Fecundity studies on herring from the north west of Ireland

Abstract

For some time past studies have been performed on herring fecundities by various scientists. Farren (1938) was the first to suggest that stocks could be separated by studying the different fecundity/length relationship of winter and autumn spawing populations from the Irish coast. Burd and Howlett (1974) calculated a fecundity index by length cubed and as a result clearly separated the spawning populations of Banks and Downs herring in the North Sea. Molloy (1979) regressed fecundity on length cubed for Celtic sea samples and was able to distinguish between the autumn spawning component and the winter spawning component in the Celtic Sea. This paper describes fecundity studies carried out on autumn spawning herring from the newly established management unit (V1a Lower and V11b) off the North west of Ireland. The results are compared with fecundity data from other Irish stocks and with the results obtained by Farran on the same stock over 40 years ago. It may be possible to use these results to calculate the spawning potential of the herring and those spawning off the Scottish coast. The spawning grounds from which these herring were taken are situated a few miles off the North West coast.