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RESUMEN.Se analizaron aspectos reproductivos de la raya eléctrica Narcine bancroftii, capturada como bycatch con una red playera de cerco en dos playas del sector de El Rodadero, Santa Marta, Caribe colombiano. Los ejemplares fueron sexados, pesados y medidos, se identificó su estado de desarrollo gonadal mediante características morfológicas externas e internas. Se evaluó la condición reproductiva con el comportamiento de los índices biológicos (gonadosomático IGS y hepatosomático IHS) y la talla a la madurez sexual (l 50% ). Los resultados obtenidos mostraron que el IGS tiene un máximo anual entre septiembre y diciembre cuando probablemente ocurre la cópula. El IHS presentó su mayor valor en enero, cuando termina su periodo reproductivo. La talla media de madurez en hembras fue de 32,2 cm y en machos de 20,2 a 22,9 cm. El período de gestación es de cuatro meses y las crías nacen de febrero a abril. Palabras clave: raya eléctrica, reproducción, fecundidad, mar Caribe, Colombia.Reproduction of the electric ray Narcine bancroftii (Torpediniformes: Narcinidae) in Santa Marta, Colombian Caribbean ABSTRACT. This paper provides information about reproductive aspects of the electric ray Narcine bancroftii, caught as bycatch with beach seines in two beaches of El Rodadero, Santa Marta, Colombian Caribbean, between August (2005) and October (2006). The electric rays obtained were separate by sex, weighed and measured; the development of reproductive stage was identified by external and internal characteristics. The reproductive condition was determinate by (gonadosomatic GSI and hepatosomatic HSI) indexes and the size at sexual maturity (l 50% ). The results showed that the GSI has one peak at year between September and December when probably the copulation carried out, the HSI presented its highest value in January, which corresponds to the end of the reproductive period. The size at sexual maturity was 32.2 cm in females and it was between 20.2 and 22.9 cm in males. We propose that the gestation period extends during four months, starting with the birth of individuals in February and finishing in April.

The reproductive condition of 172 guitarfish Rhinobatos percellens was evaluated in animals incidentally captured in the captures of chinchorro playero between August 2005 and October 2006 at Salguero beach on Santa Marta, Colombia. To understand the reproductive cycle and how it is influenced by the environmental conditions, the reproductive systems were described. The guitarfish is a viviparous matrotrophic ray, with compound ovaries. Four ovarian developmental stages and nine espermatogenic phases of compound testis were observed. The vitellogenetic development was simultaneous to embryonic growth, with an active reproductive (matting, births, gestation) period between October and April, and a reduction in activity from May to September when embryos stop their growth. North hemisphere rhinobatids show an inverse cycle. Guitarfish females produced between two and four embryos with a gestation period of ten months from April to December; maternal size did not have any relation with embryo length and number. Biological indexes (gonadosomatic, hepatosomatic and condition factor) did not show clear time tendencies in relation to reproductive dynamics; they must be analyzed altogether with environmental condition and food availability.

Se analizó el espectro trófico de 122 tiburones zorro Alopias superciliosus capturados artesanalmente en playa Tarqui, Manta (Ecuador), entre julio y diciembre de 2003. Los individuos fueron categorizados por sexo y estados de madurez (maduro e inmaduro) y sus contenidos estomacales se fijaron y separaron por componentes. Se aplicaron índices tróficos cuantitativos (numérico, gravimétrico y frecuencia de ocurrencia) que se analizaron en la escala temporal. Se encontraron 27 componentes alimentarios, siendo las principales presas Larimus argenteus (IIR= 1497), Merluccius gayi (IIR= 333), Dosidicus gigas (IIR= 281) y Benthosema panamense (IIR= 239). El índice de Levin permitió definir a A. superciliosus como un depredador especialista, presentando tendencia a alimentarse en zonas oceánicas.