Pacific Sardine Research

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The Pacific sardine was once the largest fishery in North America, with peak landings of 664,000 metric tons during 1936 and peak biomass (ages 2+) of 3.6 million metric tons during 1934 (Murphy 1966; MacCall 1979). Less than 30 years later, however, sardine biomass fell to less than 10,000 MT by 1965; the fisheries collapsed; and the stock did not increase noticeably for about fifteen years (Barnes et al. 1992). Meanwhile, the demise of the Pacific sardine fishery became a well-known, textbook example (Hilborn and Walters 1992) of the boom-and-bust cycles characteristic of clupeoid stocks and fisheries. Periods of low recruitment success can lead to longer periods of low population abundance, even in the absence of fishing.

Sardine science and research following the collapse of the historical sardine fishery set the stage for current research and, more important, provides decades worth of data and analyses. Research during the historical period included large scale tagging studies (Clark and Janssen 1945), the development of the CalCOFI program for regular and intensive ichthyoplankton sampling (Hewitt 1988), and the development of cohort analysis (Murphy 1966), also called virtual population analysis or VPA (Megrey 1989), for estimating trends in stock biomass from fisheries data. Many of these data sets (Roemmich and McGowan 1995; Jacobson and MacCall 1995) and methods (Murphy 1966; Megrey 1989) are used today to address important problems and issues.

Since the collapse of the sardine fishery in the early 1930s, the sardine biomass has experienced periods of expansion and contraction. Recently, the sardine population has experienced a depressed state. A trend of declining stock biomass has been observed in the sardine assessed off the West Coast, plateauing at recent low levels since 2014, and projected to an estimate of 27,547 metric tons in July 2019. The numbers of young fish added to the population from 2011 to 2017, known as recruitment, have been among the lowest in recent history.

NOAA Fisheries scientists assess the sardine population and oceanographic environment off the West Coast annually. Conducted on one of the most technologically advanced fisheries vessels in the world, surveys extend along the length of the United States west coast and into Canadian waters. The Fisheries Resources Division uses data from these surveys to conduct annual stock assessments to help determine the annual fishing levels for the upcoming fishing season. If the population biomass falls below a precautionary level of 150,000 metric tons, three times greater than when the stock could be considered overfished, then directed fishing for Pacific sardines is closed. This occurred in 2014 and the directed fishery for sardines has since remained closed. This threshold aims to preserve enough sardines to jump-start a new cycle of population growth when ocean conditions become more favorable.

In April 2019, at the advisement of the 2019 Pacific Sardine Stock Assessment, the Pacific Fisheries Management Council determined the sardine biomass was overfished. The fisheries remains closed for the fifth year in a row.