Feeding strategy of the night shark (Carcharhinus signatus) and scalloped hammerhead shark (Sphyrna lewini) near seamounts off northeastern Brazil

Um total de 425 estômagos de tubarão-toninha (Carcharhinus signatus) e 98 estômagos de tubarão-martelo-entalhado (Sphyrna lewini), oriundos da pesca de espinhel e pesca com rede de emalhe nas adjacências dos bancos oceânicos do nordeste do Brasil, foi analisado entre 1992 e 1999. Ambas as espécies predam sobre peixes bento-pelágicos e recifais, cefalópodes migradores, e crustáceos de águas profundas, apresentando nichos alimentares similares (Índice de Schoener T=0.75). A alta riqueza de presas nas dietas deve ser um reflexo de que as teias alimentares para estas espécies são consideravelmente longas nessa região. Devido à concentração alimentar de ambos predadores nos bancos oceânicos, a pescaria intensa deve ser monitorada para evitar depleções locais.A total of 425 stomachs of night shark (Carcharhinus signatus), and 98 stomachs of scalloped hammerhead shark (Sphyrna lewini), from longline and surface gillneters near seamounts off northeastern Brazil, were analysed between 1992 and 1999. Both predators prey upon reef and benthopelagic fishes, migrant cephalopods and deep water crustaceans, showing similar feeding niches (Schoener Index T=0.75). The great prey richness of the diets may reflect the fact that the marine food web for these species is very extensive in this region. Due to the concentration for feeding of both predators in the seamounts, intense fisheries should be monitored to avoid localised depletions

Notes sur les habitudes alimentaires de Rioraja agassizi (Chondrichthyes, Rajidae) dans le sud du Brésil.

Copyright © 2011 Société Française d’Ichtyologie.Feeding habits of the skate Rioraja agassizi were analyzed in southeastern Brazil from samples obtained along São Paulo coast. A total of 258 specimens were examined, ranging between 96 and 532 mm total length. About 57.85% were females and 42.15% were males, resulting in a 1:1.37 sex-ratio to females. From 223 stomachs collected (94 males and 129 females) empty stomachs represented only 1.4%. Nine prey categories were identified: Polychaeta, Copepoda, Cumacea, Isopoda, Gammaridea, Dendrobranchiata, Brachyura, Teleostei, and one non-animal category (nonidentifiable items). Crustaceans were the most important item, indicating that the species has a carcinophagic preference. The presence of fish was just verified in juveniles and some adult individuals, with predominance in summer. Sex, maturity stage and seasonality did not influence the feeding habits of the species.RÉSUMÉ: Les habitudes alimentaires de Rioraja agassizi on été analysées dans le sud-ouest du Brésil, tout au long de la côte de l’État de São Paulo. Au total, 258 exemplaires ont été examinés, leurs tailles variant entre 96 et 532 mm de longueur totale. Les femelles ont représenté 57,85% de l’échantillon, conduisant à un sex-ratio secondaire de 1 : 1,37 en leur faveur. Sur 223 estomacs recueillis (94 mâles et 129 femelles) ceux qui étaient vides représentaient seulement 1,4%. Neuf catégories de proies ont été identifiées: Polychaeta, Copepoda, Cumacea, Isopoda, Gammaridea, Dendrobranchiata, Brachyura, Teleostei, et des restes inorganiques (items non identifiables). Les crustacés sont la proie la plus importante, indiquant une préférence carcinophage pour cette espèce. La présence de poissons a été vérifiée seulement dans les estomacs de juvéniles avec une prédominance durant les mois d’été. Aucune influence des variables “sexe”, “maturité” et “saison” sur les habitudes alimentaires n’a été détectée

Annelida, Hirudinida, Stibarobdella moorei (Oka, 1910): new distribution and host records

The present report is the northernmost capture of the piscicolid leech Stibarobdella moorei in the western South Atlantic Ocean. This is also the first time S. moorei is found associated to a batoid fish in the Brazilian coast, the eyespot skate Atlantoraja cyclophora. Stibarobdella moorei was found fixed in the dorsal side of a male eyespot skate, caught by bottom trawl around of the São Paulo coast, southeastern Brazil. A brief description of the morphology of the parasite and a discussion on the taxonomic status of the S. moorei are presented

Forage fauna in the diet of bigeye tuna (Thunnus obesus) in the western tropical Atlantic Ocean

