Recent Papers

A cold oceanographic regime with high exploitation rates in the Northeast Pacific forecasts a collapse of the sardine stock

The oceanographic conditions in the north Pacific have shifted to a colder period, Pacific sardine (Sardinops sagax) biomass has declined precipitously in the California Current, the international sardine fishery is collapsing, and mackerel (Trachurus symmetricus and Scomber japonicus) are thriving. This situation occurred in the mid-1900s, but indices of current oceanographic conditions and the results of our acoustic-trawl surveys indicate it likely is recurring now, perhaps with similar socioeconomic and ecological consequences. Also alarming is the repetition of the fishery's response to a declining sardine stock—progressively higher exploitation rates targeting the oldest, largest, and most fecund fish. Furthermore, our data indicate the recent reproductive condition of sardine is poor, and their productivity is below modeled estimates used to derive the current fishery-exploitation rates. Consequently, the sardine population has been reduced to two cohorts that are unlikely to produce an appreciable new cohort. Thus, a near-term recovery of this important stock is unlikely, depending on the return of warmer oceanographic conditions, reduced pressure from mackerel species, and perhaps the adoption of a more precautionary strategy for managing the residual sardine population. Juan P. Zwolinski and David A. Demer. http://www.pnas.org/content/early/2012/02/24/1113806109.abstract

Reconsidering the Consequences of Selective Fisheries

Concern about the impact of fishing on ecosystems and fisheries production is increasing (1, 2). Strategies to reduce these impacts while addressing the growing need for food security (3) include increasing selectivity (1, 2): capturing species, sexes, and sizes in proportions that differ from their occurrence in the ecosystem. Increasing evidence suggests that more selective fishing neither maximizes production nor minimizes impacts (4–7). Balanced harvesting would more effectively mitigate adverse ecological effects of fishing while supporting sustainable fisheries. This strategy, which challenges present management paradigms, distributes a moderate mortality from fishing across the widest possible range of species, stocks, and sizes in an ecosystem, in proportion to their natural productivity (8), so that the relative size and species composition is maintained. S. M. Garcia et al. http://www.sciencemag.org/content/335/6072/1045.summary