Health and Safety: High-Priority Concepts in Aquaculture
GREENHOUSES AND POND LINERS
Comparative Study of Hydrobiological Parameters Between Earthen and HighDensity Polyethylene (HDPE) Brackishwater Shrimp Ponds in Ratnagiri, Maharashtra
ARTICLE
Innovating Sustainable Aquaculture: Fishlab’s Pioneering Work in Live Feed and Fish Fry Production
Alternative Strategies to Combat AntibioticBased Treatment in Aquaculture
ARTICLE ARTICLE
Interview with Eduardo Del Castillo, Commercial Director of ETEC Revolutionizing Aquaculture Pumping: ETEC and the Power of Floating Pumps
Anaerobic Degradation of Excess ProteinRich Fish Feed Drives CH4 Emissions in Aquaculture Systems
Anaerobic Degradation of Excess ProteinRich Fish Feed Drives CH4 Emissions in Aquaculture Systems
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editor`s comments
* Marco Linné Unzueta Associate Editor
Health and Safety: High-Priority Concepts in Aquaculture
The development of aquaculture, despite its continuous progress, has exhibited fluctuations in production rates. These variations can be attributed to various factors, including sanitary challenges. Since its inception, aquaculture’s growth has been hindered by emergencies arising from numerous diseases that have rapidly disseminated globally.
In his study on the historical emergence, impact, and status of shrimp pathogens in Asia, Flegel (2012) highlights that, according to the Global Aquaculture Alliance (GOAL), losses in shrimp farming are predominantly attributed to viral diseases (60%), bacterial diseases (20%), and a diverse range of pathogens, including helminths and fungi, or associated with environmental factors such as toxicity or climate, nutritional deficiencies, or congenital conditions. These pathogens and parasites are also prevalent in the cultivation of other crustacean, mollusk, and fish species.
It is crucial to recognize that diseases of infectious origin in aquatic organisms can originate from bacteria, fungi, protozoa, helminths, or viruses. Conversely, non-infectious
diseases are rooted in genetic, environmental, nutritional, or functional causes. Consequently, it is imperative to acknowledge that these diseases alter the normal functioning of the host and can directly influence susceptibility to predation, reproduction, and survival. They can also lead to reduced growth, a low feed conversion factor, and consequently, increased production costs. Therefore, it is of paramount importance to shift the perception of prevention and treatment for optimal health from an expense to an integral component of sustainable production strategies. This shift aims to provide consumers with safe and healthy aquatic organisms.
In light of the aforementioned considerations, it is imperative to conduct comprehensive risk analysis studies for aquaculture activities. These studies are crucial in elucidating the factors that influence production costs and, of course, the processes that guarantee high-quality and safe production. This process comprises four distinct stages:
1. Identification of Hazards: This phase involves systematically listing the parasites and pathogens
associated with the farmed organism and ascertaining whether these agents are present within the country or the designated origin zone.
2. Risk Assessment: This phase entails determining the likelihood of the agent’s entry, the potential exposure of the pathogen at the destination, the potential consequences, and ultimately, the risk estimate.
3. Risk Management: This phase compares the findings from the risk analysis with the established protection levels within the country through the agreements established by the World Organization for Animal Health (WOAH).
4. Risk Communication: This phase necessitates a multidirectional approach to disseminate information to all relevant sectors. It should consider the scientific environment that is actively developing integrated multi-trophic systems on a global scale. These systems are recognized for their environmentally friendly and biosecure characteristics.
Organizadores:
Organizadores Locales:
Comparative Study of Hydrobiological Parameters Between Earthen and High-Density Polyethylene (HDPE) Brackishwater Shrimp Ponds in Ratnagiri, Maharashtra
* By Aquaculture Magazine Editorial Team
India is a global leader in shrimp production due to rapid growth rates, shorter cultivation periods, high export value, and increasing market demand. Meeting this demand requires expanding farming areas and adopting innovative methods to improve productivity and close the supply-demand gap. Shrimp production is significantly influenced by the water´s physico-chemical characteristics, which affect shrimp growth and survival. In particular, hydrogen ion concentration (pH) in both water and pond soil are critical, as are nutrient inputs that can deteriorate water quality if retained or degraded.
Monitoring water quality is essential for both shrimp health and farm productivity, yet pond management often lacks adequate attention. Since shrimp physiology depends heavily on water temperature, farming protocols must be adjusted accordingly. In tropical and subtropical regions, phytoplankton play a vital role in maintaining energy balance and water quality, with seasonal and climatedriven fluctuations affecting their populations. Because phytoplankton perform photosynthesis and generate oxygen, they are key indicators of primary productivity and serve as a natural food source for shrimp. Zooplankton also contribute significantly by linking primary producers with higher trophic levels.
However, challenges like poor soil quality and disease make shrimp cul-
As India leads global shrimp production, innovative practices like high-density polyethylene (HDPE) ponds are reshaping aquaculture. This study compares water quality and plankton productivity in HDPE versus traditional earthen ponds in Ratnagiri, Maharashtra. Results reveal significant differences in key hydrobiological parameters suggesting that HDPE ponds offer better environmental control and improved productivity.
tivation in traditional earthen ponds difficult. To address this, farmers have started using Litopeneaus vannamei in lined ponds. These alternatives, particularly high-density polyethylene (HDPE) liners, offer benefits such as improved disease control and suitability in acidic soils, outperforming traditional systems. HDPE ponds are also easier to manage. This study compares earthen and HDPE ponds regarding water quality and plankton productivity to evaluate their relative efficiency in shrimp farming.
Materials and Methods
The present study was conducted between June to October 2022 and January to May of 2023. Samples of water and plankton were collected from Kelbai Aqua farm Ranpar, Ratnagiri,
including two consecutive crops from four earthen and four high-density polyethylene (HDPE) ponds. Weekly water samples were collected from the farm, assessing pH, salinity, temperature, biochemical oxygen demand, dissolved oxygen, alkalinity, hardness, ammonia, nitrite-nitrogen by Strickland and Parsons (1972), Boyd (1979). Primary productivity using standard light and dark bottle method (Gaarder and Gran, 1927).
Plankton samples were collected at 7-day intervals from ponds by filtering 50 L of water using a 50 μm mesh net and preserved in Lugol’s solution and a 5% neutralized formalin solution for future analysis. In the laboratory analyzed phytoplankton and zooplankton qualitatively by pipetting 1 ml sample and quantitatively using Sedgewick-
( GREENHOUSES AND POND LINERS )
Rafter density per liter of water samples, observing under microscope at 10x and 40x magnification and identifying plankton using a taxonomic key (Newell and Newell, 1977).
The Analysis of Variance (ANOVA) was performed using SPSS 16.0 software to determine the statistical significance (p < 0.05) of the effect of pond types and experiment days on water quality parameter, primary productivity and plankton.
Results and Discussion
Water quality parameters
For both crop cycles, the ANOVA showed significant differences
(p < 0.05) in temperature, pH, salinity, dissolved oxygen (DO), and alkalinity between earthen and HDPE ponds (Table 1). Total hardness, total ammonia, and nitrite-nitrogen showed significant differences for crop one (Table 1) but not for crop two (p > 0.05). Biochemical Oxygen Demand (BOD) differed significantly only for crop two.
Primary productivity and plankton
ANOVA revealed significant differences (p < 0.05) in Gross Primary Productivity (GPP) and Community Respiration (CR) between pond types for crop one (Table 1) , but no difference
for crop two. Net Primary Productivity (NPP) showed significant differences in both crops.
ANOVA showed significant differences in phytoplankton density across pond types. Zooplankton differed significantly in crop one but not in crop two.
Temperature and pH
Temperature impacts shrimp growth and metabolism. Ranges were 2731°C in both pond types. Ideal shrimp growth occurred at 26-30°C. For earthen ponds, the optimal range was 26.34-28.69°C; for HDPE ponds, 26.93-28.96°C. Temperature showed
positive correlation with GPP, NPP, CR, and plankton (Figure 1). The water pH remained within the ideal range (6.6-8.5). Measured values ranged from 4.5 to 8.7 depending on pond type and season. Mean values ranged from 7.9 to 8.1 in both pond types, correlating negatively with plankton and productivity.
Salinity
and dissolved oxygen
Salinity ranged from 21.52-40.21 practical salinity unit (PSU) in earthen and 21.93-39.58 PSU in HDPE ponds, optimal for shrimp growth. Salinity correlated negatively with plankton and productivity. DO ranged from 4-7 mg/L. Mean values were 4.6-5.0 mg/L in earthen and 4.7-5.3 mg/L in HDPE ponds, suitable for L. vannamei. DO positively correlated with GPP, NPP, CR and zooplankton in crop one, but showed mixed trends in crop two.
Biochemical
oxygen demand and alkanility
BOD values ranged between 3.33-4.06 mg/L (earthen) and 3.38-4.45 mg/L (HDPE). These values indicated suitable pond conditions. BOD correlated positively with plankton and productivity. Alkalinity ranged from 66.5696.82 mg/L (earthen) and 76.57-115.50 mg/L (HDPE), supporting shrimp health. Seasonal variability was noted due to monsoonal freshwater input. Alkalinity positively correlated with plankton and productivity.
Challenges like poor soil quality and disease make shrimp cultivation in traditional earthen ponds difficult. To address this, farmers have started using Litopeneaus vannamei in lined ponds.
For both crop cycles, the Analysis of Variance (ANOVA) showed significant differences (p < 0.05) in temperature, pH, salinity, dissolved oxygen (DO), and alkalinity between earthen and high-density polyethylene (HDPE) ponds.
Hardness, ammonia and nitrite
Total hardness ranged from 3,334.76,313.0 mg/L (earthen) and 3,379.86,320 mg/L (HDPE). Hardness negatively correlated with productivity in crop one and positively in crop two for GPP, NPP, and zooplankton. Am-
monia levels were higher in earthen (0.6-0.7 mg/L) than HDPE ponds (0.40.5 mg/L). Ammonia negatively correlated with CR and positively with GPP, NPP, and plankton in crop one. In crop two, it remained positively correlated with productivity.
Nitrite-nitrogen ranges from 0.1189-0.502 mg/L (earthen) and 0.1056-0.1671 mg/L (HDPE). Ideal levels (~0.01-0.1 ppm) were occasionally exceeded. Nitrite was positively correlated with productivity and plankton, and negatively with CR during
crop one. Similar positive trends were found in crop two.
Primary productivity
» Gross Primary Productivity (GPP). GPP values ranged from 0.85400.9153 mg C/L/hr (earthen) and 0.7991-1.0677 mg C/L/hr (HDPE). GPP was highest pre-monsoon and lowest and lowest during monsoon. It correlated positively with temperature, alkalinity, BOD, ammonia, and nitrite and negatively with pH, salinity, and hardness in crop one; similar trends were observed in crop two.
» Net Primary Productivity (NPP). NPP ranged from 0.6896-0.8353 mg C/L/hr (earthen) and 0.68550.9254 mg C/L/hr (HDPE). Higher NPP occurred in summer. Correlation trends matched those of GPP.
» Community Respiration (CR). CR ranged from 0.0798-0.1724 mg C/L/hr (earthen) and 0.0929-0.1411 mg C/L/hr (HDPE). Higher respiration was attributed to biotic activity. CR positively correlated with temperature, DO, alkalinity, BOD; negatively with Ph, salinity, hardness, ammonia, and nitrite.
