Description of diet of pelagic fish in the southwestern Atlantic, Brazil / Descrição da dieta de peixes pelágicos no Oceano Atlântico, Brasil

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.

Este estudo descreve a composição da dieta de peixes pelágicos que vivem no Oceano Atlântico Sudoeste. Como tais espécies pelágicas são consideradas predadoras de topo, o estudo propõe conhecer o que constitui sua principal fonte de alimento. Peixes não são comumente encontrados em seus conteúdos estomacais, em vez disso, os cefalópodes são os alimentos mais comuns. Como pode ser observado, cefalópodes Teuthida compreendem sua dieta principal. O conteúdo estomacal de espécimes de Xiphias gladius, Thunnus albacares, T. obesus, T. alalunga, Isurus oxyrinchus e Alopias superciliosus, capturados durante julho de 2007 a junho de 2009 prela frota atuneira, foram estudados. Cefalópodes Teuthida constituem o principal item alimentar das três espécies de atum, enquanto X. gladius alimenta-se principalmente de cefalópodes Ommastrephidae. Embora as diferenças entre os tipos de cafalópodes existam, eles constituem o principal recurso que estes peixes usam para viver, pelo menos no Oceano Atlântico Sudoeste.

Diet and feeding strategy of the dusky grouper Mycteroperca marginata (Actinopterygii: Epinephelidae) in a man-made rocky habitat in southern Brazil

A garoupa-verdadeira (Mycteroperca marginata) é uma espécie marinha geralmente associada a fundos rochosos e recifes. O presente trabalho investiga a dieta e estratégia alimentar de uma população da garoupa-verdadeira que habita um longo (4,5 km) par de molhes de pedra na desembocadura do estuário da laguna dos Patos, sul do Brasil. Não há trabalhos anteriores realizados nesse tipo de habitat construído pelo homem e este trabalho fornece uma base de comparação com estudos de dieta de outras populações da garoupa-verdadeira ocorrendo em habitats naturais. De modo similar ao encontrado em estudos prévios realizados em substratos naturais, caranguejos e peixes foram as principais categorias de alimento consumidas (%IRI = 85,1 e %IRI = 12,6, respectivamente), enquanto camarões e moluscos tiveram menor importância na dieta (%IRI = 1,9 e %IRI = 0,4, respectivamente). Como reportado anteriormente para populações de garoupa-verdadeira que habitam recifes e fundos rochosos, o presente trabalho revelou marcadas mudanças na dieta em função do tamanho da espécie. Siri-azul e peixes tornam-se gradativamente mais importantes na dieta de indivíduos maiores (> 500 mm de comprimento total, CT). Finalmente, foi observado que a população de garoupa-verdadeira teve uma estratégia alimentar generalista com uma elevada variação entre indivíduos no consumo de presas. Essa estratégia permaneceu similar ao longo do aumento em tamanho da espécie. Os resultados do presente trabalho sugerem que substratos rochosos estabelecidos pelo homem propiciam locais de alimentação adequados para a garoupa-verdadeira no sul do Brasil e que poderiam ser usados como ferramentas adicionais nos esforços de conservação dessa espécie ameaçada.

The dusky grouper (Mycteroperca marginata) is a marine species usually associated with rocky bottoms and reefs. The present work investigated the diet and feeding strategy of a dusky grouper population inhabiting a 4.5 km long pair of rocky jetties located in the mouth of Patos Lagoon estuary. No prior research has been conducted in such man-made habitat and the current study provides a basis for comparative studies on the diet of the dusky grouper populations inhabiting natural vs. manmade rocky habitats. Similarly with previous studies on natural substrates, crabs and fishes were the main food categories consumed (%IRI = 85.1 and %IRI = 12.6, respectively), whereas shrimps and mollusks had lower importance in the diet (%IRI = 1.9 and 0.4, respectively). As previously reported for dusky grouper populations inhabiting reefs and rocky bottoms, the present work revealed conspicuous size related dietary shifts. Blue crabs and fishes become increasingly important food itemsin the diet of larger individuals (> 500 mm, TL). Finally, it was found that the studied dusky population has a generalist feeding strategy with a high between-individual variation in prey consumption. Such strategy remained similar across the size increment of the species. Our findings suggest that man-made rocky substrates provide suitable feeding grounds for the dusky grouper in southern Brazil and could be used as an additional tool in the conservation efforts of this endangered species.

