Biomass estimate of Pacific herring Clupea harengus pallasi, in California from the 1983-84 spawning-ground surveys

Spratt, Jerome D. (1984) Biomass estimate of Pacific herring Clupea harengus pallasi, in California from the 1983-84 spawning-ground surveys. Monterey, CA, California Department of Fish and Game, Marine Resources Region, (Marine Resources Administrative Report, 84-2)

Preview

PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader Download (2093Kb) | Preview

Abstract

The spawning biomass of Pacific herring, Clupea harengus pallasi, in San Francisco Bay and Tomales Bay was estimated to be 40 000 tons and 1300 tons, respectively during the 1983-84 season. The San Francisco biomass estimate declined for the second consecutive year and is now 60% below the peak year of 1981-82, when 100 000 tons of herring spawned. In Tomales Bay the population estimate declined 88% from one of the higher estimates the year before, to the lowest estimate recorded. These declines in biomass were not totally unexpected, due to the continued high ocean temperatures off California during 1983. One of the major contributors to the decline was the poor growth rate exhibited by individual herring during 1983. There is also a strong possibility that part of the decline this season was due to a northerly shift in the distribution of California's herring stocks. The ocean temperatures off California returned to normal in 1984, and both San Francisco Bay and Tomales Bay populations are expected to respond in a positive manner during the year. (32pp.)

Actions (login required)