Changes in catchability of cod, haddock, and whiting associated with the Scottish seine-net fleet

The catchability coefficient, Q, of cod, haddock, and whiting associated with the Scottish seine-net fleet is examined. Cod and haddock show increasing catchability for the period 1963–1979. The rise in Q is related to the spatial distribution of the fleet as vessels increasingly fish in areas of higher fish abundance. Additionally, for haddock, catchability is related to year-class strength. The utility of catchability trends in the prediction of fishing mortality is discussed.