Plankton
Phytoplankton and zooplankton are key nutritional sources for aquatic larvae. In this study, phytoplankton density ranged from 80 to 5,550 Nos. L-¹ across various ponds. These values align with previous research in
tiger shrimp ponds. Dominant phytoplankton groups included Bacillariophyceae, Dinophyceae, Cyanophyceae, and Chlorophyceae, with species such as Actinoptychus, Coscinodiscus, Nitzchia, Oscillatoria, Nostoc, Gymnodinium, and Prorocentrum were observed.
Zooplankton density ranged from 30 to 320 Nos. L-¹, with primary groups being protozoans, copepods, and rotifers. Key protozoans included Tintinnopsis, Favella, and Vorticella. Rotifers were dominated by Branchionus, Keratella, and Lecane, while copepods included Acartia, Calanus, Cyclops, and Microsetella. Similar species distributions have been reported in other shrimp ponds across Tamil Nadu, including findings of crustacean nauplii, mysidacea, and pelagic polychaetes.
Overall, plankton populations showed positive correlations with temperature, dissolved oxygen, alkalinity, hardness, and biological oxygen demand, while pH and salinity were negatively correlated (Figure 2). These results highlight the ecological dynamics and water quality interactions influencing primary productivity in shrimp aquaculture systems.
Conclusion
The research included information on hydrobiological assessments and management role of shrimp farmers located in Ratnagiri, Maharashtra. The results of this investigation
indicated that most hydrobiological parameters were within the optimal recommended ranges found in the published literature. It was observed that the shrimp growth and survival rates appeared to benefit for the high-density polyethylene (HDPE) ponds, which leads to increased production efficiency over traditional earthen ponds. The experimental observations recorded during the specified period can be utilized as reference by other entrepreneurs from the Konkan region of Maharashtra, as our findings provide them with the necessary information and knowledge to implement effective management practices for shrimp culture in the future.
This informative version of the original 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 “COMPARATIVE STUDY OF HYDROBIOLOGICAL PARAMETERS BETWEEN EARTHEN AND HIGH-DENSITY POLYETHYLENE (HDPE) BRACKISHWATER SHRIMP PONDS IN RATNAGIRI, MAHARASHTRA” developed by: Kawade, S.S. - College of Fisheries (DBSKKV) Ratnagiri Maharashtra; Sapkale, P. H. - Taraporevala Marine Biological Research Station; Sawant M.S. and Dhamagaye, H.B. - College of Fisheries (DBSKKV) Ratnagiri Maharashtra; Gangan, S.S. - Taraporevala Marine Biological Research Station and Chauhan, S. - College of Fisheries (DBSKKV) Ratnagiri Maharashtra. The original article, including tables and figures, was published on SEPTEMBER, 2024, through ENVIRONMENT AND ECOLOGY. The full version can be accessed online through this link: https://doi.org/10.60151/envec/ZKTJ1135
Innovating Sustainable Aquaculture:
Fishlab’s Pioneering Work in Live Feed and Fish Fry Production
* By Fishlab
Introduction
In the changing landscape of aquaculture, the demand for sustainable and scientifically grounded practices has never been more pressing. Fishlab, a Danish company established in 2004, is facilitating this evolution by merging
state-of-the-art research with practical solutions in fish fry cultivation and live feed production. With over two decades of experience, Fishlab has become a vital link between academic research and industry application, creating collaborations that drive innovation in aquaculture.
Advancing Fish Fry Production
Fishlab specializes in semi-extensive and intensive fish larvae production, offering comprehensive guidance on production planning, live feed cultivation, health monitoring, and disease prevention. Their expertise ensures high survival rates and robust
In the changing landscape of aquaculture, the demand for sustainable and scientifically grounded practices has never been more pressing. The Danish company Fishlab is facilitating this evolution.
growth in commercially cultured fish species. By integrating knowledge of water quality management, hatching strategies, and feed composition, Fishlab delivers tailored solutions that meet the specific needs of aquaculture operations.
Innovations in Live Feed: The Enchytraeus Initiative
Recognizing the challenges associated with traditional live feeds like Artemia, Fishlab, in collaboration with partners, is pioneering the use of Enchytraeus albidus (white worms) as a sustainable alternative. These terrestrial worms can be mass-produced using organic by-products from industries such as brewing and coffee production, aligning with circular bioeconomy principles. Notably, feeding juvenile fish with white worms has demonstrated up to a 200% increase in growth rates and reduced mortality, marking a significant advancement in aquaculture nutrition.
Collaborative Research Projects: DELIFEED and LiveFishHealth
Fishlab’s commitment to innovation is exemplified through its active participation in groundbreaking research projects:
» DELIFEED: This project aims to develop sustainable, nutritious, and immune-stimulating live feeds for juvenile farmed fish. By focusing on invertebrates like nematodes and white worms, DELIFEED seeks to replace suboptimal feeds, enhance fish health, and reduce antibiotic reliance in aquaculture. The consortium includes esteemed institutions such as Aarhus University, DTU, and Aalborg University, alongside Aquaculture partners in Denmark and Norway and live feed producers in Germany.
» LiveFishHealth: Addressing the absence of commercial vaccines for Rainbow Trout Fry Syndrome (RTFS), this project explores the innovative use of white worms
Fishlab delivers tailored solutions that meet the specific needs of aquaculture operations.
Juvenile turbot feeding on live Enchytraeus.
By focusing on terrestrial invertebrates like nematodes and white worms, DELIFEED seeks to replace suboptimal feeds, enhance fish health, and reduce antibiotic reliance in aquaculture.
Newly hatched turbot larvae produced by Fishlab and partner.
as vectors for oral vaccination. By feeding trout fry with worms containing inactivated RTFS bacteria, the approach aims to naturally stimulate the immune system, reducing disease-related losses and antibiotic treatments.
Strategic Partnerships and Industry Impact
Fishlab’s extensive network includes collaborations with universities, con-
sulting firms, and aquaculture companies.
Their role as a facilitator between research and industry ensures the practical application of scientific findings, creating advancements in live feed production and aquaculture practices. Accredited by DANAK in ISO 17025:2017, Fishlab upholds the highest standards in its services, reinforcing its reputation as a trusted partner in the aquaculture sector.
Conclusion
Through its dedication to scientific excellence and collaborative innovation, Fishlab is redefining sustainable practices in aquaculture. Their work in live feed development and fish fry production not only addresses current industry challenges but also sets a precedent for future advancements in aquaculture sustainability.
Fishlab and project partner observing live feeding of juvenile ballan wrasse in production tanks.
Alternative Strategies
to Combat Antibiotic-Based Treatment in Aquaculture
* By Kunal Samadhan Tayde, Nayan Chouhan, Manish Kumar and Bhavesh Choudhary
Introduction
The discovery of antibiotics in the early 20th century alleviated several life-threatening disorders (Kalia et al., 2007). Nearly a century later, the excessive and indiscriminate use of antibiotics has resulted in the formation of multiple drug-resistant (MDR) bacterial strains (Ciofu et al., 1994). The escalation of aquaculture to satisfy the growing demand for fish has resulted in the endorsement of circumstances conducive to the use of various chemicals and pharmaceuticals to combat microbial infections. Antimicrobials have significantly enhanced the health and well-being of animals; nevertheless, their effectiveness has been undermined by the evolution of antimicrobial resistance (AMR) in reaction to their use. The emergence of AMR in farmed fish is a significant concern in aquaculture. AMR is increasingly acknowledged as a significant worldwide public health issue, exacerbated by the indiscriminate use of antimicrobial drugs in both human and animal health, as
Antimicrobials have significantly enhanced the health and well-being of animals; nevertheless, their effectiveness has been undermined by the evolution of antimicrobial resistance (AMR) in reaction to their use. The emergence of AMR in farmed fish is a significant concern in aquaculture. Alternatives to antimicrobial treatments include effective husbandry, appropriate feed formulation, vaccinations, biological control agents, and immunostimulants.
well as their prevalence in the environment. The increased incidence of bacterial diseases in fish necessitates the frequent use of antibiotics, resulting in their persistence in aquatic ecosystems and thus fostering the emergence of antibiotic-resistant bacteria. AMR in aquaculture may be transmitted to clinically significant strains in the natural environment via horizontal gene transfer, conjugation, transmission, transduction therefore impacting the whole ecosystem.
Microbial resistance in aquaculture renders disease treatments ineffective, exacerbates disease severity, diminishes output, and results in economic losses. Furthermore, over fifty percent of the antimicrobials administered to animals and fish are excreted as waste, so polluting soil, water, and the environment. This also facilitates the evolution and dissemination of resistance by exerting selection pressure on environmental microbes. Many cultivated fish species, including ornamental varieties, harbour many infections that
demonstrate numerous antibiotic resistances. Furthermore, antimicrobial use may result in the presence of antimicrobial residues in consumable animal or fish products, posing a potential public health concern. The overuse of antibiotics in aquaculture has generated significant apprehension about antimicrobial resistance, environmental deterioration, and the disturbance of microbial ecosystems. To promote sustainable aquaculture and alleviate the detrimental impacts of antibiotic overuse, many alternative solutions have been investigated. This article emphasises potential alternatives to antibiotic therapy in aquaculture. Although chemicalbased medications are effective and beneficial, their usage results in environmental degradation and presents health risks to people upon consumption (Hoque et al., 2016). Alternatives to antimicrobial treatments include effective husbandry, appropriate feed formulation, vaccinations, biological control agents, and immunostimulants (Figure 1).
Prebiotics are a non-digestible food ingredient which when consumed shows beneficial effect on gut microbes. Probiotics are live advantageous bacteria that promote fish health when provided in sufficient amounts by battling with infections, enhancing digestion, and strengthening immune.
Prebiotics and Probiotics
Prebiotics are a non-digestible food ingredient which when consumed shows beneficial effect on gut microbes. It includes fructooligosaccharides and inulin, that enhance the proliferation of advantageous gut microbiota, hence indirectly augmenting disease resistance. Numerous prebiotics are often used in aquaculture, hence enhancing the immune systems of fish and other aquatic organisms. Prebiotics are sourced from several origins, including mannan oligosaccharides, fructo-oligosaccharides and galacto-oligosaccharides. Probiotics are live advantageous bacteria that promote fish health when provided in sufficient amounts by battling with infections, enhancing digestion, and strengthening immune. It aids in maintaining a balanced microbial ecosystem, especially inside the digestive tract, by fostering a healthy equilibrium of gut bacteria, enhancing digestion, and influencing immune system regulation. Probiotics often used in aquaculture include organisms
In aquaculture, phage therapy is gaining recognition as a viable alternative to antibiotics for addressing bacterial infections. Bacteriophages are viruses that exclusively infect and destroy bacterial pathogens.
from the genera Lactobacillus, Bacillus and Pseudomonas. The incorporation of prebiotics and probiotics into fish diets enhances and co-modulates the immune system.
Plant-Derived Compounds and Essential Oils
Plant-derived bioactive chemicals often known as phytobiotics provide antibacterial and immunostimulatory capabilities. These compounds are attractive supplements and alternatives owing to their efficacy, tolerability, environmental sustainability and reduced medication resistance. The use of polyphenols, polyphenolrich flora and plant-derived phenolic compounds to enhance aquatic animal health and wellbeing may represent viable ways for advancing pathogenic microbial mitigation strategy and ensuring the sustainability of the aquaculture sector. Numerous plants possess aesthetic appeal due to their diverse bioactive compounds, namely phytochemicals and polyphenols. Phytocompounds are bioactive substances present in several plant species and possess significant potential. Extracts from garlic (Allium sativum), neem (Azadirachta indica) and turmeric (Curcuma longa), etc. have shown effectiveness against fish infections without promoting AMR. The incorpo-
ration of aquatic plants in aquaculture may be the optimal solution to address these issues and advance sustainable aquaculture output (Hossain et al., 2024). Essential oils extracted from thyme, oregano, cinnamon and eucalyptus have antibacterial activities that suppress fish infections. according to several studies the integration of these compounds directly into feed formulations, bath and dip treatments helps mitigate disease without the danger of development of resistance.
