Herring tagging experiments around Ireland, 1991

Abstract

The assessment and management of the herring fisheries around Ireland assumes that there are three distinct and separate populations. The management units are based on ICES Areas which, however, are not based on the distribution of the stocks and which do not take into account the mixing that takes place between the different stocks. In July 1992 a herring tagging experiment was carried out, designed to provided information on the migration of the herring around Ireland which would be useful in establishing more realistic management units. In the experiment over 20,000 herring were tagged and liberated - 10,000 southwest of the Isle of Man and 10,000 in Broadhaven Bay. Over 450 tagged fish have been recovered to date and the results suggested considerable movement of herring between the different management units. There appears to be a major link between the Irish Sea stocks and the part of the Celtic Sea stock that spawns off the south east coast of Ireland. A small number of fish tagged off the Mayo coast migrated south to the coast of Kerry. The mixing of these stocks should be taken into account when the various stocks are assessed and when the annual TAC's are estimated.