New records of the Pacific sleeper shark, Somniosus pacificus (Chondrichthyes: Squalidae), from the southwest Atlantic

DIAZ DE ASTARLOA, J. M.; FIGUEROA, D. E.; LUCIFORA, L.; MENNI, R. C.; PRENSKI, B. L.; CHIARAMONTE, GUSTAVO ENRIQUE

Ichthyological Research

The Ichthyologlcal Socicty of Japan

Lugar: Tokyo; Año: 1999 vol. 46 p. 303 - 308

1341-8998

T he genus Somniosus Lesueur, 1818, is representedworldwide by three species: the Greenlandshark (X microcephahts (Bloch and Schneider,1801)), the Pacific sleeper shark (S. pacificus Bigetowand Schroeder, I944) and the little sleeper shark (S.rostrams (Risso, 1826) (Compagno, 1984; Francis etal., 1988)).There are few records of Somniosus from the SouthAtlantic. A female about 440 cm TL was caught in adepth of 677m off Cape Columbine, South Africa(Bass et al., 1976), and Gushchin et al. (1986) reporteda male 416cm TL from 42 ~ 24'S, 58 ~ 19'W,oft" Patagonia, Argentina, at 800 m depth. These specimens,at first tentatively identified as S. microcephalus,were subsequently referred to X pacific'usby Francis et at. {1988). A brief reference withoutdata (Soto et at., 1995) refers to X microcephahts offRio Grande do Sul, Brazil, and an identified Somniosuswas sighted by Diaz de Astartoa (unpub[.) nearthe South Georgia Islands. The last-mentioned specimenwas collected incidentally during a commercialcatch of Patagonian toothfish (Dissostichus eleginoides)and returned immediately to the sea, beforeany detailed information could be obtained.Recent exploratory cruises aboard the R/V AzuchiMaru to investigate potential fisheries resources offthe South American continental shelt-; such as thetooth fish (Dissostichus eleginoides), facilitated thegathering of new information on the occurrence ofsleeper sharks in the region.The present paper reports new records of Somniosuspacificus from the southwest Atlantic.