Reproductive biology of the lesser guitarfish Zapteryx brevirostris from the south-western Atlantic Ocean

Abstract

This study provides the first detailed information on the reproductive biology of the lesser guitarfish Zapteryx brevirostris in the south-western Atlantic Ocean between latitudes 34° and 42° S. A total of 320 males (196-647 mm total length, L(T)) and 336 females (200-640 mm L(T)) were analysed. No significant differences were observed in size at 50% maturity between males (499 mm L(T)) and females (506 mm L(T)). Three seasonal patterns were related to the testes mass, the development of spermatocysts and the presence of spermatozoa in genital ducts. Females showed a 3 year reproductive cycle, with 2 years of ovarian maturation and 1 year of gestation, including a mean annual fecundity of one to two embryos. Synchronicity of both ovulating females and males with sperm in genital ducts indicated that ovulation and hence mating occurs during winter. Birth was assumed to occur during winter, but neither ovulation nor mating is simultaneous with this reproductive event. Despite its low economic value, a decline in abundance in the region, together with a low reproductive efficiency, indicates that the Z. brevirostris population should be monitored closely.

Rapid Life-History Diversification of an Introduced Fish Species across a Localized Thermal Gradient

“…Lengths at which 50% of individuals were sexually mature were estimated at each site using logistic regressions (i.e, via 50% cutoff values, L T50 ). A log-likelihood ratio test was used to examine differences in maturity- L T relationships among the three sites [33]. Normality and homogeneity of data were determined using Shapiro's and Levene's tests.…”

Age and growth of three endemic threatened guitarfishes Pseudobatos horkelii, P. percellens and Zapteryx brevirostris in the western South Atlantic Ocean

“…Despite the occurrence and distribution of these species along the south‐east to south coast of Brazil, most of the few studies undertaken to date have focused on reproduction (Abilhoa et al ., ; Batista, ; Colonello et al ., ; Lessa et al ., ; Martins et al ., ; Rocha & Gadig, ) and feeding habits (Bornatowski et al ., ; Carmo et al ., ; Marion et al ., ). The knowledge of other aspects of their basic biology, including age and growth parameters, is fairly limited and only available for P. horkelii and Z. brevirostris in southern Brazil (Carmo et al ., ; Lessa, ; Vooren et al ., ) and for P. Percellens in north‐eastern Brazil (Nunes, ).…”

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

“…Clasper growth with L T exhibited the three‐phase sigmoid curve pattern commonly observed among elasmobranchs, also applicable to the L CG (Motta et al, ; Ebert & Cowley, ; Colonello et al, ). Clasper maturation occurred between 23·0 and 27·0 cm and represented an abrupt growth in length suggesting a reproductive investment in clasper development which leads to mating ability.…”