Reproductive biology of the Brazilian blind electric ray Benthobatis kreffti (Chondrichthyes: Narcinidae)

This study provides information on the reproductive biology of the Brazilian blind electric ray Benthobatis kreffti, endemic to southern and southeastern Brazil. Individuals were caught by bottom trawl carried out in 2003 and 2007, at 492-501 m depth off the São Paulo State continental slope. A total of 152 females (115-299 mm) and 144 males (91-243 mm) were sampled. Maturity was first observed at 177 and 162 mm, with total length at 50% maturity of 191 and 176 mm in females and males respectively. Uterine fecundity ranged from 1-3 and was not related to female total length. Size at birth estimated from the largest near-term observed embryos and smallest free-swimming ray was 91-100 mm. The low fecundity observed is typical of deepwater elasmobranch species, as well as late maturity in comparison with costal species. The relatively large size-at-birth suggests that this species invests more in length of each embryo than in litter size, increasing the offspring's survival chance. In this context, these parameters highlight the vulnerability of this and other deepwater species to non-natural death, mostly caused by deep-sea fisheries.(AU)

Este estudo apresenta informações sobre a biologia reprodutiva da raia elétrica cega brasileira Benthobatis kreffti, endêmica do sul e sudeste brasileiros. Os indivíduos foram capturados com arrasto de fundo, em 2003 e 2007, a 492-501 m de profundidade no talude continental do Estado de São Paulo. Um total de 152 fêmeas (115-299 mm) e 144 machos (91-243 mm) foram capturados. A maturidade foi observada em fêmeas de 177 mm e machos de 162 mm, com o tamanho onde 50% dos indivíduos encontra-se maduros calculado em 191 mm (fêmeas) e 176 (machos). O tamanho da prole foi de 1-3 embriões e não foi relacionado ao comprimento materno. O tamanho ao nascer foi estimado a partir do tamanho do maior embrião à termo e o menor neonato e foi de 91-100 mm. A baixa fecundidade observada é típica de elasmobrânquios de profundidade, bem como a maturidade tardia, comparados com espécies costeiras. O grande tamanho ao nascer sugere que essa espécie investe no tamanho de cada embrião em vez do número de embriões produzidos, aumentando a chance de sobrevivência da prole. Neste contexto, estes parâmetros ressaltam a vulnerabilidade desta e outras espécies de elasmobrânquios a mortes ocasionadas pela pesca em maiores profundidades.(AU)

Parámetros biológicos de Pseudocurimata boulengeri (Characiformes: Curimatidae) en el embalse Chongón, Ecuador / Biological parameters of Pseudocurimata boulengeri (Characiformes: Curimatidae) inhabiting the Chongón dam, Ecuador

ResumenPseudocurimata boulengeri, es una especie endémica del Ecuador, que da sustento a un importante grupo de familias de pescadores. Los antecedentes biológicos para esta especie corresponden a reportes en los sistemas loticos de la Provincia de los Ríos, se desconoce si estos parámetros siguen igual tendencia en un sistema lentico. En este trabajo se describe la proporción de sexo, la relación talla peso total, el desarrollo gonadal, la época de desove y el tamaño de primera madurez reproductiva de P. boulengeri, en el embalse de Chongón, Ecuador. Se capturaron peces con redes de enmalle (2.5") entre 2003 y 2009. La longitud total (Lt) de los peces capturados fue de 10.5 a 36.0 cm, el desove ocurre de noviembre a marzo y el tamaño de primera madurez para las hembras se estimó en 17.96 cm (Lt) y para los machos en 20.05 cm (Lt). La proporción de machos y hembras entre mayo y octubre, se ajusta a lo esperado (1:1), mientras que entre noviembre y abril, la proporción de hembras fue mayor que los machos, situación que coincide con la época de desove. Las características limnéticas y productivas del embalse, harían que esta especie pueda disponer de una mayor cantidad de alimento y un ambiente más favorable que le permitiría tener una postura más extendida en el año.

