Abstract

The intense fishing pressure on Strombus gigas has taken its population to the extinction risk, situation that has promoted the information necessity that supports tending strategies to its conservation. In this sense, for the Natural National Park Corales del Rosario and San Bernardo (PNNCR and SB) the following questions are addressed: ¿Which is the location, size and characterization of the potential habitats for juveniles and adults? and ¿What kind of spatial distribution its population structure presents?. For this purpose a systematic survey of 248 stations was conducted up to 10 m in depth during rainy (2004) and dry (2005) seasons. In each station, the habitat was characterized in terms of the substrate cover type, whereas individuals of S. gigas were counted and measured. Using remote sensing, preexisting cartography and fields observations, maps of the bottom type were obtained. Five main habitats were occupied by S. gigas: mixed bottoms (the one of greater extension), sand-gravel, seagrasses beds, macro algae bed and rodolitos-sand. Geoestatistical techniques (variography and kriging) allowed determining that the S. gigas population presents patch distribution. Rosario was dominated by adults all year with patches of densities between 14,3 and 1,06 ind/ha on the Bajo Tortugas and Tesoro, finding greater densities in rain season, while juveniles occurred mainly at dry season on the Arena Island (32 ind/ha). San Bernardo was dominated by juveniles all year with patches of densities between 16,2 and 6,5 ind/ha on the Maravilla Island, Panda and Múcura, showing high densities on rainy season, while adults were only present in rain season on Bajo Nuevo. For Rosario, the adults preferred the sand-gravel habitat, while juveniles the seagrasses beds. For San Bernardo, the adults preferred the mixed bottoms and seagrasses beds, while juveniles the seagrasses beds.

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