Feeding Habits ofAlepocephalus Rostratus(Pisces: Alepocephalidae) in the Western Mediterranean Sea

Abstract

The present study examines the feeding habits of Alepocephalus rostratus, the only species of the family Alepocephalidae in the Mediterranean Sea and the second most important fish species, in terms of biomass, inhabiting the deep slope of the Catalan Sea. Samples were obtained at depths between 1000-2250 m. Diet was analysed for two different size-classes (immature and mature specimens) at three different bathymetric strata during two different seasons. The feeding habits of A. rostratus included a narrow range of mobile macroplanktonic organisms (e.g. Pyrosoma atlanticum and Chelophyes appendiculata) and some material of benthic origin. Pyrosoma atlanticum was the preferred prey item in spring at 1000-1425 m, being very scarce in summer at the same depth as a consequence of its scarcity in the environment during this season. There were some ontogenic differences in the diet of A. rostratus at 1425-2250 m. Adults ingested more and larger prey than juvenile specimens. The scarcity of resources below 1200-1400 m fostered a more diversified diet, as well as passive predation of sedimented material.

Body fish size tendencies within and among species in the deep-sea of the western Mediterranean

“…In addition, this factor may have imposed a strong selection pressure for a diversification in the trophic strategies of the fish species inhabiting the lower slope, which may explain the already mentioned coexistence of small and large-sized species (e.g. Bathypterois mediterraneus, Lepidion lepidion, Alepocepahlus rostratus and Centroscymnus coelolepis; Carrassón et al, 1992;Carrassón et al, 1997, Carrassón andMatallanas, 1998).…”

Mediterranean and Atlantic deep-sea fish assemblages: differences in biomass composition and size-related structure

“…These differences have been attributed to the fact that trophic webs in the Algerian basin depend more directly on food of planktonic origin, while in the Balearic basin, where there are important submarine canyons, benthic prey enhances food availability and allows a broader trophic spectrum. Thus, the greater percentage of biomass on the lower slope of the Algerian basin corresponds to the middle-sized species Alepocephalus rostratus (almost 75%), whose diet is based on gelatinous macroplankton (Carrasón and Matallanas, 1998), while in the Balearic basin its importance decreases (representing 36%) and other small-sized species such as Bathypterois mediterraneus and Lepidion lepidion, which prey upon benthopelagic crustaceans (Carrasón and Matallanas, 2001) and benthic decapods (Carrasón et al, 1997) respectively, also represent an important fraction of the biomass (23 and 21% respectively). The greatest similarities between Mediterranean and Atlantic deep-sea fish assemblages were found on the middle slope.…”

“…Stefanescu et al, 1993;Moranta et al, 1998) and distribution and biology of the main species have been studied (e.g. Massutí et al, 1995Massutí et al, , 1996Morales-Nin et al, 1996;Carrasón and Matallanas, 1998, 2001. In the eastern North Atlantic, there are also many publications, both on species composition and structure of assemblages (e.g.…”

Feeding habits of <i>Cataetyx alleni</i> (Pisces: Bythitidae) in the deep western Mediterranean

“…We identified thirty-nine categories of prey items from the stomachs containing food (Table 1). Of all the demersal species of fish in the Catalan sea below a depth of 1000 m, it has the highest dietary diversity (Table 1), together with the macrourids (Carrassón and Matallanas, 1998, 2001, 2002Carrassón et al, 1992Carrassón et al, , 1997.…”

“…The general procedure for data obtaining and processing exactly follows that described in previous papers (Carrassón and Matallanas, 1998).…”