Um total de 291 estômagos de albacoras-bandolins capturadas no oceano Atlântico tropical oeste variando entre 60 e 195 cm de comprimento furcal, foram analisados entre outubro de 2004 e dezembro de 2005. A distribuição vertical das presas foi estudada em relação às estratégias alimentares. Um total de 83 itens alimentares foi identificado dos quais 46 foram peixes representados principalmente por peixes brefoepipelágicos e mesopelágicos, 20 cefalópodes, 13 crustáceos pelágicos, um tunicado, um heterópode e um pterópode. A palombeta-do-Caribe, Brama caribbea, foi o item alimentar mais importante, seguida de outros peixes mesopelágicos como Alepisaurus ferox, Omosudis lowei, Gempylus serpens, Brama brama e Diretmus argenteus. A lula Ornithoteuthis antillarum foi o principal cefalópode predado, e os crustáceos Caridea e megalopas de Brachyura também foram itens importantes. A alimentação deve ocorrer de forma contínua, toda hora, ou pelo menos durante a maior parte do dia ou da noite, como parte da estratégia de predar sobre presas espalhadas na coluna d'água. A relativa equitabilidade de proporções de organismos de superfície, meia-água e água profunda na dieta refletem um comportamento de constante deslocamento vertical a procura de presas. Embora a albacora-bandolim prefira camadas subtermoclinais, a maioria de suas presas realiza migrações verticais diárias e podem então, serem predadas tanto próximas à superfície como em águas mais profundas.A total of 291 stomachs of bigeye tuna caught in the Western tropical Atlantic Ocean ranging between 60 and 195 cm fork length, were analyzed between October 2004 and November 2005. The vertical distribution of prey was studied in relation to their feeding strategies. A total of 83 prey items were identified of which 46 were fishes, represented mainly by brephoepipelagic, and meso-bathypelagic fishes; 20 cephalopods, 13 pelagic crustaceans, one tunicate, one heteropod and one pteropod. The Caribbean pomfret Brama caribbea was the most important food item, followed by other mesopelagic fishes such as Alepisaurus ferox, Omosudis lowei, Gempylus serpens, Brama brama and Diretmus argenteus. The squid Ornithoteuthis antillarum was the main preyed-on cephalopod, and the crustaceans Caridea and Brachyuran megalopae were also important food items. The feeding may occur continuously, all the time, or at least during the greater part of the day or night, as part of the feeding strategy to prey upon a vertically scattered small prey distributed in the water column. The relative equality in the proportions of surface, mid-water and deep-water prey organisms reflects the behavior of constant vertical displacement in the search for prey. Although the bigeye tuna prefers subthermocline layers, most of its prey items perform diel migrations and can be preyed on both near the surface and in deeper waters

First record of the choicy ruff, Seriolella porosa Guichenot, 1848 (Perciformes: Centrolophidae) in Brazilian waters=Primeiro registro do savorin, Seriolella porosa Guichenot, 1848 (Perciformes: Centrolophidae) em águas brasileiras

A female specimen of choicy ruff, Seriolella porosa, is reported for the first time in Brazilian waters, 384 mm total length captured by the bottom trawl commercial fishery on August 12th, 2007, at 36 meters local depth off the São Paulo coast, southeastern Brazil (23º49'56''S; 45º53'24''W). The occurrence may be uncommon, probably associated with a branch of cold water of the Malvinas current.<br><br>É reportada pela primeira vez em águas brasileiras a ocorrência de um exemplar de fêmea de savorin, Seriolella porosa, de 348 cm CT capturado por arrasto comercial de parelha no sudeste do Brasil em 12 de agosto de 2007, a 36 metros de profundidade local (23º49'56''S; 45º53'24''W). A ocorrência deve ser incomum, provavelmente associada com um braço da corrente das Malvinas

Feeding ecology of the beach silverside Atherinella blackburni (Atherinopsidae) in a tropical sandy beach, Southeastern Brazil

Abstract The feeding ecology of the beach silverside (Atherinella blackburni) in the surf zone of a tropical sand beach, located in the southeastern Brazil, was accessed through the gut content analysis of 198 fish. Factors such as fish's size, season and day period were analysed to understand how these variables affect the diet composition of the species. Results show that A. blackburni is a coastal neritic fish with a broad feeding niche. Most recurrent prey were zooplanktonic crustaceans, insects and benthic molluscs, in which Copepoda crustaceans were the dominant dietary item in occurrence and abundance. A. blackburni appears to have a slight ontogenetic shift in its diet, changing from benthic molluscs to crustaceans and insects along its life cycle. The diel activity also reveals to be an important factor to the A. blackburni feeding ecology. The predominant occurrence of small fish during the morning, along with the main preys for this size class, suggests that small individuals use shallower waters as feeding grounds during the morning and, during the night, they move to deeper waters for protection against predators