ResumoO presente estudo tem como objetivo caracterizar o hábito alimentar do peixe-espada adulto, Trichiurus lepturus, no norte do Rio de Janeiro através da avaliação de conteúdos estomacais. A amostragem incluiu 350 espécimes, com comprimento total entre 100 e 163cm, coletados entre 2004 e 2006. Para cada espécie de presa calcularam-se as freqüências de ocorrência, numérica e de biomassa, porte (comprimento e peso) e Índice de Importância Relativa (IIR) na dieta. O comportamento alimentar de canibalismo foi registrado. De acordo com o IIR, os itens preferenciais foram os peixes T. lepturus, Pellona harroweri, Chirocentrodon bleekerianus, Lycengraulis grossidens, Peprilus paru, Chloroscombrus chrysurus, Odontognathus mucronatus, Stellifer brasiliensis e Isophisthus parvipinnis, além do crustáceo Pleoticus muelleri. Os cefalópodes Loligo plei e L. sanpaulensis ocorreram ocasionalmente nos conteúdos estomacais analisados. Na costa norte do Rio de Janeiro, T. lepturus apresenta dieta composta por organismos neríticos de hábitos pelágicos e/ou demersais associados a áreas costeiras e estuarinas, sendo peixes e crustáceos os itens mais representativos na dieta. Unitermos:Trichiurus lepturus, peixe-espada, hábito alimentar, canibalismo, norte do Rio de Janeiro AbstractFeeding habits of the cutlassfish, Trichiurus lepturus, in northern Rio de Janeiro. The aim of the present study was to describe the diet of the adult cutlassfish, Trichiurus lepturus, in northern Rio de Janeiro, through stomach content analysis. The sampling included 350 specimens measuring between 100 and 163cm in total length, collected from 2004 to 2006. For each prey species, the frequency of occurrence, density and biomass, body length and weight, and Index of Relative Importance (IRI) were calculated. The cannibalistic feeding behavior of the cutlassfish was also recorded. According to the IRI, the preferential prey species were the fishes T. lepturus, Pellona harroweri, Chirocentrodon bleekerianus, Lycengraulis grossidens, Peprilus paru, Chloroscombrus chrysurus, Odontognathus mucronatus, Stellifer brasiliensis and Isophisthus parvipinnis, and the crustacean Pleoticus muelleri. The cephalopods Loligo sanpaulensis and L. plei occurred occasionally in the stomach contents analyzed. The diet of T. lepturus in northern Rio de Janeiro was composed of pelagic and demersal prey species, associated with estuarine and coastal areas. The fish species and one crustacean species were the most representative items in its diet.

ABSTRACT. This study describes the diet and assesses potential overlap in the feeding habits of Trichiurus lepturus Linnaeus, 1758 and Pontoporia blainvilleiGervais & D'Orbigny, 1844 in northern Rio de Janeiro, southeastern Brazil. Fishes were numerically dominant in both diets, followed by cephalopods for P. blainvillei and crustaceans for T. lepturus. Both predators move along similar coastal feeding areas in northern Rio de Janeiro, but our results indicate differences in their resource exploitation, what allows for their coexistence.

The present study raised the hypothesis that the trophic status in a tropical coastal food web from southeastern Brazil can be measured by the relation between total mercury (THg) and nitrogen isotope (δ(15)N) in their components. The analysed species were grouped into six trophic positions: primary producer (phytoplankton), primary consumer (zooplankton), consumer 1 (omnivore shrimp), consumer 2 (pelagic carnivores represented by squid and fish species), consumer 3 (demersal carnivores represented by fish species) and consumer 4 (pelagic-demersal top carnivore represented by the fish Trichiurus lepturus). The values of THg, δ(15)N, and trophic level (TLv) increased significantly from primary producer toward top carnivore. Our data regarding trophic magnification (6.84) and biomagnification powers (0.25 for δ(15)N and 0.83 for TLv) indicated that Hg biomagnification throughout trophic positions is high in this tropical food web, which could be primarily related to the quality of the local water.

