Densidad, estructura de tallas y actividad reproductiva del caracol rosado Eustrombus gigas (Mesogastropoda: Strombidae) en Banco Chinchorro, México / Density, size structure and reproductive activity of the pink conch Eustrombus gigas (Mesogastropoda: Strombidae) in Banco Chinchorro, Mexico

The pink conch Eustrombus gigas is an important fisheries resource. At the regional level in the Caribbean, over-exploitation and habitat destruction have caused a decrease in the abundance of this resource. In order to provide necessary information for the species management in Mexico, this work aimed to analyze the total density, adult density, size structure and reproductive behavior of pink conch population at Banco Chinchorro during 2009-2010. Data from three seasons were obtained (rainy, dry and cold fronts periods) in three areas: Norte (North), Centro (Center) and Sur (South). The organisms were separated into two groups: (a) the criteria based upon legal harvest in Mexico: legal size conchs (siphonal length≥200mm) and illegal size conchs (siphonal length<200mm), and (b) the criteria based upon sexual maturity using the 15mm lip thickness standard: lip<15mm as juvenile conch and lip≥15mm as adult conch. Copulation, spawning, egg masses and aggregations were evaluated as reproductive evidences. The highest total density was observed during the dry season with 384ind./ha, and the lowest during the rainy season with 127ind./ha. The highest density was reported at Sur (385ind./ha) and the lowest at Norte (198ind./ha). The highest adult density was observed during the rainy season (8.33ind./ha), and the lowest occurred in the dry season (6.11ind./ha). Adult density values were 5.55, 7.05 and 8.33ind./ha for Centro, Sur and Norte areas, respectively. Adult densities were lower than the threshold needed for reproduction, and 42% of the population may be vulnerable to fishing, as they had the minimum size for catch (Lsi 200mm). Furthermore, only 2.2% of the population reached a Gl>15mm as sexual maturity indicator. During the study period, only six evidences of reproductive activity were observed. The smaller densities reported at Banco Chinchorro may cause reproduction events to be almost absent which in turn is sufficient ...

Eustrombus gigas es uno de los recursos pesqueros costeros más valiosos en la región del Caribe y constituye un molusco con un elevado valor estético y ecológico. En esta investigación se evalúa su densidad total, densidad de adultos, la estructura de tallas y frecuencia de evidencias reproductivas en Banco Chinchorro, México, periodo 2009-2010; durante tres períodos (de lluvias, seca y de frentes fríos) en tres zonas: Norte, Centro y Sur. La densidad total para el área de estudio varió de 127ind./ha en lluvias a 384ind./ha en seca, la menor densidad se presentó en la zona Norte del Banco (198ind./ha) y la mayor en la zona Sur (385ind./ha). La densidad de caracoles adultos fue baja (6.11ind./ha en seca y 8.33ind./ha en lluvias y 5.55, 7.05 y 8.33ind./ha para las zonas Centro, Sur y Norte, respectivamente). Las densidades de adultos estuvieron por debajo del umbral mínimo necesario para mantener la reproducción. El 42% de la población es vulnerable a la pesca (Lsi≥200mm); sin embargo, solo 2.2% de la población alcanza un Gl>15mm. Solo se observaron seis evidencias de reproducción durante el período de estudio, lo que señala la presencia del efecto Allee en la población y la urgente necesidad del cierre de su pesquería. Se proponen tres puntos importantes para el manejo de la especie: cierre de la pesca, monitoreo de la población y la implementación refugios pesqueros.

Density and reproduction of the Queen Conch Eustrombus gigas (Mesogastropoda: Strombidae) at Cabo Cruz, Desembarco del Granma National Park, Cuba / Densidad y reproducción de la concha reina Eustrombus gigas (Mesogastropoda: Strombidae) en Cabo Cruz, Parque Nacional Desembarco del Granma, Cuba

The queen conch Eustrombus gigas is an important fisheries resource in the Caribbean region. In Cuba Island the studies about this resource are very scarce and particularly in the Southeastern regions of the country. With the aim to get important fishery information about this gastropod, adult Queen Conch density and frequency of reproductive activity were evaluated in Cabo Cruz, Cuba, during 2009-2010. Data from three seasons were obtained (rainy, dry and cold fronts periods) from three different areas: Farito, Guafe and Laguna. The highest density was observed in cold fronts season (468.5ind./ha) and the lowest occurred during the dry season (268.5ind./ha). The highest density was reported at Laguna (520.4ind./ha) and the lowest at Farito (290.9ind./ha). In total, 158 reproductive events were observed. The highest frequency was reported in rainy season (36%), followed by dry (9%) and cold fronts (5%) seasons. Reproductive behavior (mating and egg laying) was related to temperature and photoperiod. Reproductive activity was observed during the whole year, which suggests the existence of an important Queen Conch reserve in the Southeastern region of Cuba and an apparently self-sufficient population for recruitment. From our results we may conclude that, the population’s sustainable exploitation is viable if the following management measures are observed: functional zoning within the area, rotation of fishing areas and a closed season. We recommend that the Laguna site should be protected as a reproduction zone and banned for fishing activities.

El Eustrombus gigas es un recurso pesquero importante en la región del Caribe. En Cuba, los estudios acerca de este recurso son muy escasos y en la zona Sur-oriental del país son casi nulos. En este trabajo se evalúa la densidad de adultos y frecuencia de la evidencia reproductiva de Eustrombus gigas Linneus 1758 en Cabo Cruz, Cuba, en el periodo 2009-2010. Se obtuvieron datos de tres períodos (lluvias, seca y frentes fríos) en tres zonas: Farito, Guafe y Laguna. La mayor densidad de adultos se observó en frentes fríos (468.5ind./ha) y la menor en seca (268.5ind./ ha). Por zonas, la mayor densidad de adultos se reportó en Laguna (520.4ind./ha) y la menor en Farito (290.9ind./ha). Se observaron 158 evidencias reproductivas. La mayor frecuencia se reportó en lluvias (36%). La temperatura se relacionó con la frecuencia de desove y cantidad de masas de huevos, y el fotoperiodo con la cantidad de agregaciones y frecuencia de cópula. Se observó actividad reproductiva intensa durante todo el año, lo que sugiere una importante reserva de la especie en la región sur-oriental de Cuba y una aparente autosuficiencia de la población para el reclutamiento. La explotación sostenible de la población es viable y Laguna debe ser protegida como zona de reproducción.