6533b825fe1ef96bd128262c

RESEARCH PRODUCT

Evaluating fish assemblages associated with gas platforms: Evidence from a visual census technique and experimental fishing surveys

subject

description

Fish assemblages associated with extractive platforms were surveyed, for the first time, using traditional fishing surveys (bottom gill net) and an underwater visual census (UVC) technique in order to test the effectiveness and to identify strengths and weaknesses of both methods. The study was carried out during three seasons at two offshore gas platforms (Eleonora and Squalo C) located in the central Adriatic Sea. Both methods recorded a similar number of fish species although with only eight species in common, thus supplying complementary information and a good estimate of the total fish species richness (39) associated with these gas platforms. The use of innovative techniques, such as UVC, to explore the inner part of the platforms, allowed the censusing of several cryptobenthic species, mostly Blennidae (8 species), never recorded during previous studies. Even if both methods were able to detect temporal variability, only the UVC technique was able to highlight spatial changes between platforms, demonstrating their high efficiency regarding the quality of the scientific information supplied. The innovative method of studying biodiversity presented in this study appears to be highly reproducible and suitable for monitoring fish diversity in artificial and very complex habitats like gas platforms. Se estudiaron, por primera vez, las comunidades de peces asociadas con plataformas extractivas mediante muestreos pesqueros tradicionales (red de enmalle de fondo) y una tecnica de censos visuales submarinos para determinar la eficacia e identificar las fortalezas y debilidades de los dos metodos. El estudio se realizo durante tres estaciones del ano en dos plataformas gaseras marinas (Eleonora y Squalo C) localizadas en el Mar Adriatico central. Los dos metodos registraron una cantidad similar de especies icticas, aunque solamente ocho especies en comun, suministrando informacion complementaria y un buen calculo de la riqueza total de las especies icticas (39) asociadas con las plataformas gaseras. El uso de tecnicas inovadoras, como los censos visuales submarinos, para explorar el interior de las plataformas permitio el censo de varias especies criptobentonicas, generalmente Blennidae (8 especies), que no se habian registrado en estudios anteriores. Aunque con los dos metodos se logro detectar la variabilidad temporal, solo los censos visuales distinguieron los cambios espaciales entre las plataformas, demostrando asi la calidad de la informacion cientifica suministrada. Este metodo inovador para estudiar la biodiversidad parece ser altamente reproducible y apropiado para observar la diversidad de peces en habitats artificiales y complejos como lo son las plataformas gaseras.