Reproductive biology of the skate, Rioraja agassizii (Müller and Henle, 1841), off Puerto Quequén, Argentina

ESTALLES, M; PEREZ COMESAÑA, J.E.; TAMINI, L.L.; CHIARAMONTE, G.E.

JOURNAL OF APPLIED ICHTHYOLOGY-ZEITSCHRIFT FUR ANGEWANDTE ICHTHYOLOGIE

Blackwell Verlag

Lugar: Berlin; Año: 2009 vol. 25 p. 60 - 65

0175-8659

A total of 230 specimens of the skate, Rioraja agassizii, wascollected from the commercial bottom trawl fishery of PuertoQueque´n, Argentina. During the warmer seasons greaterproportions of females were sampled. The largest male andfemale sampled were 629 and 698 mm total length (TL),respectively. Sexual dimorphism was detected in the relationshipbetween weight (W))TL and disc width (DW))TL, inthat females were heavier and wider than males. The smallestmature male and female were 485 and 530 mm TL, respectively.TL at 50% maturity (TL50%) was estimated at 504 and570 mm for males and females, respectively. Females exhibitedheavier livers than males throughout their lifetimes. Seasonalvariations in the gonadosomatic (GSI) and hepatosomatic(HSI) indices, and in the width of the left oviducal gland (OG),along with the greater number of pregnant females sampledduring spring, suggested that the peak of the egg laying seasoncould be during this season. The egg cases presented a meanlength of 69.01 ± 5.53 mm, mean width of 43.40 ± 1.86 mmand mean weight of 17.00 ± 4.59 g. According to these resultsspecimens from Puerto Queque´n and southern Brazil appearedto differ in size, the peak of the egg-laying season and in eggdimensions.