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ResumenLa parte norte del Golfo de California es una zona mega diversa de alto endemismo con gran interés económico por las pesquerías multiespecíficas que se desarrollan, principalmente de camarón. Existe carencia de estudios recientes sobre ensamblajes de peces componentes de la fauna acompañante. Por lo que, durante las temporadas de pesca 2009-2010 y 2010-2011 se realizaron 14 viajes de pesca comercial a bordo de 13 barcos camaroneros, con un total de 119 lances, efectuados entre los 5 y 90 m de profundidad. Los 119 lances fueron analizados para evaluar la estructura de la comunidad de peces. Se utilizaron índices de diversidad taxonómica para detectar cambios taxonómicos en la comunidad siguiendo el índice de distinción taxonómica promedio Δ+ y el índice de variación taxonómica Δ* (TAXDEST del programa PRIMER v6). Para la conformación de grupos funcionales se consideró las similitudes de rasgos ecológicos y morfológicos entre las especies. Los resultados mostraron que los índices Δ+ y Δ* estuvieron dentro del promedio estimado y por dentro de los intervalos de confianza al 95 %, se encontraron diferencias significativas entre los índices. Los análisis mostraron una comunidad bien estructurada debido a la gran variedad de formas y funciones de las especies dentro de la comunidad. En la composición de grupos funcionales, el atributo ecológico que más contribuyó para conformación grupos, fue el gremio reproductivo. La estructura de la comunidad fue representada por niveles tróficos intermedios 3-3.9, preferencialmente carnívoros primarios y carnívoros secundarios, dentro de las categorías tróficas de ictiobentófagos y zoobentófagos, pertenecientes a especies demersales de fondos blandos y mayormente de cuerpo fusiforme.Se concluye que el NGC presentó alta redundancia funcional de acuerdo a los grupos funcionales estimados, por lo que se considera un ecosistema estable y de gran diversidad. Es recomendable dar seguimiento a este tipo de estudios utilizando información de esfuerzo pesquero y ambiental, debido a la gran importancia biológica y ecológica del área.

Abstract The Northern Gulf of California (NGC) is a mega diverse area of high endemism with major economic interest because of the multi-specific fisheries developed, mainly shrimp. There is a lack of recent studies on bycatch fish assemblages, so during the fishing seasons from 2009-2010 and 2010-2011, on board 13 shrimp boats, 14 commercial fishing trips were performed from 5 m - 90 m in depth with a total of 119 catches. The 119 catches were analyzed to assess fish community structure using taxonomic diversity indices to detect changes in the community following the taxonomic distinctness average Δ+ and the diversity index Δ* (TAXDEST of the PRIMER v6 program). To confirm the structure of functional groups, we considered similarities of ecologic and morphologic traits among species. The results showed that the indices Δ+ and Δ* were within the expected average and confidence intervals at 95%, finding significant differences between the indices. The analyses showed a well-structured community because of the great variety of forms and functions of the species within the community. In the community of the functional groups, reproduction was the ecological attribute that contributed the most to their structure. The community structure was represented by intermediate trophic levels (3-3.9), preferably primary and secondary carnivores within the trophic categories of predators of benthic ichthyo-fauna that belong to demersal species of soft bottoms and mostly fusiform body. To conclude, the NGC showed high functional redundancy according to the estimated functional groups, thus the ecosystem was considered stable and with great diversity. This type of studies should be followed using fishing and environmental effort due to the great biological and ecologic importance in the area.

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The Northern Gulf of California (NGC) is a mega diverse area of high endemism with major economic interest because of the multi-specific fisheries developed, mainly shrimp. There is a lack of recent studies on bycatch fish assemblages, so during the fishing seasons from 2009-2010 and 2010-2011, on board 13 shrimp boats, 14 commercial fishing trips were performed from 5 m - 90 m in depth with a total of 119 catches. The 119 catches were analyzed to assess fish community structure using taxonomic diversity indices to detect changes in the community following the taxonomic distinctness average Δ+ and the diversity index Δ* (TAXDEST of the PRIMER v6 program). To confirm the structure of functional groups, we considered similarities of ecologic and morphologic traits among species. The results showed that the indices Δ+ and Δ* were within the expected average and confidence intervals at 95%, finding significant differences between the indices. The analyses showed a well-structured community because of the great variety of forms and functions of the species within the community. In the community of the functional groups, reproduction was the ecological attribute that contributed the most to their structure. The community structure was represented by intermediate trophic levels (3-3.9), preferably primary and secondary carnivores within the trophic categories of predators of benthic ichthyo-fauna that belong to demersal species of soft bottoms and mostly fusiform body. To conclude, the NGC showed high functional redundancy according to the estimated functional groups, thus the ecosystem was considered stable and with great diversity. This type of studies should be followed using fishing and environmental effort due to the great biological and ecologic importance in the area.

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Bottom trawling has been considered a fishing activity that affects and modifies habitats, because of its impacts in species composition and abundance, and the alteration in the structure and function of the eco-system, that generates biodiversity loss. The Northern part of the Gulf of California has been considered a mega diverse zone with high endemism, and it is of growing interest by the international scientific community. In order to assess its potential changes in the fish community components of shrimp by-catch (FAC) in this area, a total of 119 trawls from 13 fishing boats were analyzed in Puerto Peñasco, based on 14 commercial fishing trips made within 9-90 m depth from 2010-2011. A random sample of 20 kg was obtained from each trawl, and was analyzed in the laboratory for species composition. In addition to the Index of Biological Value (IVB), Shannon diversity (H'), and Pielou evenness (J'), comparative abundance-biomass curves (ABC) were also estimated. Eucinostomus dowii showed the highest IVB = 480.25; Porichthys analis showed greater relative abundance; and Pomadasys panamensis showed greater frequency of occurrence. The mean monthly values in diversity H' = 3.05 (2.72 > H' < 3.25) and J' = 0.71 (0.66 < J' >0.81) showed a tendency to decrease as the fishing season progressed. The comparative abundance-biomass curves (ABC), and the value of statistical W showed moderate stress levels in March (W= -0.022) and September (W= -0.02) 2010, and January 2011 (W= -0.042). In conclusion, the Northern Gulf of California showed a well-structured community with a degree of moderate fishing stress.

