Catch and Effort and Size Distribution in the Irish Lobster and Lobster/Crawfish Fisheries

Abstract

In recent years, increasing attention has been paid to the interpretation of the effects of fishing effort upon the stock abundance of commercially valuable decapod crustacea. Simpson (1970) has emphasised the value of and urgent need for, precise information concerning the effects of fishing effort on lobster and crawfish stocks. By their very nature, lobsters and crawfish do not lend themselves particularly well to conformity with established methods of catch and effort analyses as applied to fish stocks. Therefore, whilst this almost traditional approach is adopted for lobster and crawfish studies, it may well be that considerable adjustments in the methodology are required if firmer estimations are to be achieved concerning the effects of fishing effort upon these animals. A most important gap in our knowledge is that of the mechanism of recruitment. Without reliable estimates of annual recruitment it is difficult to interpret its effects on abundance of good or poor year classes. Fully reliable methods of ageing lobsters have not been perfected.