Assessing the exposure risk of large pelagic fish to oil spills scenarios in the deep waters of the Gulf of Mexico.

Exposure risk is assessed based on modeling suitable habitat of large pelagic fish and oil spill scenarios originating at three wells located in the western GM's deep waters. Since the fate of the oil depends on the oceanographic conditions present during the accident, as well as the magnitude and duration of the spill, which are not known a priori, the scenarios used are a statistical representation of the area in which oil spilled from the well could be found, given all possible outcomes. The ecological vulnerability assessment identified a subset of bony fish with low-medium vulnerability and elasmobranchs with medium-high vulnerability. The oiling probability and exposure risk of both bony fish and elasmobranchs hotspots vary by well analyzed. Thus, these results provide essential information for a risk management plan for the assessed species and others with economic or conservation importance distributed in the GM and worldwide.

Mercury and arsenic in muscle and liver of the golden cownose ray, Rhinoptera steindachneri, Evermann and Jenkins, 1891, from the upper Gulf of California, México.

Mercury and arsenic levels in muscle and liver of Rhinoptera steindachneri were determined in organisms collected in 2006. Element concentrations in both tissues were directly related to size. Maxima mean concentrations of Hg and As (0.41 and 59.9 microg g(-1) dry wt, respectively) were found in adults muscle. Mercury concentrations were significantly different between juveniles and adults in muscle and liver. For As concentrations, differences between juveniles and adults were found only in muscle. Mercury concentrations were higher in muscle of juveniles and adults. Arsenic concentrations were higher in liver of juveniles, and in muscle of adults. Maximum Hg concentration in muscle (0.65 microg g(-1) dry wt) was below the safe limit established by Mexican regulations for seafood.

The fish species composition and variation of catch from the small-scale gillnet fishery before, during and after the 1997-1998 ENSO event, central Mexican Pacific.

In the tropical and subtropical coastal zone, were highly diverse fish communities occur, it is important to study the small scale fisheries exploiting these communities. For this study, 219 fishing days were carried out in Bahia de Navidad, Jalisco, Mexico. Four gillnets with different mesh sizes (76.2, 88.9, 101.6 and 114.3 mm) were used for the fishing operations, from April 1994 to March 1995 and from January 1998 to December 2000. A total of 26126 organisms weighting 11680 kg were caught. One hundred and eighty three species belonging to 57 families and 19 orders were identified. Ten species accumulated more than 60% of the total abundance and biomass, the remaining species (173) individually contributed with less than 2% of the total abundance and biomass. The most important species in the catch were Microlepidotus brevipinnis, Caranx caballus, Haemulon flaviguttatum, Scomberomorus sierra, C. caninus, C. sexfjasciatus, Lutjanus guttatus and L. argentiventris. The catch per unit of effort showed a large variation during the study, both in number and biomass. On average, 110 fishes and 48.5 kg fishing day(-1) were caught. The maximum values were recorded during January and October 1998 (250 fishes and 100 kg fishing day(-1)), and the minimum values were recorded during September and November 1994 (25 org. and 10 kg fishing day(-1)). The total abundance and biomass was lower during the 1994-95 period (F=6.16, 8.32, P<0.05). There were statistically significant differences among the annual catch from each gillnet. All the environmental changes caused by the ENSO event had ecological and economic effects that can be rated from moderate to severe.

The fish species composition and variation of catch from the small-scale gillnet fishery before, during and after the 1997-1998 ENSO event, central Mexican Pacific

In the tropical and subtropical coastal zone, were highly diverse fish communities occur, it is important to study the small scale fisheries exploiting these communities. For this study, 219 fishing days were carried out in Bahia de Navidad, Jalisco, Mexico. Four gillnets with different mesh sizes (76.2, 88.9, 101.6 and 114.3 mm) were used for the fishing operations, from April 1994 to March 1995 and from January 1998 to December 2000. A total of 26126 organisms weighting 11680 kg were caught. One hundred and eighty three species belonging to 57 families and 19 orders were identified. Ten species accumulated more than 60% of the total abundance and biomass, the remaining species (173) individually contributed with less than 2% of the total abundance and biomass. The most important species in the catch were Microlepidotus brevipinnis, Caranx caballus, Haemulon flaviguttatum, Scomberomorus sierra, C. caninus, C. sexfjasciatus, Lutjanus guttatus and L. argentiventris. The catch per unit of effort showed a large variation during the study, both in number and biomass. On average, 110 fishes and 48.5 kg fishing day(-1) were caught. The maximum values were recorded during January and October 1998 (250 fishes and 100 kg fishing day(-1)), and the minimum values were recorded during September and November 1994 (25 org. and 10 kg fishing day(-1)). The total abundance and biomass was lower during the 1994-95 period (F=6.16, 8.32, P<0.05). There were statistically significant differences among the annual catch from each gillnet. All the environmental changes caused by the ENSO event had ecological and economic effects that can be rated from moderate to severe.

Se llevaron a cabo 219 días de pesca experimental en la Bahía de Navidad, Jalisco, México. Se utilizaron cuatro redes de enmalle de diferente luz de malla (76.2, 88.9, 101.6 and 114.3 mm de luz de malla), de abril de 1994 a marzo de 1995 y de enero de 1998 a diciembre de 2000. En total se capturaron 26126 organismos que pesaron 11680 kg. Fueron identificadas 183 especies pertenecientes a 57 familias y 19 órdenes. Diez especies acumularon más del 60% de la abundancia y biomasa total, el resto de las especies (173) individualmente aportaron menos del 2% de la abundancia y biomasa total. Las especies más importantes en la captura fueron Microlepidotus brevipinnis, Caranx caballus, Haemulon flaviguttatum, Scomberomorus sierra, C. caninus, C. sexfasciatus, Lutjanus guttatus y L. argentiventris. La captura por unidad de esfuerzo mostró una gran variación durante todo el periodo de estudio, tanto en número de organismos como en biomasa. En promedio se capturaron 110 organismos/día de pesca (48.5 kg/día de pesca). Los valores máximos se registraron durante enero y octubre de 1998 (250 peces y 100 kg por día de pesca), y el mínimo se registró durante septiembre y noviembre de 1994 (25 organismos y 10 kg por día de pesca). La abundancia y biomasa total fue menor durante el periodo 1994-1995 (F=6.16, 8.32, P<0.05). Se encontraron diferencias estadísticamente significativas entre la captura anual de las diferentes redes. Los cambios ambientales provocados por el evento ENOS tuvo efectos que pudieran considerarse de moderados a severos, tanto ecológicos como económicos.