Polyunsaturated fatty acid content of wild and farmed tilapias in Thailand: effect of aquaculture practices and implications for human nutrition

Effect of Smoking and Grilling on Polycyclic Aromatic Hydrocarbons in Ghanaian Tilapia

The study assessed 18 Polycyclic Aromatic Hydrocarbons (PAHs) in O. niloticus (Nile tilapia) sampled from an aquaculture cage (farm) and a wild catch. The PAHs in fish samples were analysed using Gas Chromatography-Mass Spectrometry. Four PAHs (in order of levels: Indeno [1,2,3-cd] pyrene > Anthracene > Perylene > Pyrene; 100-0.8 µg/kg) and only one PAH (Pyrene: 4 µg/kg) were detected in raw samples from the cage and wild catch respectively. Chargrilling significantly increased Pyrene levels after cooking (wild: 4-11 µg/kg; cage: 5-23 µg/kg, p < .05), and likewise Anthracene levels in cage samples (13-153 µg/kg) but decreased Indeno [1,2,3-cd] pyrene levels from 100 ± 20 to 1.2 ± 0.2 µg/kg in cage samples. Smoking significantly increased 13 to 15 PAH congeners' levels (from < 1.0 up to 340 µg/kg) and total PAHs (wild: 4 to 840 µg/kg; cage: 110 to 560 µg/kg), and decreased Indeno [1,2,3-cd] pyrene (100 to 1.3 µg/kg) in cage samples but showed no effect on Benzo [g, h, i] perylene and Dibenzo [a, h] anthracene levels in all samples. For smoked samples, Benzo [a] pyrene and PAH4 (Benzo [a] anthracene, Chrysene, Benzo [b] fluoranthene, and Benzo [a] pyrene) exceeded the respective maximum permissible limits of 2 µg/kg and 12 µg/kg, and significantly influenced the levels of carcinogenic PAHs (CPAH, 135-170 µg/kg). Nevertheless, the Excess Cancer Risk (ECR) estimates, from a conservative approach, were far below the threshold (10-4), implying that consuming smoked or grilled tilapia from the study site is safe.

Trace metal exposure and human health consequences through consumption of market-available Oreochromis niloticus (L.) in Bangladesh

Using Oreochromis niloticus (L.), commonly known as tilapia, as a model, this study evaluated the exposure of trace metal and their risk assessment on human health. In addition, the status of amino acids, fatty acids, vital elements, and their benefits is also studied. Estimating the nutrient composition of fish muscle is necessary to ensure that it meets the requirements for human health, food regulations, and commercial specifications. The species examined contained appreciable concentrations of amino acids, fatty acid content, and minerals, suggesting that the fish species could be a good source of protein, fat, and minerals. Hazardous heavy metals were found to be lower compared to their corresponding maximum tolerable limits. The order of trace metals is Zn (22,709 µg/kg) > Fe (19,878 µg/kg) > Cu (1261 µg /kg) > Mn (1228 µg/kg) > Cr (474 µg/kg) > Ni (152 µg/kg) As (318 µg /kg) > Pb (281 µg/kg) > Co (24 µg /kg) > Cd (13 µg/kg) > Hg (5 µg/kg); a number of health-related indices, including estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI), as well as carcinogenic risk (CR) indices for adult and children, were calculated to evaluate the human health hazard of the heavy metals. The THQ and HI of heavy metals for tilapia are lower than 1, posing a non-carcinogenic threat to human health due to the biomagnifications of these deadly poisonous metals. Principal component, cluster, and correlation analyses delineated the common probabilistic sources of metal contamination origin and significant inter-parameter associations. Although no human health risks for the consumption of tilapia was found, more attention must be paid for the monitoring of Oreochromis niloticus before entering the market.