In the present study we analysed the proximate-composition and caloric values of the preferred prey consumed by ribbonfish, Trichiurus lepturus L. 1758 (adult females), that are distributed in the inner continental shelf from northern Rio de Janeiro State, southeastern Brazil (~22ºS), assessing the potential of nutritional and energetic approach as a tool to understand the feeding selective pattern of this marine top carnivore. The preferred prey of this predator composed of fish co-specifics, Pellona harroweri, Chirocentrodon bleekerianus, Lycengraulis grossidens, Peprilus paru, squid Doryteuthis plei, and shrimp Xiphopenaeus kroyeri were collected from 2007 to 2010 for proximate-composition (water, protein, lipid, ash, and carbohydrate) and caloric value analyses. The correspondence analysis showed that protein is the main component in the prey species (61.32% of variance explained), standing out from the other nutrients. Lipid has the highest percentage related to L. grossidens, ash to X. kroyeri and carbohydrate to D. plei. The strong correlations between protein and caloric value (positive) and lipid and caloric value (negative) indicated that T. lepturus is attending its energy demand through the prey protein content. This work elucidated the feeding preference of adult females of T. lepturus in relation to nutritional and caloric content of their preferred prey. The species showed food selectivity to prey that provide more energy per ingested biomass, so that the feeding events can maximize the predator's caloric gain, which is obtained by a protein-based diet.No presente estudo foram analisadas a composição centesimal e o valor calórico das presas preferenciais consumidas pelo peixeespada, Trichiurus lepturus L. 1758 (fêmeas adultas), que se distribuem na plataforma continental interna do norte do estado do Rio de Janeiro, sudeste do Brasil (~ 22ºS). O objetivo foi avaliar o potencial da abordagem nutricional e energética como ferramenta para compreender o padrão de seletividade alimentar deste carnívoro marinho. As presas preferenciais deste predador, compostas por co-específicos e pelos peixes Pellona harroweri, Chirocentrodon bleekerianus, Lycengraulis grossidens e Peprilus paru, pela lula Doryteuthis plei e pelo camarão Xiphopenaeus kroyeri, foram coletadas entre 2007 e 2010 para análise da composição centesimal (água, proteína, lipídio, cinzas e carboidratos) e do valor calórico. A análise de correspondência mostrou que a proteína é o principal componente nas espécies de presa (61,32% da variância explicada), destacando-se dos outros nutrientes. Para o lipídio a maior porcentagem esteve relacionada com L. grossidens, cinzas com X. kroyeri e carboidratos com D. plei. As fortes correlações entre proteína e valor calórico (positiva) e lipídio e valor calórico (negativa) indicaram que T. lepturus está atendendo sua demanda de energia através do teor de proteína das presas. Este trabalho elucidou a preferência alimentar de fêmeas adultas de T. lepturus em relação ao conteúdo nutricional e calórico das pr...

This study applies total mercury (THg) concentration and stable isotope signature (δ15N and δ13C) to evaluate the trophic status and feeding ground of Trichiurus lepturus during its ontogeny in northern Rio de Janeiro, south-eastern Brazil. The trophic position of T. lepturus is detected well by THg and δ15N as the sub-adult planktivorous specimens are distinct from the adult carnivorous specimens. The δ13C signatures suggest a feeding ground associated with marine coastal waters that are shared by fish in different ontogenetic phases. The diet tracers indicated that the fish feeding habits do not vary along seasons of the year, probably reflecting the prey availability in the study area. This fish has economic importance and the concentration of THg was compared to World Health Organization limit, showing that the adult specimens of T. lepturus are very close to the tolerable limit for safe regular ingestion.

