Reproductive biology of Psammobatis rutrum (Chondrichthyes: Arhynchobatidae) in south Brazil, south-west Atlantic.

This study presents information on the reproductive biology of Psammobatis rutrum based on 55 males and 53 females obtained as by-catch from bottom trawlers off southern Brazil during July 2013 and September 2014 and includes a detailed description of the egg capsule. Total lengths (LT ) ranged from 22·3 to 31·6 cm and most of the sample comprised larger individuals, although there were no sexual differences in length-frequency distributions. Significant sexual differences were found for total length-disc width, LT -body mass and LT -eviscerated body mass relationships, with females being heavier and larger. Males started to mature at 25·5 cm LT and females, at 25·9 cm LT , while LT at maturity was calculated in 26·67 and 26·81 cm, respectively. Attaining larger sizes and mass may represent a reproductive investment for females, as observed in other rajoid species. Egg bearing females were first observed over 27·1 cm LT and ovarian fecundity was 1-12 vitellogenic follicles. The egg capsules were 2·22-2·62 cm length and had attaching fibrils on both lateral sides. Microscopically, the ventral face of the egg capsule was rougher than the dorsal face.

Reproductive biology of the stingrays, Myliobatis goodei and Myliobatis ridens (Chondrichthyes: Myliobatidae), in southern Brazil.

This study, carried out between spring 2012 and winter 2014, characterized the sexual development and reproductive cycle of Myliobatis goodei and Myliobatis ridens in the extreme south of Brazil to support future management and conservation plans. Ninety-five specimens of M. goodei (24 males and 71 females) and 175 M. ridens (24 males and 151 females) were sampled. Female M. goodei attained disc-width-at-50% maturity (WD50 ) at 683 mm. Uterine fecundity was four to five embryos. The largest male recorded, a mature individual, had a disc width of 650 mm. In M. ridens, WD50 was 662 mm. Uterine fecundity varied from one to eight embryos. The largest male on record was a maturing 590 mm WD individual. The hepato-somatic index was higher in autumn in females of M. goodei, and in the summer in M. ridens. The gonado-somatic index and the largest vitellogenic follicle diameter were higher in spring in both species. Pregnant females of both species were recorded during spring, although for M. ridens, these females also occurred in summer. Embryos had WD of 61-218 and 40-236 mm for M. goodei and M. ridens, respectively. The incidence of pregnant females in southern Brazil in spring-summer coincides with the small-scale beach artisanal fisheries season peak, when M. goodei and M. ridens suffer fishing mortality, while using the coastal shallow areas in the warmer periods (spring-summer) to give birth.

Reproductive biology of Zearaja chilensis (Chondrichthyes: Rajidae) in the south-east Pacific Ocean.

Between 2000 and 2002, three artisanal landing sites were sampled in southern Chile, with data on population structure and reproductive development collected from 5477 yellownose skates Zearaja chilensis. Total length (L(T) ) ranged from 33 to 158 cm for females and 34 to 155 cm for males. No sexual dimorphism was evident in disc size (length or width) or in L(T)-mass relationships. The smallest mature female was 95 cm L(T) and the size at which 50% were mature (L(T50) ) was 109 cm. Males matured between 80 and 90 cm L(T) with a L(T50) of 88 cm. Although the largest Z. chilensis captured by the artisanal fishery was 155 cm L(T) , 89% of landings comprised relatively small, immature fish. This situation may compromise the stock integrity if intrinsic vulnerability and probable long-life span of Z. chilensis are considered. Consequences for the survival of the species and possible signs of a fishery collapse must be reviewed by management authorities by consideration of both artisanal and industrial landings in Chile.

Egg capsules of the dusky catshark Bythaelurus canescens (Carcharhiniformes, Scyliorhinidae) from the south-eastern Pacific Ocean.

The external morphology of the egg capsule of Bythaelurus canescens and its fixation to the substratum are described. Bythaelurus canescens egg capsules are typically vase-shaped, dorso-ventrally flattened, pale yellow in colour when fresh and covered by 12-15 longitudinal ridges. The anterior border of the capsule is straight, whereas the posterior border is semicircular. Two horns bearing long, coiled tendrils arise from the anterior and posterior ends of the capsule. The presence of longitudinal ridges and long coiled tendrils at both anterior and posterior ends of the capsule readily distinguish these egg capsules from those of other chondrichthyans occurring in the south-east Pacific Ocean.