Bacteriophage Therapy
Bacteriophages were identified and designated by Felix d’Herelle in 1917 (d’Herelle, 1961). Bacteriophages are the natural adversaries of bacteria and are efficacious in combating bacterial infections. In aquaculture, phage therapy is gaining recognition as a viable alternative to antibiotics for addressing bacterial infections. Bacteriophages are viruses that exclusively infect and destroy bacterial pathogens. This method is highly targeted, ecologically sustainable, and does not disturb advantageous microbial populations. The three predominant families of bacteriophages in aquatic ecosystems are Myoviridae, Siphoviridae and Podoviridae. In contrast to antibiotics, phages have a reduced issue of bacterial resistance. Bacteriophages provide a unique advantage over antibiotics by continuously multiplying at the infection site as long as the host bacteria are there (Choudhury et al., 2017). Phage treatment would be especially beneficial during the first phases of fish development, such as eyed-eggs and fry, which possess an underdeveloped immune system and are thus unable to use vaccinations (Bhat and Altinok, 2023). Phage treatment has shown efficacy against Aeromonas hydrophila, Vibrio spp, and several prevalent aquaculture diseases. Since 2011, phages have been regarded as a therapeutic agent in the United States (Fauconnier, 2019) or a pharmaceutical product in the European Union. A chemical or mixture of substances designed to cure, prevent, or diagnose a disease, or to restore, correct, or change physi-
ological functioning by pharmacological, immunological, or metabolic actions, as defined by the European Medicines Agency (EMA).
Immunostimulants
An immunostimulant is a naturally occurring chemical that enhances the immune system by augmenting the host’s resistance to diseases often induced by infections (Bricknell and Dalmo, 2005). Inactivated natural microorganisms or microbial derivatives, including beta-glucans, lipopolysaccharides, lactoferrin, nucleotides, chitin, fucoidan, peptidoglycans, and certain polysaccharides, might elicit immune system activation. Immunostimulants that may enhance and elicit a robust defensive response in the host include polysaccharides, hormones, vitamins, various bacterial components, physiologically active substances, traditional Chinese medicines, and synthetic pharmaceuticals (Kasahara & Sutoh, 2014; Buchmann, 2014; Shrestha et al., 2015). These chemicals enhance the capacity of fish to combat illnesses independently of antibiotics. Immunostimulants are essential for provoking immunological responses that may provide comprehensive protection against certain infections (Wang et al., 2017). The use of natural immunostimulants in aquafeeds to enhance immune response shows promise in augmenting disease resistance (Traifalgar et al., 2013).
Vaccination
Vaccination serves as a compelling strategy to prevent the onset of infections and diseases in people and animals, diminishing antibiotic use and hence hindering the formation and dissemination of resistance microorganisms. The mechanism through which vaccines diminish pathogens and AMR circulation markedly differs from that of antibiotics, leading to minimal selective pressure on microorganisms; consequently, the likelihood of resistant pathogen emergence is significantly lower compared to antibiotics (Murugaiyan et al., 2022). Vaccination offers enduring protection against bacterial and viral diseases. Vaccines provide a direct and indirect function in combating AMR. Vaccines directly impact resistant pathogens by decreasing infection rates and indirectly by diminishing the transmission of AMR-resistant strains to non-resistant species. A decreased prevalence of infections is associated with a lower prescription of antibiotics and a lowered occurrence of secondary infections and superinfections that would otherwise need extensive antibiotic use. Vaccines have been successfully produced for Aeromonas, Edwardsiella, and Streptococcus infections in aquaculture species. Progress in oral and immersion vaccinations is enhancing the feasibility of immunisation for extensive fish farming. Vaccine resistance has been recorded for
Immunostimulants that may enhance and elicit a robust defensive response in the host include polysaccharides, hormones, vitamins, various bacterial components, physiologically active substances, traditional Chinese medicines, and synthetic pharmaceuticals
many significant diseases, including the hepatitis B virus (Hoan et al., 2021) and Bordetella pertussis (Octavia et al., 2014).
Quorum Sensing (QS) Inhibitors
QS is a bacterial cell-cell communication system that regulates several processes, including biofilm formation, virulence gene expression and stress adaption. The process encompasses the synthesis, secretion and identification of extracellular signalling mol-
ecules known as autoinducers (Gupta and Kumar, 2022). Bacteria function as unicellular creatures at low cell densities; but they may alter their behaviour to a “multicellular” form upon detecting that their population density has reached a critical threshold. At this juncture, they convey information by diminutive signalling molecules, which facilitate the expression of genes associated with various phenotypes, including those governing their virulent behaviour. Opportunis-
tic pathogens such as Pseudomonas aeruginosa tend to remain “dormant” and postpone their virulent phenotype until their population reaches a level sufficient to surpass the host’s defence systems. The QS process can be impeded by various mechanisms: (i) diminishing the activity of AHL cognate receptor proteins or AHL synthases, (ii) obstructing the synthesis of QS signal molecules, (iii) degrading AHL, and (iv) mimicking signal molecules, primarily through the use of synthetic com-
pounds as analogues. Among several options, the enzymatic degradation of quorum sensing signal molecules (AHLs) has been the most recognised and used (Kalia and Purohit, 2011).
Metal-Based Antibacterial Agents
Historically, metal ions have often been used for antibacterial applications (Alexander, 2009). Metals may be complexed with a biomolecule, complexed with an antibiotic, or used with an antibiotic for antibacterial applications. The use of metal-based antibiotics has the benefit of varied mechanisms of action in contrast to traditional organic antibiotics (Simpson et al., 2019). Furthermore, the incorporation of metals into organic antibiotics allows innovative and supplementary mechanisms of action in contrast to the organic drug alone (Gasser, 2015). Consequently, the use of these metalbased complexes, either alone or in conjunction with antibiotics, shows potential as an efficacious therapy for resistant bacterial infections via innovative and supplementary mechanisms of action (Table 2).
Conclusion
The growing awareness of antibiotic resistance has accelerated the search for alternative strategies in aquaculture. Probiotics, phytobiotics, bacteriophage therapy, immunostimulants, vaccination, and essential oils are emerging as effective solutions. A combination of these approaches, tailored to specific aquaculture systems, can significantly reduce dependence on antibiotics while ensuring sustainable fish production. Several methods discussed here are still in research phase, while some are tested in real aquaculture farm settings. Therefore, it is essential to advance several techniques that may be integrated or used in succession to optimise the likelihood of effectively safeguarding the animals and to avert the development of resistance.
References and sources consulted by the author on the elaboration of this article are available under previous request to our editorial staff. Kunal Samadhan Tayde, Nayan Chouhan, Manish Kumar and Bhavesh Choudhary College of Fisheries, Central Agricultural University, Lembucherra, Tripura, 799210 Email: nayan101chouhan@gmail.com
Interview with Eduardo Del Castillo, Commercial Director of ETEC Revolutionizing Aquaculture
Pumping: ETEC and the Power of Floating Pumps
Discover how ETEC is changing the rules of the game in the shrimp farming industry with exclusive technology, all-inclusive service, and a strong presence across Latin America.
* By Salvador Meza
Salvador Meza: Eduardo, welcome. For those less familiar with ETEC, can you summarize the company’s global reach?
Eduardo Del Castillo: We started in Colombia nearly 40 years ago,
where we continue to operate our production plant. Today, we are also present in Mexico, Ecuador, and Central America, with our corporate headquarters based in Panama. Our projects extend to Saudi Arabia, Oman, New Caledonia, Iraq, Egypt,
and beyond. Wherever there’s a need to move large volumes of water, that’s where we are.
Salvador Meza: One of your most innovative concepts is floating pumps. What makes them unique in the shrimp farming industry?
We are the only company that manufactures and installs floating pumps for shrimp farms.
Eduardo Del Castillo: ETEC floating pumps are portable, modular, and 100% relocatable solutions—ideal for bodies of water with variable levels and unstable terrain. They adapt to tidal fluctuations, minimize the need for civil works, and operate efficiently
in environments impacted by climate change. Quick to install and requiring minimal structural intervention, they deliver high operational efficiency. Perfect for aquaculture, these are not pontoons or barges with pumps installed, they are fully integrated, self-
contained units, it adapts to tides, eliminates heavy civil works, and is fully relocatable.
Salvador Meza: That must have a big operational impact. What about the costs?
Producers
no longer buy pumps—they rent a complete pumping service from us.
Eduardo Del Castillo: It’s a triple win, it saves on three fronts: initial investment, operational efficiency, and maintenance. Most importantly, it’s a mobile asset. If you sell your farm or move, you take your pump with you. It matches vertical pumps in efficiency but offers far more in flexibility, additional benefits and added value.
Salvador Meza: Another standout is your all-inclusive service model. Tell us about that.
Eduardo Del Castillo: Three years ago, we launched a full-service rental program. We rent the pump, install it, handle all preventive and corrective maintenance, and replace it if need-
ed. The client focuses on growing shrimp; we take care of all the pumping. It’s been extremely well received.
Salvador Meza: What benefits have producers found with this model?
Eduardo Del Castillo: Peace of mind. Many farms have pumps out of service for weeks. With us, uptime is over 95%. Every 45 days we inspect the equipment, change oil and filters, and deliver predictive maintenance reports. It’s about outsourcing what doesn’t directly generate value in shrimp production.
Salvador Meza: In addition to efficiency, you maintain local operations. Why is that key?
Eduardo Del Castillo: Being close makes all the difference. No one wants to invest in equipment without local support. We have staff and infrastructure in Mexico, Ecuador, Central America, and Colombia. We move fast. For us, after-sales support is just as critical as the product itself.
Salvador Meza: In terms of adoption, what’s the ratio between floating and vertical pumps today?
Eduardo Del Castillo: Right now, about 65–70% of our pump sales in Latin America are floating pumps. More and more producers are choosing mobility, efficiency, and no civil works.
Salvador Meza: Can you share a success story?
A floating pump is installed in 10 days; a fixed station can take up to 18 months.
Eduardo Del Castillo: In Saudi Arabia, a farm needed 100 m³/s of pumping capacity. Civil works would’ve taken 18 months. With our floating pumps, they had 25 m³/s installed and operating in just 10 days. Now their entire water system is based on floating pumps.
Salvador Meza: Lastly, what’s ETEC’s vision for 2030?
Eduardo Del Castillo: To be the leading company in large-scale water management solutions. Not just pumps, we also offer farm design, harvesters, recirculation systems, and more. We innovate and support
our clients from design to operation, delivering exceptional after-sales service that ensures our products perform at their best every step of the way.
ETEC isn’t just selling equipment—it’s delivering peace of mind, efficiency, and a future-ready model. With proprietary technology, fullservice support, and local presence, it is redefining aquaculture pumping across Latin America.
Anaerobic Degradation of Excess Protein-Rich Fish Feed Drives CH4 Emissions in Aquaculture Systems
* By Aquaculture Magazine Editorial Team
Methane (CH4) is a potent greenhouse gas, with atmospheric concentrations nearly tripling since pre-industrial times, now contributing about 25% of total atmospheric warming. Freshwater ecosystems are increasingly recognized as significant CH4 sources. In these environments, CH4 is primarily produced in sediments through methanogenesis, influenced by temperature, redox conditions, and the availability and quality of organic matter. CH4 reaches the atmosphere either via diffusion or ebullition (gas bubble release). Ebullition is particularly dominant in shallow, organic-rich systems where gas bubbles bypass oxidation in the water column, accounting for up to 80-90% of CH4 emissions.
