expansion of shrimp culture is securing the supply of balanced feeds, which in turn can represent more than 50% of the production costs. In this context, here are presented findings that contributes to a better understanding on the physiological effects produced during compensatory growth in shrimp, which in turn could assist in the development of improved feeding strategies in benefit of the aquaculture industry. By: Aquaculture Magazine Editorial Team*

ne of the main challenges for the expansion of shrimp culture is securing the supply of balanced feeds, which in turn can represent more than 50% of the production costs. In this regard, different strategies of feed management have been proposed to reduce the production costs, including the use of trays, variations on feed frequency, and temporary feed restriction. Temporary feed restriction may promote an increased growth rate when optimal feeding conditions are restored (including decapod crustaceans); this biological response has been called compensatory growth. The compensatory response after refeeding is linked to the dura16 »

tion and severity of the previous feed restriction, and the length time of the refeeding period. The promotion of compensatory growth to reduce operating costs during animal production is a well-documented strategy; nevertheless, there is still relevant information to disclose on the physiological effects occurring in the white shrimp Litopenaeus vannamei. In this context, here is provided new insights on the physiological responses occurring during compensatory growth, by evaluating the metabolic turnover rate of nitrogen in muscle, by measuring the digestive enzyme activities and changes in the bacterial communities of the digestive tract of juvenile L. vannamei.

Materials and methods Two experimental diets were formulated: (a) a pre-conditioning diet and (b) a reference diet. The pre-conditioning diet was manufactured with poultry by-product meal (55%) to promote a specific isotopic signature in shrimp before the feed restriction assay. The reference diet was based on fish meal as main ingredient (56%) having a different isotopic signature for nitrogen. In this way, the dietary shift had the objective of promoting clear, exponential isotopic changes that eventually allowed estimating the metabolic turnover rate of nitrogen. Shrimps were received at the Aquaculture Nutrition Laboratory at CIBDECEMBER 2023 - JANUARY 2024

NOR, and acclimated for 30 days in an 800-L fiber glass tank under controlled conditions.

Results Survival of shrimp during the experimental trial was higher than 90% for all treatments. After 7 and 14 days of the experimental period, shrimp under 70% feed restriction during 3 (T3) and 6 (T6) days showed significantly lower growth compared to the control group. On experimental day 35, shrimp under T3 treatment showed the highest final weight (3.47 ± 0.13 g) compared to Control (3.38 ± 0.14 g) and T6 (3.23 ± 0.04 g) treatments; nevertheless, no statistical differences were observed (Table 1). DECEMBER 2023 - JANUARY 2024

Table 1 Shrimp Litopenaeus vannamei performance and survival after 35 days of feeding on different regimes. Mean initial weight: 0.44 ± 0.03 g. Control: shrimps without feed restriction, T3: 3 days of 70% feed restriction as compared to Control, and T6: 6 days of 70% of feed restriction as compared to Control. Values are given as mean ± SD (n = 3). Different letters indicate significant differences (p < 0.05) among treatments in the same column determined by Tukey’s test.

Treatments

WG (%)

SGR (% day -1)

FI (g)

FCR

Survival (%)

Control

668 ± 32

5.82 ± 0.12

3.91 ± 0.08c

1.32 ± 0.05b

100 ± 0

676 ± 28

5.86 ± 0.10

3.70 ± 0.02b

1.23 ± 0.05a

97 ± 6

640 ± 11

5.72 ± 0.04

3.44 ± 0.02a

1.23 ± 0.02a

93 ± 12

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Discussion The compensatory growth is a mechanism that allows organisms to improve nutrient utilization and growth when food is abundant along natural fluctuations, including aquatic environments (Fraser et al., 2007; Buckup et al., 2008). Results showed that shrimp under 3 and 6 days of 70% feed restriction showed compensatory growth with full recovery of growth after ad libitum feeding was restored. As in 40-day-old postlarvae L. vannamei (116 ± 4 mg, avg. wt.) fasted for 3 days, full compensatory growth reached after 9 days of refeeding (Lin et al., 2008). On the other hand, determination of the SGR provides a valuable tool to identify specific periods 18 »

Figure 1 Enzymatic digestive activity of trypsin, amylase, and lipase in shrimp Litopenaeus vannamei fed without restrictions (Control) and subjected to a 70% feed restriction during 3 (T3) and 6 days (T6) (n = 4). Different letters indicate significant differences (p < 0.05) among treatments in the same time period determined by Tukey’s test

Trypsin (U mg protein -1)

600 500 400

b a

300 200 100 0 9

Amylase (U mg protein -1)

0.0024 0.002

0.0016 0.0012

0.0008 0.0004 0 9 70

Lipase (U mg protein -1)

Considering the shrimp growth between days 1 and 7, the specific growth rate (SGR) was significantly higher for shrimp in the Control treatment compared to feed-restricted shrimps. Nevertheless, during the recovery period without feed restrictions (from day 7 to 28), the SGR was significantly higher for T3 and T6 treatments compared to Control. The digestive enzyme activities measured in the shrimp’s hepatopancreas are shown in Figure 1. The trypsin activity at day 9, during compensatory response, showed a significantly higher activity in shrimps belonging to T3 and T6, as compared to values observed in shrimp in the Control treatment (F2,11 = 9.24, p = 0.007). Nevertheless, after day 14, no significant differences were shown among treatments (p > 0.05). In terms of bacterial digestive biota all replicate samples showed an average of 95,367 sequences assigned to 455 different OTUs. According to alpha-diversity in terms of Chao and Shannon indexes, the shrimp bacterial community in the digestive tract of shrimp were statistically similar (p > 0.05) among treatments and between sampling days (14 and 35) (Figure 2).

60 50

40 30 20 10 0 9 Day Control

of high growth rates (Ricker, 1975). In the study, shrimp showed a significantly higher SGR during the feeding recovery period, revealing a compensatory response, as observed in other studies conducted on the same species (Yu et al., 2008; Liu et al., 2022). In the present work, treatments with feed restriction promoted between 5% and 12% feed saving as compared to Control shrimp. Fur-

Treatments with feed restriction promoted between 5% and 12% feed saving as compared to Control shrimp.

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Figure 2 Alpha-diversity, in terms of richness by Chao estimator and evenness according to Shannon index, in the digestive tract of shrimp L. vannamei fed without restrictions (Control) and subjected to a 70% feed restriction during 3 (T3) and 6 days (T6).

Alpha Diversity Chao

1,200

Shannon

8 7

1,000

6 800

600

4 3

400

2 200

0 Control

T6 Day 14

thermore, when natural food sources are available in the culture systems, as in biofloc systems, the feed saving could represent between 25% and 50%. At the end of the experimental period, shrimp under all treatments approached isotopic equilibrium with values of δ15N = 14.31 ± 0.26‰, reflecting not only the fast growth, but also a high assimilation and utilization of nutrients supplied by the reference diet. Although the

Control

Day 35

feed restrictions caused a significant reduction of the nitrogen turnover rates in muscle tissue, an isotopic equilibrium was still reached and it was mainly promoted by tissue accretion. Previous studies in crustacean and fish indicate that starvation can promote changes in the bacterial community structure with loss of bacterial diversity (Xia et al., 2014; Foysal et al., 2020; Sakyi et al., 2020). In the showed results, at day 14 dur-

ing compensatory growth, bacterial diversity was similar among treatments and few differences were found within taxonomic levels. It is possible that a partial feed restriction applied in short periods (3 and 6 days) might have a lower impact on the bacterial community structure in the shrimp gut, or that the period (at day 14) was long enough to reestablish the potential change of bacterial diversity lost during feed restriction.

Conclusions Shrimp under 3 and 6 days of feed restriction achieved full compensatory growth, leading to up to 12% feed savings after 35 days of experiment. During the feeding recovery period, the nitrogen metabolic turnover rate was lower in shrimp under compensatory growth than in the Control group shrimps, reflecting an increased dietary nitrogen utilization destined for growth. The bacterial community in shrimp gut was also modified during compensatory growth, with bacterial abundances pointing to potential benefits on nutrient metabolism and assimilation. When full compensatory growth was achieved at the end of the experimental period, the evaluated parameters showed similar results as those determined in the Control treatment, suggesting a normalization of metabolism and the physiological state.

