Feeding habits and trophic status of Merluccius hubbsi along the northernmost limit of its distribution in the South-western Atlantic

Abstract

Stomach contents analysis and stable isotope results indicate M. hubbsi is a generalist predator that feeds mainly on demersal fishes, followed by crustaceans and cephalopods. Ontogenetic changes in diet were identified, with fish importance increasing in the diet with hake size. Smaller hake (<250 mm) fed mostly on the sepiolid Semirossia tenera (89.45%IRI) and engraulid fish (89.96%IRI). Mid-sized hake (250–300 mm) fed mainly on benthic fish such as Bellator brachychir (95.63%IRI) and euphausiids (56.46%IRI), while larger hake (>300 mm) fed heavily on Dactylopterus volitans (94.80%IRI) and occasionally on a variety of teleosts. Significant correlations between δ13C (P < 0.05), THg (P < 0.001) and hake size occurred, whereas no relationship was observed between δ15N and hake size or δ15N and total mercury. Signatures were lowest in smaller hake with a tendency of increasing with size. Smaller and larger hake were significantly different in δ13C. Differences regarding isotopic niche width were quantified for each size group; trophic diversity and trophic redundancy among them were negligible, but hake >300 mm possibly have a larger feeding plasticity due to the combination of prey from a wide trophic level range.

Ficha de Semirossia tenera

“…Espécie migratória? Não Semirossia tenera foi encontrada em conteúdo estomacal de diversas espécies nas regiões sudeste e sul (Santos & Haimovici, 2001;Baldassin et al, 2010;Lopes et al, 2012;Costa et al, 2019). No Brasil, essa espécie é bastante comum em capturas no Rio Grande do Sul, dos 60 aos 160 metros de profundidade (Haimovici et al, 2009).…”

Development and Occurrence of Early Stages of Dules auriga in the Northern Patagonian Gulfs of Argentina

“…It is a very frequent rocky-reef species in the catches: it occurs in 32% of tows made by the pair-trawl fishery in southern Brazil, which makes its populations susceptible to fishery effects (Genzano et al, 2011;Rovani and Cardoso, 2017;Hauser-Davis et al, 2019). Due to the importance of D. auriga as a prey item for other fishes (Cussac and Molero, 1987;Costa et al, 2019), overfishing may affect its functional trophic role (e.g., availability as prey for other species), causing negative effects on the food web (Rovani and Cardoso, 2017).Like most serranines, D. auriga is a demersal and sedentary species that often rests on the bottom. It has synchronous…”