Pacific herring, Clupea harengus pallasi, studies in San Francisco Bay, Monterey Bay, and the Gulf of the Farallones, May 1983 to March 1984

Reilly, Paul N. and Moore, Thomas O. (1984) Pacific herring, Clupea harengus pallasi, studies in San Francisco Bay, Monterey Bay, and the Gulf of the Farallones, May 1983 to March 1984. Menlo Park, CA, California Department of Fish and Game, Marine Resources Region, (Marine Resources Administrative Report, 84-3)

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Abstract

Herring stocks were surveyed hydroacoustically and sampled in San Francisco Bay from November 1983 to March 1984. A maximum of 12 schools entered the Bay and spawned between October 29 and March 20, although large schools (at least 1000 tons) occurred only from January 2 to March 14. Total biomass estimate from hydroacoustic surveys was only 29 300 tons, compared with 67 040 tons during the 1982-83 season. Although different from MRR's biomass estimate from spawn deposition plus catch (59 000 tons in 1982-83 and 40 000 tons in 1983-84), hydroacoustic estimates showed the same declining trend. One hundred-four samples, containing a total of 13 940 herring, were collected with variable-mesh gill net and midwater trawl or obtained from the roundhaul and gill net fisheries. The normal pattern of decreasing mean length and age of herring as the season progressed was observed. Small schools that spawned in November and December consisted primarily of 4- to 7-yr-old herring. In general, the absence of large aggregations of older fish during most of the fishing season resulted in a poor season for the fleet. An encouraging sign was the strength of the 1982 yr class. These 2-yr-old fish completely dominated schools from 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 by length/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 and ranged from 10% for 2-yr olds to almost 20% for 8-yr olds. Average fecundity was estimated from egg counts from 153 unripe herring. Mean value was 220.9 eggs/g of fish +/- 4.9 eggs/g. A positive correlation has been observed for the past three seasons between the relative abundance of young-of-the-year herring, as noted from midwater trawl samples collected by the Department's Bay-Delta Project, and the resultant year class strength of newly recruited 2-yr-old herring in San Francisco Bay's spawning stocks. Data from 1983 summer sampling indicate the 1983 yr class is relatively weak. (77pp.)

Item Type: Monograph or Serial Issue
Title: Pacific herring, Clupea harengus pallasi, studies in San Francisco Bay, Monterey Bay, and the Gulf of the Farallones, May 1983 to March 1984
Personal Creator/Author:
CreatorsEmail
Reilly, Paul N.
Moore, Thomas O.
Series Name: Marine Resources Administrative Report
Number: 84-3
Date: 1984
Publisher: California Department of Fish and Game, Marine Resources Region
Place of Publication: Menlo Park, CA
Latitude: 37.423
Longitude: 122.165
Issuing Agency: California Department of Fish and Game
Uncontrolled Keywords: Pacific herring; Clupea harengus pallasi
Subjects: Management
Fisheries
Biology
Item ID: 323
Depositing User: Joan Parker
Date Deposited: 04 Oct 2007 15:32
Last Modified: 29 Sep 2011 22:14
URI: http://aquaticcommons.org/id/eprint/323

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