Edad y crecimiento del pez Haemulon steindachneri (Perciformis: Haemulidae) en el suroeste de la isla de Margarita, Venezuela

Age and growth of the grunt, Haemulon steindachneri (Perciformis: Haemulidae), from the Southwest area of Margarita Island, Venezuela. Studies on fish age and growth are essential to establish models on population dynamics. We determined age and growth of the grunt Haemulon steindachneri from the Southwest Margarita Island using sagita otoliths (direct method) and length frequency (indirect method). A total of 953 individuals were captured by the handcrafted fleet from Boca del Río (Margarita Island) between July 2005 and June 2006. The length-weight relation was established and growth parameters from both curves (length and weight) were estimated using the von Bertalanffy model. The analysis of the annual rings in otoliths established four age groups, and group 3+ was the most representative, with 44.5% of the sample. The calculation of marginal increases of otoliths suggested the development of an annual ring in April, which coincides with the maximum reproduction period. There were no significant differences in the slopes of the curves b (t s=-1.81; p>0.05) and the intercepts a (t s=-1.17; p>0.05) of females and males. Length-weight for both sexes was W=0.0003*L2.89, which indicates an alometric growth pattern. Growth parameters were established as: L∞=231mm, W∞=203g, k=0.569year-1 (direct method) and L∞=228mm, W∞=195g, k=0.580year-1 (indirect method), which suggests that it is a short life species that grows moderately rapidly. The index of growth phi prime (ؒ) coefficient of variation (CV), showed similarity between the growth parameters obtained by both (direct and indirect) methods. The application of the indirect method is recommended, as well as the periodic analysis of population parameters. Rev. Biol. Trop. 58 (1): 299-310. Epub 2010 March 01.

La edad y el crecimiento del pez Haemulon steindachneri fueron determinados por medio de los otolitos sagitales (método directo) y la distribución de frecuencia de tallas (método indirecto). Un total de 953 individuos fueron capturados por la flota artesanal de Boca del Río, suroeste de la isla de Margarita, entre julio 2005-junio 2006. Se estableció la relación talla-peso y se estimaron los parámetros de crecimiento de las curvas en longitud y peso del modelo de von Bertalanffy. El recuento de los anillos anuales en otolitos, permitió establecer cuatro grupos de edad, siendo el grupo 3+ el más representativo, con un 44.5% de la población muestreada. El cálculo de los incrementos marginales del crecimiento mensual de los otolitos, sugirió la formación de un anillo hialino anual en el mes de abril, el cual coincide con la época máxima de reproducción. No se observó diferencia significativa en las pendientes b (t s=- 1.81; p>0.05) e interceptos a (t s=-1.17; p>0.05) de hembras y machos, con una relación talla-peso para ambos sexos de W=0.0003*L2.89, la que indicó un crecimiento alométrico. Los parámetros de crecimiento quedaron establecidos en: L∞=231mm, W∞=203g, k=0.569año-1 (método directo) y L∞=228mm, W∞=195g, k=0.580 año-1 (método indirecto), lo que sugiere que se trata de una especie de vida corta y crecimiento moderadamente rápido. El coeficiente de variación (CV) del índice de crecimiento phi prima (ؒ), demostró semejanza de los parámetros de crecimiento en longitud obtenidos por los métodos directo e indirecto; por lo que se recomienda la aplicación del método indirecto, así como el análisis periódico de los parámetros poblacionales.

Reproducción de la sardina, Sardinella aurita (Cupleiformes: Clupeidae) del sureste de la Isla de Margarita, Venezuela

Reproduction of the Spanish sardine, Sardinella aurita (Clupeiformes: Clupeidae) from the south-eastern area of Margarita Island, Venezuela. Sex ratio, sexual maturity, fecundity and time of spawning of the Spanish sardine (Sardinella aurita) from the south-eastern area of Margarita Island were determined through monthly samplings of commercial fisheries, from January 2004 to April 2005. A total of 3 736 individuals were examined. Sex ratio was 55.47% females and 44.53% males, with a 1:1.25 sexual proportion (χ2 = 44.454, p < 0.05). Length at first sexual maturity (L50) was 20 cm. Spawning of the species was confirmed to be partial and continuous throughout the year, with two peaks of intensity during the first and last quarters. Absolute fecundity ranged from 10 530 to 83 779 oocytes and it was proportional to body length (F = - 100 900 + 6 696.2 * L) and to body weight (F = 13 327 + 5 666.3 * P). Relative fecundity ranged from 149 to 1 020 oocytes/g and also was proportional to body length and weight. We concluded that the Spanish sardine exhibits two peaks of spawning activity per year with a very fluctuating partial fecundity which could possibly be explained by environmental variability. Rev. Biol. Trop. 56 (4): 1813-1824. Epub 2008 December 12.