Aquaculture ponds, which span over 8 million hectares globally, are such hotspots. These systems promote methanogenesis due to the input of biodegradable organic matter from uneaten feed, feces, and primary production. The highest recorded CH4 ebullition rate was recently reported at a fishpond feeding site. CH4 ebullition correlated more strongly with pore water-bound nitrogen (N) and dissolved organic carbon (C) than with solid-phase sediment content, highlighting the role of organic matter quality.
To characterize this quality, ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), combined with high-performance liquid chromatography (LC), enables detailed profiling of molecular formulas (MF) in complex mixtures like water-extractable organic matter (WEOM).
This study investigates WEOM from fishpond sediment to explain high CH4 ebullition rates, comparing the feeding site to open water. Anaerobic protein degradation pathways, potentially limits by hydrolysis, may lead to accumulation of intermediates at feeding sites. This analysis aims to support improved management strategies for reducing CH4 emissions from aquaculture.
Excessive use of protein-rich fish feed in aquaculture ponds significantly drives methane (CH4) emissions, mimicking biogas reactor conditions. This study reveals how anaerobic protein degradation produces nitrogen and sulfur rich compounds that fuel CH4 ebullition, with rates up to 155 times higher at feeding zones. By analyzing organic matter composition, the findings offer insight into greenhouse gas generation in aquaculture and the urgent need for more sustainable feed management strategies.
Methods
The study was conducted in Gerstenteich, a 2.5 ha freshwater pond near Bautzen, Germany, with a mean depth of 1.2 ± 0.3 m. The pond has been used for aquaculture for over 400 years. In March 2021, it was semiintensively stocked with 580 kg ha-1 of two-year-old catfish: Silurus glanis and Tinca tinca. A stationary automatic pellet feeder, dispensing feed with 45% protein, was located at the deepest point (1.65 m). By October 2021, 4,000 kg ha-1 of feed yielded 1,600 kg ha-1 of fish biomass. No fertilization, aeration, or dredging had occurred in the past three years. The pond had no significant surface water inflow/outflow and supported submerged vegetation and phytoplankton, surrounded by a littoral belt of reeds and trees.
Ebullition was previously studied in September 2021, revealing the highest recorded CH4 ebullition rate of 1,238 mmol m-2 d-1 at the feeding site (F1), dropping to 8 ± 7 mmol m-2 d-1 beyond 20 m. Thus, the pond was divided into “feeding area” (F1-3) and “open water area” (W1-9). During the 8 months cycle, 85% of C input derived from protein-rich feed. Pore water total bound N and dissolved C strongly correlated with CH4 ebullition (R2=0.98 and 0.92), unlike solidphase sediment contents.
Fieldwork involved sediment sampling (top 5 cm) using a gravity corer, with anaerobic transport in Anaerocult® A bags. Due to precipitation in acidified pore WEOM was extracted from freeze-dried sediment using ultra-pure water, then shaken and centrifuged. Aqueous extracts were filtered (0.45 µm), diluted 1:10, and analyzed via LC-FT-ICR MS.
The LC setup included a reversedphase polar C18 column and mobile phases of ultrapure water and methanol, both acidified with 0.05% formic acid. The LC-FT-ICR MS system used electrospray ionization (ESI) in negative mode with high-resolution mass detection (m/z 147-1,000). Mass spectra were segmented into five retention time intervals, averaged, recalibrated, and assigned MFs based on stringent elemental and double bond equivalent (DBE) criteria.
MFs found in at least two-thirds of feeding area (F) or water area (W) samples were grouped into average spectra “F” and “W.” Peak magnitude changes (δRAW) indicated enrichment or repletion of compounds. Wilcoxon and t-tests were used to assess differences in sediment protein, sulfur (S), and MF classes between areas. Correlation between CH4 ebullition, sediment protein, and MF abundances were analyzed using R software for statistical evaluation and visualization.
Results and Discussion
Protein-rich feed as a driver of methane (CH4) ebullition
In the aquaculture pond Gerstenteich, protein content in sediments peaked in the feeding zone (F1) at 118.0 mg/g and declines to 33.4 ± 5.9 mg/g in open waters (Figure 1). These values surpass those reported in other eutrophic marine and aquaculture settings. The scarcity of freshwater data on sedimentary protein is likely due to the rapid degradation of proteins in natural ecosystems though aquaculture ponds, enriched by feet inputs, exhibit significantly higher nutrient loads.
Proteins accounted for 34.5% to 66.1% of organic matter depending on the site, confirming enrichment from the 45%-protein feed used. It is estimated that 4,500 kg of protein were added over the growing season, equating to approximately 720 kg of nitrogen. However, only 25% of feedN is typically assimilated by fish, leaving 540 kg to return to the ecosystem primarily through feces mostly in a dissolved, microbially accessible form.
Given the fish biomass and feed conversion, about 50% of the feed-N, especially protein-N, is lost to eutrophication and sediment accumulation. This inefficiency aligns with prior findings from similar systems, where only a quarter of nutrients translate into biomass. The result is heavy sedimentation (up to 3.7 cm/ year) and high nitrogen content, consistent with observed values at Gerstenteich.
Significantly, sediment protein levels strongly correlated with CH4 ebullition (R2 = 0.58). Proteins, while initially undigestible by microbes, undergo anaerobic degradation, producing monomers like amino acids, which are transformed into ammonium and volatile fatty acids, eventually fueling CH4 production. The strong link between porewater nitrogen and CH4 ebullition (R2 = 0.98) suggest that the quality specifically nitrogenrich, labile organic matter drives microbial methanogenesis. This ex-
Freshwater ecosystems are increasingly recognized as significant CH4 sources. In these environments, CH4 is primarily produced in sediments through methanogenesis, influenced by temperature, redox conditions, and the availability and quality of organic matter.
To understand the composition of the organic matter responsible for CH4 production, researchers analyzed WEOM using LC-FT-ICR MS. The majority of compounds belonged to CHNO (35%), followed by CHOS (27%), CHNOS (22%), and CHO (15%). CHNO compounds were significantly more abundant in feeding areas (Figure 2).
A van Krevelen diagram revealed clear differences in molecular structure between feeding and open water zones. Unlike most natural organic matter, which contains up to three nitrogen atoms, the feed-derived CHNO compounds often contained up to eight nitrogen atoms suggesting the presence of oligopeptides (short chains of amino acids). ChemSpider database matches confirmed the presence of such protein fragments, particularly in the feeding zone.
δRAW indicated a higher relative abundance of CHNO, CHNOS, and CHOS in feeding areas, CHNO com-
The strong link between porewater nitrogen and CH4 ebullition (R2 = 0.98) suggest that the quality ─ specifically nitrogen-rich, labile organic matter ─ drives microbial methanogenesis. This explains Gerstenteich´s extremely high CH4 ebullition rates, reaching 1,238 mmol m-2d-1.
pounds with more nitrogen atoms were especially abundant and associated with higher molecular masses (e.e., CHN1O: 342 Da vs. CHN8O: 630 Da), supporting the presence of longer oligopeptides. These protein-like compounds correlated strongly with CH4 ebullition.
While CHN1O and CHN2O compounds were less abundant, likely due to their rapid degradation by microbial exoenzymes in the feeding area, larger oligo peptides persisted due to constant feed input. The microbial community seems adapted to maintain high enzymatic activity, facilitating the break down of feed pro-
teins and contributing to CH4 generation.
Sulfur-containing compounds (CHOS, CHNOS) also showed increased intensities in the feeding area, accounting for ~50% of total detected organic matter. Although solid-phase sulfur levels were similar throughout the pond, only the feeding area has detectable sulfate in porewater, suggesting localized resuspension and oxidation of sulfur compounds due to fish activity.
High levels of CHOS and CHNOS compounds often formed through abiotic sulfurization in anoxic environments ─ were found. Some
compounds, like C8H13N103S1 likely originated from sulfurized oligopeptides. Their presence, even 83 meters from the feeding area, indicates widespread impact of localized feed inputs on the pond´s organic matter.
Implications for a more climate-friendly aquaculture
Aquaculture is promoted as a sustainable alternative to wild fisheries, yet current practices particularly the excessive use of protein-rich feed ─ have environmental downsides. These include organic matter accumulation, anoxic sediment conditions, and elevated emissions of
greenhouse gases like CH4 and carbon dioxide (CO2). In Gerstenteich, CH4 ebullition in the feeding area was 155 times higher than in open waters, driven largely by protein degradation by products.
Methane emission in this zone accounted for 98% of total pond CH4 release, with bubble gases even containing high levels of CO2 unusual outside of biogas reactors. This highlights the extreme microbial activity induced by unbalanced protein inputs, essentially mimicking biogas fermentation conditions.
The observed CH4 ebullition rate (1.24 mol m-2d-1) is unprecedented in natural or aquaculture systems. Literature on biogas suggests that protein hydrolysis is the rate-limiting step in methane production. Here, >100-fold higher oligopeptide intensities at the feeding site support that analogy and emphasize the urgent need for more sustainable practices.
Scientific evidence indicates that high protein feed is often unnecessary and may even hinder fish growth. Salmon aquaculture has demonstrated that lowering protein content and optimizing feed composition improves efficiency and reduces environmental damage. Likewise, the considerable variability in greenhouse gas emissions across aquaculture systems shows that climatefriendly models are feasible.
Alternative technologies like biofloc systems, which enhance protein use efficiency and reduce organic waste, may offer a more sustainable path. However, further research is needed to evaluate their climate impact. Adjusting feed strategies and improving management practices could drastically reduce eutrophication and greenhouse gas emissions in aquaculture.
Conclusion
Aquaculture is a climate-relevant source of greenhouse gases like CH4 CH4 emissions from aquaculture systems are heterogenous and depend on various parameters, with organic matter quality playing a crucial role.
Nevertheless, little is known about the molecular composition of organic matter in aquaculture systems and the influence of applied fish feed. We investigated the effects of excessive loading of high-protein fish feed pellets on sediment organic matter quality using a transect from the stationary feeding site to the center of am temperate, semi-intensively managed fishpond to explain the extremely high CH4 ebullition rates (bubble flux) measured. Analyzing the molecular composition of water-extractable organic matter with LC-FT-ICR MS, we found a strong enrichment of low-molecular weight nitrogen and sulphur-rich organic compounds at the feeding area compared to the open water area. The measured CH4 ebullition correlated well with sediment protein content and total bound nitrogen in the pore water. In addition, Spearman rank correlation analysis evidenced that high protein-like component abundance drove CH4 ebullition. The results indicate that feed proteins were hydrolyzed to oligopeptides (CHNO) and drove methanogenesis resulting in CH4 ebullition rates of 1.24 mol m-2 d-1 at the feeding site. In addition, subsequent conversion to CHOS and CHNOS components during anaerobic deamination of protein and peptide fragments in the presence of inorganic sulphides was indicated. These metabolites accumulated at the feeding area due to continuous feed supply. The findings illustrate the adverse effects of excessive protein feeding leading to bioreactorlike CH4 emissions and provide new insights into the composition and transformation of organic matter in aquaculture systems. Aquaculture is an important contributor to global food production but often involves excessive feeding with expensive, protein-rich feeds. Improving feed management has the potential to make aquaculture more climatefriendly and sustainable and, with our study, we hope to provide further incentives to rethink aquaculture feed management.