Microorganisms in Fish Feeds, Technological Innovations, and Key Strategies for Sustainable Aquaculture

Aquaculture, the world's fastest growing food sector, produces over half of all fish for human consumption. Aquaculture feeds include fishmeal and fish oil, extracted from wild-caught fish such as sardines, and poses ecological, food security, and economic drawbacks. Microalgae, yeasts, fungi, bacteria, and other alternative ingredients show promise as potential ingredients in aquafeeds that provide protein/amino acids, lipids, or omega-3 sources and sources of bioactive molecules. This review article discusses the issues that the literature often lacks data on, such as the recent development of using microorganisms, technological innovation, challenges, and opportunities to develop a low environmental footprint of aquaculture diet. The ingredients often require novel processing technology to improve digestibility and fish growth and reduce antinutritional factors. This is an important gap to fill because microalgae are the most frequently used organism in fish feed, particularly as a dietary supplement or mixed with other ingredients. The production, processing, and formulating steps can affect the nutritional qualities. Stepwise strategies are required to evaluate these ingredients for feed application, and in this article, I articulated the stepwise key approaches of evaluating nutritional and environmental response metrics to develop highly sustainable aquaculture feed using these microorganisms, which would guide a more judicious inclusion of these novel ingredients.

More Than Fish-Framing Aquatic Animals within Sustainable Food Systems

Aquatic animals are diverse in terms of species, but also in terms of production systems, the people involved, and the benefits achieved. In this concept piece, we draw on literature to outline how the diversity of aquatic animals, their production, and their consumption all influence their impact within the food system. Built on evidence from an array of reductionist and non-reductionist literature, we suggest that food systems researchers and policymakers adapt current methods and theoretical frameworks to appropriately contextualise aquatic animals in broader food systems. We do this through combining current understandings of food systems theory, value chain, livelihoods, nutritional outcomes, and planetary boundaries thinking. We make several claims around understanding the role of aquatic animals in terms of nutritional output and environmental impacts. We suggest a need to consider: (1) the diversity of species and production methods; (2) variable definitions of an "edible yield"; (3) circular economy principles and the impacts of co-products, and effects beyond nutrient provision; (4) role of aquatic animals in the overall diet; (5) contextual effects of preservation, preparation, cooking, and consumer choices; (6) globalised nature of aquatic animal trade across the value chain; and (7) that aquatic animals are produced from a continuum, rather than a dichotomy, of aquaculture or fisheries. We conclude by proposing a new framework that involves cohesive interdisciplinary discussions around aquatic animal foods and their role in the broader food system.

Advantage of Species Diversification to Facilitate Sustainable Development of Aquaculture Sector

Intensified agrochemical-based monoculture systems worldwide are under adoption to meet the challenge of human population growth and the ever-growing global demand for food. However, this path has been opposed and criticized because it involves overexploitation of land, monoculture of few species, excessive input of agrochemicals, and adverse impacts on human health and the environment. The wide diversity among polyculture systems practiced across the globe has created confusion over the priority of a single strategy towards sustainable aquaculture development and safer products. Herein, we highlight the significance of polyculture and integrated aquaculture practices in conveying the successful transition of the aquaculture industry towards sustainable development. So far, the established thought is that the precise selection of aquatic species and a focus on compatible and complementary species combinations are supposed to facilitate rapid progress in food production with more profitability and sustainability. Therefore, the advantages of species diversification are discussed from an ecological perspective to enforce aquaculture expansion. This account asserts that a diverse range of aquaculture practices can promote synergies among farmed species, enhance system resilience, enable conservation, decrease ecological footprints, and provide social benefits such as diversified income and local food security.