Hábitos alimenticios del pez Lagodon rhomboides (Perciformes: Sparidae) en la laguna costera de Chelem, Yucatán, México

Feeding habits of the fish Lagodon rhomboides (Perciformes: Sparidae) at the coastal lagoon of Chelem, Yucatán, México. Stomach contents of Lagodon rhomboides, the most abundant fish species from seagrass beds in Chelem Lagoon, Yucatan, Mexico, were analyzed. The specimens were collected using a beach seine at eight stations distributed randomly in the lagoon during July, September and November 2002. The trophic components were analyzed by means of the relative abundance (%A) and frequency of occurrence (FO) indices. The trophic similarity between different ontogenetic stages was determined using the Bray-Curtis Index. A total of 90 stomach contents were analyzed. This species is omnivorous, including vegetal and animal material and has a wide trophic spectrum with 58 alimentary items. Trophic ontogenetic variation was significant with a transition from one feeding stage to the next. Small individuals (4.0 -8.0 cm LE) preferentially consume plankton preys and microcrustaceans, while in bigger sizes, the macrocrustaceans, annelids and macrophytes were the main food. Rev. Biol. Trop. 56 (4): 1837-1846. Epub 2008 December 12.

Se analizó el contenido estomacal de Lagodon rhomboides (Sparidae), la especie más abundante de pez en la zona de pastos marinos en la laguna de Chelem, Yucatán, México. Los especímenes se recolectaron utilizando un chinchorro playero en ocho estaciones distribuidas aleatoriamente durante julio, septiembre y noviembre del 2002. Los componentes tróficos fueron analizados por medio del porcentaje de la abundancia relativa (%A) y la frecuencia de presencia (FO). La similitud trófica entre las diferentes etapas ontogénicas fue determinada usando el índice de Bray-Curtis. Se analizaron un total de 90 contenidos estomacales. Esta especie es omnívora e incluye en su alimentación componentes tanto de origen vegetal como animal; muestra una amplia generalización trófica con 58 componentes alimenticios. La variación trófica ontogénica fue significativa con una progresión alimenticia de una etapa alimenticia a la siguiente. Los individuos de menos talla, consumen preferentemente presas planctónicas y microcrustáceos s (4.0 - 8.0 cm de LE), mientras que en los de mayor talla, los macrocrustáceos (carideos), poliquetos y macrófitas constituyen el alimento principal.

Distribución, abundancia y preferencias alimenticias del pez sapo Opsanus phobetron (Batrachoididae) en la laguna costera de Chelem, Yucatán, México

Distribution, abundance and alimentary preferences of the fish Opsanus phobetron (Batrachoididae) at the Chelem coastal lagoon, Yucatan, Mexico. Fish are important ecological components in tropical coastal lagoons. In order to evaluate the distribution and feeding preferences of the toadfish Opsanus phobetron in the Chelem Lagoon, Yucatan, Mexico, fish samples were collected using a beach seine in eight stations distributed randomly, from March 2002 to January 2003. The components were analyzed by means of the relative abundance percentage and occurrence frequency. The trophic similarity between ontogenetic stages was determined with the Morisita Index. A total of 221 organisms were collected, with a density and biomass of 92.09 ind/100 m² and 930.39 g/100 m² respectively. The highest density and biomass were recorded in the same station. A total of 94 stomach contents were analyzed. Results showed a wide trophic generalization, including 40 alimentary items and great ontogenetic variation: juvenile stages consume preferentially microcrustaceans, while adults mainly feed on fish (96 %). Rev. Biol. Trop. 55 (3-4): 979-988. Epub 2007 December, 28.

El objetivo del presente estudio es evaluar la distribución y la preferencia alimenticia del pez sapo Opsanus phobetron en la Laguna de Chelem, Yucatán, México. Se recolectaron los peces de marzo 2002-enero 2003 en ocho estaciones distribuidas aleatoriamente. Los componentes del espectro trófico fueron analizados por medio del porcentaje de la abundancia relativa y la frecuencia de presencia. La similitud trófica entre las etapas ontogenéticas fue determinada usando el índice de Morisita (1959). Se capturó un total de 221 organismos, con una densidad y una biomasa de 92.09 ind/100 m² y de 930.39 g/100 m² respectivamente. Una misma estación registró los valores más altos de densidad y biomasa. El análisis de 94 de contenidos estomacales indicó una amplia generalización trófica, incluyendo 40 artículos alimenticios, y una gran variación ontogenética: las etapas juveniles consumen preferencialmente microcrustáceos, mientras que en los adultos el consumo de peces alcanza 96 % de todo el contenido.