Se determinó la proporción y madurez sexual, fecundidad y época de desove de la sardina, Sardinella aurita Valenciennes, 1847 del sureste de la Isla de Margarita, Venezuela; a través de muestreos mensuales provenientes de la pesca comercial desde enero 2004 hasta abril 2005, examinándose un total de 3 736 individuos. La composición global por sexos fue de 55.06% hembras y 44.19% machos, siendo la proporción sexual 1:1.25 (χ² = 44.454, p < 0.05). La talla de primera madurez sexual del 50% de la población fue de 20 cm de longitud. Se corroboró el carácter parcial y continuo del desove de la especie, cuyo periodo ocurrió durante todo el año, con dos periodos de relativa intensidad, correspondientes al primer (enero, febrero, marzo) y último trimestre (octubre, noviembre, diciembre) del año. La fecundidad absoluta osciló entre 10 530 a 83 779 óvulos, y la relativa varió entre 149 a 1 020 óvulos/g; siendo la fecundidad proporcional a la talla (F = - 100 900 + 6 696.2 * L) y al peso (F = 13 327 + 5 666.3 * P). Se concluye que la sardina presenta un potencial reproductivo alto y fluctuante, atribuida posiblemente, a la variabilidad ambiental.

La pesca de sardina, Sardinella aurita (Teleostei: Clupeidae) asociada con la variabilidad ambiental del ecosistema de surgencia costera de Nueva Esparta, Venezuela / Association of sardine fishery, Sardinella aurita (Teleostei: Clupeidae) and environmental variability of the coastal upwelling ecosystem of Nueva Esparta, Venezuela

The present research is an analysis of Spanish sardine fishing (Sardinella aurita) associated with some climatic and meteorologic parameters of the ecosystem from El Morro Nueva Esparta, Venezuela. The catch and environmental data from the area were taken in the period 1996-2000. Catch data as a function of wind speed, sea surface temperature, air temperature and rain were analyzed by means of simple lineal regression and multiple models. We found a positive correlation of catch with wind speed, and a negative correlation with sea surface temperature, air temperature, and rain. The multiple regression model with intercept had a poor fit, therefore, we made a model without intercept, which improve greatly the fit. A selection of the variables using the forward procedure verified that the independent variables "wind speed" and "air temperature" have a significant relation with catch (p < 0.001) at real time. This method suggests that sea surface temperature and rain have little influence on the catch, and suggests a major availability of resources in the months with low air temperature and the highest wind speed (January-June). Rev.

Association of the abundance and vertical distribution of tuna and beakfish in the southeast of the Caribbean sea / Asociación de la abundancia y la distribución vertical de atunes y peces de pico en el sureste del Mar Caribe

The longline hooks suspension depth was estimated using the Mechanic Imitation of Flexible Systems method. The vertical distribution of tunas and billfish was determined by the relative abundance index, obtained from the catch by 11 to 25 m -long longline vessels, -based at Cumaná, Venezuela, South-eastern Caribbean Sea in depths of 65 to 142 m. The CPUE was evaluated per species, according to depth. High values were found for most of the captured species in the layer from 105 to 125 m. Yellowfin tuna (Thunnus albacares) showed the highest yield (3.37 fish/100 hooks) and blue marlin (Makaira nigricans) the lowest (0.04 fish/100 hooks). However, the statistical comparison did not allow to reject the hypothesis of lack of depth efect (Kruskal-Wallis p > .05), and demonstrated a homogeneous distribution of yellowfin tuna (Thunnus albacares), albacore (Thunnus alalunga), bigeye tuna (Thunnus obesus), sailfish (Istiophorus albicans), white marlin (Tetrapturus albidus) and blue marlin (Makaira nigricans) in the water column. The conclusion is that fish concentration in the Southern border of the Caribbean Sea is possibly due to several hydroclimatic factors--which affect tuna and billfish catching--such as water temperature and dissolved oxygen concentration which limit the distribution according to depth.