Export-Driven, Extensive Coastal Aquaculture Can Benefit Nutritionally Vulnerable People

Export-orientated shrimp and prawn farming in coastal ghers has been associated with negative environmental, social, and nutritional impacts. This study challenges these perceptions based on field observations from four communities in South West Bangladesh. Most households observed (&gt;60%) were either directly involved in seafood farming or engaged elsewhere in the seafood value chain. Our study set out to establish how the type and location of aquaculture impacted on access to and consumption of aquatic animals. Additionally, we assessed the effects of both household socioeconomic status and intra-household food allocation on individual diet and nutritional outcomes. We used a blended approach, including a 24-h consumption recall on two occasions, analysis of the proximate composition of aquatic animals and biomarkers from whole blood from a sample of the target population. The diverse polyculture systems generated broad social benefits, where “export-oriented” production actually supplied more food locally than to global markets. Key findings: (1) worse-off households achieved higher productivity of farmed aquatic animals on smaller landholding than better-off households with larger landholdings; (2) vegetable production on gher dikes was a significant source of nutrition and income in lower saline gradients; (3) more fish was eaten in lower saline gradients although fish consumption was highly variable within and between households; (4) intra-household allocation of specific foods within diets were similar across communities; (5) recommended nutrient intakes of protein and zinc exceeded daily requirements for adolescent females, but energy, calcium, and iron were below recommended intake levels; (6) n-3 LC-PUFA, expressed as percentage of total fatty acids, in whole blood samples of adolescent females declined with ambient salinity level regardless of household socioeconomic status; (7) analysis of aquatic animals consumed found that mangrove species and tilapia harvested from higher saline ghers contained high levels of desirable PUFAs. These findings suggest that export-driven, extensive coastal aquaculture can be nutrition sensitive when co-products are retained for local consumption.

The impact of the COVID-19 pandemic on fish consumption and household food security in Dhaka city, Bangladesh

The effects of COVID-19 are continuing to increase around the world as the pandemic claims thousands of lives. Bangladesh is no exception and has been greatly affected by SARS-CoV-2. Apart from the number of people who are or have been directly getting infected with this disease, millions of people are directly or indirectly facing many challenges to their livelihoods and the security of their food and nutritional supply, along with other societal issues created by the pandemic. In this study, a hybrid approach of online and telephone questionnaire surveys was used to investigate the food security of Dhaka city's inhabitants at household level. Approximately 80% of the respondents reported reduced income, and a quarter of respondents lost their jobs between March and June 2020. The frequency of fish consumption, an essential component of Bangladeshi diets, significantly reduced during the pandemic. This was especially apparent in affluent segments of the community. Out of the respondents, 75% reported an increase in the price of fish in Dhaka city. A range of coping strategies were observed: including decreasing the frequency of grocery shopping, shifting to online shopping, reducing consumption of high price commodities, reducing junk food consumption, cleaning fish and meat with hot water and vinegar, and increasing the consumption of protein and vitamin C rich food items. Prior to COVID-19, 80% of the households surveyed bought fish from wet markets. This number dropped to 45% during the pandemic. Many households substituted fish and meat with poultry, eggs and dried fish. About half of the households stockpiled rice, lentils and potatoes during the peak of the pandemic. However, if the pandemic lasts for a prolonged period, those living on low incomes in urban areas will experience some level of food insecurity from a reduced income or loss of work. Because of this, a large-scale sustainability policy should be undertaken to secure the food and nutritional security of low-income and middle-class household.

Microalgae-blend tilapia feed eliminates fishmeal and fish oil, improves growth, and is cost viable

Aquafeed manufacturers have reduced, but not fully eliminated, fishmeal and fish oil and are seeking cost competitive replacements. We combined two commercially available microalgae, to produce a high-performing fish-free feed for Nile tilapia (Oreochromis niloticus)—the world’s second largest group of farmed fish. We substituted protein-rich defatted biomass of Nannochloropsis oculata (leftover after oil extraction for nutraceuticals) for fishmeal and whole cells of docosahexaenoic acid (DHA)-rich Schizochytrium sp. as substitute for fish oil. We found significantly better (p < 0.05) growth, weight gain, specific growth rate, and best (but not significantly different) feed conversion ratio using the fish-free feed compared with the reference diet. Fish-free feed also yielded higher (p < 0.05) fillet lipid, DHA, and protein content (but not significantly different). Furthermore, fish-free feed had the highest degree of in-vitro protein hydrolysis and protein digestibility. The median economic conversion ratio of the fish-free feed ($0.95/kg tilapia) was less than the reference diet ($1.03/kg tilapia), though the median feed cost ($0.68/kg feed) was slightly greater than that of the reference feed ($0.64/kg feed) (p < 0.05). Our work is a step toward eliminating reliance on fishmeal and fish oil with evidence of a cost-competitive microalgae-based tilapia feed that improves growth metrics and the nutritional quality of farmed fish.