In Gerstenteich, CH4 ebullition in the feeding area was 155 times higher than in open waters, driven largely by protein degradation by products.
This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “N ANAEROBIC DEGRADATION OF EXCESS PROTEIN-RICH FISH FEED DRIVES CH4 EBULLITION IN A FRESHWATER AQUACULTURE POND ” developed by: Waldemer, C. - Department Lake Research, Helmholtz Centre for Environmental Research-UFZ; Lechtenfeld, O. and Gao, S. - Helmholtz Centre for Environmental Research-UFZ; Koschorreck, M. and Herzsprung, P. - Department Lake Research, Helmholtz Centre for Environmental Research-UFZ. The original article, including tables and figures, was published on SEPTEMBER 2024, through SCIENCE OF THE TOTAL ENVIRONMENT. The full version
SCA:
Women & Children First
* By Seafood Consumers Association
Women, particularly during pregnancy and lactation, as well as young children, are vulnerable populations whose diets should be emphasized to ensure adequate nutrient intake while mitigating potential health risks from environmental contaminants (FAO, 2023).
The significance of seafood in dietary practices for women and children cannot be overstated. The newly formed Seafood Consumers Association recognizes this as an essential area for concentration.
Seafood is widely recognized as a rich source of essential nutrients, including omega-3 fatty acids, which are crucial for cognitive and physical development in children (Hibbeln et al., 2019; Méndez et al., 2009). Consumption of fatty fish has been positively correlated with neurocognitive development in offspring (Hibbeln et al., 2019; Méndez et al., 2009), which is particularly important for pregnant women seeking to enhance fetal growth and brain development (Oken et al., 2008; Oken, 2004).
Guidelines often caution women of childbearing age against consuming certain seafood high in mercury, which can adversely affect both maternal and child health (Oken et al., 2005; Zilversmit et al., 2017). This duality — promoting seafood for its benefits while addressing concerns over
The necessity for seafood-focused education tailored for women and children arises from the intricacies of nutritional needs, consumption habits, and health risks associated with seafood intake.
mercury exposure — highlights the need for focused educational interventions that clarify safe seafood consumption practices.
Whilst completely understanding the precautionary principle we need to understand the consequences of such warnings.
In the document “Total Mercury Exposure in Early Pregnancy Has No Adverse Association with Scholastic Ability of the Offspring Particularly If the Mother Eats Fish” (Hibbeln et al. 2018) it states categorically:
“There is a public perception that relatively low doses of mercury found in seafood are harmful to the fetal brain but little consistent evidence to support this. In earlier publications we have shown no adverse associations between maternal total blood mercury levels and child behavior, early development or cognitive function as measured by IQ. However, for IQ the lack of adverse association was conditional upon the mother being a fish eater.”
Additionally, according to the World Health Organization, “Women die as a result of complications during and following pregnancy and childbirth. Most of these complications develop during pregnancy and most are preventable or treatable. Other complications may exist before pregnancy but are worsened during pregnancy, especially if not managed as part of
the woman’s care. The major complications that account for around 75% of all maternal deaths are:
» Severe bleeding (mostly bleeding after childbirth)
» Infections (usually after childbirth)
» High blood pressure during pregnancy (pre-eclampsia and eclampsia)
» Complications from delivery
» Unsafe abortion.”
The WHO in this area make NO mention whatsoever of mercury or other environmental causes creating issues for pregnant women. This highlights how much education is a critical role in shaping dietary behaviors.
Selenium: Nature’s Safeguard in Ocean Fish
Ocean fish are often scrutinized for their methylmercury content, but research led by Dr. Nicholas Ralston has shown that this concern needs important context. Selenium, a trace element abundant in many ocean fish, plays a critical protective role. Ralston’s studies demonstrate that selenium binds with mercury in the body, forming biologically inert compounds that prevent mercury from interfering with essential enzymes and brain function.
The key measure is the Selenium Health Benefit Value (HBVSe) — a ratio of selenium to mercury in seafood.
There is a public perception that relatively low doses of mercury found in seafood are harmful to the fetal brain but little consistent evidence to support this. In earlier publications we have shown no adverse associations between maternal total blood mercury levels and child behavior, early development
Most ocean fish, including tuna, sardines, and snapper, have HBVSe values above zero, meaning they contain more selenium than mercury and are therefore safe — even beneficial — to consume. In fact, avoiding these fish for fear of mercury may do more harm than good, especially in populations needing selenium for brain development, such as pregnant women and children.
Ralston’s work urges a shift in public messaging: it’s not just about mercury levels, but the selenium-mercury relationship. When viewed through this lens, responsibly sourced ocean fish emerge not as a threat, but as vital, nutrient-rich foods that protect and nourish human health.
Research indicates that higher education levels are linked to better nutrition knowledge and increased seafood consumption, suggesting that improving educational outreach could effectively enhance dietary habits, especially among women and children (Govzman et al., 2020). Unfortunately, many women lack awareness regarding the types of seafood that are both healthy and beneficial.
For instance, a study demonstrated that pregnant women significant-
ly reduced their seafood intake due to perceived health risks from contaminants, often substituting seafood with less nutritious options (Oken et al., 2005; Zilversmit et al., 2017). Thus, the development of educational tools must address misconceptions about seafood safety, nutritional value, and preparation techniques to encourage regular intake (Christenson et al., 2017; Burns et al., 2024).
Additionally, barriers such as lack of culinary confidence among parents can hinder children’s seafood consumption (Burns et al., 2024; McManus et al., 2007). Educational programs that provide cooking demonstrations, easy recipes, and information on sourcing sustainable seafood could empower families to incorporate more seafood into their diets. Programs addressing these educational needs are neces-
From Globefish Navigating Global Fish Trade Products presentation 9 June 2025 highlighting seafood consumption across the globe.
Chinese boiled feed-based red swamp crayfish culture. (Photo courtesy of Lukas Manomaitis, Seafood Consulting Associates).
An Ode to the Ocean and Those Who Taste Its Gift
(for World Oceans Day – June 8, 2025)
O mighty blue, deep-breathing sea, You cradle life so endlessly. From hidden reefs to distant shoal, You feed the body, stir the soul.
Your waters teem with silver grace, A fleeting catch, a fragile place. You give us food, you give us air — Yet ask we only that we care.
Each bite we take, each fish we choose, Can heal your wounds or make you lose. So let us honour all you give, And change the way we eat — and live.
We stand in wonder, hand in hand, Consumers walking on the land. But in our hearts, the ocean makes a call Sustain the sea, or see it fall.
Seafood Consumers Association (www.seafoodconsumers.global)
sary to break down resistance stemming from negative perceptions of seafood, such as taste aversion during meal preparation or lack of familiarity (McManus et al., 2007).
To further reinforce these educational tools, evidence suggests that maternal seafood intake during pregnancy directly influences childhood development (Hibbeln et al., 2019; Méndez et al., 2009). Women who consume varied types of seafood are more likely to have children with improved cognitive development outcomes (Hibbeln et al., 2019; Oken, 2004). Hence, targeted education that emphasizes the benefits of seafood together with context-specific guidance explaining the risks vs benefits in different fish species can create a comprehensive strategy to promote seafood consumption among women and children globally.
In summary, the demand for a seafood-focused educational tool stems from the critical need to balance the nutritional benefits of seafood with the risks associated with contaminants. Such tools must be developed through a framework that acknowledges the barriers faced by women and children and empowers them to make informed seafood choices for improved health outcomes.
The Five Most Important Issues for Board of Seafood Consumers Association
The Seafood Consumers Association (SCA) has been formed to be proactive in this area plus lifting the standards in many areas of the seafood industry worldwide. The website (www.seafoodconsumers.global) has been designed to engage consumers and share information and knowledge to eliminate the ‘fog’ that is often created due to ignorance floating in social media.
The SCA Board is building programs around company objectives and is aligning them with UN Sustainable Development Goals (SDG’s):
Consumer Education and Advocacy
» Everything SCA does should be about education – ensuring seafood consumers have facts and
information that enable them to make informed choices.
» Common language: taking the jargon out of the equation. Creating clear language on each issue.
» Educating consumers about food safety, health benefits/potential risks and sustainable seafood choices.
» Advocacy: Representing consumer interests in policy discussions and regulatory decisions related to seafood production and trade. Attempting to take unnecessary costs out of the systems thus making seafood more affordable for all. Support and promote initiatives that address food security and nutrition through seafood consumption. costs out of the systems thus man.
Transparency and Traceability
» Supply Chain Transparency: SCA want clear information about where and how seafood is caught or farmed which includes labeling accuracy guaranteeing that seafood labels accurately reflect the species and origin.
» Traceability: Promotion of systems that allow consumers to trace the journey of seafood from the water
to their plate, ensuring accountability and trust in the chain.
» Fraud: We want to see CADMUS introduced in all legislation and businesses as SCA want to be a catalyst for eliminating the USD 160 billon seafood fraud industry.
» CADMUS training: C-Counterfeit A-Additions D-Dilutions M-Misrepresentation U-Undisclosed and S-Substitution.
Health and Safety
» Food Safety: Ensuring that seafood is handled, processed, distributed and stored properly to prevent foodborne illnesses.
» Health Benefits: the most nutritious product you can put in your mouth! Detailing the facts.
» Health Risks: Monitoring and understanding all issues relating to issues that may impact seafood eating risks – explaining contaminants like mercury/ PCBs, etc.; Parasites; microplastics in seafood, and Seafood Allergies.
Sustainability & Environmental Impact
» Explaining all issues like Overfishing; Bycatch and Habitat Destruc-
tion, etc., as part of the common language process.
» Explaining Certification Programs: the history; the costs v benefits; relevancy and confusion. We will advocate for minimal number of programs to eliminate the confusion.
Ethical Labor Practices
» Promote Fair Labor Conditions: Ensuring that workers in the seafood industry are treated fairly, paid adequately, and work in safe conditions.
» Advocate against Forced Labor: Addressing issues of human trafficking and forced labor in the seafood supply chain.
If you are interested in working with SCA on these lofty goals then please connect with them directly (email: seafoodsdg@outlook.com) and let us hope that SCA can create some energy and be the answer to the missing link that has existed.
This photo is from same presentation as 1 Highlights the increasing importance of the seafood industry in proving employment and livelihood, especially women in aquaculture and secondary sector.
Microalgae Aquaculture: Growing the Next Generation of Painkillers
Millions of people suffer from the devastating effects of opioid addiction, so finding alternative ways to manage pain is a global priority. It may seem unlikely, but a toxic microalgae — a former villain, now potential hero — could help reduce our reliance on opioids in the future. Below I explain how farming a specific microalgae through aquaculture could produce a powerful, non-addictive painkiller.
* By Dr. Johan Svenson
Millions of people suffer from the devastating effects of opioid addiction, so finding alternative ways to manage pain is a global priority. It may seem unlikely, but a toxic microalgae — a former villain, now potential hero — could help reduce our reliance on opioids in the future.
Below I explain how farming a specific microalgae through aquaculture could produce a powerful, non-addictive painkiller.
Aquaculture of finfish, shellfish, macroalgae, and emerging low-trophic species is a growing global industry, offering sustainable, low-carbon food sources. Microalgae aquaculture
is gaining attention as a land-based source of proteins and lipids, but its development is still constrained by high production costs and technical challenges associated with scaled production. As a result, global microalgae production remains relatively small.
