Life-history traits of an exploited skate: The short-tail yellownose skate Zearaja brevicaudata (Chondrichthyes: Rajiformes).

The short-tail yellownose skate, Zearaja brevicaudata, occurs off southern Brazil and along the Argentine continental shelf, including waters surrounding the Islas Malvinas and the upper slope, and is very frequently caught by trawl fisheries throughout its range. The age, growth, and maturity of Z. brevicaudata were investigated using 204 individuals collected by commercial fishing vessels from northern Argentina, between March 2016 and September 2019. Age was determined on a sample comprising vertebrae from 151 individuals, 60 males, ranging in size from 391 to 956 mm total length (TL), and 91 females, ranging in size from 324 to 1060 mm TL. Maximum ages determined for males and females were 22 and 29 years, respectively. A Bayesian framework was employed with a set of three candidate models to estimate growth parameters (von Bertalanffy, Gompertz, and Logistic). The von Bertalanffy model had the best fit, and the sexes showed undistinguishable growth parameters. For sexes combined, derived growth mean parameters (± S.D.) were L∞ = 1081 mm ± 64.34 mm, k = 0.09 ± 0.01 years-1, and L0 = 248 mm ± 23.52 mm. The age at maturity was estimated at 13.15 and 14.66 years for males and females, respectively.

Age-based life history of three groupers in the southern Gulf of Mexico.

The three most important grouper fishery species in southern Gulf of Mexico, Epinephelus morio, Mycteroperca bonaci and Mycteroperca microlepis, do not have life history parameters data reported such as growth, age and natural mortality essential to management. Individuals from the three species were captured in the Campeche Bank (CB) at different times from 1988 to 2001. Sagittae were thin-sectioned to count annuli: n = 1081 for E. morio, n = 920 for M. bonaci and n = 251 for M. microlepis. Otoliths from the three species exhibited successive opaque and translucent bands deposited with an annual frequency, occurring between January and April for E. morio and M. bonaci, and between January and March for M. microlepis. Estimated age in the three grouper species ranged from 0+ to 20 years. The most frequent ages were 7-10 years for E. morio and 8-12 years for M. bonaci and M. microlepis. The von Bertallanfy Growth Function model parameters (L∞ , K and t0 ) were consistent with reported growth patterns for Epinephelidae family species, as established by growth performance Ф' (near 3). The CB groupers appear to reach maximum ages over 13 years with K values between 0.09 and 0.12 year-1 , indicating all three studied species displayed relatively slow growth rate and medium longevity. Lifespan values ranged from 13 to 33 years for E. morio, from 18 to 30 years for M. bonaci and from 17 to 33 years for M. microlepis. A50 was 6.1 years for E. morio and 5.5 years for both M. bonaci and M. microlepis. Age at which all females were mature was 8 years for M. bonaci and 10 years for E. morio and M. microlepis. P50 was 9.3 years for E. morio, 13.6 years for M. bonaci and 11.6 years for M. microlepis. Age at which 100% of individuals were male was 13 years for E. morio, 19 years for M. bonaci and 15 years for M. microlepis. Values of M at age exhibited an exponential decrease with age for all three species, but overall values were 0.13 year-1 for E. morio, 0.14 year-1 for M. bonaci and 0.17 year-1 for M. microlepis. For the three species size at age varied by geographical distribution area, but particularly for E. morio the discrepancy in average size between published studies may be the consequence of the fishing effort exerted on the stock and/or the lack of regulation for the fishery prior to 2001; after this stock biomass fell below the reference limit point and was declared overexploited. Resource managers could use the information provided in this study as a reference, representing pre-overexploitation values, to evaluate the current status of these populations and ensure sustainable management actions for the CB grouper fisheries.

Age, growth, maturity and extinction risk of an exploited and endangered skate, Atlantoraja castelnaui, from off Uruguay and northern Argentina.

The spotback skate Atlantoraja castelnaui (Arhynchobatidae) is a large and threatened skate species subjected to fishing pressure, endemic to the Southwest Atlantic that occurs from Rio de Janeiro, Brazil, to San Jorge Gulf, Argentina. The age, growth, age at maturity and the maximum intrinsic rate of population increase rmax of A. castelnaui were studied using 152 specimens collected from off Uruguay and north Argentina (35°-42° S), between June 2013 and February 2020. Vertebrae from 143 individuals were used for ageing (females: n = 83, size range 404-1300 mm total length, TL; males: n = 60, size range 400-1270 mm TL). Maximum ages determined for females and males were 30 and 28 years, respectively. To fit growth models, non-linear and Bayesian estimation approaches were considered. For the first approach, a set of four candidate growth (size-at-age) models were fitted: three-parameter von Bertalanffy, two-parameter von Bertalanffy with fixed L0 , Gompertz and Logistic. In the second approach, von Bertalanffy, Gompertz and Logistic were fitted. For non-linear estimation, model selection indicated that the entire set of candidate growth models were supported by the data. The von Bertalanffy was selected as the best model for Bayesian estimation. There were no differences in growth between sexes. For the sexes combined, the von Bertalanffy growth model by Bayesian method was considered the most adequate to describe the growth of A. castelnaui (growth mean parameters ± S.D.: L∞  = 1210.29 ± 40.68 mm; k = 0.12 ± 0.01 years-1 ; L0  = 179.20 ± 11.62 mm). The age at maturity was estimated at 16.21 and 14.04 years for females and males, respectively. The maximum intrinsic rate of population increase rmax was estimated as 0.252 years-1 . Life-history traits and rmax provided in the present study suggest that this species has a relatively low productivity and may be vulnerable to an intense fishing pressure.

