Exploring nursery sites for oviparous chondrichthyans in the Southwest Atlantic (36°S-41°S)

VAZQUEZ, D. M.; MABRAGAÑA, E.; GABBANNELLI, V.; DÍAZ DE ASTARLOA, J.M.

MARINE BIOLOGY RESEARCH

TAYLOR & FRANCIS AS

Lugar: Londres; Año: 2016 vol. 12 p. 715 - 725

1745-1000

The aim of this paper was to explore egg-laying areas of oviparous chondrichthyans occurring inthe northern part of the Southwest Atlantic Ocean (36°S?41°S) at between 50 and 200 metresdepth and the Mar del Plata Canyon (from 200 to 3447 m). A total of 515 capsules were collectedcorresponding to 10 species. Four species accounted for 87.6% of the total catch: Psammobatisnormani, Bathyraja macloviana, Amblyraja doellojuradoi and Bathyraja brachyurops. Theremaining corresponded to Schroederichthys bivius, Psammobatis rudis, Zearaja chilensis,Bathyraja albomaculata, Psammobatis lentiginosa and Bathyraja sp. Most hauls weremonospecific and relatively few hauls contained four or five species (southern part of thearea, in sites located at 75 and 94?105 m depth). No egg capsules were recorded between1712 m and 3447 m. Highest densities (>3000 capsules/km2) were mainly found between 39°46.2′ and 40°29.9′S from 85 to 105 m and they were also recorded near the Mar del PlataCanyon at 37°59.7′S and at 852 m. The highest value recorded was 12,326 capsules/km2(located at 40°18.9′S and 85.4 m). The highest densities for each of the most abundantspecies are discussed. The finding of high densities of egg cases near the Argentine shelfbreakfront indicates that many skate species use this area as a nursery site. The egg-layingareas explored here are the first reported sites of this kind in the Southwest Atlantic Ocean.Recognizing and protecting egg-laying habitats may be important steps to a long-termconservation of oviparous chondrichthyan populations