Browsing Scientific Papers by Subject "Survey"
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Herring larval surveys in the Celtic Sea and division VIIj in 1982/83Surveys for herring larvae in the Celtic Sea were conducted between October 1982 ~ and February 1983 for the fifth successive season. To take account of the amalgamation of the Celtic Sea and Div VIIJ herring for assessment purposes and to ascertain if many larval drift into the Irish Sea, the survey grid of previous years was modified for the 1982/83 season. However, because of the nature of the larvae distribution it appears reasonable to compare the larvae index for 1982/83 with those of the previous seasons. The increase in indices since 1978/79 has continued up to 1982/83 indicating a steady, but slow, recovery of the spawning stock. Very few larvae appear to drift into the Irish Sea.
Herring larval surveys in the Celtic Sea in 1981/82The distributions of herring larvae sampled on ten cruises off the south coast of Ireland during the 1981/82 spawning season are described. A new larval abundance index, which is based on the abundances of <10mm larvae prior to 15 December and on <11mm larvae afterwards,has been calculated for the last four seasons. This index shows an increase each year since 1978/79 indicating that the spawning stock biomass has also increased.