Reproducción y alimentación del tiburón enano Mustelus dorsalis (Pisces: Triakidae) en el Golfo de Nicoya, Costa Rica: elementos para un manejo sostenible / Reproduction and feeding habits of Mustelus dorsalis (Pisces: Triakidae) in the Gulf of Nicoya, Costa Rica: elements for a sustainable management

A total of 311 sharptooth smooth-hound Mustelus dorsalis were collected in the Gulf of Nicoya, Costa Rica from March 1999 to May 2000 to determine reproduction and feeding habits. The fishes were collected using hook and line. 250 females and 61 males were identified. The females are bigger (550-660 mm) and heavier (400-1,000 g) than males (500-585 mm and 200-300 g, respectively). All samples collected were mature and the minimum length to first maturity observed is 500 and 541 mm for females and males, respectively. From September to March individuals were mature, while samples caught during April and August were immature. A total of 1,259 embryos were analyzed. Number of embryos per liter ranged from two to six, the total length is from 130 to 205 mm and the weight from 6 to 35 g. This shark is a polyphagous opportunistic carnivore that preys on crustaceans (Squilla hancocki, S. parva, Litopenaeus sp.), fishes (Anchoa sp., Caranx sp., Lutjanus sp., Engraulis sp.) and mollusks (Loligo sp. and Octopus sp.). Main prey item was S. hancocki. The presence of mature sharks of both sexes along the year and the consumption of food items associated to shallow coastal rocky waters suggest that this sector of Nicoya Gulf is a nursery ground and an essential habitat. Based on these results the establishment of an integral management plan is proposed.

Se determinaron aspectos reproductivos y alimentarios del tiburón enano Mustelus dorsalis, a partir de 311 ejemplares capturados con línea y anzuelo en el Golfo de Nicoya, Costa Rica, durante marzo de 1999 y mayo de 2000. Se reconocieron 250 hembras y 61 machos. Las hembras son más grandes (550 a 660 mm) vs. (500-585 mm) y más pesadas (400-1 000 g) vs. (200-300 g) que los machos. Todos los ejemplares estaban maduros, la talla mínima de especimenes maduros fue de 500 y 541 mm para hembras y machos respectivamente. Entre septiembre y marzo todas las hembras y machos estaban maduras, e inmaduras entre abril y agosto. Se estudiaron 1 259 embriones, con una variación entre dos y seis embriones por litera. La longitud total de los embriones es entre 130 y 205 mm y el peso entre 6 y 35 g. Este tiburón es carnívoro polífago oportunista que consume crustáceos (Squilla hancocki, S. parva, Farfantepenaeus sp.), peces (Anchoa sp. Caranx, sp, Lujanus sp., Engraulis y Ophistonema sp.), y moluscos (Loligo sp. y Octopus sp.). Squilla hancocki es el ítem alimentario mas importante. La presencia de tiburones maduros de ambos sexos a lo largo del año en aguas poco profundas, y el consumo de presas bentónicas que viven en fondos rocosos costeros, sugiere la posibilidad de que este sector del Golfo de Nicoya esté funcionando como una zona de crianza y hábitat esencial. Con base en estos resultados se propone el establecimiento de un plan de manejo integral.

Feeding habits of four species of mesopelagic fishes from the Northern Chilean

The feeding habits of four species of mesopelagic fishes from northern Chile are described: Triphoturus mexicanus, Diogenichtys atlanticus, Vinciguerria lucetia and Cyclothone acclinidens. Samples were captured in September 1988 between 18 degrees 25' and 19 degrees 09'S in the South West Pacific. The quantitative and qualitative analyses of the stomach content showed that the species have a zooplanktophagous opportunistic behavior, mainly predating on Crustaceans, especially on Copepods. The evaluation of the trophic spectrum and diversity of T. mexicanus and C. acclinidens suggests that these are nictoepipelagic species, while D. atlanticus and V. lucetia would be typical mesopelagic.

Se describen los hábitos alimenticios de cuatro especies de peces mesopelágicos del norte de Chile: Triphoturus mexicanus, Diogenichtys atlanticus, Vinciguerria lucetia and Cyclothone acclinidens. Las muestras fueron capturadas en setiembre de 1988 entre 18°25’ y 19°09’ S en el Pacífico suroeste. El análisis cualitativo y cuantitativo del contenido estomacal mostró que las especies tienen un comportamiento zooplantofago oportunista, depredando principalmente crustáceos, especialmente copépodos. La evaluación del espectro trófico y diversidad de T. mexicanus y C. acclinidens sugiere que estas son especies nictoepipelágicas, mientras que D. alanticus y V. lucetia serían mesopelágicas típicas.