A Life History Approach to the Assessment and Management of Deepwater Fisheries in the Northeast Atlantic

Abstract

It has been generally stated that fish exploited by deepwater fisheries cannot sustain high levels of exploitation because of their characteristic slow growth, longevity and low reproductive output. Irish surveys (19932000) allowed for studies of age, growth, fecundity and maturity of several deepwater teleosts and elasmobranchs. These data show that the teleost roundnose grenadier Coryphaenoides rupestris is slow growing and has low fecundity. Other teleosts also displayed rather conservative life-history characteristics. The birdbeak dogfish shark Deania calceus was slower growing than the teleosts and leafscale gulper shark Centrophorus squamosus attained ages of up to 70 years. The implications of these life-history parameters for sustainable exploitation are discussed by way of comparison with continental shelf species from this region. These data allowed for the estimation of the rate of potential population increase that supports the view that deepwater species are more vulnerable to exploitation. Whilst there may be scope for compensatory changes in fecundity such scope is likely to be limited, especially for sharks. Fisheries management plans should consider these differing life-history traits. The very different life history strategies exhibited by shelf and deepwater species suggests that different management systems will be required for deepwater fisheries to those prosecuted on the shelf.