High levels of docosahexaenoic acid are present in eight New World silversides (Pisces: Atherinopsidae)

ABSTRACT Docosahexaenoic acid (DHA) is the most critical and least available omega-3 fatty acid in the Western human diet. Currently, the source of omega-3 long chain polyunsaturated fatty acids (LC-PUFA) is mainly dependent on wild fisheries, making this resource unsustainable in the foreseeable future. In recent years, a high rate of biosynthesis and accumulation of DHA has been discovered in a freshwater species (Chirostoma estor) belonging to the Atherinopsidae family. Interest in evaluating fatty acid composition in other members of the family has emerged, so this study compiles original data of flesh composition of eight atherinopsid species from freshwater and brackish environments, either wild or cultured. High levels of DHA (16 to 31%) were found in all analyzed members of the family, except in C. grandocule, independently of their habitat or origin. The analyzed species of the Jordani group (C. estor, C. promelas and C. humboldtianum) showed high DHA and low EPA levels (<0.5%) as previously reported for cultured C. estor. The low trophic niche of these atherinopsids and their fatty acid accumulation capabilities are factors that make these species noteworthy candidates for sustainable aquaculture.

Towards sustainable aquafeeds: Evaluating substitution of fishmeal with lipid-extracted microalgal co-product (Nannochloropsis oculata) in diets of juvenile Nile tilapia (Oreochromis niloticus)

Microalgae companies increasingly seek markets for defatted biomass that is left over after extracting omega-3 rich oil for human nutraceuticals and crude oil for fuels. Such a protein-rich co-product is a promising alternative to unsustainably sourced fishmeal in aquaculture diets. We report the first evaluation of co-product of the marine microalga Nannochloropsis oculata (N. oculata co-product) for replacing fishmeal in diets of Nile tilapia, a globally important aquaculture species. We conducted a nutrient digestibility experiment with N. oculata dried whole cells and N. oculata co-product, followed by an 84-day nutritional feeding experiment with N. oculata co-product. N. oculata co-product, more nutrient-dense than whole cells, had the highest digestibility for lysine, an essential amino acid that is often deficient in terrestrial crop meals; and for 20:5 n-3 EPA, making it a good option for EPA supplementation in tilapia feed. N. oculata co-product, despite containing higher amounts of protein than whole cells, had significantly lower digestibility for crude protein than whole cells. Apparent digestibility coefficients (ADC) of methionine were significantly lower in N. oculata co-product than in whole cells. The nutritional feeding experiment compared diets with N. oculata co-product that replaced fishmeal as follows: 0% replacement in reference diet (fishmeal as 7% of total diet) and test diets with 33%, 66% and 100% replacement of fishmeal (3%, 5.5%, and 8% of total diet, respectively). Results showed the 33% replacement diet yielded fish growth, feed conversion, and survival similar to the reference diet. Reduced digestibility and growth at greater N. oculata co-product inclusion levels may have been due to higher levels of anti-nutrients in co-product than whole cells. All diets yielded a n3:n6 ratio of tilapia fillet that is favorable for human consumption. Depositions of macro minerals and several trace elements in the fillet were not significantly different across diets. Thus, N. oculata co-product, when replacing 33% of fishmeal in tilapia feed, led to fish performance and flesh composition comparable to that of fish fed the reference diet, but its nutrient digestibility needs to be improved to achieve higher replacement levels.