This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “METABOLIC TURNOVER RATE, DIGESTIVE ENZYME ACTIVITIES, AND BACTERIAL COMMUNITIES IN THE WHITE SHRIMP LITOPENAEUS VANNAMEI UNDER COMPENSATORY GROWTH)” developed by: QUINTINO-RIVERA, J. Centro de Investigaciones Biológicas del Noroeste (CIBNOR), ELIZONDO-GONZÁLEZ, R. - Conacyt– CIBNOR, Gamboa-Delgado, J. - Universidad Autónoma de Nuevo León, GUZMÁN-VILLANUEVAM L., y PEÑA-RODRIGUEZ, A. - Conacyt– CIBNOR. The original article was published, including tables and figures, on FEBRUARY, 2023 , through PEELJ. The full version can be accessed online through this DOI 10.7717/peerj.14747.

DECEMBER 2023 - JANUARY 2024

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Feed-food competition in global aquaculture: Current trends and prospects Feed-food competition is a current but unsustainable practice in aquaculture, where resources are allocated to feed humans to animal feed instead. This study analyzes feed-food competition in aquaculture using natural trophic levels (TLs) and species-specific human-edible protein conversion ratios (HePCRs). By: Aquaculture Magazine Editorial Team*

n the future, the role of aquaculture in circular food systems will most likely consist of a balanced mix of species at different natural trophic levels (TLs) and from different aquaculture systems, depending on the by-products available. In this paradigm, farm animals, including aquaculture species, should not consume human edible biomass but instead convert by-products from crops, livestock, and fisheries that are inedible for humans, into edible biomass. In addition to these by-products, animals in circular food systems can also convert plant-based food waste and grass resources into food. The fish-in: fish-out ratio (FIFO) is an indicator for feed efficiency of aquaculture species, which differs greatly among species. Over the years, the FIFO has decreased to around 0.3 for global aquaculture due to a growing trend to replace fishmeal with plant-based protein sources, such as soy protein concentrate. These replacement ingredients often cause feed-food competition because they can be used directly as 20 »

food. Plant-based ingredients, such as soya-bean-based ingredients, could influence feed-food competition indirectly by increasing land use for the production of animal feed instead of human food. Fish and shellfish are rich in macronutrients and micronutrients and can be a valuable addition to a healthy

diet even when consumed in small amounts. They are also the main source of essential omega-3 longchain polyunsaturated fatty acids in human diets. Farmed fish convert feed into food relatively efficiently, with Atlantic salmon having a feed conversion efficiency similar to that of chicken. DECEMBER 2023 - JANUARY 2024

Global aquaculture

productions have seen a 50% increase in volumen.

To determine the unique role of aquaculture in the transition towards healthy and circular food systems, more insight is needed into feedfood competition in global aquaculture. One way to do so is to explore an animal’s natural ability to upgrade specific by-products into food, which is determined by animal species, breed, and production-system intensity. Aquaculture species at higher trophic levels — omnivores and carnivores species — have diets more similar to those of humans and are well adapted to convert fish or other animal-based by-products into food. The study aims to understand feedfood competition in aquaculture by using the Human Edible Protein Conversion Ratio (HePCR) to quantify the net contribution of farmed fish to the supply of human edible protein. HePCR equals the ratio of human edible protein in feed (input) to the human edible protein in the animal product (output). The research focuses on the current status and trends in aquaculture production based on TLs and calculated HePCRs of current intensive aquaculture systems.

Methods The study first reviewed generic data on aquaculture production by retrieving production (wet weight) and economic data (USD) at global and continental levels from FishstatJ. Then, it selected the 50 species produced most (in wet weight). To quantify the relative contribution of each TL to current global aquaculture production (in kg wet DECEMBER 2023 - JANUARY 2024

weight and edible protein), aggregated by species groups, the researchers categorized production data of the 50 aquaculture species produced most by TL range. Each species’ natural TL (1–5) was based on information from FishBase (Figure 1), a good data source for the trophic ecology of finfish. The protein content of individual fish species was collected from the U.S. Department of Agriculture (USDA) database. The protein contribution was based on raw fish, and cooking losses were not included. The trend in the mean TL of aquaculture production globally and by continent from 1980–2019 was quantified. Data on annual production and the natural TL of the 25 species produced most (wet weight) globally and categorized them by continent. To embed HePCR results in the existing aquaculture literature, the protein conversion ratio (PCR) was calculated as an indicator of feed efficiency. Four case-study species — three finfish (one from each natural TL) and one crustacean — chosen based on two criteria: having the highest economic value and being produced in intensive systems. Consequently, the study selected Atlantic salmon (TL 4–5), common carp (TL

3–4), Nile tilapia (TL 2–3), and whiteleg shrimp (TL 2–3). In conclusion, the study provides valuable insights into feed-food competition in aquaculture, highlighting the importance of understanding the conversion efficiency of human edible feed protein into aquatic protein. The study focuses on the diet composition of Atlantic salmon, common carp, Nile tilapia, and whiteleg shrimp for intensive cultivation in 2020. The diet composition was based on confidential surveys with five people active in the aquaculture feed industry. The crude protein content of diet ingredients was calculated based on the International Aquaculture Feed Formulation database. The human edibility of each feed ingredient was defined as either foodcompeting or non-food-competing based on Sandström et al. (2022) and Mottet et al. (2016). Both studies reported the same human edibility for most ingredients, except for soya bean meal and fishmeal. Sandström et al. considered fishmeal made from whole fish food-competing but fishmeal made from fish by-products non-food-competing, while Mottet et al. (2016). considered all fishmeal non-food-competing. Furthermore, while soy protein concentrate is foodcompeting, soya bean meal is considered non-food-competing because it is a by-product of soya bean oil production, and the meal is used almost entirely as a feed ingredient. For the human edibility of the output of the species, the study focused on the current habits of eating primarily fillets. To represent protein quality, the digestible indispensable amino acid score (DIAAS) was included for the mean ingredient composition of the four selected aquaculture species. Animal-based ingredients included blood meal, feather meal, fish meal, krill meal, meat and bone meal, poultry meal, plant-based ingredients like cassava meal, corn bran, corn gluten meal, distillers grains, faba beans, » 21

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gar protein, pea flower, pea protein concentrate, rice bran, soy lecithin, soybean meal, sunflower meal, wheat gluten meal, wheat meal, wheat bran, and wheat flour. The Food and Agriculture Organization of the United Nations (FAO) recommends the DIAAS as a measure of protein quality. The DIAAS reflects the content of the first limiting indispensable amino acid in a feed/food ingredient relative to the requirement for the same amino acid by humans. The amino acid requirement pattern for a 6-month to 3-year-old child was used as the reference protein’s amino acid profile, similar to studies by Laisse et al. and Ertl et al., and as recommended by the FAO. The DIAASs of feed ingredients were extracted from Ertl et al. or, if not included by them, estimated using their method. Due to a lack of data on the human ileal amino acid digestibility of fish fillets, the DIAASs of the case-study species were calculated based on amino acid scores from the USDA, assuming an amino acid digestibility of 94% for fillets/meat. In conclusion, the study highlights the importance of considering the human edibility of feed ingredients in aquaculture production. By focusing on the grow-out phase and

22 »

incorporating the DIAAS score, the study contributes to the understanding of the nutritional value of fish in aquaculture.

Results Global aquaculture productions have seen a 50% increase in volume, with Asia dominating the sector at 90%, followed by the Americas (4%), Europe (3%), Africa (2%), and Oceania (0.2%). Africa showed the highest growth over the previous decade (130%), more than 2.5 times that of China. The continent (Asia) and country (China) that produced the largest volume had the lowest economic values, while the continents with the lowest volumes (Oceania, Europe, and the Americas) had the highest economic values. The contribution of each aquaculture species group to global aquaculture production in 2019 varied (Figure 2). TL 2-3 produced the most wet weight (59%) and edible protein (60%), dominated by freshwater fish and molluscs. Aquaculture species at lower TL (TL 1–3) contributed less to global protein production than to global aquaculture wet-weight volumes. This is due to their high water and low protein content, while fish from low TLs have lower edible yields than at higher TLs.

