The exploitation of angler fish Lophius Spp. in Irish waters

Abstract

Two species of European angler, Lophius plscatorius and L. budegassa occur In Irish waters. L piscatorius is dominant, particularly closer to the coast; L. budegassa becomes more important moving south and in landings from medium/deep water. Three stocks of anglers are recognized; this work concerns the fish in the central one, specifically in ICES Divisions Vllb, c and j,k. Anglers are taken in a mixed demersal fishery, and they are particularly associated with hake and megrim. Most landings of the species come from ICES Divisions VlIg-k. The species have traditionally been taken in a mixed demersal fishery, mainly by France and Scotland. Ireland's landings have increased from 100t in 1977 to in excess of 2,000t in recent years. Species composition of the landings was determined by port sampling. The proportion of Lophius piscatorius, while still dominant, has declined since the mid 1980s. A short CPUE time series from joint venture vessels fishing medium/deep water (approximately 200 m) shows no consistent trends although the values for 1991 were the lowest in the six years. Irish vessels take anglers of slightly greater weight than do their joint venture (Spanish) counterparts. Length frequency distributions of both species from the Irish trawl fishery are available from 1987 to 1991 inclusive. They are redistributed by age using French ALKs. The age distribution shows no particular trend for L. budegassa whereas that for L. piscatorius shows evidence of strong year classes from the mid 1980s passing through the population. The sharp reduction in angler CPUE in 1991 may have resulted from the exhaustion of strong mid 1980s year classes of L. piscatorius. A large plus group in the age distribution of L. piscatorius restricted interpretation of its population structure. Discarding of anglers appears to be very low in the south western Irish trawl fisheries, an estimate of 6.8% landed weight being used in this assessment. A catch curve for L. piscaforius suggested a value of Z+0.48; taking M=0.15 provides a value for F=0.33, to the right of Fmax and in general agreement with what has been concluded for this species in recent assessments.