Aspects of the exploitation of hake Merluccius merluccius belonging to the northern stock by fleets based in Ireland

The development of the hake fishery in the ICES Divisions adjoining Ireland displays strong similarities to the fishery for megrim; Ireland's landings of hake rose from 100t per year in 1979 to 2,000t ten years later. Most hake comes from Divisions Vllg-k. The Communities Logbook of the Irish-Spanish joint venture fleet provides a short time series. CPUE by both demersal trawl and long line declined sharply between 1985 and 1991. The second quarter is the most productive of hake landings but otherwise there is no clear seasonal pattern. Hake were sampled on a half yearly basis and the fish were aged on the otoliths with a success rate of 70%. Ages in the first half were adjusted to a birth date of 1 January. Mean lengths at age were higher than those calculated by statistical methods (Normsep.). Length frequencies indicated two age groups in the discards. Methods of capturing hake have altered over the past five years, gill nets have increased their share of the Irish catch and, in 1991, were a close second to demersal trawl. Age of recruitment to the landings is 2-4 years. Discard hake was calculated at 25-163% by weight of landings per quarter in 1991, higher values coming from small-meshed nets targeting Nephrops. Survivorship curves based on aged length frequencies of hake taken by whitefish boats provided F values of between 0.40 and 0.76. These results are high and together with sharply declining CPUE would seem to suggest the part of the stock in Divisions Vllb-c and Vllg-k is more heavily fished than the stock in other parts of Sub-area VII.

URI

http://hdl.handle.net/10793/181

Citation

Fahy, E. & Gleeson, P., "Aspects of the exploitation of hake Merluccius merluccius belonging to the northern stock by fleets based in Ireland", Irish Fisheries Bulletin, Department of the Marine 1993