Over the past 40 years,

the mean natural total length (TL) of aquaculture species increased slightly.

Over the past 40 years, the mean natural total length (TL) of aquaculture species increased slightly, but it differed greatly among regions, especially China and Europe. In Europe, it increased due to the large increase in production of diadromous fish, particularly Atlantic salmon, over the past 35 years. However, the mean TL of aquaculture species in Asia/China remained relatively low and stable over the past 30 years due to higher growth of production of freshwater fish, molluscs, and aquatic plants than other species groups. In scenario 1, Atlantic salmon had the highest percentage of food-competing ingredients in the diet (45%), as soy protein concentrate was the primary protein source (Figure 3). The study analyzed the feed-food competition in aquaculture diets of

DECEMBER 2023 - JANUARY 2024

common carp, whiteleg shrimp, and Nile tilapia. food-competing ingredients provided the most edible protein, while food-competing ingredients provided the least. In scenario 2, soya bean meal and fishmeal food-competing increased the percentage of human edible protein for all diets, ranging from 49% to 65%. Atlantic salmon and whiteleg shrimp had the highest percentages of food-competing ingredients, followed by livestock by-products, gluten meals, and cereal bran. The conversion ratios of the casestudy species ranged from 3.4 to 8.7, with Atlantic salmon converting protein the most efficiently. Differences in PCR among species were caused by differences in the FCR, edible yield, and protein content of the feed. Atlantic salmon had the lowest FCR and highest fillet/meat yield. In scenario 1, Atlantic salmon consumed more human edible protein than it produced, while other species

DECEMBER 2023 - JANUARY 2024

had lower values due to the higher quality of fillet protein. In scenario 2, all four species were net consumers of protein, with HePCRe increasing to 2.0 - 4.6 and HePCRd increasing to 1.7 - 3.5. The range of HePCRe/d overlapped, indicating smaller changes in the human edibility of protein in salmon diets compared to other species. This study serves as a starting point for exploring and analyzing feed-food competition for additional species, systems, and locations.

Discussion and conclusions The study focuses on the potential of aquaculture to produce food while avoiding feed-food competition. It uses TLs as a starting point to analyze feed-food competition, as the natural ability of an animal to upgrade specific by-products into food can determine its role in a circular food system. In both Europe and the Americas, Atlantic salmon was the species at a high TL, whose production was larg-

est and grew the most rapidly, driving the increase in average produced natural TL. Feeding compound feeds has generally resulted in aquaculture diets with an effective TL lower than that of natural diets (natural TL). This decrease may appear positive if assuming that diets at lower TLs generally cause less feed-food competition because they include more plant-based ingredients and less fishmeal. However, when fishmeal is replaced by soy protein concentrate, as for salmon, the positive impact on feed-food competition is not apparent because soy protein concentrate is human edible and has higher protein quality (i.e., a higher DIAAS) than fishmeal. As a result, species at a naturally high TL, such as salmon, continue to receive relatively higher quality (plant-based) ingredients, resulting in highly human edible diets. When investigating feed-food competition in the present study, classifying soya bean meal and fish-

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Livestock by-products

and fishmeal from fish by-products could replace 99% of the fishmeal made from whole fish.

meal as either food-competing or non-food-competing ingredients had large influence on the net contribution to protein supply of the four aquaculture species. Soya bean meal is considered inedible, but its production is the main mean trophic level of aquaculture production by continent. This causes indirect feed-food competition, as the land used to produce soya bean meal could have been used to grow food crops for direct human consumption. Fishmeal does not re24 »

quire land, but its production can lead to overfishing and greenhouse gas emissions. Replacing soya bean meal in aquaculture feeds would reduce feed-food competition in aquaculture drastically. When soya bean meal and fishmeal were considered food-competing, Nile tilapia, which has a low TL, had the highest HePCR, while Atlantic salmon, which has a high TL, had the lowest HePCR. This may seem surprising, but it can be explained by its

relatively high growth rate and feed efficiency. Intensive aquaculture systems do not optimally align with the natural ability of species at a low TLs to upgrade lower quality by-products or natural biomass. For these species, extensive systems and ecological intensification, such as nutritious ponds, are better suited. The study focuses on feed-food competition in aquaculture, which accounts for only 1.2% of global feed consumption compared to cattle (73%), pigs (20%), and poultry (7%). However, it represents a larger percentage (3.8%) of global human-edible feed consumption, likely due to the high protein requirements of fed aquaculture species. The most significant gain to reduce feed-food competition is to be made with livestock. Comparing the Human-Edible Protein Conversion Ratio (HePCR) of livestock and aquaculture is hampered by differences in metabolism and housing. The most logical comparison is with monogastric species, such as poultry and pigs. When comparing their HePCR ratios, broilers (HePCRe ∼ 5.2) and industrially produced pigs (HePCRe ∼ 4.5) have higher HePCRs than the aquaculture species examined. The study attempted to approach feed-food competition scenarios in aquaculture using all available information and objective criteria, but improvements are always possible. Factors such as complete feed formulation, feed quantity and growth rate, DECEMBER 2023 - JANUARY 2024

feed quantity and growth rate, and protein efficiency were considered. Future studies could focus on the entire life cycle of one specific system and species, as HePCR depends on the animal, its feed and efficiency, and the definition of human edible products. Another limitation of this study was related to its scope, as it focused only on intensive systems to enable comparison of HePCRs between species at low versus high TLs and between aquaculture and livestock. Most aquaculture species are produced in extensive or semi-intensive systems, especially finfish species at a low TL, in which they can obtain some of their nutritional requirements from the natural environment. As the efficiency of converting byproducts is affected by species as well as production systems, comparative case studies of specific species and production systems are needed. In conclusion, the study highlights the importance of reducing feed-food competition in aquaculture and the need for more detailed estimates of HePCRs for selected aquaculture species in intensive production systems. Animals can play a crucial role in circular food systems by upgrading by-products, and the transition towards circular systems should focus on minimizing feed-food competition for both livestock and aquaculture. To ensure a net contribution of aquaculture to food security, focus should be placed on feed efficiency metrics such as Feed Conversion Ratio (FCR) and HePCR. For example, Atlantic salmon consume more protein than they produce (HePCR > 1), indicating the importance of HePCR. In recent years, an increasing number of animal and plant-based by-products have been used as aquaculture feeds. Livestock by-products and fishmeal from fish by-products could replace 99% of the fishmeal made from whole fish. Novel protein sources to replace fishmeal, such as insects, algae, and yeasts, should not DECEMBER 2023 - JANUARY 2024

be incorporated into aquaculture feeds. A combination of novel protein sources and by-products could replace current food-competing ingredients. To encourage the feed industry to develop and apply innovations to increase by-product use, the government could develop targets for the inclusion of by-products in aquatic feeds for feeding companies or tax the use of food-grade feed materials. Certification schemes such as the Aquaculture Stewardship Council, Best Aquaculture Practices, and SafeFeed/Safe Food (SF/SF) Certification Program could include targets for the inclusion of by-products in aquatic feed. To monitor the efficacy of these policies or certification schemes, indicators of feed-food competition, such as HePCR, are needed. A final strategy to optimize the role of aquaculture in the food system is to increase the edible yield of harvested species. If humans would consume not only fillets but also all edible parts, the HePCR e/d would decrease by 27% for Atlantic salmon, 37% for common carp, 21% for whiteleg shrimp, and 35% for Nile tilapia. Consuming a larger fraction of the fish has an environmental benefit, as it allows for better use of all raw materials and primary resources used through the life cycle of the fish. The role of aquaculture in circular food systems will most likely consist of a balanced mix of species at different Total Lengths (TLs) and from different aquaculture systems, depending on the by-products available. As the natural Total Length (TL) is not the only factor that influences feed-food competition, future research should focus on including more species (e.g., diets, FCRs) and systems (e.g., intensities). This study focuses on the role of farm animals in a circular food system and the potential benefits of aquaculture for the global food system. The authors acknowledge the contributions of three anonymous

reviewers and Micheal Corson for their valuable comments and suggestions. The research was supported by Wageningen University as part of Anne-Jo van Riel’s PhD project. The study also discusses the use of fish as feed and the environmental impact of animal source foods. The authors also discuss the importance of isotopic baselines in evaluating fish trophic position in Mediterranean lagoons. The authors also discuss the utilization of feed resources in the production of Atlantic salmon (Salmo salar) in Norway and the comparison between Atlantic salmon post-smolts rear and pre-smolts rear. The authors also discuss the role of aquaculture in reducing the environmental impact of animal-based food production. They discuss the use of aquaculture as a sustainable food source and the potential benefits of using aquaculture feeds as a feed source. The study concludes that aquaculture can contribute to the global food system by increasing the availability of food and reducing the environmental impact of animal-based food production. The authors emphasize the need for further research and development in this area to ensure the sustainability of aquaculture practices.

