Although the initial description of the northern rockling, Ciliata septentrionalis (Collett, 1875 a, b) was based on specimens collected off the Norwegian coast in the late nineteenth century, this species was not recorded from British waters until 1960, when a specimen was found in the Clyde Sea area (Bagenal, 1961). Subsequently, northern rockling have been recorded by Wheeler (1965, 1968) from the Moray Firth and in the waters off the Isle of Man and Southern Ireland, and by Dando (1975) from the Plymouth area. A single specimen has also been captured in a rock pool on the Yorkshire coast (Wheeler, 1971). The only investigation into the biology of C. septentrionalis has been conducted by Dando (1975), who obtained the fish from the Plymouth area, both by trawling and from cod stomachs. He outlined the early development of the egg and larva, and suggested that the northern rockling had greatly increased in abundance in the Plymouth region since 1968.