Buoyancy in the LumpsuckerCyclopterus Lumpus

Abstract

The lumpsucker or lumpfish,Cyclopterus lumpusL. (Cyclopteridae, Scorpaeniformes), is a cottoid teleost, and, like other fish in its family, exhibits many characteristics of a coastal, bottom-dwelling fish. It is globiform, has no swimbladder, possesses a large abdominal sucker (formed from the pelvic fins), and lays demersal eggs which are brooded by the male parent for many weeks (Fulton, 1907; Cox & Anderson, 1922; Yesipov, 1937; Zhitenev, 1970; Mochek, 1973). The species spends the breeding season in shallow water, where both sexes may be seen attached to the rocks by their suckers. Early researchers (Couch, 1863; Day, 1880–4; Smitt, 1892) believed that the adults retreated to rocky bottoms in deep water after breeding. However, later workers (Cox & Anderson, 1922; Saemundsson, 1926, 1949; Andriyashev, 1954; Bagge, 1964; Blacker, 1983; Daborn & Gregory, 1983) have demonstrated that the lumpsucker spends much of its larval and adult life living epipelagically and in mid water in coastal and oceanic areas upon macrozooplankton (e.g. ctenophores, mysids). The term ‘semi-pelagic’ seems the most appropriate label for its mode of life.