Habitat use by Gadiculus argenteus (Pisces, Gadidae) in the Galician and Cantabrian Sea waters (NE Atlantic)

Abstract

Forage fish species play a crucial role in most ecosystems, transferring energy from plankton to larger fishes. Therefore, understanding the factors driving the dynamics of forage fish populations is essential in marine ecosystems. Gadiculus argenteus is an important forage fish species in the Galicia and Cantabrian Sea ecosystem. In this study, the influence of several biotic and abiotic factors on the distribution of this species was examined using generalized additive models in a 2-step approach. G. argenteus habitat preference was not affected by changes in annual abundance during the study period (1998-2019). From the variables selected in the final models, depth and geographic location (latitude and longitude) were the most important factors to describe the presence of G. argenteus. Peak abundance was found on the upper slope and although the species was found throughout the study area, its higher abundance values were located in Galician waters. The species seemed to avoid coarse sand bottoms, with mean chlorophyll a concentration showing a positive effect on the presence and abundance of G. argenteus. Interestingly, the observed aggregations of G. argenteus showed a remarkable similarity to the commercial trawling footprint in the area, suggesting a strong link between the distribution of this forage species and the distribution of its predators, most of which are important commercial species. Further work should focus on a better understanding of this relationship to provide important information on the study of the structure and functioning of the marine ecosystem of the northern Spanish continental shelf.