Descripción del crecimiento en ovinos criollos utilizando el modelo Brody

El objetivo de este estudio fue determinar la curva de crecimiento en una población de ovinos criollos en condiciones de pastoreo extensivo, utilizando el modelo Brody. Se utilizaron 448 pesajes de 59 animales nacidos entre los meses de agosto y septiembre del año 2012, pertenecientes al aprisco Altamar S.A, en el municipio de Buenavista, Córdoba (Colombia). Los estimados del modelo se obtuvieron mediante el procedimiento NLIN de SAS, considerando los efectos fijo de número de partos de la madre y número de crías por parto. Se encontró que el estimado para ß0 fue de 58.47 ± 7.8, para ß1 de 0.98 ± 0.03 y para ß2 de 0.0054 ± 0.003. No se encontró efecto significativo (P>0.05) del número de partos sobre ß0, ß1, y ß2. Se encontró efecto significativo (P≤0.05) del número de crías por parto sobre ß0 y ß1. El porcentaje de madurez estimada a los cuatro y siete meses fue 46.6 ± 4.6 y 66.1 ± 4.5%, respectivamente. La edad al 75% de madurez fue de 274 ± 84 días y al 95% de madurez de 596 ± 202 días. Los resultados de este estudio permiten concluir que los valores estimados para porcentaje de madurez y edad a la madurez en la población ovina fueron bajos, por lo que se debería implementar un programa de selección y mejorar el manejo zootécnico de los animales, con el fin que estos logren una madurez en el menor tiempo posible.

This study was aimed at using the Brody model for determining the growth curve for a creole sheep population kept on extensive grazing. The data came from weighing 59 animals (448 readings) born between August and September 2012 which were kept on Altamar SA's sheep-farm in Buenavista in the Córdoba Department in Colombia. Statistical Analysis System's (SAS) univariate nonlinear (NLIN) regression mode was used for obtaining the estimates, considering the fixed effects of the mothers' amount of births and the amount of lambs per birth. ß0 was estimated as being 58.47 ± 7.8, ß1 0.98 ± 0.03 and ß2 0.0054 ± 0.003. No significant effect was found on ß0, ß1 and/or ß2 (p>0.05) regarding the amount of births. A significant effect (p≤0.05) on ß0 and ß1 was found regarding the amount of lambs per birth. Percentage maturity estimated at four months was 46.6 ± 4.6 and 66.1 ± 4.5% at seven months. Estimated age at 75% maturity was 274 ± 84 days and 596 ± 202 days at 95% maturity. It can be concluded from this study's results that the estimated values for percentage maturity and age at maturity in the target sheep population were low; this means that a selection programme should be introduced and the animals' zootechnical management improved to ensure maturity being reached in the shortest time possible.

O objetivo deste estudo foi determinar a curva de crescimento de uma população de ovelhas crioulas em condições de pastagem extensiva, utilizando o modelo Brody. Foram utilizados 448 pesando dados de 59 animais nascidos entre os meses de agosto e setembro de 2012, pertencentes ao rebanho Altamar SA, na cidade de Buenavista, Córdoba (Colômbia). As estimativas do modelo foram obtidos usando o procedimento SAS NLIN, considerando os efeitos fixos de número de partos da mãe e número de cordeiros por parto. As estimativas foram 58.47 ± 7.8 para ß0, 0.98 ± 0.03 para ß1 e 0.0054 ± 0.003 para ß2. Nenhum efeito significativo (P>0.05) no número de partos sobre ß0, ß1 e ß2. Houve efeito significativo (P≤0.05) no número de cordeiros por parto em ß0 e ß1. A percentagem de maturidade estimada em quatro e sete meses, foi de 46.6 ± 46 e 66.1 ± 4.5%, respectivamente. Idade de 75% de maturidade foi de 274 ± 84 dias e em 95% o vencimento de 596 ± 202 dias. Os resultados deste estudo, portanto, levaram à conclusão de que os valores estimados para percentual de maturidade e idade de maturação em ovinos foram baixos, por isso deve implementar uma selecção programa e melhorar o tratamento zootécnico de animais, a fim de eles atingem a maturidade no menor tempo possível.