Ecology of demersal fish species from Potter Cove. En ?The Potter Cove coastal ecosystem, Antarctica

BARRERA-ORO E.; CASAUX R.,

Berichte zur Polarforschung

Alfred Weggener Institute

Año: 1998 vol. 299 p. 156 - 167

0176-5027

FISH   Esteban Barrera-Oro and Ricardo Casaux   Instituto Antártico Argentino, Cerrito 1248, 1010 Buenos Aires, Argentina. e-mail: <eboro@ muanbe.gov.ar>; <postmaster@ mndian.gov.ar>     Species composition and their distribution   The fish species inhabiting Potter Cove are coastal notothenioids of the South Shetlands Islands area (Fig. 1, A). They are demersal shallow water fish (< 120 m deep) which spend all or part of their life cycles in inshore waters, although some of them also occur in the offshore fraction of the shelf, at depths down to a range of 200-550 m (Barrera-Oro 1996). The most frequent fish species found are the nototheniids Notothenia coriiceps (previously referred to as N. neglecta), N. rossii, Lepidonotothen nudifrons, Trematomus newnesi, Gobionotothen gibberifrons and T. bernacchii, the harpagiferid Harpagifer antarcticus, and in less frequency the bathydraconid Parachaenichthys charcoti and the channichthyid Chaenocephalus aceratus. The sampling gear used to catch these fish have been trammel/gill nets, hook and lines and traps (Barrera-Oro and Casaux 1990, Casaux et al. 1990, Barrera-Oro and Marschoff 1991). Trammel/gill nets have shown to be the best gear, their advantages are capture of a higher quantity of fish in a short time, negligible by-catch of benthic organisms and easy operation from rubber boats. Pelagic nets aimed to sample pelagic stages of fish (larvae, postlarvae, early juvenile) and pelagic fish (i.e. myctophids, Pleuragramma antarcticum) which may occur in the cove temporally, have not been used. Harpagifer antarcticus (from tide-pools), N. coriiceps (from 5 m depth) and N. rossii (from 10 m depth) are the more neritic species, G. gibberifrons, L. nudifrons and T. newnesi occur more frequently from 30-45 m depth, whereas T. bernacchii, P. charcoti and C. aceratus are caught from a depth range of 70-90 m downwards. Notothenia rossii occurs in the cove in the juvenile stage exclusively, after which they migrate offshore to join and spawn with the adult part of the population (Casaux et al. 1990, Barrera-Oro and Casaux 1992). Gobionotothen gibberifrons displays an evident length stratification as a function of depth; mainly juvenile and part of the adult population coexist in inshore shallow waters (Casaux et al. 1990, Barrera-Oro  1989, Kulesz 1994). Notothenia coriiceps is the dominant fish in the area of study, both in number and biomass (Barrera-Oro and Marschoff 1991). Our data on its depth distribution from Potter Cove and data from South Georgia suggest that this species remains nearshore during its whole life cycle (Casaux et al. 1990, Burchett et al. 1983). However, other studies indicate that at least around Elephant Island, South Shetland Islands N. coriiceps migrates to deeper waters to spawn (Everson 1970, Hureau 1970, Kock 1989).