The trophic transfer of total mercury (THg) and its bioaccumulation from prey species to the predator fi sh Trichiurus lepturus was analysed in coastal waters of southeastern Brazil to evaluate the trace element dynamic in this predator-prey system. The isotopic (δ 13 C and δ 15 N) relation between this predator and its prey allowed inferences on prey assimilation and predator feeding habits. The THg increment varied from 4.5 to 19.5 times between prey and predator, with a biomagnifi cation power of 0.59. The prey species could be divided into three groups regarding δ N highlighted juvenile conspecifi cs as the main via of this trace element and the most assimilated prey. The isotopic relation between predator and its prey species showed a feeding activity preferably coastal and pelagic.

This study verifies the food assimilation of a carnivorous teleost in different timescales (weeks vs months) and evaluates how it uses the food sources. The target species is the adult ribbonfish, Trichiurus lepturus, a voracious teleost caught in commercial fisheries off south-east Brazil (21°S–22°S). The isotope models indicated Chirocentrodon bleekerianus as the main food in the ribbonfish diet in the last weeks (liver: 38.5%; 95% credible intervals: 3.4–73.9%) and last months (muscle: 36.2%; 95% credible intervals: 3.4–68.7%). The contribution of other food sources ranges from 10–16% (liver) and from 10–20% (muscle). Food assimilation remains similar at different timescales. The isotope models suggested a strong and long-lasting association of the adult females of ribbonfish with coastal waters along the study area.

ResumoO objetivo deste trabalho é fornecer informações sobre a composição centesimal e o valor calórico dos peixes Clupeiformes Chirocentrodon bleekerianus, Pellona harroweri e Lycengraulis grossidens. Os espécimes foram coletados entre 2007 e 2010 na costa norte do Estado do Rio de Janeiro. Análises bromatológicas (proteína, lipídio e matéria mineral) foram realizadas em amostras compostas; o teor de carboidrato e a energia EUXWD IRUDP FDOFXODGRV D SDUWLU GH UHODo}HV HQWUH DV YDULiYHLV $V HVSpFLHV GH SHL[HV IRUDP VLJQL¿FDWLYDPHQWH distintas em relação ao porte (comprimento total e peso), composição centesimal e energia bruta; apenas o teor de carboidrato foi similar. A espécie L. grossidens foi representada por indivíduos maiores e com teor de lipídio superior, enquanto C. bleekerianus e P. harroweri apresentaram os maiores percentuais de proteína e matéria mineral, além de valores de energia bruta mais elevados. O percentual de proteína foi diretamente proporcional ao valor de energia bruta, enquanto o percentual de lipídio apresentou relação inversa com essas duas variáveis. Este estudo servirá de base para o entendimento da seletividade alimentar de carnívoros marinhos em regiões costeiras e para a elaboração de modelos de bioenergética. Palavras-chave: Clupeiformes, Composição centesimal, Energia bruta, Oceano Atlântico Ocidental Abstract 3UR[LPDWH FRPSRVLWLRQ DQG FDORULF YDOXH RI &OXSHLIRUPHV ¿VKHV IURP WKH 1RUWKHUQ 5LR GH -DQHLUR coast.The aim of this study is to provide information on the proximate composition and caloric value of WKH &OXSHLIRUPHV ¿VKHV Chirocentrodon bleekerianus, Pellona harroweri, and Lycengraulis grossidens. The specimens were collected between 2007 and 2010 in Northern Rio de Janeiro. The bromatological analysis (protein, lipid, and mineral matter) was performed on composite samples; carbohydrate content and gross energy ZHUH FDOFXODWHG IURP UHODWLRQVKLSV EHWZHHQ YDULDEOHV 7KH ¿VK VSHFLHV ZHUH VLJQL¿FDQWO\ GLIIHUHQW LQ VL]H WRWDO length and weight), proximate composition, and gross energy; only the carbohydrate content was similar. The species L. grossidens was represented by larger individuals with higher lipid content, as C. bleekerianus and P. Biotemas, 24 (2): 57-64, junho de 2011