Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1988-89 spawning-ground surveys

Spratt, Jerome D. (1989) Biomass estimates of Pacific herring, Clupea harengus pallasi, in California from the 1988-89 spawning-ground surveys. Monterey, CA, California Department of Fish and Game, Marine Resources Region, (Marine Resources Administrative Report, 89-6)

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Abstract

The 1988-89 spawning biomass estimate of Pacific herring, Clupea harengus pallasi, in San Francisco Bay is 66,000 tons, a 3,000-ton decrease from the 1987-88 biomass estimate of 69,000 tons. The San Francisco Bay herring population which had been increasing since 1984, remains above the 10-year population mean of 60,000 tons. In Tomales Bay the 1988-89 herring spawning biomass was estimated at 380 tons. This is the lowest spawning biomass recorded and follows a poor 1987-88 season, when 2,000 tons of herring spawned. It is believed that spawning herring are not returning to Tomales Bay. The current drought condition in California may be the cause of the change in spawning behavior. January was the month of peak spawning activity in San Francisco Bay, with 40,000 tons of herring spawning during the month. In Tomales Bay, nearly all herring also spawned in January. In San Francisco Bay, 50% of all spawning occurred along the San Francisco waterfront, 25% occurred in the Oakland-Alameda area, and 25% occurred in the Belvedere, Tiburon, and Angel Island areas. No spawning was found near Richmond, Berkeley, Candlestick Point, Sierra Point, or Oyster Point. During the past seven 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. Estero Americano was included in spawning-ground surveys this season. Only trace amounts (<1 ton) of herring spawned in the estero. (35pp.)

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