Rafael Chávez-López

Elthusa alvaradoensis Rocha-Ramírez, Chávez-López & Bruce, 2005 (Isopoda, Cymothoidae) parasitizing the inshore lizardfish, Synodus foetens (Linnaeus, 1766) on the continental shelf off central Veracruz, Mexico

[The prevalence, fecundity, and size distribution of the isopod, Elthusa alvaradoensis, parasitizing the inshore lizardfish, Synodus foetens on the continental shelf off central Veracruz, Mexico, were studied. A total sample of 136 fish with a 46.3% prevalence of E. alvaradoensis was obtained during a survey cruise in February, 1996. The isopods were preferentially located on the second and third branchial arches; the lesions ranged from a slight abrasion of the branchial filaments to their complete removal. Mean host size did not vary significantly between the parasitized and unparasitized fractions. Maximum total length for male parasites was 12 mm, while female size ranged from 14.5 to 26.3 mm. Parasite fecundity varied from 100 to 2280 eggs and was unrelated to female size (p < 0.05). Male parasites exhibit a positive allometric growth, while this is negative for females. Se estudio la prevalencia, fecundidad y distribucion de tallas del isopodo Elthusa alvaradoensis parasitando el lagarto maximo, Synodus foetens, en la plataforma central de Veracruz, Mexico. De la muestra total de 136 peces obtenida de un crucero de estudio en febrero de 1996, la prevalencia de E. alvaradoensis fue del 46.3%. Los isopodos fueron localizados preferentemente en el segundo y tercer arco branquial; las lesiones observadas fueron desde la abrasion de los filamentos branquiales hasta la remocion completa de los mismos. La talla promedio del hospedero no vario significativamente entre la fraccion parasitada y la no parasitada. La longitud total maxima de las machos parasitos fue de 12 mm, mientras la talla de las hembras vario de 14.5 a 26.3 mm. La fecundidad del parasito oscilo de 100 a 2280 huevos y no se relaciono con la talla de la hembra (p < 0.05). Los machos parasitos exhiben crecimiento alometrico positivo y negativo en las hembras., The prevalence, fecundity, and size distribution of the isopod, Elthusa alvaradoensis, parasitizing the inshore lizardfish, Synodus foetens on the continental shelf off central Veracruz, Mexico, were studied. A total sample of 136 fish with a 46.3% prevalence of E. alvaradoensis was obtained during a survey cruise in February, 1996. The isopods were preferentially located on the second and third branchial arches; the lesions ranged from a slight abrasion of the branchial filaments to their complete removal. Mean host size did not vary significantly between the parasitized and unparasitized fractions. Maximum total length for male parasites was 12 mm, while female size ranged from 14.5 to 26.3 mm. Parasite fecundity varied from 100 to 2280 eggs and was unrelated to female size (p < 0.05). Male parasites exhibit a positive allometric growth, while this is negative for females. Se estudio la prevalencia, fecundidad y distribucion de tallas del isopodo Elthusa alvaradoensis parasitando el lagarto maximo, Synodus foetens, en la plataforma central de Veracruz, Mexico. De la muestra total de 136 peces obtenida de un crucero de estudio en febrero de 1996, la prevalencia de E. alvaradoensis fue del 46.3%. Los isopodos fueron localizados preferentemente en el segundo y tercer arco branquial; las lesiones observadas fueron desde la abrasion de los filamentos branquiales hasta la remocion completa de los mismos. La talla promedio del hospedero no vario significativamente entre la fraccion parasitada y la no parasitada. La longitud total maxima de las machos parasitos fue de 12 mm, mientras la talla de las hembras vario de 14.5 a 26.3 mm. La fecundidad del parasito oscilo de 100 a 2280 huevos y no se relaciono con la talla de la hembra (p < 0.05). Los machos parasitos exhiben crecimiento alometrico positivo y negativo en las hembras.]