Microalgae and cyanobacteria (photosynthetic bacteria) are fasci-
A single dose of neosaxitoxin, combined with adrenaline and the approved anesthetic bupivacaine, could provide up to 72 hours of pain relief. The compound is so potent that one gram is enough for a staggering 25,000 doses — a remarkable achievement.
nating organisms that sit at the base of the marine food web, using sunlight to generate both nutrition and oxygen — a vital function for life on Earth. However, under certain environmental conditions, some species of freshwater and marine microalgae produce harmful algal toxins during what are known as harmful algal blooms
(HABs). These toxins vary in form, and some — such as ciguatoxins, saxitoxin, and microcystins — are among the most potent known to science.
Shellfish, which are filter feeders, can accumulate these toxins. When consumed by humans through contaminated seafood or water, they can cause serious illness or even death.
Fortunately, scientists closely monitor these species, and any microalgae grown for consumption are rigorously screened to ensure they are safe and non-toxic.
With that in mind, it may seem surprising that a team of scientists at Cawthron Institute in New Zealand is actively scaling up aquaculture of one
The team is farming Alexandrium pacificum, a dinoflagellate commonly linked with HAB events in the South Pacific and responsible for many cases of seafoodrelated poisoning.
of these toxic species in large, shiny photobioreactors. The team is farming Alexandrium pacificum, a dinoflagellate commonly linked with HAB events in the South Pacific and responsible for many cases of seafoodrelated poisoning. Ingesting this algae would be dangerous — luckily, that’s not the purpose of the farming. Cawthron scientists, who have spent decades studying HABs, are well
aware of the toxic cocktail this algae can produce. In fact, those very toxins are the reason they’ve chosen to grow it at scale.
To understand why, we need to take a step back and explore the world of drug discovery. Simplified, modern medicine is based on synthetic compounds and bioactive compounds from nature with an ability to cure or prevent diseases. Initially, all drugs were derived from natural products and these compounds still play a big role, despite the development of modern synthetic chemistry, computational chemistry and AI. Currently, about one third of all approved drugs are derived from natural compounds and their contributions is even more pronounced in the fields of antibiotics and cancer. Mother Nature is unrivalled in coming up with exciting chemistries and unexpected bioactivities. Natural toxins and venoms are produced for defensive purposes or for hunting, and while they are certainly not originally designed to be neither beneficial or helpful, some of them have pharmacological properties that allows them to be used in
medicine. Examples include snake venom derived drugs against high blood pressure as well as marine drugs against cancer and pain.
The Opportunity
This brings us to algal toxins. Many of these compounds work by blocking ion channels — protein pores in our cells that regulate essential functions by allowing ions to flow in and out. Block the wrong one, and the results can be fatal: paralysis, loss of breathing, or cardiac arrest. This is how many HAB-related toxins affect the body.
But not all ion channels are created equal, and not all toxins act indiscriminately. Some show a preference for certain channels over others, which opens the door to selective medical use. For example, a toxin might block pain-sensing nerve receptors (nociceptors) without interfering with other vital systems. One such compound is neosaxitoxin — a relative of the potent algal toxin saxitoxin, which is an effective sodium channel blocker.
This discovery — that neosaxitoxin can block pain signals in sensory neurons — sparked interest among scientists from the Chilean company Proteus, Boston Children’s Hospital, and Harvard Medical School. Their early research showed neosaxitoxin was a promising treatment for post-operative pain when used in combination with adrenaline and the approved painkiller bupivacaine: long-lasting, localized, with no systemic side effects, and crucially, non-addictive. This makes it a compelling alternative to opioids.
A single dose of neosaxitoxin, combined with adrenaline and the approved anesthetic bupivacaine, could provide up to 72 hours of pain relief. The compound is so potent that one gram is enough for a staggering 25,000 doses — a remarkable achievement.
The Challenges
So why isn’t this compound being used in drugs already if these initial promising discoveries were made and published almost two decades ago?
There are several reasons. First, any drug must pass through stringent clinical trials to show safety and function. To conduct those trials, you need access to reliable, pure material — something that’s been extremely difficult for neosaxitoxin. While it’s a small molecule, it is chemically complex and has proven difficult to synthesize in useful quantities.
Early trials relied on toxins extracted from contaminated shellfish, but this is not a scalable or reliable method. The complexity of the molecule has also prevented cost-effective production using recombinant or microbial fermentation technologies.
Even more challenging is the fact that algae produce these toxins as part of a chemical cocktail — a mix of compounds so similar it becomes difficult to isolate pure neosaxitoxin. So, is the idea dead in the water?
The Solution: Microalgae
Aquaculture
Not quite. This is where Cawthron’s team devised a clever workaround.
Rather than isolate neosaxitoxin directly, they found a way to extract and isolate a more abundant compound — gonyautoxin 1,4 (GTX-1,4) — from the algal mixture and convert it into neosaxitoxin through a single, targeted chemical step. This semisynthetic route made large-scale production theoretically viable, but only if Alexandrium pacificum could
be reliably domesticated and grown at scale.
As anyone familiar with aquaculture knows, domesticating a new species is no easy task and toxic marine microalgae are no exceptions. The team began by screening Cawthron’s national microalgae collection to identify a strain that could grow efficiently and produce large quantities of GTX-1,4. This was done at a small scale (200 mL), eventually yielding a strong candidate strain.
With the right strain selected, the next hurdle was scaling up. While some researchers have grown dinoflagellates in lab-scale volumes (litres), few have succeeded at large scale. Strict control over growth conditions is essential for pharmaceutical production, so natural seawater couldn’t be used given the associated natural variability and risk of contamination. Instead, the team developed a custom artificial seawater solution prepared in-house — no small feat, since dinoflagellates typically dislike artificial media. Growth and toxin yields had to be meticulously optimized to generate a satisfactory yield.
Light and temperature, being key to photosynthesis, also had to be finely tuned. After extensive experimentation, the team succeeded in producing dense cultures with toxin concentrations 30 times higher than in natural algal blooms.
The result? A reliable, scalable process producing 1–1.5 grams of GTX-1,4 from a single 1,250-litre photobioreactor every two weeks.
This perhaps doesn’t sound like much but given that the global demand is estimated at 500–1,000 grams annually, this process could supply both clinical trials and future commercial production. It also shows that aquaculture is about more than fish, mussels, and seaweed — we’re only beginning to unlock its full potential.
Will This Be the Next Paracetamol?
Neosaxitoxin is a highly potent, watersoluble drug lead designed for hospital use only. It must be injected and is co-administered with other compounds, so it won’t replace over-thecounter options — but it could offer a game-changing option for post-surgical pain relief by dramatically reducing the need opioid pain medications.
The compound has successfully completed Phase 1 clinical trials. Now, the Cawthron team and its partners, including AlgavitaBio Inc., a U.S. based biotechnology company, are working to secure funding for Phase 2 — a crucial step toward turning this promising compound into a realworld solution for pain.
* By Antonio Garza de Yta, Ph.D.
My grandfather had a saying that was very true: “The more noise a cart makes, the less load it carries.”
Since I never saw many carts in my life, perhaps I did not give that wise saying the importance it deserved. Now, when I see what happens daily with social media and aquaculture, I appreciate the saying more. I see people who do nothing but spend their time on social media writing blogs and commenting on everything. That would be fine if they weren’t doing it with a hidden agenda. Unfortunately, they usually aim to sell us something that is often unsound, both scientifically and financially.
How to Survive in the Age of “Influencers” and “ExcelSheeters”
I agree that all companies must have a promotional phase. However, when a company or technology suddenly appears everywhere and is presented as the best, most innovative way to produce something that breaks all paradigms, it’s wise to exercise caution before investing in that technology or changing our approach. Recently, the reputation of aquaculture has been severely damaged by these incredible projects that include all the right buzzwords to satisfy international organizations and financiers: sustainable ecosystems, resilience, adaptation to climate change, blue jobs, inclusivity, and improved quality of life.
All of that is necessary. I say this from the bottom of my heart. However, hearing all of that together only means that the project lacks substance or that the promoter is not from the aquaculture sector. This is where the “excelsheeters” come in. A friend taught me this term, but for the sake of keeping this column suitable for all audiences, I will spell it this way. These financial experts have the magical ability to reduce production times, lower feed conversions, find niche markets that will buy our product at a price well above the market average and/or produce at a cost per kilo that would be nearly impossible for even the most experienced
When a company or technology suddenly pops up everywhere and is hailed as the best, most innovative way to produce something that breaks all paradigms, it’s always good to proceed with caution. The combination of “influencers” and “excelsheeters” has raised hundreds of millions of dollars for unrealistic projects, and they continue to solicit investments from around the world, damaging the reputation of our industry.
Anyone can be a millionaire for a day by creating financial models in Excel, which is why “excelsheeters” are so dangerous.
farmers. They know how to present these projections in a way that makes aquaculture appear more profitable than aerospace technology. Anyone can be a millionaire for a day by running financial spreadsheets in Excel, which is why “excelsheeters” are so dangerous. These “influencers” and “excelsheeters” have raised hundreds of millions of dollars for projects that are impossible and unrealistic. They continue to solicit investments from around the world, damaging the reputation of our industry.
Real farmers rarely try to communicate what they do. Perhaps it would be good for the industry if these great entrepreneurs had better communication skills and conveyed what is truly important. The first thing they would tell us, I think, is that we must
remain humble and stick to basic principles in order to navigate these times. The ability to raise substantial funds for an operation does not guarantee profitability. The important thing is not how much money we can raise, but how much money we can consistently generate to pay back what we have raised. Before thinking about grandiose projects, we must consider how we will pay for them. This may be unglamorous and result in “influencers” not selling advertising, but I prefer to continue looking people in the face without deceiving them with false expectations. Let’s be realistic, pragmatic, and modest. Above all, remember that this is a marathon, not a 100-meter dash, and we have many miles to go before reaching the finish line.
* Antonio Garza de Yta is COO of Blue Aqua International-Gulf, 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 Certification for Aquaculture Professionals (CAP) Program with Auburn University.
How to Feed the World’s Future, We don’t Need to Produce More
Dr. Vaclav Smil, in his book How to Feed the World: The History of Food and Its Future, states that the food currently produced globally is sufficient to provide 3,000 calories per capita worldwide. He highlights that much of the issue does not rely in producing more food but rather in making processing, preservation, distribution, and marketing more efficient.
* By Alejandro Godoy
Bill Gates recommended reading this book, expressing that it was written by his favorite author. The book has a scientific and quantitative focus, offering a statistical and analytical approach to the future of food and its historical background.
Who is the Author?
Dr. Vaclav Smil is a distinguished professor and writer at the Faculty of Ecology in Winnipeg, Canada. He studied sciences at Prague University
and engineering in Mining at the University of Pennsylvania. He has interdisciplinary expertise in topics such as energy, food, population, and the environment, and has impressively written 40 books.
Key Points from the Book
The book emphasizes that food produced globally today is enough to provide 3,000 calories per person worldwide; however, 30% is wasted, and in wealthy countries, the rate goes up to 45%.
It discusses aquaculture as an industry that has grown over the last 40 years and currently supplies more fish and seafood than traditional fishing, making it a scalable model for the global demand for proteins. It zooms in on species like tuna and salmon, which are carnivorous and have a low feed conversion rate (11.12), as well as the controversial issue of pollution due to fish farming cages. However, the book continuously highlights the benefits of aquaculture.
The book emphasizes that food produced globally today is enough to provide 3,000 calories per person worldwide; however, 30% is wasted, and in wealthy countries, the rate goes up to 45%.
Furthermore, the book considers important variables like climate change and population growth, reiterating that the challenge is not merely producing more food but enhancing the efficiency of processing, conservation, distribution, and marketing.