AbstractPseudocurimata boulengeri is an endemic species of Ecuador, which sustains a large group of fisher families. The biological data of this species correspond to reports from lotic systems of Los Ríos province; nevertheless, their trend in a lentic system is not yet known. This paper describes the sex ratio, length-weight relationship, gonad development, spawning season and size at reproductive maturity of P. boulengeri, inhabiting the lentic system of Chongón dam, Ecuador. Fish were caught between 2003 and 2009 using gill nets (2.5"). The total length (Lt) of caught specimens ranged from 10.5 to 35.5 cm, spawning occurred between the months of October and March, and size at first maturity for females was estimated at 17.9 cm (Lt) and 20.0 cm (Lt) for males. Between May and October male and female ratios were as expected (1:1), whereas for May, November and April, females ratios were higher than males, situation that coincided with the spawning season. The limnetic conditions and high production characteristics of Chongón dam, have promoted the availability of a great amount of food for this species, which may have allowed P. boulengeri to have a more extended reproductive season in this favorable environment.

Patrón reproductivo y talla media de madurez sexual de hembras de la langosta Panulirus gracilis (Decapoda: Palinuridae) en Playa Lagarto, Guanacaste, Costa Rica / Reproductive pattern and mean size of sexual maturity of female lobsters Panulirus gracilis (Decapoda: Palinuridae) in Playa Lagarto, Guanacaste, Costa Rica

The lobster P. gracilis is important as a fishery resource and also contributes to food security of fishers in coastal communities in the North Pacific of Costa Rica. Due to the importance of updating knowledge related to the reproductive pattern of this species, we analyzed 357 specimens of female lobsters caught by the fishing methods of “hookah” and lung diving, from November 2007 to October 2008 in Playa Lagarto. Furthermore, we examined the size composition by depth; monthly pattern of reproductive activity (RAI) associated with the relative increase in sea surface temperature, and also the mean size at maturity using Generalized Linear Models. Four physiological states of sexual maturity showed that females with no signs of mating or sexual maturity have a minimum mean size of 62.3mm of cephalothorax length (CL). There are characteristics of functional maturity from very small sizes ranging from 30 to 50mm CL, being the smallest berried female reported for this specie of 35.8mm CL and the highest percentage of mature females between 70 and 80mm CL. Percentages of RAI remained above 50% during the year except October and January. In addition, it observed an increase in the RAI that started from April and continued until August associated with a relative increase in temperature on March, although the correlation was not significant (r²=0.49, p>0.05). It is possible that the low mean size at maturity (70.2mm LC) for P. gracilis in this region is related to the fishing activity. It recommends the establishment of a ban in the region of at least five months (April-August) in order to protect the reproductive seasonality of the species and to promote a recruitment increase in the fishing areas.

La langosta Panulirus gracilis es importante como recurso pesquero de las comunidades costeras en el Pacífico Norte de Costa Rica. Debido a la importancia de actualizar el conocimiento relacionado con el patrón reproductivo de esta especie, se analizaron 357 especímenes de langostas P. gracilis hembras capturados mediante el buceo con compresor y el buceo a pulmón durante noviembre de 2007 a octubre del 2008 en Playa Lagarto. Se examinó la composición de las tallas por estrato de profundidad, el patrón mensual de la actividad reproductiva (IAR) asociado al aumento relativo de la temperatura superficial del océano, y además se determinó la talla media de madurez sexual utilizando Modelos Lineales Generalizados. Los cuatro estados fisiológicos de madurez sexual mostraron que las hembras sin masa espermatófora y no ovígeras, presentaron las menores tallas con una media de 62.3mm de longitud cefalotoráxica (LC). Se observaron características de madurez sexual a partir de tallas muy bajas que van desde 30 a 50mm de LC, encontrándose la menor hembra ovígera reportada para esta especie de 35.8mm de LC y el mayor porcentaje de hembras maduras entre 70 y 80mm de LC. Los porcentajes del IAR se mantuvieron por encima del 50% durante el año, con excepción de los meses de octubre y enero. Además, se observó un aumento en el IAR que inició a partir de abril y continuó hasta agosto asociado a un relativo aumento en la temperatura a partir del mes de marzo, sin embargo esta relación no fue significativa (r²=0.49, p>0.05). No se descarta que la baja talla media de madurez sexual de 70.2mm de LC para P. gracilis en esta región sea causada por las prácticas de pesca. Se recomienda que se establezca una veda en la región de cinco meses (abril-agosto) con el fin de proteger la estacionalidad reproductiva de la especie y promover un mayor reclutamiento a las áreas de pesca.

