SUMMARY: Specimens of Rioraja agassizi were collected at Guarujá pier, São Paulo State, Brazil, from March 2005 to March 2006. A total of 275 males were captured. Based on the analysis of the clasper length, gonad weight, clasper gland length, alar thorns and lobule diameter, the size-at-maturity was estimated to be 32 cm. There were 1049 females in the record. Size-at-maturity was calculated in 40 cm. Sexual resting females were observed. Gonadosomatic and hepatosomatic indexes varied significantly in both sexes throughout the year. However, ovulation, egg-laying and presence of sperm in the seminal vesicle were observed all year round. For this reason, an annual cycle with at least one peak in the sexual activity is proposed for this species. De acuerdo con el análisis de la longitud del clasper y de la glándula del clasper, el peso de las gónadas, el diámetro de los lóbu-los y el número de espinas alares, el tamaño de primera madurez sexual fue estimado en 32 cm. Se capturó un número de 1049 hembras. El tamaño de primera madurez sexual fue calculado en 40 cm. Se observó reposo sexual en hembras de esta especie. Los índices gonadosomáticos y hepatosomáticos variaron significativamente en ambos sexos a lo largo del año. Sin embargo, la ovulación y la deposición de cápsulas ovígeras sucedieron continuamente durante todo el año, así como la presencia de esperma en la vesícula seminal en ejemplares adultos. Por este motivo, se propone para esta especie, un ciclo reproductivo anual, con por lo menos un pico en la actividad sexual. KeywordsPalabras clave: clasper, elasmobranquios, glándula nidamentária, deposición de cápsulas ovígeras, gónadas. and hatch. Oviparity in skates is single (external) (Musick and Ellis, 2005) and all Rajids have the same general reproductive cycle, in which egg capsules are deposited in pairs with intervals of 0-5 days between successive depositions (Holden et al., 1971). In the wild, there is a peak in egg laying during the summer and spawning occurs throughout the entire year (Clark, 1922).The Rio skate Rioraja agassizi Whitley, 1939 (Rajidae: Arhynchobatidae) is endemic to the southwestern Atlantic coast of South America (Compagno, 2005) and occurs from coastal waters to depths of up to 130 m (Figueiredo, 1977). Females deposit egg capsules with mean dimensions of 47x31 mm (Oddone et al., 2006). Apart from the description of the egg capsule, the reproductive biology of R. agassizi-i.e. its sexual development, size-at-maturity and cycle-is unknown.The assessment of chondrichthyan populations requires a quantitative approach to the study of reproductive biology, size-at-maturity being a key parameter to be estimated (Walker, 2005). In addition, over the past thirty years, catches of rajids have increased in the western Atlantic, mainly as a bycatch of target fisheries, but sustainable catch rates are completely unknown (Frisk et al., 2002). Thus, knowledge of the reproductive parameters, in particularly size-at-maturity, is especially important for making decisions on stock management. I...

The population structure and reproductive biology of Mustelus schmitti was analysed during autumn (1994, 1995) and spring (1994) in the Rio de la Plata oceanic front. The samples consisted mainly of adult males and immature females, indicating that nursery areas are situated elsewhere. In autumn, the highest female densities occurred between 368S and 358S, with densities decreasing further south, and high male densities occurred over all latitudes of the study area. In spring, both sexes occurred north of latitude 36830 0 S. Males attained maturity at 59 cm total length (TL), and females at 72 cm TL. Litter size varied from one to ten in spring and two to nine in autumn, with embryos ranging from 9 to 26 cm and 7 to 26 cm TL respectively. The mean TL of embryos was signi¢cantly higher in spring (22 cm), suggesting that parturition occurs in late spring and summer. Litter size was found to increase with female TL.

A total of 459 (245 females, 214 males) Atlantoraja cyclophora was captured by bottom trawl off the coast of Rio Grande do Sul between 30°40′S and 34°30′S during surveys conducted in winter 2001 and summer/autumn 2002 at depths of 100–300 m. Total length at maturity was 52.8 cm for females and 48.5 cm for males. Symmetry and functional parity of the gonads were observed in both sexes, but there was no significant temporal variation in either sex for any of the reproductive parameters studied. Ovulation and egg-deposition were similarly intensive in both seasons. In adult females, there was an ovarian resting period at an individual level, though it was not synchronized at a population level. Distribution of egg-bearing females was not related to depth or species' range.

A total of 3518 specimens (1607 males, 1911 females) of Dipturus chilensis were sampled. Males ranged from 44.0 to 99.0 cm and females from 45.0 to 110.0 cm. Total length composition of the grouped catches differed significantly among sexes, with females being larger than males. The sex ratio favored the females. The total length at which 50% of the specimens were retained by the gear was 69.0 cm for the males and 73.0 cm for the females. A sub-sample of 124 specimens (48 males, 76 females) was analyzed for reproductive assessment. For the males, size at 50% maturity was estimated at 78.5 cm, while for the females this parameter was estimated at 81.4 cm. Preliminary observations on the description of the egg capsules are also provided.
Um total de 3518 espécimes (1607 machos e 1911 fêmeas) de Dipturus chilensis foi amostrado. Os machos tiveram comprimentos totais entre 44.0 e 99.0 cm e as fêmeas entre 45.0 e 110.0 cm. A composição de comprimentos totais das capturas agrupadas foi significativamente diferente entre ambos os sexos, sendo as fêmeas maiores do que os machos. A razão sexual favoreceu as fêmeas. O comprimento total em que 50% dos espécimes foram retidos pelo aparelho de pesca foi de 69.0 cm nos machos e de 73.0 cm nas fêmeas. Uma sub-amostra de 124 espécimes (48 machos e 76 fêmeas) foi analisada para avaliação dos parâmetros reprodutivos. Para os machos, o tamanho de 50% de maturidade resultou em 78.5 cm enquanto que para as fêmeas este parâmetro foi estimado em 81.4 cm. Observações preliminares sobre a descrição da cápsula ovígera são também fornecidas

Total length (TL) at first sexual maturity was estimated for Atlantoraja castelnaui and Dipturus chilensis from the southwestern Atlantic Ocean. Total length at which 50% of the females were captured (50% c) was less than the TL at first sexual maturity (ML) in both species. Immature females are being captured and thus will not become sexually mature to reproduce because of early fishing mortality. Females of A. castelnaui and D. chilensis reach sexual maturity at TLs of 110-114 cm and 102-106 cm, respectively. Males mature with TL between 91 and 95 cm for A. castelnaui and between 83 and 87 cm for D. chilensis.

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.

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.

Resumen.-En diciembre de 2005 se recolectaron cápsulas ovígeras de dos hembras de Psammobatis scobina, capturadas en Caleta Montemar, Chile central (32º57'S-71º33'W). La superficie de las cápsulas fue suave y finamente estriada, de color café y translúcida. Además presentaron la típica forma de barril. La longitud central fluctuó entre 35,25 mm y 38,45 mm y su ancho varió entre 25,91 mm y 27,94 mm. La cara dorsal es convexa con respecto a la ventral. Los cuernos anteriores son más cortos que los posteriores, se orientan hacia el interior y se estrechan hasta adquirir forma de zarcillos hacia las puntas. Los zarcillos laterales resultaron ser un carácter diagnóstico entre especies del mismo género en Chile. Esta es la primera descripción de las cápsulas ovígeras de P. scobina, especie endémica para las costas del sur de Sudamérica.