Mapping QTL for Omega-3 Content in Hybrid Saline Tilapia

Tilapia is one of most important foodfish species. The low omega-3 to omega-6 fatty acid ratio in freshwater tilapia meat is disadvantageous for human health. Increasing omega-3 content is an important task in breeding to increase the nutritional value of tilapia. However, conventional breeding to increase omega-3 content is difficult and slow. To accelerate the increase of omega-3 through marker-assisted selection (MAS), we conducted QTL mapping for fatty acid contents and profiles in a F₂ family of saline tilapia generated by crossing red tilapia and Mozambique tilapia. The total omega-3 content in F₂ hybrid tilapia was 2.5 ± 1.0 mg/g, higher than that (2.00 mg/g) in freshwater tilapia. Genotyping by sequencing (GBS) technology was used to discover and genotype SNP markers, and microsatellites were also genotyped. We constructed a linkage map with 784 markers (151 microsatellites and 633 SNPs). The linkage map was 2076.7 cM long and consisted of 22 linkage groups. Significant and suggestive QTL for total lipid content were mapped on six linkage groups (LG3, -4, -6, -8, -13, and -15) and explained 5.8-8.3% of the phenotypic variance. QTL for omega-3 fatty acids were located on four LGs (LG11, -18, -19, and -20) and explained 5.0 to 7.5% of the phenotypic variance. Our data suggest that the total lipid and omega-3 fatty acid content were determined by multiple genes in tilapia. The markers flanking the QTL for omega-3 fatty acids can be used in MAS to accelerate the genetic improvements of these traits in salt-tolerant tilapia.

Environmental health impacts of feeding crops to farmed fish

Half of the seafood consumed globally now comes from aquaculture, or farmed seafood. Aquaculture therefore plays an increasingly important role in the global food system, the environment, and human health. Traditionally, aquaculture feed has contained high levels of wild fish, which is unsustainable for ocean ecosystems as demand grows. The aquaculture industry is shifting to crop-based feed ingredients, such as soy, to replace wild fish as a feed source and allow for continued industry growth. This shift fundamentally links seafood production to terrestrial agriculture, and multidisciplinary research is needed to understand the ecological and environmental health implications. We provide basic estimates of the agricultural resource use associated with producing the top five crops used in commercial aquaculture feed. Aquaculture's environmental footprint may now include nutrient and pesticide runoff from industrial crop production, and depending on where and how feed crops are produced, could be indirectly linked to associated negative health outcomes. We summarize key environmental health research on health effects associated with exposure to air, water, and soil contaminated by industrial crop production. Our review also finds that changes in the nutritional content of farmed seafood products due to altered feed composition could impact human nutrition. Based on our literature reviews and estimates of resource use, we present a conceptual framework describing the potential links between increasing use of crop-based ingredients in aquaculture and human health. Additional data and geographic sourcing information for crop-based ingredients are needed to fully assess the environmental health implications of this trend. This is especially critical in the context of a food system that is using both aquatic and terrestrial resources at unsustainable rates.

Saturated Branched Chain, Normal Odd-Carbon-Numbered, and n-3 (Omega-3) Polyunsaturated Fatty Acids in Freshwater Fish in the Northeastern United States