This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “FEED-FOOD COMPETITION IN GLOBAL AQUACULTURE: CURRENT TRENDS AND PROSPECTS” developed by: VAN RIEL, A.; NEDERLOF, M.; CHARY, K.; WIEGERTJES, G. and DE BOER, I. - Wageningen University & Research, The Netherlands. The original article was published, including tables and figures, on JUNE, 2023, through REVIEWS IN AQUACULTURE. The full version can be accessed online through this DOI: 10.1111/ raq.12804.

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Health-promoting additives supplemented in inert microdiets for whiteleg shrimp (Penaeus vannamei) post-larvae:

Effects on growth, survival, and health status There is evidence that dietary additives can stimulate the shrimp immune system, but few studies have focused on the initial developmental stages. Findings suggest that tailored diets including health-promoting additives as vitamins C and E and β-glucans may address some of the larviculture problems and may contribute to the success of whiteleg shrimp farming in the long term, affecting the By: Aquaculture Magazine Editorial Team*

he whiteleg shrimp (Penaeus vannamei) is currently the most representative animal species in aquaculture, constituting in 2020 a share of 4.7% in global production. To meet the market demands, whiteleg shrimp larvae and post-larvae (PL) yields in hatcheries has increased intensively. However, problems in larviculture can have an enormous impact on shrimp performance in the long-term, affecting the downstream production of high-quality juveniles and adults. Initial developmental stages are frequently associated with sub-optimal growth, high size dispersion, and low survival due to cannibalism and reduced disease resistance to opportunistic pathogens. The latter results 26 »

downstream production of high-quality juveniles and adults.

from a high dependence on optimal zootechnical conditions and nutrition, as shrimp lack an adaptive immune response and depend uniquely on their innate immune system to maintain a good health status and avoid pathogenic outbreaks that can result in disastrous consequences to production and significant economic losses. Therefore, innovative nutritional solutions that enhance development and resistance to stress and pathogenic factors during these critical stages and thus improve shrimp quality in posterior phases of production have tremendous potential to reinforce the success of shrimp farming. Below are the results of a study aimed to evaluate the effects of several health promoting nutri-

ents/additives (i.e., vitamins C and E, β-glucans, taurine, and methionine) supplemented in inert microdiets on the growth performance and health status of whiteleg shrimp post-larvae.

Materials and methods Four experimental microdiets were evaluated in triplicates. A positive control diet (PC) was formulated to meet the nutritional requirements of whiteleg shrimp post-larvae, containing 515 g kg−1 of SPAROS proprietary marine protein mix, 160 g kg−1 of SPAROS proprietary plant protein mix, 103 g kg−1 of fish protein hydrolysate, 19 g kg−1 of fish oil, 28 g kg−1 of marine phospholipids, and 57 g k−1 of SPAROS proprietary vitamins and minerals premix. On the DECEMBER 2023 - JANUARY 2024

remaining treatments, three experimental variants based on the PC were used, differing only in the ingredient formulation by the following: (1) decreasing inclusion levels of the vitamins and minerals premix by 7 g kg−1 to reduce vitamin C and E contents in the negative control diet (NC); (2) supplementing 5 g kg−1 of taurine and 10 g kg−1 of methionine to increase the levels of both molecules in the T + M diet; and supplementing the PC diet with 1 g kg−1 of Saccharomyces cerevisiae β-(1, 3)/(1,6)-glucans (BG). Whiteleg shrimp post-larvae (PL16), originated from Blue Genetics (La Paz, Mexico), were reared for 18 days at Riasearch Lda facilities (Murtosa, Portugal). Shrimp were randomly distributed to 12 tanks with approximately 50 L that were part of a clear water recirculating system. Each tank was stocked with 200 individuals averaging 9 mg of wet weight. For the oxidative stress and immunity-related biomarkers the sample DECEMBER 2023 - JANUARY 2024

preparation consisted in a total of 40 whole whiteleg shrimp post-larvae from each tank sampled at end of the trial were weighed and homogenized in quadruple groups of 10 individuals for oxidative stress and immune parameters analysis. The catalase (CAT), lipid peroxidation (LPO), and total glutathione (tGSH) activities as well as total proteins content were determined in the homogenized samples.

Results Growth performance No significant differences in growth performance and survival were observed among dietary treatments. Final wet weight averaged around 100 mg, relative growth rate (RGR) values 15% day−1, feed conversion ratio (FCR) was close to 1, and survival ranged between 86 to 88% for all treatments (Table 1).

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Oxidative stress and immune status related biomarkers Regarding the oxidative stress parameters measured, CAT levels were similar, with no significant differences being detected across treatments; LPO levels were significantly lower in shrimp PL fed the BG dietary treatment than those fed the PC diet, with no significant differences between the remaining treatments; tGSH levels were significantly higher in shrimp PL fed the BG treatment than in their counterparts fed the NC diet, with no significant differences between the remaining treatments. As for the immune condition, no significant differences between treatments were observed regarding the parameters measured (Table 2).

28 »

Gene expression analysis The normalized relative mRNA expression of the PvHm117 crustin P gene decreased significantly in shrimp PL fed the NC diet compared to those fed the T + M and BG dietary treatments. Similarly, the penaeidin3a mRNA expression level decreased significantly in shrimp PL fed the NC diet compared to their counterparts fed the PC and BG dietary treatments. Hemocyanin transcripts increased significantly in shrimp PL fed the NC diet compared to PL fed the T + M dietary treatment. As for the normalized relative mRNA expression of the remaining genes, no significant differences between treatments were observed (Table 3).

Inert diets with adequate

levels of vitamins C and E can be vital during critical stages of production.

Discussion This study aimed at evaluating the potential health-promoting effects of including several dietary supplements in inert microdiets for whiteleg shrimp PL. Vitamin C and E, methionine, taurine, and β-glucans were selected for this purpose since their potential ability to enhance the health status of whiteleg shrimp in the initial stages of development is still promising but yet to be experimentally validated. A control diet formulated to fulfill the nutritional requirements of whiteleg shrimp PL was used as positive control, and the remaining experimental diets were based on it, differing only in the reduction or addition of the previously mentioned nutrients. In overall, the formulation changes in the diets did not compromise their adequacy, as good growth performances and survival results were obtained in all experimental treatments, also revealing that good zootechnical conditions were maintained during the trial. Growth results were similar to those reported by Wang et al. (2017) when using graded levels of Schizochytrium meal and as a replacement of fish oil in practical diets for whiteleg shrimp PL, but survival results were considerably inferior in those studies (40.3 – 44.5% and 42.7 – 45.6%, respectively) than in the current trial. Increasing the vitamin C and E supplementation levels in the PC dietary treatment did not produce any changes in growth performance and survival when compared with the NC, DECEMBER 2023 - JANUARY 2024

suggesting that the levels of these vitamins present in the NC diet still allowed the shrimp post-larvae to maintain an adequate development. Like other vitamins, vitamin C and E are essential nutrients, as animals are unable to synthesize sufficient amounts to meet their physiological needs, and a deficient supply in the diet often results in poor growth, possibly leading to severe health issues and even compromising survival (Dawood et al., 2018; Nutrient Requirements of Fish and Shrimp; National Academy Press, 2011). Additionally, no changes were verified in the activity levels among most of the immune and antioxidant parameters measured in this study when increasing the levels of these vitamins in the diets. Inert diets with adequate levels of vitamins C and E can be vital during critical stages of production, particularly in farms where a nursery system is employed (intermediate step between the early PL stage and the grow out phase), in which PL are kept at DECEMBER 2023 - JANUARY 2024

extremely high stocking densities that can induce stress and vulnerability to opportunistic pathogens (Mishra et al., 2008). Lipid peroxidation levels dropped significantly in shrimp PL fed the BG dietary treatment compared to those fed the PC diet, suggesting that β-glucans improved the antioxidant mechanisms of the animals.

