Managing fisheries for maximum nutrient yield

Abstract

Wild-caught fish are a bioavailable source of nutritious food that, if managed strategically, could enhance diet quality for billions of people. However, optimising nutrient production from the sea has not been a priority, hindering development of nutritionsensitive policies. With fisheries management increasingly effective at rebuilding stocks and regulating sustainable fishing, we can now begin to integrate nutritional outcomes within existing management frameworks. Here, we develop a conceptual foundation for managing fisheries for multispecies Maximum Nutrient Yield (mMNY).We empirically test our approach using size-based models of North Sea and Baltic Sea fisheries and show that mMNY is predicted by the relative contribution of nutritious species to total catch and their vulnerability to fishing, leading to trade-offs between catch and specific nutrients. Simulated nutrient yield curves suggest that vitamin D, which is deficient in Northern European diets, was underfished at fishing levels that returned maximum catch weights. Analysis of global catch data shows there is scope for nutrient yields from most of the world's marine fisheries to be enhanced through nutrient-sensitive fisheries management. With nutrient composition data now widely available, we expect our mMNY framework to motivate development of nutrientbased reference points in specific contexts, such as data-limited fisheries. Managing for mMNY alongside policies that promote access to fish could help close nutrient gaps for coastal populations, maximising the contribution of wild-caught fish to global food and nutrition security.

Assessing seafood nutritional diversity together with climate impacts informs more comprehensive dietary advice

“…Seafood statistics and research often defaults to a production perspective, with even consumption being measured in liveweight mass 1 . If human nutrition is the ultimate objective of fisheries and aquaculture, it is important that outputs are understood and evaluated on a nutritionally relevant basis particularly given the diversity of species involved 4 and maximising the nutritional output while minimising environmental costs of seafood provisioning should be a guiding principle for policy-making in these areas 41 . As both fisheries and aquaculture face many environmental challenges-in terms of sustainable utilisation of stocks, reduction of by-catch and impacts on local ecosystem structure and function, nutrient enrichment, and disease amplification-restricting the analysis of sustainability to GHG emissions may seem very limited.…”

Sustainable reference points for multispecies coral reef fisheries

“…Against site-specific BMMSY benchmarks, we found that 52 % of our sites open to extraction activities had median biomass values below their site-specific BMMSY from the Gompertz-Fox model (Fig. 1i) and only 49 [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] % of sites were in the range of producing "Pretty good multispecies yields" (PGMY, defined as the sustainable yield that is within 0.8 of MMSY (27; Fig. 1j).…”

“…Combining both standing stock biomass and catch estimates, we found that 54 [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] % of jurisdictions with both standing stock biomass and spatial catch data available had reef fisheries of "conservation concern" (4), failing one or both sustainable reference points based on weighted biomass values (Fig. 2e-f).…”

“…Finally, we believe that future multispecies reference points for coral reef fisheries would benefit from including a range of sustainability criteria beyond long-term production. In a similar way as our ecosystem metrics, there may be trade-offs between long-term yields and other desirable goals 14 th of September 2022 14 such as economic return (43) or nutritional yields (44), that will have to be evaluated to assess the overall sustainability of reef fisheries.…”

Wild-caught fish populations targeted by MSC-certified fisheries have higher relative abundance than non-MSC populations

“…Stock biomass and corresponding target and limit reference points represent only some of the information that managers must consider when grappling with decisions that often involve trade-offs among competing objectives. Different benchmarks, for example considering B MSY as a limit rather than a target, or alternatives to MSY-based quantities such as maximum economic yield or focus on nutrient provision (Robinson et al, 2022), all involve societal as well as biological considerations that we do not address in this study. More broadly, best-practice management extends beyond evaluating single-population measures of relative biomass, also considering wider impacts of fishing activities on food webs and ecosystems.…”