FAO Study on Supply Chain Analysis
According to an April 2025 FAO study analyzing the fisheries and aquaculture supply chain, the problem requires multidimensional solutions. FAO states that it can be solved and
funded through mixed public and private funds, as well as international donor foundations.
To improve the seafood supply chain in fishing and aquaculture, the following aspects must be strengthened:
Comparison of the Mercas Network and Public Fish Markets in Mexico.
» Policies and regulatory framework: In Mexico and Latin America, appropriate fishing and aquaculture laws.
» Technology application: Utilizing tools and devices to streamline and enhance efficiency.
» Skills and learning: Passing down knowledge to new generations and developing training centers.
» Services and infrastructure: Port services for fishing and aquaculture, as well as preservation and processing facilities.
» Environmental regulation: Ensuring that productive activities respect environmental limits.
» Gender and social equity: Equal opportunities for men and women regardless of their social background.
» Markets: Regulating and facilitating the seafood trade with transparency and traceability.
Mercas market network: A Success Story
Feeding more people requires better infrastructure for cold storage and markets. Spain’s Mercas market Network is the world’s largest public wholesale market network, with state-owned and privately-owned shares. The network consists of 24 public food markets across Spain, 17 of which handle 50% of the country’s seafood consumption. This infrastructure provides cold storage and coverage in major cities, making seafood products fresher and more accessible to consumers. This system enables fishers and farmers from various regions to sell their products, recognizing Spain as Europe’s gateway market.
Comparative Analysis
To gain perspective on the Mercas Network versus Mexico’s public fish markets, Mexico should at least have twice as many markets to efficiently distribute seafood. Spain’s setup has allowed for a 42 kg per capita seafood consumption, while Mexico’s rate remains at 12.9 kg per capita. Mexico’s markets lack infrastructure, organization, and services.
Building new markets seems straightforward, but raising awareness among producers is crucial. My personal experience in 2017, when constructing a market in Guaymas, Sonora (Mercaguay), illustrates the challenge. Despite its strategic central location, modern infrastructure, refrigeration facilities, restaurants, and direct pier access — costing approximately USD 1.2 million — local fishers refused to relocate. They were reluctant to comply with regulations, weighing requirements, and rental fees of MXN 1,200 (USD 62.29) per month for maintenance. To this day, the market remains unopened.
Conclusion
Aquaculture production in Mexico needs optimization and expansion
since the country relies heavily on USD 1 billion worth of imported seafood — mainly tilapia, basa swai, and salmon.
Moreover, improving supply chain infrastructure is essential to ensure quality seafood reaches consumers. Otherwise, street vendors with minimal sanitary conditions will still sell on streets.
Mexico and Latin America urgently need modern markets equipped with:
Improving supply chain infrastructure is essential to ensure quality seafood reaches consumers. Otherwise, street vendors with minimal sanitary conditions will still sell on streets.
» Processing and packaging facilities
» Retail areas separated from wholesale operation.
» Electronic auctions to increase supply and attract foodservice and wholesale buyers.
This would ultimately lead to higher-quality seafood, encouraging repeating consumption feeding more people.
Signing off, dear readers—time to read more of Dr. Vaclav Smil’s books
* Alejandro Godoy is the founder of Seafood Business Solutions, a consulting firm that specializes in aquaculture and fisheries market intelligence. Godoy has over 20 years of experience conducting studies for governments and companies worldwide.
Challenges of Using Non-Specific Immune Stimulant Tools for Farmed Shrimp
* By Stephen Newman, Ph.D.
In the early 1990s, International Aquaculture Biotechnology Ltd. (IABL) researched, developed and marketed a non-specific immune stimulant for shrimp. Our preliminary tests of the product demonstrated that animals that were exposed to a dilute suspension of the material prior to being challenged showed increased survival against both bacterial and viral pathogen laboratory challenges. The product was subsequently used on many billions of PLs in Ecuador and elsewhere. A variety of benefits were noted although they were not always consistent. Many variables impact shrimp health, and we still do not have a firm grasp on the extent and nature of them.
When the white spot syndrome virus (WSSV) entered Ecuador as the result of a deliberate introduction of the virus in infected PLs from Central America in the late 1990s, hundreds of millions of PLs in the field had been given the product. As the outbreak spread and viral loads increased, we noted that the primary benefit was a delay of the onset of mortality albeit most of the animals eventually die, often from secondary bacterial infections. Simultaneously, we were conducting trials of many different compounds in the feed. This included several different beta glucans, peptidoglycans and lipopolysaccharides from a variety of yeast, fungi and bacteria. What we found was that none of the products performed the way that they did in controlled lab studies. Highly stressful production environments with a constant onslaught of obligate and opportunistic pathogens overwhelmed any benefits.
Since then, there have been many published observations on the use of a wide variety of non-specific immune stimulants in farmed shrimp. Experimental designs are highly variable and at least some of the conclusions reached are a result of flaws in the experimental design rather than a real-world reproducible effect that would result in a cost-effective benefit. The marketplace is crowded with companies selling non-specific im-
The use of non-specific immune stimulants under field conditions can impact the ability of shrimp to tolerate exposure to pathogens. However, their effectiveness is related to a number of variables, including but not limited to the level of exposure to a pathogen or pathogens and the stress that the animals are placed under because of the production environment.
mune stimulants today, despite little evidence that they provide a consistent cost benefit.
Shrimp are highly evolved invertebrates with the oldest fossilized remains of shrimp date dating back 360 million years ago. Their immune systems are complex although in a much different way than that of the mammals. The preponderance of evidence supports the theory that their immune reaction has no memory component to it, and it can be characterized largely as a non-specific effect. There have also been many reports of what had been claimed to be immunization although there is little if any evidence to suggest that shrimp mount anything that could be characterized as a classic immune response.
The ecosystems that shrimp are farmed in are very different from their natural environments. Much as with other agricultural endeavors, nothing about farming shrimp even remotely resembles how they live in the wild. We are farming a single species at densities never found in nature with animals confined to relatively small areas where they are largely reliant on what we feed them. For most paradigms, compound feeds that have been “developed” for farmed shrimp are increasingly being delivered via automatic feeders along with heavy aeration. These are important elements for success.
There are strains of the common white shrimp, Penaeus (also known as Litopenaeus) vannamei, that are domesticated (i.e. genetically selected)
and that display varying degrees of tolerance to the stressors encountered in these production environments. This does not mean that they cannot be and are not stressed. Stress can manifest itself in many ways including variable growth rates, high FCRs, disease outbreaks from both obligate and opportunistic pathogens, etc. Monoculture production systems, by their very nature, are stressful.
It has been well documented that stress has an overall negative impact on a given animal’s physiology. This includes their immune system. The notion is that if a product works in chickens or swine, it must of course work in shrimp. Nothing could be further from the truth. Shrimp do not form antibodies, they double grind their feed to ensure that the final particle sizes being ingested are the size of or smaller than bacteria, their digestive systems function at near neutral pH levels and the length of time that food is resident in their guts is measured in minutes. They have little in common physiologically with mammals or birds.
Feeding shrimp immune stimulants on a continual basis seems like a good idea, even though there are risks of depleting critical aspects of their immune systems. Their immune systems are not proliferative as are mammalian systems. There is no evidence that being exposed to immune stimulating substances (of which the cell walls of bacteria are one group, including lipopolysaccharides, beta glucans, and peptidogly-
Shrimp are highly evolved invertebrates with the oldest fossilized remains of shrimp date dating back 360 million years ago. The preponderance of evidence supports the theory that their immune reaction has no memory component to it, and it can be characterized largely as a non-specific effect.
cans) that their lymphocytes proliferate in response. Actually, it appears that they do the opposite. They are depleted. This limits the nature and intensity of any immune response in a healthy animal.
From our many trials we noted that it was more than likely a shortterm impact that we were looking at, measured in weeks or a few months at best. It was easily overwhelmed if the shrimp were held in a manner that ensured high levels of obligate pathogens and, often, preventable stress. Our conclusions, based on extensive field trials in many countries, was that feeding farmed shrimp nonspecific immune stimulants did not
appear to give them a consistent benefit. However, there is a caveat in all of this. Domesticated animals reared in environments where there is little if any stress and that are free of obligate pathogens are much more likely to be able to gain a meaningful benefit from being exposed to these materials.
So, the next time somebody tells you all about the great immune stimulant that they have that will protect your farmed shrimp from endemic pathogens, consider this. Is this yet another example where farmers are being told that they can grow shrimp under highly stressful conditions without ensuring that obligate pathogens are not present. To be clear, I
am saying that there are not circumstances under which these materials provide some benefit. We have extensive field data from billions of shrimps that supports this with a product that was used on animals once.
Pathogens need to be kept out of production systems using specific pathogen free (SPF) animals from pathogen free nucleus breeding centers. Unfortunately, many animals that are sold as SPF still carry opportunistic pathogens and some even the pathogens that they are purportedly free from. Stay away from all pathogen exposed animals (APE), which stipulates that the best approach to generate strong animals
is to allow them to be exposed to all pathogens, known and unknown. The development of tolerance (defined as requiring higher loads of exposure to produce disease) and resistance (defined here as an absolute, yes or no in terms of susceptibility) to pathogens is not necessarily achievable via this approach. You are better off paying attention to the basics. Make sure that each brood animal is tested for all known obligate pathogens. Follow what happens in the ponds to ensure that this, or the nauplii or PLs are not the source of the problem. Aerate your ponds. Do not use too much or too little. Use compound feeds that are designed for shrimp that contain highly digestible proteins and adequate levels of vitamins and minerals. Use automatic feeders that allow you to feed small amounts of feed either on demand or as you want. If you do all of this, then the use of a non-specific immune stimulant has a greater chance of being beneficial. There are clear short-term impacts established both in the field and the lab that show that exposing animals prior to stocking will afford them some measure of immunity against viral and bacterial obligate pathogens.
Pathogens need to be kept out of production systems using specific pathogen free (SPF) animals from pathogen free nucleus breeding centers. Unfortunately, many animals that are sold as SPF still carry opportunistic pathogens and some even the pathogens that they are purportedly free from.
A common approach today is to include these materials in the feed. Inclusion of living bacteria in feed is problematic as feed manufacturing methods typically result in the generation of high levels of pressure and heat that kill most of the bacteria. Bacillus spores are widely sold for bioremediation and can be included in the feed with reasonable survivals under most conditions. There is not enough time for the Bacillus spores to germinate before they are defecated (in shrimp). The feces are nutrient rich, and the bacteria will have a place to grow when the spores do germinate. How many spores are needed to consume the feces is not defined. The level in the feed depends on the method of manufacture of the feed and the inclusion rate of the dried spores blended with an excipient. To calculate the potential lifetime dosage of bacteria per gram of feed consumed it depends on the initial dose (say 1 kg per MT of feed), the method of feed manufacture as this can impact spore survival rates through the milling process. For example, when you add a 4 trillion spores in one kg added to a MT of feed will result in 4 trillion divided by one million (grams in a MT) or 4 million spores per gram. The animal will not ingest all of this as they grind the feed twice before it enters the gut. The spores typically will end up in the water and not in the shrimp. They germinate in the feces and the shrimp can re-ingest them.
This is what would pass out in the feces assuming that the spores are evenly distributed in the feed. This is likely not going to be enough to have much of an impact as the niche that the feces end up in contains many other bacteria. The lifetime dosing of a 30-gram shrimp with an FCR of 1.5 depends on what percentage of the spores germinate. Starting with the same dose per gram of product as above, 100% survival would be a total of 180 million, 70% is 126 million, and 50% is 90 million. This is over the entire life cycle of the shrimp assuming that the material is fed daily.
