Diet and feeding strategy of thornback ray Raja clavata

Abstract

The diet and feeding strategy of thornback ray Raja clavata, from the eastern-central Adriatic Sea, were investigated. Stomach contents of 428 specimens, total length (L(T)) of 14·0-75·1 cm, were collected from commercial bottom trawls. The prey items identified in the stomachs belong to eight major groups: Cephalopoda, Polychaeta, Stomatopoda, Decapoda (Natantia and Reptantia), Mysidacea, Isopoda, Amphipoda and Teleostei. Decapods were the most important prey (index of relative important, %I(RI) ,= 72·8) followed by teleosts (%I(RI) = 20·4), whereas other prey groups were only occasionally ingested. Small-sized individuals (<25 cm L(T)) fed primarily on small crustaceans (mysids and amphipods), whereas large-sized specimens consumed larger prey, such as decapods, cephalopods and teleosts. Diet composition showed little seasonal variation; decapods were the most important prey in all seasons. There was high dietary similarity between sampling locations. The percentage of empty stomachs did not differ significantly among size classes and seasons. In terms of composition by species, the diet of R. clavata was characterized by a variety of rare or unimportant prey. As a result, R. clavata could be considered a generalist predator.

Resource partitioning among sympatric elasmobranchs in the central-western Mediterranean continental shelf

“…As previously reported by other authors worldwide (e.g. Farias et al 2006;Valls et al 2011;Martinho et al, 2012;Šantić et al 2012b;Barría et al 2015Barría et al , 2018, these species exhibited a high degree of full stomachs. This could be indicative of these fishes' "continuous feeder" alimentary patterns (Wetherbee et al 2012) typical of most skates and stingrays (Jacobsen and Bennett 2013) which can also be extended to Scyliorhinus canicula.…”

Diet and feeding behaviour of longnosed skate Dipturus oxyrinchus

“…Crustaceans were always the main prey, while teleosts and cephalopods were of secondary importance and consumed in almost the same proportions. This result is similar to that of previous studies carried out on other rajids (Muto et al ., ; San Martin et al ., ; Navia et al ., ; Šantić et al, ).…”

Two’s company, three’s a crowd: fine-scale habitat partitioning by depth among sympatric species of marine mesopredator

“…as generalist feeders, with considerable overlap in prey identified from stomach content analyses (Ellis et al 1996, Farias et al 2006, there are significant differences in the most important prey items for each species (Pinnegar 2014). For example, R. brachyura and R. microocellata have a similar dietary preference, with a slightly greater proportion of teleost prey (54% and 56% of the diet respectively) while R. clavata and R. montagui are similar in having considerably more crustaceans (79% and 81% of the diet respectively) (Ellis et al 1996, Šantić et al 2012, Pinnegar 2014. One species from each pair therefore has a greater preference for crustaceans in the diet (R. clavata and R. montagui), rather than fish.…”