The Distribution of Chondrichthyan Fishes Around the British Isles and Implications for Conservation

Abstract

Over 50 species of chondrichthyan fishes are known from waters around the British Isles, of which 26 have been recorded in CEFAS trawl surveys. The distribution and relative abundance of dogfishes, skates and rays are described from groundfish surveys in the North Sea, eastern English Channel, Irish Sea and Celtic Sea. The contemporary distribution of species is examined in relation to their biogeography and their distribution from historical records, and major changes in the distribution and relative abundance of species discussed in relation to stock status. Nursery areas of elasmobranchs are typically in shallower water than adult habitats and such patterns were evident for blonde Raja brachyura , thornback R. clavata, small-eyed R. microocellata and spotted ray R. montagui . In contrast, juvenile cuckoo ray Leucoraja naevus occurred in relatively deep waters and were most abundant in the western Irish Sea and northern St George’s Channel. Nursery areas are typically areas of high productivity with abundant food resources and low predation rates. Oviparous species also require a suitable substratum for the deposition of eggs. Sites where the egg-cases and juvenile stages of dogfishes and rajid skates occur, and may be important nursery habitats, are identified.