The fatty acid profiles of wild freshwater fish are poorly characterized as a human food source for several classes of fatty acids, particularly for branched chain fatty acids (BCFA), a major bioactive dietary component known to enter the US food supply primarily via dairy and beef fat. We evaluated the fatty acid content of 27 freshwater fish species captured in the northeastern US with emphasis on the BCFA and bioactive polyunsaturated fatty acids (PUFA) most associated with fish, specifically n-3 (omega-3) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Mean BCFA content across all species was 1.0 ± 0.5% (mean ± SD) of total fatty acids in edible muscle, with rainbow smelt (Osmerus mordax) and pumpkinseed (Lepomis gibbosus) the highest at >2% BCFA. In comparison, EPA + DHA constituted 28% ± 7% of total fatty acids. Across all fish species, the major BCFA were iso-15:0, anteiso-15:0, iso-16:0, iso-17:0 and anteiso-17:0. Fish skin had significantly higher BCFA content than muscle tissues, at 1.8% ± 0.7%, but lower EPA and DHA. Total BCFA in fish skins was positively related with that in muscle (r² = 0.6). The straight chain saturates n-15:0 and n-17:0 which have been identified previously as markers for dairy consumption were relatively high with means of 0.4% and 0.6%, respectively, and may be an underappreciated marker for seafood intake. Consuming a standardized portion, 70 g (2.5 oz), of wild freshwater fish contributes only small amounts of BCFA, 2.5-24.2 mg, to the American diet, while it adds surprisingly high amounts of EPA + DHA (107 mg to 558 mg).

A higher dietary ratio of long-chain omega-3 to total omega-6 fatty acids for prevention of COX-2-dependent adenocarcinomas

Compelling evidence that daily low-dose aspirin decreases risk for a number of adenocarcinomas likely reflects the fact that a modest but consistent inhibition of cyclooxygenase-2 (COX-2) activity can have a meaningful protective impact on risk for such cancers. The cancer-promoting effects of COX-2 are thought to be mediated primarily by prostaglandin E2 (PGE2), synthesized from arachidonic acid. The long-chain omega-3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), abundant in many fatty fish, can interfere with the availability of arachidonate to COX-2 by multiple complementary mechanisms; moreover, the PGE3 produced by COX-2 from EPA is a competitive inhibitor of the receptors activated by PGE2. These considerations have given rise to the hypothesis that a high dietary intake of EPA/DHA, relative to omega-6 (from which arachidonate is generated), should lessen risk for a number of adenocarcinomas by impeding PGE2 production and activity-while not posing the risk to vascular health associated with COX-2-specific nonsteroidal antiinflammatory agents. Analyses that focus on studies in which the upper category of fish consumption (not fried or salt-preserved) is 2 or more servings weekly, and on studies that evaluate the association of long-term fish oil supplementation with cancer risk yields a number of findings that are consistent with the hypothesis. Further studies of this nature may help to clarify the impact of adequate regular intakes of long-chain omega-3 on cancer risk, and perhaps provide insight into the dose-dependency of this effect.

Meeting the food and nutrition needs of the poor: the role of fish and the opportunities and challenges emerging from the rise of aquaculture

People who are food and nutrition insecure largely reside in Asia and Sub-Saharan Africa and for many, fish represents a rich source of protein, micronutrients and essential fatty acids. The contribution of fish to household food and nutrition security depends upon availability, access and cultural and personal preferences. Access is largely determined by location, seasonality and price but at the individual level it also depends upon a person's physiological and health status and how fish is prepared, cooked and shared among household members. The sustained and rapid expansion of aquaculture over the past 30 years has resulted in >40% of all fish now consumed being derived from farming. While aquaculture produce increasingly features in the diets of many Asians, it is much less apparent among those living in Sub-Saharan Africa. Here, per capita fish consumption has grown little and despite the apparently strong markets and adequate biophysical conditions, aquaculture has yet to develop. The contribution of aquaculture to food and nutrition security is not only just an issue of where aquaculture occurs but also of what is being produced and how and whether the produce is as accessible as that from capture fisheries. The range of fish species produced by an increasingly globalized aquaculture industry differs from that derived from capture fisheries. Farmed fishes are also different in terms of their nutrient content, a result of the species being grown and of rearing methods. Farmed fish price affects access by poor consumers while the size at which fish is harvested influences both access and use. This paper explores these issues with particular reference to Asia and Africa and the technical and policy innovations needed to ensure that fish farming is able to fulfil its potential to meet the global population's food and nutrition needs.

