Reproductive biology of two sympatric skates in the south-west Atlantic: Psammobatis rudis and Psammobatis normani

摘要

The total lengths (L-T) at which 50% were mature of Psammobatis rudis and Psammobatis normani, in the south-west Atlantic were: P. rudis, 428 mm for males and 414 mm for females and P. normani, 443 mm for males and 403 mm for females. Clasper length in mature males was greater in P. normani than in P. rudis, whereas oviducal gland width was not different between species. Females of P. normani with egg cases were found in every month sampled, and in January, March, April and July in P. rudis, although insufficient samples were available to identify peak oviposition times. Geographic variation in size frequency and maturity were found. The effects of oceanographic conditions and fishing pressure are discussed. Size at 50% maturity in both species was >74% of the maximum L-T, indicating late sexual maturity and low potential stock recovery rate.