Information About Grenadiers from Bottom Trawl Surveys in the Gulf of Cadiz
Juan Gil, Jesús Canoura, Yolanda Vila, and Ignacio Sobrino
Abstract.—The principal aim of this study is to describe the distribution patterns of abundance and biomass, on a seasonal and bathymetric basis of the main macrourid species from the Spanish Gulf of Cadiz. The results from 23 bottom-trawl surveys carried out in the study area in spring and autumn of 1993–2006 were analyzed. The most abundant species captured were common Atlantic grenadier Nezumia aequalis and saddled grenadier Coelorinchus coelorhincus. In terms of biomass, softhead grenadier Malacocephalus laevis was the third most important species and bluntsnout grenadier Nezumia sclerorhynchus and glasshead grenadier Hymenocephalus italicus were the least abundant species. Of the five species caught in the surveys, only N. aequalis, M. laevis and C. coelorhincus were analyzed in detail; their yields expressed in number of individuals/h represented the higher values and showed higher yields in spring than in autumn, suggesting a seasonal pattern of abundance. However, C. coelorhincus did not show this pattern except between 1999 and 2004. N. aequalis showed the widest bathymetric range. The observed yields in the depth gradient for the three species revealed species-specific preferences for a determinate depth range. In relation to mean total size, larger individuals of M. laevis and N. aequalis were observed during the March surveys. C. coelorhincus was the only species that showed a slight increase in mean size with increasing depth.