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Unassessed Fisheries

Status and Solutions for the World's Unassessed Fisheries

Christopher Costello, Daniel Ovando, Ray Hilborn, Steven D. Gaines, Oliver Deschenes, and Sarah E. Lester

A new study recently published in the journal Science features an innovative method developed by SFG researchers Costello, Ovando, Gaines, and Lester for assessing the status of the world’s data-poor fisheries. The paper, “Status and Solutions for the World’s Unassessed Fisheries”, provides insight on the health of thousands of previously unassessed fisheries – that is, fisheries for which the fish stock size and condition has not been evaluated – that account for more than 80% of the world’s catch. Until now, our understanding of the status of fisheries has been based on a tiny fraction of the world’s fisheries – the large, valuable ones for which we have ample data. However, these well-studied fisheries only represent a few hundred of the over 10,000 fisheries worldwide, providing a skewed view of the overall health of the world’s fisheries. The Science study provides a new global status report that includes these previously unmeasured fisheries.

This new research confirms suspicions that previously unassessed fisheries are in poor condition, as indicated by low current biomass levels relative to the biomass that would be achieved from harvesting the fish populations for maximum sustainable yields (B/Bmsy; see figure). At present, about 18% of unassessed stocks are collapsed. And the future does not look bright for many unassessed fisheries, at least if fishing continues at the current levels: although large-scale unassessed stocks are performing about as well as assessed stocks right now, they show a trajectory of continued decline. Small-scale unassessed stocks, which are important for local food security and economic well-being (especially in the developing world), are in particularly bad shape and declining. But, ailing unassessed fisheries are not just a developing world problem; many small-scale fisheries in developed nations, including the United States, are in similar condition to those in developing nations. Assessed stocks, on the other hand, show signs of ongoing recovery and stabilization at sustainable levels, a trend that is consistent regardless of the country that manages them. While management institutions play an important role in fishery condition, the biological characteristics of the target species can also render a fishery vulnerable to overfishing; the study found that many struggling fisheries share the common thread of targeting species with life history traits including slow growth, late maturation, and large body sizes.

While the new study raises concerns for many of the world’s fish stocks, it also identifies great opportunity for improvement in both fishery yield and conservation – improvements that could be achieved in part by implementing innovative fishery reform techniques (e.g. data-poor stock assessments and rights-based fishery management). Results suggest that if overfished stocks were rebuilt to sustainable levels, the benefits would be great: more than 60% of unassessed stocks would provide increased sustainable harvests; recovering fisheries would produce future yields 40% higher than they would be with continued status quo fishing levels; and average in-water biomass would increase by more than 50%. In particular, results suggest that yields in regions or countries dominated by small-scale fisheries stand to increase the most – a promising finding for sustaining food security and vibrant coastal economies worldwide.

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Photo: Indonesian fish seller in the Lesser Sunda region, Jono Wilson.

Graph: Kelsey Jacobsen.