Reproduction and recruitment of white mullet (Mugil curema) to a tropical lagoon (Margarita Island, Venezuela) as revealed by otolith microstructure

The reproductive activity and recruitment of white mullet (Mugil curema) was determined by observations of gonad development and coastal juvenile abundance from March 1992 to July 1993. Adults were collected from commercial catches at three sites in northeastern Venezuelan waters. Spawning time was determined from the observation of macroscopic gonadal stages. Coastal recruitment was determined from fish samples collected biweekly by seining in La Restinga Lagoon, Margarita Island, Venezuela. The examination of daily growth rings on the otoliths of coastal recruits was used to determine their birth date and estimate the period of successful spawning. Fish with mature gonads were present throughout the year but were less frequent between September and January when spawning individuals migrated offshore. In both years, juvenile recruitment to the lagoon was highest between March and June when high densities of 25–35 mm juveniles were observed. Back-calculated hatching-date frequency distributions revealed maximum levels of successful spawning in December–January that were significantly correlated with periods of enhanced upwelling. The relation between the timing of successful spawning and the intensity of coastal recruitment in white mullet was likely due to variations in food availability for first-feeding larvae as well as to variations in the duration of the transport of larvae shoreward as a result of varying current conditions associated with upwelling

Age, growth and fecundity of the silver mullet, Mugil curema (Pisces: Mugilidae), in coastal arcas of Northeastern Venezuela

We studied fecundity and growth in populations of the silver mullet, Mugilcurema, in coastal areas of northeastern Venezuela between March 1992 and July 1993. The average number of oocytes in gonads of 23-42 cm adults was 54 x 104, and lhe relative fecundity was ! 311 oocytes g-I of fish. The size of mature oocytes did not vary in different portions of the same gonad (p > 0.05) or among the adults in three populations studied. The average egg diameter for adults was 426 ¡lm (CI=4.34). Age of juveniles, colIected from the La Restinga Lagoon at about monthly intervals, from counts of growth lines on the otoliths ranged from 50 to 240 days. The relation of age (number of growth lines) to standard length follows an exponential growth curve. The growth ofjuveniles varied seasonally and was greatest during the rain y season C April to August), when temperatures were highes!. The time of spawning has probably been adapted so Ihat peak recruitment into the lagoons occurs just prior lo the rainy season when conditions for growth are most favorable.We studied fecundity and growth in populations of the silver mullet, Mugilcurema, in coastal areas of northeastern Venezuela between March 1992 and July 1993. The average number of oocytes in gonads of 23-42 cm adults was 54 x 104, and lhe relative fecundity was ! 311 oocytes g-I of fish. The size of mature oocytes did not vary in different portions of the same gonad (p > 0.05) or among the adults in three populations studied. The average egg diameter for adults was 426 ¡lm (CI=4.34). Age of juveniles, colIected from the La Restinga Lagoon at about monthly intervals, from counts of growth lines on the otoliths ranged from 50 to 240 days. The relation of age (number of growth lines) to standard length follows an exponential growth curve. The growth ofjuveniles varied seasonally and was greatest during the rain y season C April to August), when temperatures were highes!. The time of spawning has probably been adapted so Ihat peak recruitment into the lagoons occurs just prior lo the rainy season when conditions for growth are most favorable

Age, growth and fecundity of the silver mullet, Mugil curema (Pisces: Mugilidae), in coastal areas of Northeastern Venezuela

We studied the fecundity and growth in populations of the silver mullet, Mugil curema, in coastal areas of northeastern Venezuela between March 1992 and July 1993. The average number of ovocytes in gonads of 23-42 cm adults was 54 x 104, and the relative fecundity was 1311 ovocytes g-1 of fish. The size of mature ovocytes did not vary in different portions of the same gonad (p 0.05) or among the adults in three populations studied. The average egg diameter for adults was 426 µm (CI= 4.34). Age of juveniles, collected from the La Restinga Lagoon at about monthly intervals, from counts of growth lines on the otoliths ranged from 50 to 240 days. The relation of age (number of growth lines) to standard length follows an exponential growth curve. The growth of juveniles varied seasonally and was greatest during the rainy season (April to August), when temperatures were highest. The time of spawning has probably been adapted so that peak recruitment into the lagoons occurs just prior to the rainy season when conditions for growth are most favorable

