Feeding ecology of conger eels (Conger conger) in north-east Atlantic waters

Abstract

In order to understand how marine ecosystems function, it is essential to study the trophic interactions among the community members, particularly from poorly known regions. In this study, the feeding ecology and diet of conger eels,Conger conger, an abundant fish species with commercial interest, was examined in the north-east Atlantic, off Algarve (southern Portugal) between May 2005 and August 2006. The diet was characterized by species composition, size and mass of prey. Conger eels are opportunistic feeders, cannibalistic, feeding on benthopelagic/pelagic prey (67% by mass and 71% by number) but also benthic prey (32% by mass and 29% by number). Fish (67.8±4.7% in mass) are the main prey of conger eels, followed by cephalopods (16.5±3.8%) and crustaceans (15.6±3.7%). The most numerous (identifiable) fish consumed wereCapros aper, occurring in 90% of the stomach samples that contained food and representing 1.4% in mass, andScomber japonicus, the most important fish in mass (21.1%), which occurred in 4.2% of the stomach samples that contained food. The present study shows that octopodids can play a more important role in the diet of conger eels than previously thought. Of the species preyed upon by conger eels, six species (21% of the total prey taxa) are caught commercially(Trachurus trachurus, Scomber japonicus, Micromesistius poutassou, Helicolenus dactylopterusandConger conger)by local fisheries. As discards by local trawl and longline fisheries do not correspond with the diet ofC. conger, it is likely that most prey ofC. congerin rocky areas were caught actively in that study region.

The diet and feeding ecology of Conger conger (L. 1758) in the deep waters of the Eastern Ionian Sea

“…Intestine content analysis proved to be useful, revealing prey taxa missing from the stomachs ( Table 1). The results of this study generally agree with (Cau & Manconi, 1984, Morato et al, 1999, O'Sullivan et al, 2004and Xavier et al, 2010. These authors classified Crustacea as accidental prey, whereas Abi-Ayad et al (2011) classified it as a favourite prey indicating that these differences may be attributed to geographical differences in prey availability.…”

“…A specialisation at the population level was found for Fish in all analyses. Some studies have suggested dietary specialization (Fish: Morato et al, 1999 andO'Sullivan et al, 2004), while Xavier et al (2010) suggested a more opportunistic behaviour. These contrasting diets indicate the adaptability of this species, which may partially explain its wide distribution.…”

“…Despite being a geographically widespread species and a commercial resource, the number of studies on this species is very limited. Information on its diet has been reported from the north-eastern Atlantic Ocean (Olaso & RodriguesMarin, 1995;Morato et al, 1999;O'Sullivan et al, 2004;Xavier et al, 2010), the Western Mediterranean (Cau & Manconi, 1984;Abi-Ayad et al, 2011) and the Adriatic Sea (Vallisneri et al, 2007). None of these works include intestine content examination.…”

Polar marine biology science in Portugal and Spain: Recent advances and future perspectives

“…For example, methods used in the identification of prey in the diet of top predators has already been applied in European waters, on the ecology and conservation of seabirds and fish (Paiva et al, 2010;Xavier et al, 2010;Xavier et al, 2011a;Xavier et al, 2012b). Also, the pharmacological potential of selected compounds in Antarctic organisms has been assessed .…”

First observations on diet and feeding strategy of boarfish, Capros aper (Actinopterygii: Perciformes: Caproidae), in the eastern Ionian Sea (central Mediterranean)

“…As zooplankton feeder, C. aper may have an impact on eggs and larvae of other species but this hypothesis has not be proved in a study conducted in Portuguese waters (Lopes et al 2006) and thus its increase in abundance can affect natural mortality of commercial fish species. Capros aper has been considered an important component of some species' diets such as seabirds, sharks, bony fishes (Clarke et al 1995, Granadeiro et al 1998, Morato et al 2003, Xavier et al 2010.…”