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

• Published in: Proceedings of the National Academy of Sciences - PNAS 2012-03, Vol.109 (11), p.4175-4180
• Main Authors: Zwolinski, Juan P, Demer, David A
• Format: Article
• Language: English
• Subjects: Animal Migration; Animal Migration - physiology; Animal populations; Animal reproduction; Animals; Biological Sciences; Biomass; California; cold; Cold Temperature; Ecosystem; Fatty fishes; Fish; Fisheries; Fishery collapse; Fishes; Fishes - growth & development; Forecasting; Geometric lines; growth & development; Mackerel; Marine; Marine fishes; Ocean fisheries; Oceanography; Oceanography - trends; Oceans; Pacific Ocean; Perciformes; Perciformes - growth & development; physiology; Population Dynamics; Sardines; Sardinops sagax; Scomber japonicus; Seasons; Species Specificity; surveys; Trachurus; Trachurus symmetricus; trends
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1113806109

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.