Conclusions In conclusion, the results obtained in this study suggest that although no improvements in growth performances and survival were observed at the end of the experimental period, all dietary additives tested have the potential to add value to inert microdiets for whiteleg shrimp PL. Benefits to the antioxidant capacity and robustness of the shrimp PL were clearer when the vitamin C and E levels were higher than those used in the NC, similar to those used in the PC. However, the control diet can be considered a premium op-

tion, and it should be expected that the positive effects provided by these supplements are augmented when incorporated into more economical alternatives. Amongst the additives tested, the inclusion of β-glucans in the diets seems to be the most promising, as it reduced lipid peroxidation in the shrimp PL even when compared to a high-quality control diet. When compared to the NC, the interaction between the supplementation of β-glucans and higher levels of vitamins C and E also seems beneficial to the antioxidant capacity of whiteleg shrimp PL.

This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “HEALTH-PROMOTING ADDITIVES SUPPLEMENTED IN INERT MICRODIETS FOR WHITELEG SHRIMP (PENAEUS VANNAMEI) POST-LARVAE: EFFECTS ON GROWTH, SURVIVAL, AND HEALTH STATUS” developed by: ANDRÉ BARRETO Riasearch Lda, CIIMAR, ICBAS-UP, DIOGO PEIXOTO - CIIMAR, ICBAS-UP, CARLOS FAJARDO - CIIMAR, Universidad de Cádiz, WILSON PINTO - Sparos Lda. The original article was published, including tables and figures, on FEBRUARY, 2023, through ANIMALS. The full version can be accessed online through this DOI 10.3390/ani13040726.

» 29

ARTICLE

Practical low-fishmeal diets for rainbow trout (Oncorhynchus mykiss) reared in RAS: Effects of protein meals on fish growth, nutrient digestibility, feed physical quality, and fecal particle size

By: Aquaculture Magazine Editorial Team*

To fulfil the future demands of seafood protein, aquaculture must promote its sustainable development. Consequently, it was evaluated the effect of the inclusion in feed formulation of commercially available protein meals alternative to fishmeal on fish growth performance and digestibility of diets, and the dietary effect on the quality of feces, with the general aim of optimizing the efficiency of waste management in RAS for rainbow trout.

n the landscape of aquafeed formulations, several protein meals (such as processed animal proteins – PAPs – or vegetable protein meals) have been tested as alternative or supplementary protein sources to satisfy the dietary requirements of targeted farmed species. Among PAPs, poultry by-product meal is one of the most promising alternatives to fishmeal due to its high protein content, relatively cheap price, and broad availability (GalkandaArachchige et al., 2020). Along with poultry by-products, feather meal is another protein-rich and cost-effective ingredient obtainable from the poultry rendering industry (Pfeuti et al., 2019). In RAS, aquafeeds must also be of excellent physical quality for the most efficient handling, storage and administration as well as produce large fecal particles for a rapid removal from the system. Changes in feed ingredients 30 »

DECEMBER 2023 - JANUARY 2024

Along with poultry by-products, feather meal is another protein-rich and cost-effective ingredient obtainable from the poultry rendering industry.

cal properties of feed pellets, and the dietary effect on the quality of feces, with the general aim of optimizing the efficiency of waste management in RAS for rainbow trout.

truded pellets and low oil leakage were measured in all diets.

Results Diets did not affect fish final live weight (191 g, on average), daily weight gain (1.71 g d-1), specific growth rate (2.16% d-1), feed conversion ratio (1.05), feed intake (1.65 g DM fish-1 day-1), and fish survival (97.7%) (Table 1). Fish viscerosomatic index (24.6% on average) and carcass yield (75.4%) did not differ among the four diets. The oil leakage in feeds ranged between 1.10% and 1.50%. The durability test showed that the shares of small and large fractures in the feed were always below 1%, with no differences between diets. At a sieve mesh interval of 0.3 – 0.5 mm, fish fed diet PBM produced a higher percentage of retained feces (64%) compared to the other diets (59.3%; p < 0.001). Regarding apparent digestibility coefficients of nutrients in the diets the ADC of protein were different among the four diets (p < 0.001) with the lowest value associated to

Materials and methods To evaluate strategies for optimizing waste in recirculating aquaculture systems, 1,020 rainbow trout (initial live weight 17.2 ± 7.50 g/fish) were distributed into 12 tanks after 21 d of acclimation and fed during 84 days with four practical diets (crude procan affect the technical quality of the tein: 49% dry matter (DM); crude fat feed, such as oil leakage, durability, and 26% DM; gross energy: 23 MJ kg-1) its stability in water as well as waste containing different rates of fishmeal production. However, knowledge and alternative protein meals, i.e. Diet about the performance of diets based FM (307 g kg-1 fishmeal, 61.2 g kg-1 on alternative raw materials in the poultry by-product meal); diet PBM aquaculture environments as for waste (183 g kg-1 fishmeal, 168 g kg-1 poulproduction is still scarce. Thus, it was try by-product meal); diet FeM (198 evaluated the effect of the inclusion g kg-1 fishmeal, 61.2 g kg-1 poultry byin feed formulation of commercially product meal, 76.5 g kg-1 hydrolyzed available protein meals alternative to feather meal); diet FeM+RM (171 g fishmeal, i.e., poultry by-product meal, kg-1 fishmeal, 61.2 g kg-1 poultry byhydrolyzed feather meal and rapeseed product meal, 76.5 g kg-1 hydrolyzed meal, on fish growth performance feather meal, 60.4 g kg-1 rapeseed and digestibility of diets, the physimeal). High structural integrity of exTable 1

Growth performance of rainbow trout fed diets including different combinations of protein meals for 84 days. RMSE: Root mean square error. Different superscript letters represent significant differences between means.

Diets

RMSE

PBM

FeM

FeM+RM

255

Initial weight (g)

26.9

27.5

27.2

26.7

0.38

4.15

Final weight (g)

199

191

189

186

0.08

36.4

Daily weight gain (g d-1)

1.72

1.73

1.69

1.70

0.96

0.10

Specific growth rate (% d-1)

2.20

2.17

2.14

2.12

0.13

0.04

Feed conversion ratio

1.03

1.05

1.07

1.06

0.72

0.04

Feed intake (g DM fish-1 day-1)

1.64

1.66

1.64

0.25

0.02

Survival (%)

99.1

97.7

94.9

99.1

0.10

2.00

Fish per treatment (n) Tanks (n)

DECEMBER 2023 - JANUARY 2024

p-value

» 31

ARTICLE Figure 1 Protein (a) and lipid (b) apparent digestibility coefficients (ADC) of the diets including different combinations of protein meals at different days of trial (significant interaction diets x days of trial). Data are represented as means ± standard error

100 c

32 »

40 28

Days of trial a)

PBM

100 e

FeM

FeM+RM e

ADC%

Discussion The results showed that the inclusion of 76.5 g kg-1 of hydrolyzed feather meal with 61.2 g kg-1 of poultry byproduct meal and 198 g kg-1 of fishmeal (diet FeM) did not affect rainbow trout growth performance and feed conversion ratio while reducing aquafeed production costs by 8%. In fact, feather meal composition and digestibility remain extremely variable (Pfeuti et al., 2019b) and a blend of hydrolyzed feather meal with other protein meals is suggested to better balance dietary amino acid profile (Yu, 2019). Based on the results and previous literature (Bureau et al., 2000), hydrolyzed feather meal could be effectively incorporated from 76.5 to 150 g kg-1 in low-fishmeal (≤ 200 g kg-1) diets for juvenile rainbow trout, whereas higher inclusion levels seem to be possible only through additional enzymatic pre-treatments of the feathers and amino acid supplementation (Pfeuti et al., 2019). It was measured the highest protein digestibility in the diet with the highest inclusion of poultry by-products (diet PBM). High digestibility of poultry by-product meal has already been reported in studies on rainbow trout (Badillo et al., 2014; GalkandaArachchige et al., 2020).