Reproductive biology of common snook Centropomus undecimalis (Perciformes: Centropomidae) in two tropical habitats

In Southeastern Mexico, Centropomus undecimalis is an important fish species of sport and commercial fisheries for coastal and riverine communities. Fisheries along rivers and coasts depend on migratory habits of this species, and these movements are probably related to reproduction. In spite of its economic importance, few studies have been conducted focusing on its reproductive biology, and this research aims to analyze these habits. Samples (fork length, somatic and gonads weight, and macroscopic maturity stages) were obtained from organisms collected by fishermen from the largest fishing cooperatives along the coastal and riverine areas of Tabasco, from July 2006 to March 2008. Fish size ranged from 34 to 112cm fork length, with an average age of 6.42 years for males and 9.12 years for females. In riverine areas, fish sizes ranged from 30 to 85cm and the average age was 5.5 years for males and 6.6 years for females. Significant differences were recorded between lengths of males and females from the two areas (Kruskal-Wallis, p<0.05). The male:female ratio was 1:0.68 in the coast, and 1:0.16 in riverine areas. The length-weight relationship did not vary between both sexes among areas (ANCOVA, p>0.05). A curve for eviscerated weight was calculated for both sexes, for coastal fishes SW=0.0059(FL) 3.07, and the riverine ones SW=0.0086(FL) 2.98, with an isometric growth (b=3). The period of maximum reproduction was from July to August, with temperatures of 28 to 30°C. A significant correlation between the gonadosomatic index (GSI) and rainfall was recorded for samples of both males and females from coastal areas (r=0.63, r=0.70) whereas only one positive correlation was recorded for riverine females (r=0.57). The size at first maturity (L50) was estimated at 60cm and 80cm (FL), corresponding to 5.5 and 8.5 years of age, for males and females, respectively. An important proportion of mature females of eight years and older, suggests that these ages contribute significantly to the reproductive biomass. The results indicate that due to changes in the exploitation period, we recommend to protect populations of the common snook. Rev. Biol. Trop. 59 (2): 669-681. Epub 2011 June 01.

En este estudio, se analizó la biología reproductiva y poblacional del robalo blanco (Centropomus undecimalis). El material biológico se obtuvo en los desembarcos de la pesca artesanal de las cooperativas de mayor contribución en la zona costera y ribereña durante julio de 2006 a marzo de 2008. En la zona costera las tallas oscilaron entre 34 a 112cm (LF) y en la zona ribereña entre 30 a 85cm. Se encontraron diferencias significativas entre las longitudes de machos y hembras en ambas zonas de estudio (Kruskal-Wallis, p<0.05). La proporción machos:hembras fue 1:0.68 en la costa y 1:0.16 para la zona ribereña. La relación longitud-peso no difirió entre sexos en las dos zonas de estudio (ANCOVA, p>0.05). El periodo máximo reproductivo fue de julio a agosto. En la zona costera, se encontró una correlación significativa entre el iGS y precipitación pluvial para machos y hembras (r=0.63, r=0.70), en la zona ribereña solo se encontró un correlación positiva en las hembras (r=0.57). La talla de primera madurez (L50) se estimó a los 60cm para hembras y 80cm (LF) para machos correspondiendo a 5.5 y 8.5 años de edad respectivamente. Los resultados sugieren un cambio en el periodo de explotación para la conservación de las poblaciones del robalo blanco y su producción.