Wild fish consumption can balance nutrient retention in farmed fish.

Wild fish used as aquafeeds could be redirected towards human consumption to support sustainable marine resource use. Here we use mass-balance fish-in/fish-out ratio approaches to assess nutrient retention in salmon farming and identify scenarios that provide more nutrient-rich food to people. Using data on Norway's salmon farms, our study revealed that six of nine dietary nutrients had higher yields in wild fish used for feeds, such as anchovies and mackerel, than in farmed salmon production. Reallocating one-third of food-grade wild feed fish towards direct human consumption would increase seafood production, while also retaining by-products for use as aquafeeds, thus maximizing nutrient utilization of marine resources.

Small-scale octopus fishery operations enable environmentally and socioeconomically sustainable sourcing of nutrients under climate change.

Small-scale octopus fisheries represent an underexplored source of nutrients and socioeconomic benefits for populations in the tropics. Here we analyse data from global seafood databases and published literature, finding that tropical small-scale octopus fisheries produced 88,000 t of catch and processed octopus in 2017, with a landed value of US$ 2.3 billion, contributing towards copper, iron and selenium intakes, with over twice the vitamin B12 content of finfish. Catch methods, primarily consisting of small-scale lines and small-scale pots and traps, produced minimal bycatch, and the fast growth and adaptability of octopus may facilitate environmentally sustainable production under climatic change. Management approaches including periodic fishery closures, size restrictions, licences and knowledge transfer of fishing gears can enable greater blue food supply and economic value to be generated while improving environmental sustainability.

Opportunities and challenges for upscaled global bivalve seafood production.

Slow growth in the bivalve mariculture sector results from production inefficiencies, food safety concerns, limited availability of convenience products and low consumer demand. Here we assess whether bivalves could meet mass-market seafood demand across the bivalve value chain. We explore how bivalve production could become more efficient, strategies for increasing edible meat yield and how food safety could be improved through food processing technologies and new depuration innovations. Finally, we examine barriers to consumer uptake, such as food allergen prevalence and bivalve preparation challenges, highlighting that appealing and convenient bivalve food products could provide consumers with nutritious and sustainable seafood options-and contribute positively to global food systems.

Vitamin Bullets. Microencapsulated Feeds to Fortify Shellfish and Tackle Human Nutrient Deficiencies.

Over two billion people worldwide are micronutrient deficient, with regionally specific deficiencies. Fortification of food with micronutrients has become an industry standard for enhancing public health. Bivalve shellfish (e.g., oysters, clams, and mussels) provide the most sustainable source of animal protein on the planet, and the market is rapidly growing-with production in China increasing 1,000-fold since 1980 to an annual 36 kg capita-1 consumption level. Bivalves are also unique in that micronutrients consumed at their end-life stage will be digested by humans, as humans consume the entire organism including the gut. We have developed a novel microencapsulated vehicle for delivering micronutrients to bivalves, tailored for optimal size, shape, buoyancy, and palatability, demonstrating the potential of fortified bivalves to tackle human nutrient deficiencies. Oysters fed vitamin A and D microcapsules at a 3% initial dosage for just 8 h had elevated tissue vitamin content. A serving of just two such bivalves provides enough vitamin A and D to meet human dietary RDAs. Scale-up of this technology and application to other bivalve species including clams and mussels could provide a low-cost and highly sustainable mechanism to contribute toward tackling nutrient deficiencies globally.

Microencapsulated algal feeds as a sustainable replacement diet for broodstock in commercial bivalve aquaculture.

The global bivalve shellfish industry makes up 25% of aquaculture, is worth USD $17.2 billion year-1, and relies upon a supply of juvenile bivalves produced by adult broodstock in hatcheries. Today large quantities of live algae are grown to feed broodstock at $220 kg-1, driving highly unsustainable energy and resource use. New advances in algal and microencapsulation technology provide solutions. We developed microencapsulated Schizochytrium algae diets, which can be produced sustainably at < $2 kg-1 from organic side-streams, and are shelf-stable to minimise waste. Physiological, histological, and cutting-edge metabolomic analyses demonstrate that in commercial settings sustainable microencapsulated diets facilitate improved sexual development and 12 × greater omega-3 levels in oysters relative to conventional live algal diets. Every tonne bivalve protein produced instead of fish spares 9 ha, 67 tonnes CO2, and 40,000 L freshwater. Further research into microencapsulated diets could support bivalve industry expansion, and contribute towards a step-change in sustainable global food production through improved aquaculture practices.