ADC%

diet FeM (79.6%) and the highest value to diet PBM (86.0%). Moreover, ADC of protein significantly increased over time (p < 0.001), from 80.3% at 28 days of trial to 86.6% at 84 days of trial (Figure 1). The highest production cost per ton of diet was measured for diet FM followed by diet PBM, diet FeM and diet FeM+RM (Table 2). When costs were expressed per kg of produced fish, the highest values were recorded for diet FM (1.01 $ kg-1) and the lowest for diet FeM+RM (0.92 $ kg-1), with diet PBM and diet FeM showing intermediate and similar values (0.96 and 0.95 $ kg-1).

40 28

Days of trial b)

PBM

FeM

FeM+RM

Table 2 Production costs of the diets including different combinations of protein meals. a Feed production cost at production plant gate: costs of labor, packaging and transport are not included.

Diets

Feed production cost ($ ton ) a

-1

Feed cost to produce 1 kg of fish ($ kg ) -1

Change with respect to control diet (FM) (%)

Finally, in RAS, the formation of large fecal particles is desirable, as they are more rapidly and easily removed from the system than smaller ones (Brinker, 2009; Unger and Brinker, 2013). Overall, compared with previous studies on rainbow trout, it was found a similar proportion of fine

PBM

FeM

FeM+RM

976.61

914.05

894 .96

870.57

1.01

0.96

0.95

0.92

-8

-10

-11

particles in feces (58–64%), but a lower percentage of mid-large fecal particles (5 – 7% vs. 21 – 38%). These differences might be likely related to the different methods used to measure fecal size, with laser diffraction (Welker et al., 2018) or microscopic analysis (Welker et al., 2020, 2021) beDECEMBER 2023 - JANUARY 2024

Conclusion Under study conditions, the partial High digestibility of substitution of fishmeal from fish by-products with alternative protein poultry by-product meals did not affect trout growth meal has already been performance and feed conversion reported in studies on ratio. The digestibility of protein resulted satisfactory (> 80%) for all rainbow trout. diets, whereas improvement for lipid digestibility is desirable in diet containing hydrolyzed feather meal and rapeseed meal. The inclusion of hydrolyzed feather meal reduced water turbidity during the first thirty minutes after ing more accurate than using the per- feed administration and the inclusion centage of retained feces at different of poultry by-product meal induced sieve mash sizes. In the study, the diet the production of larger particles of PBM, containing poultry by-product feces, which are considered positively meal and fishmeal as main protein in view of the reduction and collecsources, showed the highest protein tion of wastes in a RAS system. digestibility and was associated to a A comprehensive evaluation of higher size of feces particles. aquafeeds, by considering not only DECEMBER 2023 - JANUARY 2024

their nutritional aspects but also their physical characteristics and effects on waste production together with economic impacts, would be paramount for future feed formulations, especially when designed for sustainable, highly controlled, and resource-efficient environments like RAS. This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “PRACTICAL LOW-FISHMEAL DIETS FOR RAINBOW TROUT (ONCORHYNCHUS MYKISS) REARED IN RAS: EFFECTS OF PROTEIN MEALS ON FISH GROWTH, NUTRIENT DIGESTIBILITY, FEED PHYSICAL QUALITY, AND FAECAL PARTICLE SIZE” developed by: FANIZZA, C. - University of Padova and Universitat Politècnica de València, TROCINO, A. University of Padova, STEJSKAL, V., DVORÀKOVÀ PROKESOVÀ, M., ZARE, M., QUANG TRAN, H. - University of South Bohemia, BRAMBILLA, F. - NaturAlleva (VRM s.r.l.), XICCATO, G., BORDIGNON, F. - University of Padova. The original article was published, including tables and figures, on DECEMBER, 2022, through AQUACULTURE REPORTS. The full version can be accessed online through this DOI 10.1016/j.aqrep.2022.101435.

» 33

CARPE DIEM

The importance of scientific method

By: Antonio Garza de Yta, Ph.D.*

n today’s society, emotions often hold more weight than truth. As a result, important decisions are sometimes made based on feelings rather than factual evidence. Although we are aware that this has caused numerous global problems, decisions have been made based on alternative facts and personal realities instead of analysis based on hard data, often with catastrophic results. In my perhaps naive thinking, I be34 »

In today’s age, emotions often hold more weight than truth. Decisions are sometimes made based on how something makes us feel, rather than the validity of the facts. While not all published material can be defended, the scientific method can. This method empowers individuals to approach reality independently of their beliefs. It is a systematic and structured way of approaching a question. lieved that this would never affect aquaculture... I was mistaken. A few weeks ago, I engaged in a debate with a prominent aquaculture blogger who discredited the work of leading aquaculture scientists worldwide. He believed that other things were happening in reality. Personal opinions about facts have already infiltrated the aquaculture industry and have been doing so for some time now, as evidenced by the current situation.

I will not defend everything that is published, but I will defend the scientific method. This method allows those who use it to approach reality independently of their beliefs. It is a systematic and structured approach to answering questions. The scientific method is a tool that allows for the generation of objective knowledge by determining the veracity or falsity of a postulate through a series of stages or steps. These steps DECEMBER 2023 - JANUARY 2024

Personal opinions about facts have already infiltrated the aquaculture industry.

include making an observation, posing a question, generating a hypothesis, making a prediction based on the hypothesis, testing the prediction, and repeating the process. The scientific method is a methodology that enables scientific progress and has been the foundation for all advancements in each scientific field. It is the basis of mankind’s knowledge. Without this method, the world would be a vastly different place. How does this impact the practical world of aquaculture? It mainly provides tools for mak-

DECEMBER 2023 - JANUARY 2024

ing correct decisions. I am often asked if a certain technology or product is effective, and my response is consistent: Has it passed the scientific method? Is there an audited publication? It is important to emphasize that the publication must be peer-reviewed to ensure its validity. While anyone can publish in a commercial journal, the scientific process requires verification through peer review. Although this process is not infallible, it serves as a valuable filter. Next time someone claims a product accelerates shrimp growth, prevents tilapia illness, or stops hair loss, use the scientific method to verify. Replicability and low failure rates indicate validity. I insist that those who promote any technology should not provide alternative facts that could mislead producers until it has been validated. While some innovative systems exist, they do not guarantee greater profitability than more traditional systems, which often involve less risk. Aquaculture is

expanding into uncharted territories with cutting-edge technologies that were once unimaginable. However, we must prioritize the safety of producers and their assets. It is crucial to adhere to the scientific method and avoid unnecessary risks, even if we strongly believe it is the right course of action. True progress is built on a foundation of science.

Senior Fisheries and Aquaculture Advisor for AWJ Innovation, Vice President of the International Center for Strategic Studies in Aquaculture (CIDEEA), President of Aquaculture Without Frontiers (AwF), Past President of the World Aquaculture Society (WAS), Former Secretary of Fisheries and Aquaculture of Tamaulipas, Mexico, and Creator of the Certi cation for Aquaculture Professionals (CAP) Program with Auburn University.

» 35

THE GOOD, THE BAD AND THE UGLY

EHP update-mitigation of the impact EHP is caused by a spore forming microsporidian, Enterocytozoon hepatopenaei. The disease is also known as hepatopancreatic microsporidiosisis (HPM). The fact that a pathogen like EHP is thriving despite the known role of broodstock, inadequate pond preparation, infected larvae and PLs in the process is not a positive statement about shrimp farming. By: Ph.D. Stephen G. Newman*

HP is caused by a spore forming microsporidian, Enterocytozoon hepatopenaei. The disease is also known as hepatopancreatic microsporidiosisis (HPM). The spores are how the pathogen infects shrimp. When spores are ingested by consuming in36 »

fected tissues (via cannibalism) and/or feces or indirectly through the water, they infect specific types of cells in the hepatopancreas and intestinal tract and germinate. They use the metabolic machinery of the cell to make more spores until the infected cell ruptures, killing it and releasing many more spores to

spread throughout the animal. Many microsporidians have intermediate hosts for some of the life stages and it has been theorized that this could help to explain why live feeds can be carrying the spores. No one has of yet identified an intermediate host for this specific microsporidian. DECEMBER 2023 - JANUARY 2024

Figure 1 EHP size variation in one infected pond. Photo by Andy Shinn for Asia Pacific Aquaculture Magazine.

