Given the mean change in δ(15)N(1.2 ± 0.6‰) and δ(13)C values (0.7 ± 0.4‰) across pelagic shark species, it is recommended that muscle tissue samples be treated with LE+DW to efficiently extract both urea and lipids to standardize isotopic values. Mathematical normalization of urea and lipid-extracted δ(15)N(LE+DW) and δ(13)C(LE+DW) values using the lipid-extracted δ(15)N(LE) and δ(13)C(LE) data were established for all pelagic shark species.

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Sex ratios and gravid characteristics were analysed for the crocodile shark Pseudocarcharias kamoharai from the tropical eastern Pacific Ocean. Gravid females ranged from 80 to 102 cm fork length (L(F) ). The mode litter size was four (two embryos per uterus), mean embryo length was linearly correlated with maternal length (r = 0·465, n = 32); there was no significant difference in L(F) between female and male embryos.

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An understanding of reproductive biology is important in evaluating the potential impacts of fisheries on shark population dynamics. Reproductive biology of the female blue shark (Prionace glauca) was evaluated using data collected in the Chinese Longline Fishery Scientific Observer Programme in the southeastern Pacific

SUMMARY: The objective of this study was to estimate depth distribution of pelagic species captured in a longline fishery and to evaluate the difference in depth distribution among species. We estimated depth distribution for 17 frequently captured species based on a Chinese longline fishing trip targeting bigeye tuna (Thunnus obesus) in the central-eastern Pacific Ocean in February-November 2006. The depth distributions of 13 bycatch species were significantly different from that of bigeye tuna. Although most of the bycatch species were found to be distributed in water depths shallower than bigeye tuna (i.e. increasing hook depths can decrease catch rates of these species), the rates of catch rates declined with increasing hook depths may be different. The depth distributions were found to be not significantly different between genders for 7 species. There was no significant correlation between fish sizes and capture depths. The information derived from this study can play an important role in reducing bycatch in pelagic tuna longline fisheries in the central-eastern Pacific Ocean.Keywords: pelagic fish, tuna, bycatch, vertical distribution, longline, Pacific Ocean. RESUMEN: Análisis comparativo de la distribución en profundidad de diecisiete especies de grandes pelági-cos, capturados en una pesquería de palangre en el océano Pacífico centro-oriental. -El objetivo de este estudio ha sido estimar la distribución en profundidad de especies pelágicas capturadas en una pesquería de palangre y evaluar la diferencia en la distribución en profundidad entre las especies. Se estimó la distribución en profundidad para 17 especies capturadas frecuentemente, sobre la base de los datos obtenidos en una marea de una pesquería de palangre china dirigida al patudo (Thunnus obesus) en el océano Pacífico centro-oriental, durante febrero-noviembre 2006. Las distribuciones en profundidad de 13 especies no objetivo de la pesquería fueron significativamente diferentes de la del patudo. Aunque la mayoría de estas 13 especies se encontraron a menor profundidad que el patudo, la medida en la que la captura acompañante disminuye puede ser diferente al situar los anzuelos a mayor profundidad. En 7 de las especies no se encontraron diferencias significativas entre sexos en relación a la distribución en profundidad. No hubo correlación significativa entre los tamaños de los peces y las profundidades de captura. La información derivada de este estudio puede jugar un rol importante en la reducción de la captura acompañante de pesquerías pelágicas con palangre dirigidas a captura de atunes en el océano Pací-fico centro-oriental.