Inter-calibration trials between the R/V Cornide de Saavedra and the R/V Miguel Oliver in bottom trawl surveys off the Spanish coast
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AuthorsSoto-Ruiz, M. (María); Velasco, F. (Francisco); Sobrino, I. (Ignacio); Baldó, F. (Francisco); Esteban-Acón, A. (Antonio); Massutí, E. (Enric)
Bottom trawl surveys are conducted by the Spanish Oceanographic Institute (IEO) to provide information independent from the fisheries of commercial stocks: DEMERSALES in the northern Spanish Shelf, ARSA in the Gulf of Cadiz and MEDITS in the Mediterranean Shelf since 1983, 1993 and 1994, respectively. Surveys have been performed annually on board the R/V Cornide de Saavedra until 2013. This vessel (67 m, 1133 GRT) was built in 1972 and nowadays has been replaced by the new R/V Miguel Oliver (70 m, 2495 GRT). To guarantee the continuity between the two vessels of the abundance and biomass indices of the main target species and their length distributions, inter-calibration experiments have been performed for each of the three bottom trawl surveys. The goal of the inter-calibration between both vessels was to establish the most similar fishing conditions to detect and isolate if there was a vessel effect that caused different results in catches. And in if those differences were significant, ...