After a long history of overexploitation, increasing efforts to restore marine ecosystems and rebuild fisheries are under way. Here, we analyze current trends from a fisheries and conservation perspective. In 5 of 10 well-studied ecosystems, the average exploitation rate has recently declined and is now at or below the rate predicted to achieve maximum sustainable yield for seven systems. Yet 63% of assessed fish stocks worldwide still require rebuilding, and even lower exploitation rates are needed to reverse the collapse of vulnerable species. Combined fisheries and conservation objectives can be achieved by merging diverse management actions, including catch restrictions, gear modification, and closed areas, depending on local context. Impacts of international fleets and the lack of alternatives to fishing complicate prospects for rebuilding fisheries in many poorer regions, highlighting the need for a global perspective on rebuilding marine resources.

Marine fish stocks are an important part of the world food system and are particularly important for many of the poorest people of the world. Most existing analyses suggest overfishing is increasing, and there is widespread concern that fish stocks are decreasing throughout most of the world. We assembled trends in abundance and harvest rate of stocks that are scientifically assessed, constituting half of the reported global marine fish catch. For these stocks, on average, abundance is increasing and is at proposed target levels. Compared with regions that are intensively managed, regions with less-developed fisheries management have, on average, 3-fold greater harvest rates and half the abundance as assessed stocks. Available evidence suggests that the regions without assessments of abundance have little fisheries management, and stocks are in poor shape. Increased application of area-appropriate fisheries science recommendations and management tools are still needed for sustaining fisheries in places where they are lacking.

Relationships between various biological reference points (BRPs) used to define thresholds and targets of fisheries management strategies were examined for a range of combinations of life history characteristics. Rank orderings of the selected BRPs were strongly influenced by the degree of density dependence in the underlying spawning–recruitment (S–R) relationship. The validity of F0.1, Fmax, F20% (the fishing mortality at which spawning per recruit is 20% of the maximum), and other reference fishing mortality rates as approximations to Fmsy or as thresholds of overfishing is highly dependent on life history characteristics, particular the degree of density dependence in the S–R relationship. It is recommended that F40% be adopted as a target fishing mortality rate when the S–R relationship is unknown and that threshold levels of biomass be related to the estimated or assumed degree of density dependence in the S–R relationship. Two new methods of calculating threshold biomass levels are suggested as alternatives to the familiar 20% B0 rule.

In 1977, Peter Larkin published his now‐famous paper, ‘An epitaph for the concept of maximum sustained yield’. Larkin criticized the concept of single‐species maximum sustained yield (MSY) for many reasons, including the possibility that it may not guard against recruitment failure, and the impossibility of maximising sustainable yields for all species simultaneously. However, in recent years, there has been a fundamental change in the perception of the fishing mortality associated with MSY (FMSY) as a limit to be avoided rather than a target that can routinely be exceeded. The concept of FMSY as a limit is embodied in several United Nations Food and Agriculture Organization (FAO) agreements and guidelines, and has now been incorporated into the US Magnuson–Stevens Fishery Conservation and Management Act. As a result, the United States now requires the development of overfishing definitions based on biological reference points that treat the FMSY as a limit reference point and must also define a lower limit on biomass below which rebuilding plans with strict time horizons must be developed. This represents a major paradigm shift from the previously mandated (but often unachieved) objective to simply maintain fishing mortalities at levels below those associated with recruitment overfishing. In many cases, it requires substantial reductions in current fishing mortality levels. Therefore, the necessity of the new paradigm is continually questioned. This paper draws on examples from several fisheries, but specifically focuses on the recent US experience illustrating the practical difficulties of reducing fishing mortality to levels below those corresponding to MSY. However, several studies suggest that even more substantial reductions in fishing mortality may be necessary if ecosystem considerations, such as multispecies interactions, maintenance of biodiversity and genetic diversity, and reduction of bycatch and waste, are taken into account. The pros and cons of moving beyond single‐species assessment and management are discussed. A US plan for improving stock assessments indicates that even a ‘basic’ objective such as ‘adequate baseline monitoring of all managed species’ may be extremely costly. Thus, the suggestion of Larkin (1983, 1997) that the costs of research and management should not exceed 10–20% of the landed value of the catch may preclude comprehensive ecosystem management. More importantly, neither single‐species nor ecosystem‐based fisheries management is likely to improve appreciably unless levels of fishing capacity are aligned with resource productivity, as is currently being promoted by FAO and several individual nations.

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