Efraín A. Rubio

Feeding habits and trophic ecology of Dasyatis longa (Elasmobranchii: Myliobatiformes): sexual, temporal and ontogenetic effects.

Sexual, ontogenic and temporal effects in the diet of Dasyatis longa were evaluated to determine feeding habits and trophic ecology. Numeric indices and the index of relative importance were applied to establish the feeding strategy of the species. Independence of the diet with respect to sex, dry or rainy season and size was evaluated with contingency tables, correspondence analysis and multivariate analysis (MANOVA). The trophic relationships of D. longa (by sex and size intervals) were determined using Levins niche breadth index and the Piankas diet overlap index and their significance was determined by null models. The trophic level for each size interval and the species was also calculated. Dasyatis longa showed a narrow niche breadth feeding mainly on shrimps and fishes and its diet was dependent on size, but not on sex or season. Juvenile individuals (class I) fed on shrimps, sub-adults (class II) on fishes and adults (class III) on stomatopods. Significant overlaps between size classes I and II and classes II and III were found. The trophic level shows D. longa to be a secondary or tertiary consumer. Due to considerable fishing pressures on shrimps, the principal prey of D. longa, it will be important to determine their ability to adapt to changes in prey populations.

Biología de la raya guitarra Rhinobatos leucorhynchus (Günther, 1867) (Rajiformes: Rhinobatidae) en el Pacífico colombiano

The guitar ray Rhinobatos leucorhynchus is commonly caught as by-catch of industrial and artisanal shrimp trawling in the shallow waters of the Colombian Pacific. The biological aspects of this species were studied using 286 animals caught as by-catch between 2001 and 2007. The females were proportionally larger than males, although growth was similar (allometric) for both sexes. The embryos showed no significant differences by sex in either size or weight. The adult sex ratio was 2.4:1 (females-males), whereas in embryos this ratio was 1:1. 51.5% of males, 51.5% had developed, calcified claspers, and 56.5% of females were pregnant, carrying between 1 and 6 embryos of 3 to 19.5 cm, suggesting a size at birth of 19 to 19.5 cm TL. The median size at maturity for females was lower than that of males (48.48 cm and 51.18 cm TL, respectively), and the females had embryos starting at 44 cm TL. The feeding habits of this species showed 30 prey items, with shrimp from the Penaeidae family and especially Trachypenaeus sp. as main food. The diets of male and female guitar rays differed significantly, and the niche breadth indicated that this species has a specialist diet. The results of this study provide useful information for proposing management measures for R. leucorhynchus, a species that requires attention given its biological characteristics and its importance in terms of commerce and human consumption.

Aspectos de la biología y dinámica poblacional del pargo coliamarillo Lutjanus argentiventris en el Parque Nacional Natural Gorgona, Colombia

Yellowtail snapper Lutjanus argentiventris (Peters, 1869) was captured during experimental fishing trips around the Gorgona National Natural Park, Colombia, from March 1997 to December 2000. Average capture size (total length, TL) was 482 mm and sex ratio was 1:1.2. Advanced sexual maturity stages in females were observed during the whole study with no clear reproductive pattern; average size at sexual maturity was 515 mm TL. The length-weight relationship was not significantly different by sex and was described by the equation: PT = (6.259 * 10 -6

Composición y análisis taxonómico de la íctiofauna del golfo de Tribugá, Pacífico norte de Colombia

Resumen es: Se realizo el analisis taxonomico y estructural de la comunidad ictica del golfo Tribuga zona norte del Pacifico colombiano, a partir de informacion reco...

NUEVO HALLAZGO DEL PEZ ESCORPION PONTINUS SIERRA (Gilbert 1890) (PISCES: OSTEICHTHYES: SCORPAENIDAE) EN AGUAS DEL OCEANO PACIFICO COLOMBIANO

RESUMEN En el presente trabajo se registra la captura de dos ejemplares adultos de Pontinus sierra (Gilbert 1890) en aguas del Oceano Pacifico de Colombia, mediante la utilizacion de trampas y como fauna acompanante de la pesqueria del camaron de profundidad

Presencia de Schedophilus haedrichi Chirichigno, 1973 (Osteichthyes: Centrolophidae) en el Pacífico colombiano y ampliación de su rango de distribución geográfica

A new record of Schedophilus haedrichi is reported. The individual was caught on a hand line in the North Colombian Pacific Ocean and constitutes the norther...

PRIMER HALLAZGO DE Myxine circifrons Garman 1899 (AGNATHA: MYXINIDAE) EN LA COSTA DEL PACÍFICO DE COLOMBIA

Los peces bruja Myxine circifrons Garman 1899 habitan sobre fondos fangosos en la zona preabisal, capturandose principalmente entre los 500 y 1.500 m de profundidad; su distribucion geografica esta ligada a las regiones sub-tropicales prefiriendo aguas relativamente frias. Este trabajo registra por primera vez en aguas del oceano Pacifico colombiano a 700 m de profundidad la presencia de los agnathos vivientes mas primitivos en los oceanos del mundo