While there may be a benefit, by itself, it is not likely to provide the
optimum benefit that the direct addition of the spores to the environment can produce. Delivering much larger numbers to “need to be treated areas” of the pond bottom is a much more powerful tool. This can deliver many billions of spores at once into a given area (such as where the feces collect). The challenge is to ensure that the frequency of application and dosage levels are sufficient to ensure maximum degradation of the organic matter. The presence of large numbers of Bacillus that germinate from the spores is more likely to result in a non-specific immune response in shrimp ingesting high levels.
In conclusion, the use of non-specific immune stimulants under field conditions can impact the ability of shrimp to tolerate exposure to pathogens. However, their effectiveness is related to a number of variables, including but not limited to the level of exposure to a pathogen or pathogens and the stress that the animals are placed under because of the production environment. Bacillus spores, used for bioremediation, once they germinate, can produce non-specific immunity but the levels that are typically present in feeds are likely not high enough for this impact to be all that is required to maximize the impact.
* 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.
We have all had those moments, a good idea has turned into a nightmare because we did not think through the whole process, we did not share with others who may be impacted by the idea, we did not understand what the consequences were going to be. In today’s society we see this increasingly.
* By FishProf
Away from seafood for a moment let us just look at ebicycles, e-scooters, and e-balancing devices (let us use the collective name ‘e-micromobility devices’). In my home state arrangements were made in 2018 for these e-micromobility devices to be used without any license and insur-
ance. They were seen as a novelty. No one thought about the mayhem that could be created.
Yet in my state from the e-micromobility devices at least two per year are being killed and the officially statistics highlight that between 2017-18 and 2022-23, there were 2,778 emergency department presentations re-
lated to injuries from e-micromobility devices. Of these 1,680 were attributed to e-scooters, 534 to e-bikes, and 564 to self-balancing devices. The most common injury type was a fracture, particularly to the wrist, hand, or forearm, and injuries were more frequent in males and adolescents/young adults. Of course, not every injury has been
ESG practices are becoming more important to all seafood businesses, and we are being told that ‘people’ want businesses to make sustainable improvements to the environment and society. Well, that is probably true but at what cost, we should be asking.
recorded, some people just went home and licked their wounds so the injury numbers would be much higher.
Moreover, in the 18 months prior to January 2023, Victoria experienced 120 fires linked to lithium-ion batteries in e-scooters and e-bikes. This is part of a broader trend of increasing fires related to these batteries across
Australia, with other states reporting similar numbers.
The product does not only harm the user. It impacts so many people.
If the FishProf produced a new seafood item and the outcome was people died and were regularly injured/hospitalized (be they the user or a bystander) and that the packag-
ing was regularly catching on fire, then clearly FishProf would finish his life behind bars… and that is not the bars where you might have a nice drink or snack and meet some friends, no prison bars are nowhere as nice (apparently!).
The FishProf just wants to put that seed into your head!
Crispy skin Salmon with vegetables.
Environmental Social Governance (ESG) which is coming to everyone’s seafood at a fast rate and will be with you before you can say ‘Every Supplier Groans.’
Now to the subject of this article – Environmental Social Governance (ESG) which is coming to everyone’s seafood at a fast rate and will be with you before you can say ‘Every Supplier Groans.’
ESG is a formal approach to measuring and reporting how your business impacts society and the environment. ESG means more than just being sustainable. ESG focuses on governance and transparent reporting on how a business manages itself.
ESG practices are becoming more important to all seafood businesses, and we are being told that ‘people’ want businesses to make sustainable improvements to the environment and society. Well, that is probably true but at what cost, we should be asking.
In some countries this has already been mandated through laws/regulations, in others it is being planned and in others it is not on the horizon. However, essentially this does not really matter as what is happening is that large companies are being engaged and they will need to bring their full supply chain with them in order to comply. Large supermarket chains generally rely on SME operations for products and services so you can see where the costs and work will be landing.
Singapore is a leader in Asia where it has been reported that the regulators advised the new climate
reporting requirements form part of the government’s efforts to strengthen companies’ sustainability capabilities, with companies able to provide climate disclosures standing to benefit from improved access to new markets, customers, and financing.
Tan Boon Gin, Chief Executive Officer of SGX Reg Co, is reported as saying “SGX-listed issuers have had a head-start in climate reporting, and many have seen its benefits. Companies are better equipped to meet demand from their lenders, customers, and investors for sustainabilityrelated information. They can also more readily access the growing pool of sustainable capital. These position Singapore well as a green economy.”
New Zealand’s large publicly listed companies (mainly insurers, banks, and investment managers) have been required to produce climate-related disclosures since April 2024. The disclosures ensure a rapid implementation of climate reporting, in line with international frameworks (IFRS S2), as well as the recommendations of the Task Force on Climate-Related Financial Disclosures (TCFD).
Reporting entities in NZ will need to disclose GHG emissions, climate
governance and their assessmentand management of - climate risk, in their own direct operations as well as their upstream and downstream value chain. To see what this looks like the best reporting in seafood that the FishProf has seen is by Sanford Ltdhttps://www.sanford.co.nz/investors/ esg-profile/ .
Australia is lagging behind, but the ball is rolling as you can see from the Table 1:
In the United States, ESG regulation is characterized by a fractured landscape with states moving in opposite directions. This ideological battle at the state level sees some states embracing ESG measures, while others enact anti-ESG legislation. Despite these differences, the overarching goal of ESG regulations and compliance is to ensure companies back up sustainability claims with actions.
This is coming on top of the uncertainty in trade due in no small part to President Trump’s trade policies and tariffs games so this will be driven by stakeholders. People/organizations who want to see transparency and accountability from companies regarding their ESG practices, will be
Did you know? Seafood has one of the lowest carbon footprints among all protein sources. This makes it a ‘climate-smart’ food that can help mitigate climate change. Great choices are small pelagic fish or farmed mussels. Seafish UK.
pushing for a shift towards sustainability and transparency in corporate practices.
ESG is a wonderful opportunity for seafood associations to guide their members through implementing and reporting on Environmental, Social, and Governance (ESG) practices to ensure sustainable and ethical seafood production and trade. This should include supporting members in understanding key ESG issues, setting goals and targets, and developing strategies to address them. Associations can also facilitate knowledge sharing through collaboration and best practice exchange among mem-
bers and building training platforms with experts.
The seafood industry is globally recognized as being important in terms of its size, contribution to food security, jobs, and sustainable development. There are clear impacts on the environment and people on which it depends threaten its future.
The new world order with the United Nations Sustainable Development Goals (SDG’s) at the forefront can be used in de-risking the seafood sector with regards to environmental and social issues. The industry has the chance to put pressure on governments to invest in a strong en-
abling environment that underpins a sustainable seafood sector.
Every Supplier could Groan but with proactivity and collaboration the industry can make the emergence of ESG its opportunity to be seen as the driver rather than the passenger then Every Supplier can Grin.
Fresh fish on display.
Humberto Villarreal Colmenares
* By Antonio Garza de Yta
Imet Humberto Villarreal 24 years ago when I was a newly graduated master’s student in Aquaculture from Auburn University, and he was already an established scientist at the Northwest Biological Research Center (CIBNOR). Since that moment, our lives became intertwined not only professionally, but I had the fortune of forming a deep friendship with one of the most wonderful human beings I have had the pleasure of knowing.
For those who knew him in his youth, his leadership and drive stood out from the very beginning. From his time at the Monterrey Institute of Technology (ITESM), Guaymas Campus, to obtaining his Ph.D. in Zoology from the University of Queensland in Brisbane, Australia, there was never a moment when Humberto did not excel — above all, he always worked as a team and motivated everyone around him.
Upon his return from Australia in 1987, he joined CIBNOR, an institution he helped transform into one of the most important aquaculture research centers in the continent. There, he first served as Head of Marine Biology from 1993 to 1995 at the Guaymas Unit and later as Coordinator of the Aquaculture Program during two separate periods, from 1998 to 2004 and then from 2007 to 2009, in La Paz, Baja California Sur, Mexico.
Over nearly 40 years, he published more than 100 scientific articles, 4 books, and 2 book chapters. He worked as an editor on 3 books and delivered more than 200 international conferences. Our friend was a great scientist, but an even better mentor. He supervised 45 undergraduate thesis and
transformed the lives of at least a hundred students and professionals who saw him as a great role model. Today, his students hold important positions in industry, government, and academia, spreading his teachings across the world.
Humberto was not only a brilliant man, but also possessed great qualities — one of them being the ability to convince those around him of anything he set his mind to. One of the qualities I admire most about him was his ability to deliver an elevator pitch and explain even the most complex topics in 30 seconds. But above all, his ability to dream big. Humberto never compromised his dreams; on the contrary, he fought tirelessly to achieve them.
A testament to this was his successful creation of the BioHelis Innovation and Technology Park in 2009, which he coordinated until his passing. Without a doubt, BioHelis is one
of the best aquaculture development projects I have seen on a global scale, benefiting dozens of companies, many of which are now thriving and expanding.
Humberto always sought ways to improve things, and that quality stayed with him throughout his life. He conducted significant research on optimizing production and nutrition for both the Australian red claw crayfish (Cherax quadricarinatus) and Pacific white shrimp (Litopenaeus vannamei) He always had the vision to integrate science with industry, advocating for good governance and ensuring the participation of all stakeholders in decision-making.
He coordinated the National Aquaculture Master Plan in Mexico in 2008, and I have no doubt that if his recommendations had been followed, Mexico would hold a far more significant position in global aquaculture.
In the World Aquaculture Society (WAS), he served as JWASl Editor, Board Director, and finally President. I had the honor of sharing this stage with him — always fighting to expand services for members, promote the internationalization of the society, and above all, ensuring that students were included in all WAS activities. His warmth and kindness immediately made him one of the most charismatic presidents the Society has ever had.
We always shared the belief that WAS’s greatest wealth was its diversity, making it unique and unparalleled. His vision will be permanently remembered in the history of our beloved Society.
I fondly recall that at the WAS event in Montpellier, Humberto lent me his phone at 3 a.m. so I could connect with my family and find out the gender of my son, Patricio — whom, due to my wife’s and my deep Star Wars fandom, Uncle Humberto always called Darth
But we did not only cross paths at WAS, but also in countless projects — some that materialized, others that remained great ideas. Our last collaboration was on the Advisory Board of Shrimp. There, as in every place he participated, he left his mark — his vision and legacy are irreplaceable.
He was not only a great scientist and an incredible friend, but also a devoted father and family man. He is survived by his wife, Berenice, and their two daughters. To them, my deepest condolences; I only hope that peace finds them soon.
As our friend Craig Browdy said, we will always remember Humberto’s smile, the wonderful dinners, and above all, his indomitable spirit. Humberto was one of those rare, irreplaceable people who came into this world to make it a better place.
The last time I saw him was when we switched trains in Denmark after one of our famously long dinners, where we “fixed” and “unfixed” the
world at least twice over. We both knew we might not see each other again, and as we said goodbye, I had the privilege of telling him, “I love you, my brother.”
Today, I believe the entire global aquaculture community joins me in that moment.
Humberto — my friend, my brother, my battle companion — wherever you are, I am certain you are igniting a revolution for good, creating, dreaming, and embracing that spark of genius that only the greatest wield with such grace.
Words alone are not enough to express our gratitude, but I can promise you this — we will love and remember you forever.
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