Larval Abundance and Mortality of Atlantic Herring ( Clupea harengus L. ) Spawned in the Georges Bank and Nantucket Shoals Areas, 1971-78 Seasons, in Relation to Spawning Stock Size

Time of hatching, abundance of recently-hatched larvae and their relative contribution from the Georges Bank and Nantucket Shoals spawning grounds, as well as mortality during the autumn-winter period are estimated for eight spawning seasons on the basis of data from the ICNAF Larval Herring Surveys...

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Bibliographic Details
Published in:Journal of Northwest Atlantic fishery science 1985-01, Vol.6 (1), p.21-35
Main Authors: Lough, R G, Bolz, G R, Pennington, M, Grosslein, M D
Format: Article
Language:English
Subjects:
Abundance
Benthos collecting devices
Clupeoid fisheries
Hatching
Larvae
Marine fishes
Mortality
Polls & surveys
Reproductive cycle
Seasons
Shoals
Spawning
Spawning grounds
Spawning populations
Spawning seasons
Submarine banks
Surveys
Year class
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Summary:Time of hatching, abundance of recently-hatched larvae and their relative contribution from the Georges Bank and Nantucket Shoals spawning grounds, as well as mortality during the autumn-winter period are estimated for eight spawning seasons on the basis of data from the ICNAF Larval Herring Surveys which were conducted during 1971 78. Indices show that the highest initial larval production occurred in 1973 and 1974 as a result of the large 1970 year-class and that there was a decline in production of about two orders of magnitude by 1976 and thereafter. The collapse of the fishery on Georges Bank in 1976 coincided with a delay in peak spawning from mid- to late October, a contraction of the spawning season, and a shift of the remaining spawning population to northwestern Georges Bank and Nantucket Shoals. Furthermore, the mean seasonal mortality rate of 5% per day, estimated over the first 6 months of life, varied significantly (3-7%/day) after the 1975 season. The initial larval production estimates are compared with abundance indices (age 3+ herring) from spring bottom-trawl surveys, and sources of bias are evaluated.
ISSN:0250-6408
1682-9786
1813-1859
DOI:10.2960/J.v6.a3