The stock–recruitment relationship is the basis of any stock prediction and thus fundamental for fishery management. Traditional parametric stock–recruitment models often poorly fit empirical data, nevertheless they are still the rule in fish stock assessment procedures. We here apply a multi-model approach to predict recruitment of 20 Atlantic cod (Gadus morhua) stocks as a function of adult biomass and environmental variables. We compare the traditional Ricker model with two non-parametric approaches: (i) the stochastic cusp model from catastrophe theory and (ii) multivariate simplex projections, based on attractor state-space reconstruction. We show that the performance of each model is contingent on the historical dynamics of individual stocks, and that stocks which experienced abrupt and state-dependent dynamics are best modelled using non-parametric approaches. These dynamics are pervasive in Western stocks highlighting a geographical distinction between cod stocks, which have implications for their recovery potential. Furthermore, the addition of environmental variables always improved the models’ predictive power indicating that they should be considered in stock assessment and management routines. Using our multi-model approach, we demonstrate that we should be more flexible when modelling recruitment and tailor our approaches to the dynamical properties of each individual stock.

Decades of intense fishing have not only caused widespread declines in marine fish populations but in recent years have also spurred progress in the development of resource policies, coinciding with reports of positive trends for selected fish stocks in several ecosystems. Anthropogenic pressures and environmental changes affect fish populations, but it is unclear whether improved fisheries management or natural conditions are responsible for the observed recoveries. We show that, for a large set of Northeast Atlantic fish stocks, long‐term declines in biomass from 1960 to 2000 were due largely to fishing, suggesting that external drivers caused stock fluctuations at a time when catch regulations were weak or largely absent. After the year 2007, a general pattern of increasing biomass and decreasing catches was observed across most taxa and geographic regions. Implementation of adequate policies to reduce fishing mortality is crucial for overexploited stocks to recover, underlining the positive impacts of science‐based management. Because attempts to rebuild Northeast Atlantic fisheries have been only partially successful, and management targets were not fully achieved, policy‐making efforts must continue.

Globally, wild decapod crustacean fisheries are growing faster than fisheries of any other major group, yet little attention has been given to the benefits, costs, and risks of this shift. We examined more than 60 years of global fisheries landings data to evaluate the socioeconomic and ecological implications of the compositional change in global fisheries, and propose that direct and indirect anthropogenic alterations and enhancements to ecosystems continue to benefit crustaceans. Crustaceans are among the most valuable seafood, but provide low nutritional yields and drive 94% of the projected increase of global fishery carbon emissions, due to low capture efficiency. Unequivocally, the increasing global demand for luxury seafood comes with serious environmental costs, but also appears to offer lucrative fishing opportunities. The potential for more prosperous fisheries carries unevaluated risks, highlighting the need for a nuanced perspective on global fisheries trade‐offs. Addressing this unique suite of trade‐offs will require substantive changes in both science and management.

As result of ocean warming, marine boreal species have shifted their distribution poleward, with increases in abundance at higher latitudes, and declines in abundance at lower latitudes. A key to predict future changes in fish communities is to understand how fish stocks respond to climate variability. Scattered field observations in the first half of the 20th century suggested that boreal fish may coherently invade Greenland waters when temperatures rise, but this hypothesis has remained untested. Therefore, we studied how local temperature variability and the dynamics of the subpolar gyre, a large-scale driver of oceanic conditions in the North Atlantic, affect abundance of boreal fishes in a region that sharply defines their lower thermal boundary. We analysed information from demersal trawl surveys from 1981 to 2017, for species distributed from shallow shelf to depths of 1,500 m, collected at over 10,000 stations along ~3,000 km of Greenland. Our results show that local temperature and variability of Labrador and Irminger Sea water in the subpolar gyre region drive interdecadal variability of boreal fish abundance in Greenland waters. Although temperature fluctuations were higher in shallow than deep regions, fish abundance changed as quickly in great depths as in shallow depths. This link between physics and biology provides an opportunity for prediction of future trends, which is of utility in Greenland, where fisheries constitute more than 90% of the national export value.

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