<title language="spa">Age, growth and fecundity of the silver mullet, Mugil curema (Pisces: Mugilidae), in coastal areas of Northeastern Venezuela

We studied the fecundity and growth in populations of the silver mullet, Mugil curema, in coastal areas of northeastern Venezuela between March 1992 and July 1993. The average number of ovocytes in gonads of 23-42 cm adults was 54 x 104, and the relative fecundity was 1311 ovocytes g-1 of fish. The size of mature ovocytes did not vary in different portions of the same gonad (p 0.05) or among the adults in three populations studied. The average egg diameter for adults was 426 &micro;m (CI= 4.34). Age of juveniles, collected from the La Restinga Lagoon at about monthly intervals, from counts of growth lines on the otoliths ranged from 50 to 240 days. The relation of age (number of growth lines) to standard length follows an exponential growth curve. The growth of juveniles varied seasonally and was greatest during the rainy season (April to August), when temperatures were highest. The time of spawning has probably been adapted so that peak recruitment into the lagoons occurs just prior to the rainy season when conditions for growth are most favorable

ESTRUCTURA COMUNITARIA DEL ZOOPLANCTON EN DOS LOCALIDADES DEL GOLFO DE CARIACO, VENEZUELA

Resumen: Se evaluó la biomasa, densidad y composición zooplanctónica del golfo de Cariaco de mayo de 2003 a marzo de 2004. Las muestras fueron colectadas con una red tipo Bongo entre 0 – 25 m en 10 estaciones del golfo, 5 extendidas en la plataforma Pariche-Manicuare (zona norte) y 5 en la plataforma Cumaná - El Peñón (zona sur). El volumen desplazado y el peso seco en la zona norte variaron entre 0,01 – 0,081 ml m-3 y 1,53 – 178,64 mg m-3, respectivamente, y para la zona sur fluctuaron entre 0,01 – 0,25 ml m-3 y 1,43 – 131,30 mg m-3, respectivamente. Las mayores densidades fueron detectadas en junio 2003, abril y marzo 2004. La comunidad mostró diferencias significativas con respecto al tiempo relacionada con la surgencia costera; sin embargo, no hubo diferencias significativas espacialmente. La mayor densidad fue registrada en la zona norte (11,90 – 9669,45 ind m-3); estos resultados pueden ser debido a que estas estaciones están más lejos de la pluma del río Manzanares que las del sur. Se contabilizó un total de 24 grupos zooplanctónicos, dominando los copépodos (54 spp.), seguido de los cladóceros, quetognatos y apendicularios. Los meses de máxima biomasa y densidad zooplanctónica coincidieron con los periodos de fuerte intensidad de la surgencia, característica de la costa nororiental de Venezuela.   Palabras Claves: Zooplancton, biomasa, composición, surgencia, golfo de Cariaco.   Abstract: The biomass, density, and zooplankton composition of the Gulf of Cariaco were assessed from May 2003 to March 2004. The samples were collected with a Bongo net at depths of between 0 and 25 m in ten stations within the gulf: five on the Pariche-Manicuare continental shelf (north zone), and five on the Cumaná – El Peñón continental shelf (south zone). The volume displaced and the dry weight for the north zone varied between 0.01 - 0.081 mL m-3 and 1.53 - 178.64 mg m-3, respectively; whereas those for the south zone varied between 0.01 – 0.25 mL m-3 and 1.43 – 131.30 mg m-3, respectively. The highest densities were detected in June 2003 and March and April 2004. The community revealed significant differences relative to the duration of the coastal upwelling. There were, however, no significant spatial differences. The highest density was registered to the north (11.90 – 9669.45 ind. m-3), most likely because the stations there are located farther away from the Manzanares River plume than those to the south. Twenty-four zooplankton groups were recorded, copepods dominating with 54 species, followed by cladoceans, chaetognaths, and appendicularians. The months of maximum biomass and zooplankton density coincided with the periods of strong upwelling activity, so characteristic of the northeastern coast of Venezuela.   Keywords: Zooplankton, biomass, composition, upwelling, gulf of Cariaco