ABSTRACT
The sea urchin Lytechinus variegatus is of some commercial importance on the Southern coast of Margarita Island (Venezuela), where artisan women fishers process and sell the roe. The reproduction cycle of this species had not been fully studied. We collected these sea urchins in two stations from November 1997 through October 1998. The samples were transported fresh to the laboratory to determine weight, diameter and height. The sexual stage was established with a macroscopic scale and the gonadosomatic index (GI). Maturity is achieved when the animals reaches a diameter of 22 mm, although 50% of the population reaches sexual development at diameters of 43 mm (males) and 45 mm (females) at Station 1, and 35 mm for both sexes at Station 2. Mature individuals, in a sexual proportion of 1:1 were collected every month. According to the monthly GI variation and frequency (%) of the development stages, on the southern beaches the main reproductive period begins in April and continues through October, and it is most intensive from May to July, when gonads reach the greatest growth.
Subject(s)
Lytechinus/growth & development , Sexual Behavior, Animal/physiology , Animals , Body Weight , Female , Male , Population Density , Reproduction/physiology , Seasons , Seawater , Sexual Maturation , VenezuelaABSTRACT
In Margarita and Cabagua Islands, Venezuela, the sea urchin Lytechinus variegatus is consumed as food but few studies concern its biology. Between January 1999 and September 2000, 25 localities of Margarita and Cubagua islands we visited to determinate the relationship between diameter and weight of living urchins according to their coloration green or white. A total of 5 066 urchins (3 421 captured in Margarita and 1 645 in Cubagua) were measured. There is no significant difference in the weight-diameter relations of green or white sea urchins of both islands. The weight-diameter equation is P = 0.00246 D252. Utilizing a quadrant (0.5 x 0.5 m) monthly samples of urchins living in a 2 m2 of surface were taken to estimate the abundance of the specimens according their color (N = 6 948 urchins). The green urchins were more abundant than the white urchins, in a 3:2 proportion.
Subject(s)
Animals , Body Weight , Pigmentation , Sea Urchins , VenezuelaABSTRACT
In Margarita and Cabagua Islands, Venezuela, the sea urchin Lytechinus variegatus is consumed as food but few studies concern its biology. Between January 1999 and September 2000, 25 localities of Margarita and Cubagua islands we visited to determinate the relationship between diameter and weight of living urchins according to their coloration green or white. A total of 5 066 urchins (3 421 captured in Margarita and 1 645 in Cubagua) were measured. There is no significant difference in the weight-diameter relations of green or white sea urchins of both islands. The weight-diameter equation is P = 0.00246 D252. Utilizing a quadrant (0.5 x 0.5 m) monthly samples of urchins living in a 2 m2 of surface were taken to estimate the abundance of the specimens according their color (N = 6 948 urchins). The green urchins were more abundant than the white urchins, in a 3:2 proportion.
Subject(s)
Body Weight , Pigmentation , Sea Urchins/anatomy & histology , Animals , VenezuelaABSTRACT
The sea urchin roe reach a very high price in the international fish product market favoring the increase in the catches of this resource and overfishing in some countries. In the Island of Margarita (Venezuela) some species, Lytechinus variegatus (Lamarck) among others, are consumed as food but studies to determine abundance of the resource are unknown. Nine sample stations (depth less than 2 m) on the North, East and West coast of Margarita Island were visited in six different occasions between February/1998 and February/1999 to study the population density (urchins/m2) of L. variegatus. Using a quadrat (0.25 m2) thrown 8 times over seagrasses (Thalassia testudinum) beds and over submerged rocks and the urchins removed by dive. The diameter of each specimen was measured and returned to the sea. The water temperature, salinity and dissolved oxygen of each site was measured. Were collected a total of 2,073 urchins with a diameter ranging from 11.0 to 84.5 mm and population density between 1 to 52 urchins/m2. The mean size of specimens collected in the stations was between 30.44 and 55.09 mm and average density fluctuated between 3.2 to 43.2 urchins/m2. The station where sea urchins were found to be most abundant was the North coast (Manzanillo fishing villae) where they live on rocks with a density (38 a 52/m2) far over the values previously cited for the Caribbean sea and Florida.
Subject(s)
Sea Urchins/growth & development , Seawater , Animals , Caribbean Region , Population Density , VenezuelaABSTRACT
RESUMEN: Las gónadas de erizo alcanzan una alta cotización en el mercado internacional de productos marinos favoreciendose así la captura mundial del recurso, y en varios países la sobrepesca. En la isla de Margarita (Venezuela) se utilizan como alimento algunas especies de erizos, entre ellas Lytechinus variegatus (Lamarck). Para estudiar su densidad poblacional (erizos /m2) en la costa norte, este y oeste de Margarita se visitaron en seis ocasiones, entre los meses de febrero /1998 y febrero /1999 nueve estaciones de muestreo fijas (profundidad menor a 2 m). Mediante buceo autónomo y utilizando una cuadrata (0,25 m2) que fué lanzada aleatoriamente 8 veces sobre rodales de Thalassia testudinum y/o rocas submareales, se extraían los erizos para contabilizarlos y medirles el diámetro de la testa y regresarlos al mar. Se midió la temperatura, el oxígeno disuelto y la salinidad del agua superficial en cada estación de muestreo. Se recolectaron un total de 2.073 erizos con diámetro entre 11,0 y 84,5 mm y densidades poblacionales entre 1 y 52 erizos /m2. La talla promedio de los ejemplares medidos varió entre 30,44 y 55,09 mm y la densidad promedio total fluctuó entre 3,2 y 43,2 erizos /m2. En la costa norte (estación Manzanillo) los erizos viven asociados a rocas, localidad donde se determinaron las mayores densidades (38 a 52 /m2) cifras que superan ampliamente a las densidades de L. variegatus previamente citadas en el Mar Caribe y la Florida.
