Trophic ecology of "Chauliodus danae" (Regan & Trevawas, 1929) off the Canary Islands (central-east Atlantic)

Abstract

The trophic ecology of Chauliodus danae (Regan & Trevawas, 1929) in the centraleastern Atlantic Ocean studied for first time, through the analysis of stomach content. A total of 407 individuals were studied with a length range between 15.63 and 165.1 mm TL, collected between 1997-2001 in waters of Canary Islands. Chauliodus danae feeds on a small group of prey, although some of them reach relatively large sizes relative to their own length (reaching up to 40% of their size). The fish were the main group of prey that make up the diet (IRI=66.7%), followed by planktonic crustaceans, such as copepods, decapod larvae and mysids (IRI=29.3%). However, the representativeness of the different preys in the diet varied depending on the size and sex of the individuals, the depth of capture and the fishing ground. The diet of individuals caught in shallower waters consisted mainly of fish (IRI=95.7%), but it change to crustaceans (IRI=65.5%) as depth of capture increase. However, individual caught in waters deeper than 800 m, fish become again more important in the diet (IRI=78.51%). This variability in the composition of the diet, together with the differences in the number of individuals caught at different hours and depths, confirm that Chauliodus danae makes daily vertical migrations as part of the Deep Scattering Layer (DSL).