Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1987-88 spawning-ground surveys


The 1987-88 spawning biomass estimate of Pacific herring, Clupea harengus pallasi, in San Francisco Bay is nearly 69,000 tons. This is the fourth consecutive year that the San Francisco Bay population has increased, after reaching a low point of 40,000 tons in 1984. In Tomales Bay the 1987-88 herring spawning biomass was estimated at 2,061 tons. During the past five seasons, the Tomales Bay spawning biomass has been low in even years and high in odd years, indicating that spawning herring are not returning to Tomales Bay consistently. In San Francisco Bay, over 42,000 tons of herring spawned in January. Similarly, 90% of Tomales Bay herring spawned in January. No spawns were found during March in either bay. For the first time, in San Francisco Bay, no herring spawned in the Belvedere, Tiburon, or Angel Island areas. In addition, herring spawning was found in the Oakland-Alameda area for the first time and over 95% of all spawning occurred in the southern part of San Francisco Bay. During the past six seasons in San Francisco Bay, over 70% of all spawning escapement has been in the southern part of the bay. For the nine seasons prior to that, 94% of all spawning escapement was in the northern part of the bay. (31pp.

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