Scoping a Public Health Impact Assessment of Aquaculture with Particular Reference to Tilapia in the UK

Background. The paper explores shaping public health impact assessment tools for tilapia, a novel emergent aquaculture sector in the UK. This Research Council’s UK Rural Economy and Land Use project embraces technical, public health, and marketing perspectives scoping tools to assess possible impacts of the activity. Globally, aquaculture produced over 65 million tonnes of food in 2008 and will grow significantly requiring apposite global public health impact assessment tools. Methods. Quantitative and qualitative methods incorporated data from a tridisciplinary literature. Holistic tools scoped tilapia farming impact assessments. Laboratory-based tilapia production generated data on impacts in UK and Thailand along with 11 UK focus groups involving 90 consumers, 30 interviews and site visits, 9 visits to UK tilapia growers and 2 in The Netherlands. Results. The feasibility, challenges, strengths, and weaknesses of creating a tilapia Public Health Impact Assessment are analysed. Occupational and environmental health benefits and risks attached to tilapia production were identified. Conclusions. Scoping public health impacts of tilapia production is possible at different levels and forms for producers, retailers, consumers, civil society and governmental bodies that may contribute to complex and interrelated public health assessments of aquaculture projects. Our assessment framework constitutes an innovatory perspective in the field.

Authentication of meat and meat products

In recent years, interest in meat authenticity has increased. Many consumers are concerned about the meat they eat and accurate labelling is important to inform consumer choice. Authentication methods can be categorised into the areas where fraud is most likely to occur: meat origin, meat substitution, meat processing treatment and non-meat ingredient addition. Within each area the possibilities for fraud can be subcategorised as follows: meat origin-sex, meat cuts, breed, feed intake, slaughter age, wild versus farmed meat, organic versus conventional meat, and geographic origin; meat substitution-meat species, fat, and protein; meat processing treatment-irradiation, fresh versus thawed meat and meat preparation; non-meat ingredient addition-additives and water. Analytical methods used in authentication are as diverse as the authentication problems, and include a diverse range of equipment and techniques. This review is intended to provide an overview of the possible analytical methods available for meat and meat products authentication. In areas where no authentication methods have been published, possible strategies are suggested.

Passing the panda standard: a TAD off the mark?

Tilapia, a tropical freshwater fish native to Africa, is an increasingly important global food commodity. The World Wide Fund for Nature (WWF), a major environmental nongovernmental organization, has established stakeholder dialogues to formulate farm certification standards that promote "responsible" culture practices. As a preface to its "tilapia aquaculture dialogue," the WWF for Nature commissioned a review of potential certification issues, later published as a peer-reviewed article. This article contends that both the review and the draft certification standards subsequently developed fail to adequately integrate critical factors governing the relative sustainability of tilapia production and thereby miss more significant issues related to resource-use efficiency and the appropriation of ecosystem space and services. This raises a distinct possibility that subsequent certification will promote intensive systems of tilapia production that are far less ecologically benign than existing widely practiced semi-intensive alternatives. Given the likely future significance of this emergent standard, it is contended that a more holistic approach to certification is essential.

n-3 PUFA fortification of high n-6 PUFA farmed tilapia with linseed could significantly increase dietary contribution and support nutritional expectations of fish

Farmed fish high in n-6 PUFA may undermine fish nutritional expectations and intake recommendations for n-3 PUFA requirements and exacerbate rather than improve already high n-6/n-3 PUFA diets. Dietary contribution of fish fortification by linseed-based n-3 PUFA was evaluated. Mango tilapia (12 months old) with high n-6 PUFA (21.8 FA%, n-6/n-3 ratio 4.6:1) were fed standard/control (T(C)) or linseed-supplemented (5%, T(5%); 7%, T(7%)) feed for 61 days regular-growth and 120 days stock-growth (to 650 g). Compared to T(C), n-3 PUFA increased in T(5%) 46% and T(7%) 58%; ALA in T(5%) increased 100% and T(7%) 167%; EPA+DHA in T(5%) increased 14% and T(7%) 23% (p < 0.05); n-6 PUFA/LCPUFA were unchanged. T(7%) EPA+DHA 168 mg/100 g of raw fillet is comparable to current American intake and Dietary Reference Intakes; controlled cooking preserved approximately 90% EPA+DHA. n-6/n-3 ratios decreased 16-38% in total PUFA to 2.3:1 and in LCPUFA to 0.61:1. Linseed supplementation could improve tilapia n-3 PUFA/LCPUFA, ameliorating n-3 PUFA scarcity and unexpectedly high fish n-6 PUFA content, potentially making a significant nutritional contribution.

