Description of diet of pelagic fish in the southwestern Atlantic, Brazil

Abstract

This study reveals the food composition of pelagic fishes living in the southwestern Atlantic Ocean. As such more common pelagic species are considered to be top predators, the study proposes to know what constitutes their main food. Fish are not commonly found within their stomach contents, but instead, cephalopods are their most common food. As can be observed, Teuthida cephalopods compose their principal diet. The stomach contents of specimens of Xiphias gladius, Thunnus albacares, T. obesus, T. alalunga, Isurus oxyrinchus and Alopias superciliosus caught during July 2007 to June 2009 by using tuna longliners were studied. Teuthida cephalopods constitute the main food item for the three tuna species, while X. gladius feeds mainly on Ommastrephidae cephalopods. Though the differences among the kinds of cephalopods exist, they constitute the principal resource these fish use to live at least in the southern Atlantic Ocean.

Comparative feeding strategies of yellowfin tuna around St Helena and adjacent seamounts of the South Atlantic Ocean

“…The most important prey were squids which represented 86% food by weight and 40% by numbers. Such high consumption of cephalopods was found also in other tuna, swordfish and sharks sampled in the same area (Gorni et al., 2013). Another area where yellowfin tuna is preying mostly on cephalopods is the Oman Sea where the species forages on Sthenoteuthis oualaniensis (Kaymaram et al., 2000).…”

Diet Composition of Pelagic Fish in the Southwestern Atlantic, Brazil: An Isotopic Mixtures Approach

“…In more detail, the most representative fish families were Paralepididae, Merluccidae and Sciaenidae. Gorni et al (2013) report great contribution of Teuthida squids and Trichiuridae fishes in A. superciliosus stomach content. Meanwhile, in this present study based on isotopic mixture results, there happens to occur a disagreement to those observations, as Scombrid fishes should compose more than 80% of the assimilated prey.…”

“…This tendency to a teutophagic habit may corroborate the observations made by Zavala-Camin (1981), who, analysing 741 stomachs, registered predominance for mollusks (59.9%), to which fish and crustaceans were secondary food items. In any case, Sabatié et al (2003), Satoh et al (2004) and Gorni et al (2013) show distinct results, in which fish and crustaceans are predominant.…”

“…These cephalopods constitute a common reference to other researches, concerning analyses about stomach contents of such fish species (Gorni et al, 2013). Some authors identify more frequently species, which belong to the genera Illex, Ommastrephes, Dosidicus and Todarodes as components of the stomach contents of X. gladius (Zavala-Camin, 1981;Stillwell & Kohler, 1985;Simões & Andrade, 2000;Vaske-Júnior, 2000;Ibañez et al, 2004;Castillo et al, 2007;Letelier et al, 2009).…”

New host records and new geographic distribution of Didymozoidae (Trematoda), parasites of Thunnus obesus (Scombridae)

“…The big eye tuna, Thunnus obesus (Lowe) is an epipelagic and mesopelagic species present in oceanic waters, that occurs from the surface to a depth of about 250 m, and is found worldwide in tropical and subtropical waters of the Atlantic, Indian and Pacific Oceans, but is absent from the Mediterranean Sea. It is an important commercial species around the world (Collette & Nauem, 1983) and its diet is opportunistic, mainly composed by fish, cephalopod mollusks, and crustaceans (Gorni et al, 2013). According with Madhavi and Ram (2000), the high vagility and endothermy of tuna fishes require high metabolic energy, which is met through foraging on large quantities of food items that serve as intermediate and paratenic hosts for helminth parasites.…”