Pacific herring, Clupea harengus pallasi, studies in San Francisco Bay, Monterey Bay, and the Gulf of the Farallones, May 1983 to March 1984
Herring stocks were surveyed hydroacoustically and sampledin San Francisco Bay from November 1983 to March 1984. Amaximum of 12 schools entered the Bay and spawned betweenOctober 29 and March 20, although large schools (at least1000 tons) occurred only from January 2 to March 14. Totalbiomass estimate from hydroacoustic surveys was only 29 300tons, compared with 67 040 tons during the 1982-83 season.Although different from MRR's biomass estimate from spawndeposition plus catch (59 000 tons in 1982-83 and 40 000tons in 1983-84), hydroacoustic estimates showed the samedeclining trend.One hundred-four samples, containing a total of 13 940herring, were collected with variable-mesh gill net andmidwater trawl or obtained from the roundhaul and gill netfisheries. The normal pattern of decreasing mean lengthand age of herring as the season progressed was observed.Small schools that spawned in November and Decemberconsisted primarily of 4- to 7-yr-old herring. In general,the absence of large aggregations of older fish during mostof the fishing season resulted in a poor season for thefleet. An encouraging sign was the strength of the 1982 yrclass. These 2-yr-old fish completely dominated schoolsfrom late January until the end of the spawning season, comprising from 40 to 83%, by number, of samples. The 1981 yr class (3-yr olds) was relatively weak, contributing no more than 16% by number to any school sampled.Poor growth conditions during 1983 were evidenced bylength/age and weight/age relationships. For most ages,mean lengths were 5 to 10 mm less than those of last season.Weight at age averaged 16% less than historical values andranged from 10% for 2-yr olds to almost 20% for 8-yr olds.Average fecundity was estimated from egg counts from 153unripe herring. Mean value was 220.9 eggs/g of fish +/- 4.9eggs/g.A positive correlation has been observed for the past threeseasons between the relative abundance of young-of-the-yearherring, as noted from midwater trawl samples collected bythe Department's Bay-Delta Project, and the resultant yearclass strength of newly recruited 2-yr-old herring in SanFrancisco Bay's spawning stocks. Data from 1983 summersampling indicate the 1983 yr class is relatively weak. (77pp.)
| Main Authors: | , |
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| Format: | monograph biblioteca |
| Language: | English |
| Published: |
California Department of Fish and Game, Marine Resources Region
1984
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| Subjects: | Management, Fisheries, Biology, Pacific herring, Clupea harengus pallasi, |
| Online Access: | http://hdl.handle.net/1834/18279 |
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