Pacific herring, Clupea pallasi, studies and fishery management in Tomales Bay, 1993-94, with notes on Humbolt and Crescent City area landings
1998
Moore, Thomas O. | Mello, John J.
The 1993-94 spawning biomass estimate for Pacific herring, Clupea pallasi, in Tomales Bay declined 40% from last season to 2,449 tons. Although this estimate is below the 20-year average of 4,700 tons, the spawning biomass estimate this year is close to the post 1982 El Nino11-year average of 2,054 tons. The overall trend of increasing biomass since the 1989-90 season still continues. There were eight distinct spawns this season, the most in five years, with the largest spawn occurring in late January.A total of 3.5 million m2 of eelgrass, Zostera marina, was measured in Tomales Bay this season. Eelgrass density increased in the majority of the beds.The commercial gillnet fleet in Tomales Bay caught a total of 219 tons of herring this season yielding an exploitation rate of 8.9%. Herring aged four, five, and six comprised 90% by number of this season's commercial gill net catch. Mean weight of herring ages three, six, and seven decreased slightly over last season while increases were seen for ages four, five, and eight. Meanlength of commercial caught herring increased slightly over 1992-93.Department variable-mesh gill nets caught a total of 455 herring of which 232 were aged. The dominant age class was four-yr-olds comprising 27% of the sample by number, followed by six-yr-olds representing the highly successful 1988 year class.In Humboldt Bay, the 1993-94 commercial catch of 62.8 tons was about 5% over the 1993-94 season quota of 60 tons and was well above Humboldt Bay's 21-year average catch of 40.4 tons.Crescent City area herring fishermen caught 32.5 tons, approximately 2% over the season quota for the Crescent City area. The 1993-94 season commercial catch is well above the 20-year average of 23.7 tons for this area. (31pp.)
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