Spatial variation in life history characteristics of common megrim (Lepidorhombus whiffiagonis) on the Northern Shelf

In recent years stock structure recommendations for megrim on the Northern Shelf have varied, primarily due to a lack of biological and fishery data. In this study, we compared a number of life history characteristics of the common megrim Lepidorhombus whiffiagonis (Walbaum) between the northern North Sea and Rockall, the latitudinal extremes of the species’ distribution on the Northern Shelf. Reproductive timing, sex ratio, maturity and growth were different between the two study areas. Reproductive timing in the northern North Sea was more protracted than at Rockall and other areas. There were differences in sex ratio between the study areas and female megrim in the northern North Sea exhibited different growth rates and larger size at maturity than at Rockall. The results of this study support the recent changes to the definition of the Northern Shelf stocks which recommend that the northern North Sea be treated separately to Rockall.