The content of favorable and unfavorable polyunsaturated fatty acids found in commonly eaten fish

Changes in diet during the past century have caused a marked increase in consumption of saturated fatty acids and n-6 polyunsaturated fatty acids (PUFAs) with a concomitant decrease in the intake of n-3 PUFAs. Increased fish consumption has been shown to be the only realistic way to increase dietary quantities of beneficial long-chain n-3 PUFAs such as eicosapentaenoic acid and docosahexaenoic acid and re-establish more balanced n-6:n-3 ratios in the diets of human beings. Our objective in this research was to characterize some of the relevant fatty acid chemistry of commonly consumed fish, with a particular focus on the four most commonly consumed farmed fish. To do this, 30 commonly consumed farmed and wild fish were collected from supermarkets and wholesalers throughout the United States. Fatty acid composition of samples from these fish was determined using gas chromatography. The 30 samples studied contained n-3 PUFAs ranging from fish having almost undetectable levels to fish having nearly 4.0 g n-3 PUFA per 100 g fish. The four most commonly farmed fish, Atlantic salmon, trout, tilapia, and catfish, were more closely examined. This analysis revealed that trout and Atlantic salmon contained relatively high concentrations of n-3 PUFA, low n-6:n-3 ratios, and favorable saturated fatty acid plus monounsaturated fatty acid to PUFA ratios. In contrast, tilapia (the fastest growing and most widely farmed fish) and catfish have much lower concentrations of n-3 PUFA, very high ratios of long chain n-6 to long chain n-3 PUFAs, and high saturated fatty acid plus monounsaturated fatty acid to PUFA ratios. Taken together, these data reveal that marked changes in the fishing industry during the past decade have produced widely eaten fish that have fatty acid characteristics that are generally accepted to be inflammatory by the health care community.

Replacement of dietary fish oils by alpha-linolenic acid-rich oils lowers omega 3 content in tilapia flesh

A 20-week feeding trial was conducted to determine whether increasing linolenic acid (18:3n-3) in vegetable oil (VO) based diets would lead to increased tissue deposition of 22:6n-3 in Nile tilapia (Oreochromis niloticus). Five isonitrogenous and isoenergetic diets were supplemented with 3% of either linseed oil (LO), a mixture of linseed oil with refined palm olein oil (PO) (LO-PO 2:1) and a mixture of refined palm olein oil with linseed oil (PO-LO 3:2) or with fish oil (FO) or corn oil (CO) as controls. The PO-LO, LO-PO and LO diets supplied a similar amount of 18:2n-6 (0.5% of diet by dry weight) and 0.5, 0.7 and 1.1% of 18:3n-3, respectively. Increased dietary 18:3n-3 caused commensurate increases in longer-chain n-3 PUFA and decreases in longer-chain n-6 PUFA in the muscle lipids of tilapia. However, the biosynthetic activities of fish fed the LO-based diets were not sufficient to raise the tissue concentrations of 20:5n-3, 22:5n-3 and 22:6n-3 to those of fish fed FO. The study suggests that tilapia (O. niloticus) has a limited capacity to synthesise 20:5n-3 and 22:6n-3 from dietary 18:3n-3. The replacement of FO in the diet of farmed tilapia with vegetable oils could therefore lower tissue concentrations of 20:5n-3 and 22:6n-3, and consequently produce an aquaculture product of lower lipid nutritional value for the consumer.