Marine Institute Open Access Repository >
Marine Institute Community of Research Publications >
Irish Fisheries Investigations >
Irish Fisheries Investigations Series B - Marine >
Please use this identifier to cite or link to this item:
|Title: ||The exploitation of megrim Lepidorhombus whiffiagonis by the Irish demersal fleet|
|Authors: ||Fahy, E|
Irish demersal fleet
|Issue Date: ||1991|
|Publisher: ||Department of the Marine|
|Citation: ||Fahy, E. & Fannon, E., "The exploitation of megrim Lepidorhombus whiffiagonis by the Irish demersal fleet", Irish Fisheries Investigations Series B, Department of the Marine 1992|
|Series/Report no.: ||Irish Fisheries Investigations Series B;38|
|Abstract: ||Two species of megrim occur in Irish waters but Lepidorhombus whiffiagonis constitutes the bulk of the catch by the Irish demersal
fleet. Megrim is exploited as a by-catch of gadoid fisheries and is particularly associated with fisheries for Nephrops, angler and ray.
Over the past 25 years megrim landings from the ICES divisions adjoining Ireland have fluctuated between 6,000 and 21,000 tonnes
but there has been a gradual upward trend of which Ireland has taken an increasing share, rising to 1,800 tonnes in 1980.
Spain exerts most influence in this fishery, being the location of the main market for megrim as well as having the greatest catching power. The most significant developments in the exploitation of megrim over the past twenty years are identified as the establishment of the European Exclusive Fishery Zone in 1977 and the entry of Spain to the Community in 1986.
The importance of division Vlla as a producer of megrim has declined and the main fisheries for the species are in divisions
This assessment of the species is based on material gathered in 1989 and 1990 when length frequency data from the landings were
collected from the west and south coasts. Lengths of approximately 8,000 megrim from landings from all divisions were collected in
1989, 28,000 the following year, and 1,400 were aged in the two years. Samples of the landings are comparable with graded exports
from the fleet. The most intensive work was undertaken on a Nephrops and mixed whitefish fishery in Vllj.
Megrim discards (round) are estimated to weigh 13.2% of landings (gutted). Few megrim of less than 20 cm were captured and no
0 group megrim was encountered.
A growth curve is calculated for females and for females and males combined. For males the to value is outside the range of that
parameter recorded elsewhere. Males are however a small proportion of the total, their higher mortality and slower growth giving them a skewed frequency distribution and reducing their contribution to the landings.
Catch curves provided values for Z of 0.45 and 0.49 for females and combined sexes. Yield per recruit curves indicate exploitation is close to F max for females and on the negative slope for the sexes combined.|
|Appears in Collections:||Irish Fisheries Investigations Series B - Marine|
Items in the Marine Institute Open Access Repository are protected by copyright, with all rights reserved, unless otherwise indicated.