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

Abstract

A total of 230 specimens of the skate, Rioraja agassizii, was collected from the commercial bottom trawl fishery of Puerto Queque´n, Argentina. During the warmer seasons greater proportions of females were sampled. The largest male and female sampled were 629 and 698 mm total length (TL), respectively. Sexual dimorphism was detected in the relationship between weight (W))TL and disc width (DW))TL, in that females were heavier and wider than males. The smallest mature male and female were 485 and 530 mm TL, respectively. TL at 50% maturity (TL 50% ) was estimated at 504 and 570 mm for males and females, respectively. Females exhibited heavier livers than males throughout their lifetimes. Seasonal variations 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 sampled during spring, suggested that the peak of the egg laying season could be during this season. The egg cases presented a mean length of 69.01 ± 5.53 mm, mean width of 43.40 ± 1.86 mm and mean weight of 17.00 ± 4.59 g. According to these results specimens from Puerto Queque´n and southern Brazil appeared to differ in size, the peak of the egg-laying season and in egg dimensions.

Annual fecundity assessment for the Rio skate Rioraja agassizi (chondrichthyes: arhynchobatidae) endemic to a neotropical area (Southeastern Brazil)

“…Such a pattern has also been observed in the egg cases extracted in utero from female R. agassizi, that were larger off Puerto Quequén (ESTALLES et al, 2009) From studies related to the brown ray Raja miraletus LINNAEUS, 1758 and the rough ray R. radula DELAROCHE, 1809 caught in Tunisian waters (CAPAPÉ; QUIGNARD, 1975), and more recently related to the thornback ray R. clavata LINNAEUS, 1758 from off the Languedocian coast (CAPAPÉ et al, 2007b), two categories of oocytes have been distinguished: translucent oocytes and yolky oocytes. Among the latter, three batches of yolky oocytes were considered, i.e., one batch of large oocytes generally ready to be ovulated, and two batches of large and small developing oocytes, respectively.…”

“…This species inhabits coastal waters from the shore down to 130 m (FIGUEIREDO, 1977), feeding on benthic organisms, mainly crustaceans and teleosts (MUTO et al, 2001). ODDONE et al (2007a) noted that male R. agassizi attained sexual maturity at 320 mm and females at 400 mm of total length (TL).…”

“…Southward, between Uruguay (34°S) and northern Argentina (42°S), COLONELLO et al (2007) also recorded that males mature at TL of 400-500 mm and females at 500-550 mm. Off Puerto Quequén (Argentina), ESTALLES et al (2009) noted that the smallest adult male and the smallest adult female were of 485 mm and 530 mm TL, respectively, while all males and females were adult over 590 mm and 629 mm, respectively. Therefore, in the three areas quoted, female R. agassizi were larger than the males -thus providing another instance of the sexual dimorphism in size recorded for rajoid species (see MELLINGER, 1989).…”

Reproductive biology of the southern thorny skate Amblyraja doellojuradoi (Chondrichthyes, Rajidae)

“…In this regard, A. doellojuradoi has no correlation between the I H and the diameter of ovarian follicles, but it is important to note that it would be necessary to collect more data to confirm the correlation analysis of the ovarian follicles diameter in relation to different variables. An I H difference between the sexes is reported for other species inhabiting the Argentinean continental shelf such as S. bonapartii (Mabragaña et al ., ), R. agassizii (Estalles et al ., ), Atlantoraja cyclophora (Regan 1903) (M. C. Oddone, unpubl. data) and Atlantoraja platana (Günther 1880) (A. S. Marcal, unpubl.…”

Condition analysis of the Brazilian sharpnose shark Rhizoprionodon lalandii: evidence of maternal investment for initial post‐natal life

“…fatty acids) and the relationship between circumference and body length measures have also been used for large sharks (Gallagher et al, 2014;. In elasmobranchs, condition metric fluctuations have usually been related with energetic costs during the reproductive cycle (Allen & Cliff, 2000;Capapé & Reynaud, 2011;Estalles et al, 2008;Fermin & Bashirulah 1984;Grijalba-Bendeck et al, 2008;Hoffmayer et al, 2006;Machado et al, 2001;Peres & Vooren, 1991), migration (King, 1984), responses to variations in food availability (Oddone & Amorim, 2007) and other factors that influence the well-being of organisms (Braccini & Chiaramonte, 2002;Hoffmayer et al, 2006;Parsons & Hoffmayer, 2005).…”