Cephalopods in the North-Eastern Atlantic: Species, Biogeography, Ecology, explotation and conservation

Abstract

Cephalopods play a significant role in coastal and oceanic ecosystems. both as consumers of invertebrates and small fish and as the prey of some fish, seabirds and marine mammals and other large predators. Approximately 30 species of cephalopod have been recorded in the north-eastern Atlantic and adjacent waters, including 18 teuthid (squid), seven sepiolid (bobtail), three sepiid (Cuttlefish) and 10 octopod (Octopus) species. A number of these are exploited commercially and support important target and by-catch fisheries in Western Europe. During the past decade, annual landings of cephalopods from the north-eastern Atlantic (international Council for the Exploration of the Sea [ICES] area) have ranged from 40,000 to 55,000 t including substantial catches of long-fin (loliginid) squid (7000-11,000 t per annum), short-fin (ommastrephid) squid (3000-10,000 t), cuttlefish (including sepiolids; 16,000-24,000 t) and octopods (12,000-18,000 t). The most important exploited species in the north-eastern Atlantic are Eledone cirrhosa, Illex coindetii, Loligo forbesi, Loligo vulgaris, Octopus vulgaris, Todarodes sagittatus, Todaropsis eblanae and Sepia officinalis Other species including Alloteuthis subulata, Gonatus fabricii and certain sepiolids, appear to be abundant and may be marketable. Cephalopods tend to rapidly concentrate heavy metals and other toxic substances in their tissues and this plays an important role in the bioaccumulation of these pollutants in marine predators as well as having implications for human consumption. High levels of cadmium and mercury are often recorded in cephalopod tissues. Another important environmental issue concerns the potential impact of widespread human activity on cephalopod spawning areas, particularly bottom-fishing operations but also shipping, and oil exploration and production. In contrast to many finfish species that spawn annually over a number of years, most cephalopods live only 1-2 yr and die after spawning. Therefore, failure to reproduce and recruit adequately in any given year may seriously impact the long-term viability of cephalopod stocks. Climate change is expected to have a significant effect on many species in the north-eastern Atlantic. This review provides a detailed account Of the zoogeography, biology and ecology of cephalopods in the north-eastern Atlantic, on a species-by-species basis. Important economic, ecological and conservation issues affecting cephalopods in this area are also discussed.