Despite the availability of common-sense measures to mitigate the spread of this obligate pathogen of Penaeus vannamei (as well as others) it continues to spread. Its impact is significant and growing. This is not a new pathogen. It was first reported almost 20 years ago. I first wrote about it in 2015 (“Microsporidian Impacts Shrimp Production – industry efforts address control, not eradication”, Global Aquaculture Advocate,16-17, March/April 2015). Today, in 2023, we are seeing increasingly frequent reports of serious impacts. It takes an accumulation of spores in the animal for the symptoms to reach the point where the syndrome is noticeable, and the impact becomes obvious. The animals grow slowly if at all and continue to consume feed. They do not grow uniformly, and they are increasingly susceptible to opportunistic pathogens. The white feces syndrome has been linked to the presence of this organism along with several bacterial species including Propigenium and some vibrios. There appears to be a relationship between rearing densities and the severity of the disease with low density production paradigms in general experiencing less of a problem. Higher density systems have worse problems. It stands to reason that in environments where the shrimp are closely packed there is a greater potential for

the spores to pass between animals. If preventative measures are not taken to limit the amount of sludge build up in ponds, reservoirs and other production related areas spore loads can reach the point where chronic EHP impacts even low-density production paradigms. Animals must be carrying a high level of spores before they are affected. Sluggish growth and excessive feed consumption follow. While for some types of microsporidians certain drugs work to suppress them, EHP is refractory to them (as most microsporidians are). The only way to control this pathogen is to exclude it and control the levels through common sense biosecurity measures. Table 1 shows some of these. Use our proprietary blend of bacteria, tableted for ease of use, PRO 4000X, to reduce accumulated organic matter during the cycle. Clients all over the world are using this targeted approach to lessen accumulated organic matter loads. Anything and everything you can do to lower the spore loads is the only path towards minimizing the impact for now. Genetic selection could give us shrimp that are refractory to spore infection or even resistant. This could turn out to be easy or impossible. Only time will tell. There are no drugs that could clear the animal of the very heavy spore loads that can

Figure 2 Spores of EHP. Photo courtesy of Tim Flegel.

DECEMBER 2023 - JANUARY 2024

» 37

THE GOOD, THE BAD AND THE UGLY

Table 1 Biosecurity measures to EHP control. Break the cycle

Do not use broodstock that are carriers or have been exposed to non-controlled production environments (like broodstock ponds outdoors). Live feeds are a serious risk if not screened or from bio secure sources (such as krill).

Screen all life stages repeatedly using RT-PCR

Take frequent random samples and look for weak animals. Make sure that you are using a primer that has been thoroughly vetted. There are many microsporidia in aquatic ecosystems that have nothing to do with shrimp some of which can cross react, leading to false positives.

Eliminate sludge build up

Where fecal material infected with spores accumulates. Shrimp forage on detritus and eat bacteria that are attached to it and can readily ingest spores as they look for food.

Use automatic feeders

Besides wasting less feed this reduces stress and discourages foraging. Proper use prevents areas of accumulated feed detritus from accumulating. If you are properly monitoring your population for growth and suvivals, you will know when your problem starts.

Ask questions

If PLs are carrying moderate levels of spores, odds are you will have problems eventually. It is important to appreciate that even low levels of spores can be amplified rapidly to undesirable levels if the conditions are ripe for it. The hatcheries that manage this the best will have more customers that are not heavily affected.

Dry ponds

Out as frequently as the weather and your cycles allow. Heavily lime and allow the sun to bake the soil. This will reduce the spore loads.

Lining ponds

Changes the pond ecology dramatically by eliminating the soil/water interaction. It is important to appreciate that spores are passed into the environment through shrimp feces and subsequently into other shrimp. Keeping pond bottoms clean is helpful and properly disposing of the accumulated organic matter is essential. Untreated, this is a huge source of spores.

accumulate. There are no quick fixes that would meet regulatory approval in the buyers’ countries. The only way to deal with this for now is to push it back as far as you can, i.e., control the levels of spores at all phases of the process and take the steps needed to ensure this. Amplification of pathogens via broodstock through PLs onto farms has cost the shrimp farming industry tens of billions of dollars over the last three decades. For shrimp farming to become sustainable this cycle needs to be broken. Progress is being made but there is more work to do. Greater oversight of broodstock production in many countries would be a good start. Screening for pathogens needs to be comprehensive, not focused on what regulators have determined to be solely of concern. Many patho38 »

gens are missed because of this. The presence or absence of a pathogen in captive broodstock held in a biosecure environment should not be based on population sampling. Every individual brood animal needs to be tested. The technology exists today to do this economically (https://genics.com.au/) although it will double the price of most commercial broodstock. Given the losses and the role of pond reared broodstock in ensuring the continued increase in the incidence and severity of this disease this is easily economically justifiable. Again, this is the only path that will lead to the cessation of this endless cycle of profit limiting diseases that have impacted shrimp farming since its inception. The fact that a pathogen like EHP is thriving despite the known role of broodstock, inadequate pond prepa-

EHP is caused by a spore forming microsporidian, Enterocytozoon hepatopenaei.

ration, infected larvae and PLs in the process is not a positive statement about shrimp farming. The industry is poorly regulated and more than likely there will continue to be dogmatic approaches with attention to myth rather than the science of what is taking DECEMBER 2023 - JANUARY 2024

There are two ways to make sure that broodstock are free of EHP spores to start with.

indication of the spore loads. Soon after stocking suggests that the spore load is high to start with. Proper animal husbandry is essential for sustainability. If the above practices were routine, the impact of WSSV and many other diseases would be dulled considerably. Perhaps what is the most important message to take home here is that by ignoring these practices, taking short cuts, hoping it will go away or desperately seeking magic bullets, the industry is guaranteeing that disease problems will be a constant in shrimp farming. Shrimp farming will not ever become truly sustainable if this is the case. place even with added oversight. EHP can be dealt with. Until there are truly resistant animals (assuming that this is even possible) this disease is here to stay. Even in countries where there seems to be little impact at this time, ignoring the commonsense measures to keep spores loads low could eventually result in the disease becoming problematic. There are two ways to make sure that broodstock are free of EHP spores to start with. These are screening and following the performance of the animals in the field, i.e., history. Screening is essential. RT PCR is a powerful tool, but it has serious limitations much as all populationbased testing of PCR does. Primers must be specific or there will be false positives. Tissues being sampled must contain the organism of interDECEMBER 2023 - JANUARY 2024

est. Too small of a sample or targeting tissue that is not infected early in the disease process can lead to false negatives. Even if these were not issues, PCR use in population testing is a statistical exercise. You take a sample of animals and test them. Most of the animals in the population are not tested. One can never be 100% sure using this approach that EHP is not present at some level. For PLs this is of course understandable. Less so for broodstock. Following the larva and PLs from each spawn is essential. If they are PCR positive as determined by routine testing, they should be destroyed and the presence of the pathogen in the broodstock should be considered. If they are “clean” then performance on the farm will provide additional clues. If it is a serious problem, how early it occurs will give some

Stephen G. Newman has a bachelor’s degree from the University of Maryland in Conservation and Resource Management (ecology) and a Ph.D. from the University of Miami, in Marine Microbiology. He has over 40 years of experience working within a range of topics and approaches on aquaculture such as water quality, animal health, biosecurity with special focus on shrimp and salmonids. He founded Aquaintech in 1996 and continues to be CEO of this company to the present day. It is heavily focused on providing consulting services around the world on microbial technologies and biosecurity issues. sgnewm@aqua-in-tech.com www.aqua-in-tech.com www.bioremediationaquaculture.com www.sustainablegreenaquaculture.com

» 39

THE FISHMONGER

Social responsibility in aquaculture

By: The Fishmonger*

As a retailer the Fishmonger used to be in awe of organizations like Mc Donalds and other giant fast-food outlets. Of course, the food was not to the Fishmongers taste e.g. the seafood offerings were minimal and were manufactured to eliminate great seafood flavors but there was much to like about their systems, their staff training, their advertising, and their connection to being part of the community.

s a retailer the Fishmonger used to be in awe of organizations like McDonalds and other giant fast-food outlets. Of course, the food was not to the Fishmongers taste e.g. the seafood offerings were minimal and were manufactured to eliminate great seafood flavors but there was much to like about their systems, their staff training, their advertising, and their connection to being part of the community. The Fishmonger is aware that some towns fought against a McDonalds franchise being established in their area but conversely there are towns who see them as part of the community fabric where you can take kids to parties and have a fun time with relatively cheap entertainment in the play areas and with the food, albeit young children probably waste much of it. Also impressive was their concept to create Ronald McDonald’s House (RMH), a non-profit organization, that provides temporary housing and 40 »

Australian Barramundi with zucchini flowers and courgette DECEMBER 2023 - JANUARY 2024

No one is immune to errors in social responsibility.

