Temperature and salinity in SW Atlantic waters inhabited by skates

FIGUEROA, D. E.; P. MARTOS; R. RETA; M. B. COUSSEAU; J.M. DÍAZ DE ASTARLOA

St. Louis, Missouri (USA)

Congreso; Joint meeting of the American Society of Ichthyologists and Herpetologists; 2007

Skates (Rajidae) are bentic fishes that are found worldwide. They are absent in waters of the inner continental shelf at tropical to warm temperate latitudes. Therefore they are well represented in the surveyed area. For the present paper we considered 613 fishing hauls, carried out by R/V of the National Institute for Marine Research and Development (INIDEP), between 34° and 55°S and from the coast to the continental slope, from 1993 to 1999. Oceanographic data (included CTD profiles) in the place of the haul were obteined and the captures were determined, following McEachran and Dunn (1998), Menni et al. (1984) and  Stehmann (1978). In the study area there are 7 genera, Atlantoraja, Rioraja and Sympterygia inhabit warmer and generally shallow waters in the northern (Group 1), Dipturus and Psammobatis present extensive distribution in the continental shelf (Group 2), and Bathyraja and Amblyraja dwell patagonian shelf and slope, and deeper waters to the north (Group 3). Group 1 is the most stenothermic and euryhaline of the region. On the contrary, Group 3 is the most eurythermic and stenohaline. Group 2 shows an intermediate behaviour. Considering the subantarctic water genus Bathyraja, four species of them (B. albomaculata, B. brachyurops, B. macloviana and B. magellanica) are more eurythermic as well as euryhaline, while the other three B. griseocauda, B. multispinis and B. scaphiops show a strict- tenothermous-stenohaline behaviour.Within Psammobatis genus, P. lentiginosa is stenohaline and relatively stenothermal; both P. bergi and P. extenta are relatively warm stenothermal. Psammobatis spp. are relatively cold-stenothermal. P. bergi, P. extenta and Psammobatis spp are euryhaline species.et al. (1984) and  Stehmann (1978). In the study area there are 7 genera, Atlantoraja, Rioraja and Sympterygia inhabit warmer and generally shallow waters in the northern (Group 1), Dipturus and Psammobatis present extensive distribution in the continental shelf (Group 2), and Bathyraja and Amblyraja dwell patagonian shelf and slope, and deeper waters to the north (Group 3). Group 1 is the most stenothermic and euryhaline of the region. On the contrary, Group 3 is the most eurythermic and stenohaline. Group 2 shows an intermediate behaviour. Considering the subantarctic water genus Bathyraja, four species of them (B. albomaculata, B. brachyurops, B. macloviana and B. magellanica) are more eurythermic as well as euryhaline, while the other three B. griseocauda, B. multispinis and B. scaphiops show a strict- tenothermous-stenohaline behaviour.Within Psammobatis genus, P. lentiginosa is stenohaline and relatively stenothermal; both P. bergi and P. extenta are relatively warm stenothermal. Psammobatis spp. are relatively cold-stenothermal. P. bergi, P. extenta and Psammobatis spp are euryhaline species.