Relationship between liver weight, body size and reproductive activity in Atlantoraja cyclophora (Elasmobranchii: Rajidae: Arhynchobatinae) in oceanic waters of Rio Grande do Sul, Brazil

Abstract

Samples of Atlantoraja cyclophora were obtained by bottom-trawling surveys on the outer continental shelf and upper slope of the Rio Grande do Sul State, Brazil, at depths between 100 and 300 m. For a sample of 459 individuals, the total length, eviscerated weight and liver weight were recorded. Liver weight of the males varied between 2.4 and 36 g, and 2.4 and 65 for the females. Females had significantly heavier livers in all total length classes. For the males, the hepatosomatic index varied between 1.5 and 3.5 and for the females between 0.53 and 4.95. Mean hepatosomatic index was signifi cantly higher in the females. Liver weight and total length according to the equations LW=0.00065*TL2.648 for males and LW=0.00309*TL2.171 for females.

Amostras de Atlantoraja cyclophora foram obtidas através de cruzeiros de pesquisa com arrasto de fundo na plataforma continental externa e talude superior do estado do Rio Grande do Sul, Brasil, em profundidades entre 100 e 300 m. Para 459 indivíduos foram registrados o comprimento total, o peso eviscerado e o peso do fígado. Este último variou nos machos de entre 2.4 a 36 g e nas fêmeas de entre 2.4 a 65 g. As fêmeas tiveram fígados significativamente mais pesados que o dos machos em todas as classes de comprimento total. Nos machos, o índice hepatossomático variou de entre 1.5 e 3.5 e nas fêmeas de entre 0.53 e 4.95. O peso do fígado aumentou com relação ao o peso total segundo a relação LW=0.00065*TL2.648 nos machos e LW=0.00309*TL2.171 nas fêmeas.