Australian Barramundi with zucchini flowers and courgette

support to families of seriously ill children who are receiving medical treatment in nearby hospitals. RMH was founded in 1974 by Philadelphia Eagles football player Fred Hill, whose daughter was diagnosed with leukemia. Today, there are nearly 400 Ronald McDonald’s Houses around the world, providing comfort and care to thousands of families each year. Kudos to them for this great social initiative. DECEMBER 2023 - JANUARY 2024

It has been reported that McDonalds and its franchisees employ approximately 1.9 million employees. McDonald’s has more than 35,000 locations in over 100 countries and that about 80 percent of locations are franchised. One of the problems with mega businesses is when something goes wrong then it has a big impact on the overall operations and, being who they are, they are often highlighted

in the media when that occurs. For example, earlier this year it has been reported that the U.S. Department of Labor (DOL) fined three McDonald’s franchisees after an investigation determined that hundreds of children - including two 10-year-olds - were working there in violation of federal labor law. Officials found that Louisville, Kentucky-based McDonald’s franchisee operator had hired two 10year old’s to work at one of its locations -unpaid- and as late as 2 a.m., with one of the children even permitted to operate a deep fryer, a task for which workers must be at least 16 years old. Note that under Kentucky’s child labor laws, minors younger than 14 years old are not allowed to work. Only a few days ago it has been reported in Australia that thousands of McDonald’s workers have joined a class action against the fast-food giant accusing them of not allowing staff to have their breaks. This follows on from the Federal Court finding that a former employee was not provided with paid 10-minute rest breaks when working shifts four hours or longer. The court heard that the franchisee misrepresented the nature of the breaks, and the former employee was subsequently paid the value of her lost breaks. The class action revolves around many staff worked in hot conditions without access to a toilet or something to drink when there is clarity » 41

THE FISHMONGER

in Australia, that McDonald’s workers are entitled to a paid 10-minute break for shifts between four and nine hours, and two paid 10-minute breaks for shifts longer than nine hours. Additionally, workers were reporting that they were told that they had to arrive for work 15 minutes early to prepare and stay 30 minutes after their shift to meet cleaning and other procedures and, yet not get paid for those times. These examples highlight that no one is immune to errors in social responsibility, and it does not end there. This is a minefield for any organization and no matter where you are and in aquaculture and its value chain it is going to be an issue that everyone needs to consider as you move forward with your business. You can either wait for compliance to hit you or you/we can build a culture within your organization and the industry that represents important values, considers ‘society’ as a shareholder, harnesses a team approach and encourages all to move forward in a socially responsible fashion. The Fishmonger recently learned that the International Labor Organization (ILO), the only tripartite U.N. agency, which has been operating since 1919 bringing together governments, employers, and workers of 187 Member States, to set labor standards, develop policies and devise programs promoting decent work for all women and men, have been talking about aspects of social responsibility in aquaculture for some time. They have included aquaculture into their agri-food sector and after about ten years of discussion with their “experts on decent work” have recently made available their “Policy guidelines for the promotion of decent work in the agrifood sector” – you can download that from https://www.ilo.org/sector/Resources/codes-of-practiceand-guidelines/WCMS_873895/ lang--en/index.htm. 42 »

Japanese Fishburgers

This would seem to have the support of the International Union of Food, Agricultural, Hotel, Restaurant, Catering, Tobacco, and Allied Workers’ Associations (IUF), a global union federation of trade unions with members in a variety of industries, many of which relate to food processing. It is also recognized as an important instrument by governments when planning policies in many of the sectors. These

instruments are being considered through FAO Committee on Fisheries (COFI) so will become entwined in what the industry does into the future. The ILO point out that Governments have the duty to adopt, implement and effectively enforce national laws and regulations and ensure that fundamental principles and rights at work and ratified international labor Conventions are applied to all workDECEMBER 2023 - JANUARY 2024

ers in the aquaculture sector, considering their obligations under other international labor standards. ILO believe that Governments should strengthen labor administration and labor inspection systems to ensure full compliance including through adequate financial resources, duly qualified inspectors, proper equipment and training, and robust recruitment procedures. Additionally, ILO expect all enterprises should respect human and labor rights in their supply chains consistent with the United Nations Guiding Principles on Business and Human Rights and the ILO Tripartite Declaration of Principles concerning Multinational Enterprises and Social Policy. The Fishmonger believes that we all would agree that aquaculture, should be regarded as a subsector of agriculture (sadly still stuck in Fishing in some countries), and is an important source of income and livelihoods, especially for many rural communities. The ILO acknowledge that aquaculture provides direct employment to more than 20 million people, with many millions more people employed through the supply chain. The sector’s exponential growth in recent decades has significantly contributed to alleviating poverty in a number of developing countries, enabling millions of the rural poor to escape from social and economic exclusion. Enterprise

Aquaculture is an important source of income and livelihoods, especially for many rural communities.

DECEMBER 2023 - JANUARY 2024

development is important for aquaculture as it will contribute to job creation, empowerment of women and youth and livelihood diversification in the rural economy. The sector contributes significantly to feeding the world’s growing population, while ensuring that no one is left behind (#leavingnoonebehind). The ILO highlight that harnessing aquacultures potential will require concerted efforts to achieve full, productive, and freely chosen employment and decent work for all in aquaculture as part of resilient food systems. Sustainable development and growth of aquaculture can make an important contribution to reducing distress out-migration from rural areas. For the future new technological solutions offer promising prospects to address many of the traditional and emerging issues facing the aquaculture sector, while improving productivity and environmental outcomes. The Fishmonger believes they could also help create new sustainable enterprises and decent employment opportunities including by replacing laborious, repetitive, and dangerous tasks with automated processes. Along this journey the industry will need effective policy to address potential negative impacts such as job losses, skills mismatches, skills polarization, wage inequality, and barriers faced by small-scale producers in adopting new technologies and practices. The digital divide hinders the small-scale producers from taking advantage of new technologies and practices. An enabling environment for digital transformation should be supported with right Information and Communication Technologies (ICT) infrastructure and digital literacy. The Fishmonger has often spoken about a lack of data about the industry and how there is a need to build a culture from top to bottom so to see those points highlighted in the ILO report was gratifying as

The sector contributes significantly to feeding the world’s growing population, while ensuring that no one is left behind.

maybe it just needs stronger voices to get these issues on the table. There can be no question that recognizing the universal right to education, investments in life-long learning and diversified skills development to promote decent work opportunities will enable the workforce and the employers to better respond to the changing requirements of the sector, including those related to technological advancements and sustainable natural resource use. Additionally, continually improving environmental sustainability of aquaculture, including through improved infrastructure, water and waste management and the creation of green jobs, will be key to the sector’s long-term economic sustainability, to food security and nutrition for the future. If you were looking to get ahead of the pack then it would pay to get a good awareness of the environmental, social, governance and health (ESGH) risks and opportunities in the aquaculture sector then you should engage at the AQUA FARM 2024 Conference/Expo – see www. aquacultureconference.com.au. The Fishmonger will there so I hope to see you!

References and sources consulted by the author on the elaboration of this article are available under previous request to our editorial staff.

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