Fish discard by-catch shrimp trawl (rainy season 2013) in south central coast of Veracruz, Mexico

The brown shrimp (Penaeus aztecus) fishery is the most important in the Gulf of Mexico. This fishery takes non-target species or by-catch fauna, mainly teleost fishes, which are incidentally captured. Some of the by-catch species has commercial use and the rest of them are discarded. Therefore, it is important to describe the composition of the discarded fauna, to determine the impacts under the ecosystem approach. Discarding catch of shrimp trawls carried out in 2013 on the continental shelf off the State of Veracruz in different depth intervals (22-46 and > 46 m) was analyzed. For each trawl, the shrimp catch, the commercial by-catch and the discarding were recorded and the catch ratios respect to shrimp, were obtained. A discard sample was taken and the species were identified, the total length was taken and the ecological parameters were calculated. The non-parametric multiple dimensional scaling test was performed. A total of 7,178 fishes were collected from 34 families, 46 genera and 51 species. The ratio of commercial species by-catch: shrimp and discard: shrimp was 15.41:1 and 40:1 kg, respectively. The species with high relative dominance were Citharichthys macrops, Synodus foetens, Diplectrum bivittatum, Rhomboplites aurorubens and Upeneus parvus. The species with greater importance index were C. macrops, S. foetens, and D. bivittatum. The 43.14% of the discarded species are used as food and 7.84% as bait. The maximum diversity (H ́) was 3.76 bits ind-1 and the trophic level was 4.31. The study of discard composition is a basis to assess the impact generated by the shrimp trawlers and provides guidelines for identify changes in the community structure.espanolLa pesqueria del camaron cafe Penaeus aztecus es la mas importante en el Golfo de Mexico. En esta pesqueria se capturan de manera incidental especies no objetivo compuestas mayormente por peces teleosteos. Es importante describir la composicion del descarte, para determinar el impacto de los arrastres camaroneros bajo un enfoque ecosistemico. Se analizo la captura de descarte de arrastres camaroneros realizados en 2013 en la plataforma continental del Estado de Veracruz en 22-46 y >46 m de profundidad. Para cada arrastre se registro la captura de camaron, fauna de acompanamiento comercial, descarte y fauna de acompanamiento. Se tomo una muestra del descarte, se identificaron las especies y se calcularon los parametros ecologicos de la muestra. Se realizo una prueba de escalamiento dimensional multiple no parametrica. De 87 lances de pesca, se analizaron 7.178 organismos correspondientes a 34 familias, 46 generos y 51 especies. Las especies con mayor dominancia relativa y mayor valor del indice de importancia fueron: Citharichthys macrops, Synodus foetens, Diplectrum bivittatum, Rhomboplites aurorubens y Upeneus parvus. Un alto porcentaje de las especies de descarte (43,14%) presentan uso potencial de alimento y 7,84% carnada. En promedio, la relacion Fauna de Acompanamiento Comercial:Camaron y Descarte:Camaron fue de 15,41:1 y 40:1 kg, respectivamente. El valor maximo de diversidad (H´) fue de 3,76 bits ind-1 y el Nivel Trofico de 4,31. El estudio de la composicion de los descartes es base para evaluar el impacto generado por los arrastres de camaron en la costa veracruzana y proporciona pautas para identificar cambios en la estructura de la comunidad. EnglishThe brown shrimp (Penaeus aztecus) fishery is the most important in the Gulf of Mexico. This fishery takes non-target species or by-catch fauna, mainly teleost fishes, which are incidentally captured. Some of the by-catch species has commercial use and the rest of them are discarded. Therefore, it is important to describe the composition of the discarded fauna, to determine the impacts under the ecosystem approach. Discarding catch of shrimp trawls carried out in 2013 on the continental shelf off the State of Veracruz in different depth intervals (22-46 and > 46 m) was analyzed. For each trawl, the shrimp catch, the commercial by-catch and the discarding were recorded and the catch ratios respect to shrimp, were obtained. A discard sample was taken and the species were identified, the total length was taken and the ecological parameters were calculated. The non-parametric multiple dimensional scaling test was performed. A total of 7,178 fishes were collected from 34 families, 46 genera and 51 species. The ratio of commercial species by-catch: shrimp and discard: shrimp was 15.41:1 and 40:1 kg, respectively. The species with high relative dominance were Citharichthys macrops, Synodus foetens, Diplectrum bivittatum, Rhomboplites aurorubens and Upeneus parvus. The species with greater importance index were C. macrops, S. foetens, and D. bivittatum. The 43.14% of the discarded species are used as food and 7.84% as bait. The maximum diversity (H´) was 3.76 bits ind-1 and the trophic level was 4.31. The study of discard composition is a basis to assess the impact generated by the shrimp trawlers and provides guidelines for identify changes in the community structure.