Reproductive ecology of the Rio Skate, Rioraja agassizi, from southern argentina.

MASSA, A. M; MABRAGAÑA, E.; LUCIFORA, L. O.,

San Andrés, Colombia

Congreso; IX COLACMAR; 2001

Size at maturity, sexual dimorphism, sex and immature-mature ratios, and population densities of the Rio skate, Rioraja agassizi, from north Argentina are described in this work. Males matured at 420- 520 mm TL (total length), and females at 526-545 mm TL. Sexual dimorphism in size at maturity and in liver size (larger in females) was observed. The sexes were equally represented. In contrast, the immaturemature ratio varied seasonally (higher in early spring than in late spring-summer). Densities were higher in late spring and summer than in early winter-spring. Fluctuations in immature-mature ratio and in densities suggest that adults come to nearshore waters for reproductive activities in summer.Rioraja agassizi, from north Argentina are described in this work. Males matured at 420- 520 mm TL (total length), and females at 526-545 mm TL. Sexual dimorphism in size at maturity and in liver size (larger in females) was observed. The sexes were equally represented. In contrast, the immaturemature ratio varied seasonally (higher in early spring than in late spring-summer). Densities were higher in late spring and summer than in early winter-spring. Fluctuations in immature-mature ratio and in densities suggest that adults come to nearshore waters for reproductive activities in summer.