Diet of Bathyraja magellanica (Chondrichthyes, Rajidae) off southern Argentinean Patagonia

BARBINI, S. A.; SCENNA, L. B; FIGUEROA, D. E.; DÍAZ DE ASTARLOA, J. M.; COUSSEAU, M.B.

New Orleans (USA)

Congreso; 2006 Joint meeting of the American Society of Ichthyologists and Herpetologists; 2006

The Magellan skate, Bathyraja magellanica, inhabits Chilean and Argentinean Patagonian waters. The diet and feeding strategy of this species on southern Argentinean continental shelf (48°-55°S) were investigated through stomach content analysis. Specimens were collected from three research cruises carried out by Instituto Nacional de Investigación y Desarrollo Pesquero during March-April 2004 and February-March- April 2005. Stomach contents were fixed in formalin 4%. Prey were counted, weighted, and identified to the lowest possible taxonomic level. Of a total of 129 stomachs examined, 65.89% contained food. Twenty two prey taxa were identified in the stomach contents. According to the Index of Relative Importance expressed as a percentage, teleost fishes (69.73%) were the most important prey group in the diet of B. magellanica. Secondary prey groups were amphipods (19.50%) and isopods (9.92%), while brachyuran and anomuran crabs, cephalopods and polychaetes were uncommon prey groups. The graphical method of prey-specific abundance against frequency of occurrence and the law value of niche breadth (Levins´ standardised index = 0.107) suggested that B. magellanica displayed a specialisation towards teleosts. The results presented are part of an ongoing study about ecology, biology and biodiversity of presented are part of an ongoing study about ecology, biology and biodiversity of Secondary prey groups were amphipods (19.50%) and isopods (9.92%), while brachyuran and anomuran crabs, cephalopods and polychaetes were uncommon prey groups. The graphical method of prey-specific abundance against frequency of occurrence and the law value of niche breadth (Levins´ standardised index = 0.107) suggested that B. magellanica displayed a specialisation towards teleosts. The results presented are part of an ongoing study about ecology, biology and biodiversity of presented are part of an ongoing study about ecology, biology and biodiversity of waters. The diet and feeding strategy of this species on southern Argentinean continental shelf (48°-55°S) were investigated through stomach content analysis. Specimens were collected from three research cruises carried out by Instituto Nacional de Investigación y Desarrollo Pesquero during March-April 2004 and February-March- April 2005. Stomach contents were fixed in formalin 4%. Prey were counted, weighted, and identified to the lowest possible taxonomic level. Of a total of 129 stomachs examined, 65.89% contained food. Twenty two prey taxa were identified in the stomach contents. According to the Index of Relative Importance expressed as a percentage, teleost fishes (69.73%) were the most important prey group in the diet of B. magellanica. Secondary prey groups were amphipods (19.50%) and isopods (9.92%), while brachyuran and anomuran crabs, cephalopods and polychaetes were uncommon prey groups. The graphical method of prey-specific abundance against frequency of occurrence and the law value of niche breadth (Levins´ standardised index = 0.107) suggested that B. magellanica displayed a specialisation towards teleosts. The results presented are part of an ongoing study about ecology, biology and biodiversity of presented are part of an ongoing study about ecology, biology and biodiversity of Secondary prey groups were amphipods (19.50%) and isopods (9.92%), while brachyuran and anomuran crabs, cephalopods and polychaetes were uncommon prey groups. The graphical method of prey-specific abundance against frequency of occurrence and the law value of niche breadth (Levins´ standardised index = 0.107) suggested that B. magellanica displayed a specialisation towards teleosts. The results presented are part of an ongoing study about ecology, biology and biodiversity of presented are part of an ongoing study about ecology, biology and biodiversity of Bathyraja magellanica, inhabits Chilean and Argentinean Patagonian waters. The diet and feeding strategy of this species on southern Argentinean continental shelf (48°-55°S) were investigated through stomach content analysis. Specimens were collected from three research cruises carried out by Instituto Nacional de Investigación y Desarrollo Pesquero during March-April 2004 and February-March- April 2005. Stomach contents were fixed in formalin 4%. Prey were counted, weighted, and identified to the lowest possible taxonomic level. Of a total of 129 stomachs examined, 65.89% contained food. Twenty two prey taxa were identified in the stomach contents. According to the Index of Relative Importance expressed as a percentage, teleost fishes (69.73%) were the most important prey group in the diet of B. magellanica. Secondary prey groups were amphipods (19.50%) and isopods (9.92%), while brachyuran and anomuran crabs, cephalopods and polychaetes were uncommon prey groups. The graphical method of prey-specific abundance against frequency of occurrence and the law value of niche breadth (Levins´ standardised index = 0.107) suggested that B. magellanica displayed a specialisation towards teleosts. The results presented are part of an ongoing study about ecology, biology and biodiversity of presented are part of an ongoing study about ecology, biology and biodiversity of Secondary prey groups were amphipods (19.50%) and isopods (9.92%), while brachyuran and anomuran crabs, cephalopods and polychaetes were uncommon prey groups. The graphical method of prey-specific abundance against frequency of occurrence and the law value of niche breadth (Levins´ standardised index = 0.107) suggested that B. magellanica displayed a specialisation towards teleosts. The results presented are part of an ongoing study about ecology, biology and biodiversity of presented are part of an ongoing study about ecology, biology and biodiversity of B. magellanica. Secondary prey groups were amphipods (19.50%) and isopods (9.92%), while brachyuran and anomuran crabs, cephalopods and polychaetes were uncommon prey groups. The graphical method of prey-specific abundance against frequency of occurrence and the law value of niche breadth (Levins´ standardised index = 0.107) suggested that B. magellanica displayed a specialisation towards teleosts. The results presented are part of an ongoing study about ecology, biology and biodiversity of presented are part of an ongoing study about ecology, biology and biodiversity of B. magellanica displayed a specialisation towards teleosts. The results presented are part of an ongoing study about ecology, biology and biodiversity of Bathyraja species on the Argentinean continental shelf.species on the Argentinean continental shelf.