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La pesca de arrastre ha sido considerada como una actividad que impacta y modifica hábitats, provoca cambios en la composición y abundancias de las especies y altera la estructura y funcionamiento del ecosistema, generando finalmente una pérdida de la biodiversidad. La parte norte del Golfo de California ha sido considerada una zona mega diversa de alto endemismo y es motivo de interés creciente por la comunidad científica internacional. Con la finalidad de evaluar potenciales cambios en la comunidad de peces componentes de la fauna de acompañamiento del camarón (FAC), durante 2010-2011 se analizaron 119 arrastres de 13 embarcaciones camaroneras con base en Puerto Peñasco, a partir de 14 viajes de pesca comercial realizados a 9-90 m. Una muestra aleatoria de 20 kg fue obtenida de cada arrastre y analizada en el laboratorio para la composición de las especies. Adicional al Índice de Valor Biológico (IVB), diversidad de Shannon (H'), equitatividad de Pielou (J') fueron estimadas las curvas comparativas Abundancia-Biomasa (ABC). Eucinostomus dowii fue la mayor en IVB = 480.25, Porichthys analis la de mayor abundancia relativa y Pomadasys panamensis presentó la mayor frecuencia de ocurrencia. Los valores mensuales promedio en la diversidad H' = 3.05 (2.72 > H' < 3.25) y J' = 0.71 (0.66 < J' > 0.81) presentaron tendencia a decrecer conforme avanza la temporada de pesca. El comparativo curvas abundancia-biomasa (ABC) y el valor del estadístico W, evidenciaron a marzo (W = -0.022) y septiembre (W = -0.02) 2010 y enero 2011 (W = -0.042) con niveles de estrés moderado. En conclusión, la región norte del Golfo de California presentó una comunidad bien estructurada con grado de estrés moderado, aunque no explicado totalmente por la pesca.

Bottom trawling has been considered a fishing activity that affects and modifies habitats, because of its impacts in species composition and abundance, and the alteration in the structure and function of the ecosystem, that generates biodiversity loss. The Northern part of the Gulf of California has been considered a mega diverse zone with high endemism, and it is of growing interest by the international scientific community. In order to assess its potential changes in the fish community components of shrimp by-catch (FAC) in this area, a total of 119 trawls from 13 fishing boats were analyzed in Puerto Peñasco, based on 14 commercial fishing trips made within 9-90 m depth from 2010-2011. A random sample of 20 kg was obtained from each trawl, and was analyzed in the laboratory for species composition. In addition to the Index of Biological Value (IVB), Shannon diversity (H'),and Pielou evenness (J'), comparative abundance-biomass curves (ABC) were also estimated. Eucinostomus dowiishowed the highest IVB = 480.25; Porichthys analisshowed greater relative abundance; and Pomadasys panamensisshowed greater frequency of occurrence. The mean monthly values in diversity H'= 3.05 (2.72 > H'< 3.25) and J'= 0.71 (0.66 < J'>0.81) showed a tendency to decrease as the fishing season progressed. The comparative abundance-biomass curves (ABC), and the value of statistical Wshowed moderate stress levels in March (W = -0.022) and September (W = -0.02) 2010, and January 2011 (W = -0.042). In conclusion, the Northern Gulf of California showed a well-structured community with a degree of moderate fishing stress.

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The Gulf of California has a high variety of ecosystems that allow different services and the fishery resources play a prominent role in its ecology, evolution and economics. Fish coastal species have been previously reported for most coastal areas, especially those species that are subject to fishing, however, little is known on the species from deep sea zones, due to sampling difficulties. We studied the deep sea fishes collected with trawl nets during three research surveys in the Gulf of California, Mexico in 2004-2005. We provide a systematic checklist and some notes on biogeographical aspects. For this, 74 fishing hauls were done, and a total of 9 898 fishes were captured, belonging to two classes, 15 orders, 35 families, 53 genera and 70 species. The best represented families in number of species were: Paralichthyidae (eight), Serranidae (six), and Scorpaenidae and Triglidae with five species each one. The typical families from deep waters were: Ophidiidae, Moridae, Lophiidae, Scorpaenidae, Triglidae, Paralichthydae, Pleuronectidae and Cynoglossidae. Size range varied from 13cm for the Splinose searobin (Bellator xenisma) to 234cm in the Pacific Cutlassfish (Trichiurus nitens). The biogeographical affinity showed that species with affinity to the East Tropical Pacific (ETP) dominated, followed by species from San Diego-Panamic, San Diego-Panamic-Peruvian-Chilean and Oregonian-Cortes provinces, respectively. A biogeographic overlap was found in the fauna, which reflects the Gulf of California's geographical position, with distribution limits of species from temperate, tropical and warm-temperature transition affinities, divisions that characterize the Gulf of California. Taxonomic status of fish with a focus on composition, location, characterization and zoogeography are fundamental to any subject of biodiversity and fisheries management actions.

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Taxonomic composition and zoogeographical aspects of deep sea fishes (90-540m) from the Gulf of California, Mexico. The Gulf of California has a high variety of ecosystems that allow different services and the fishery resources play a prominent role in its ecology, evolution and economics. Fish coastal species have been previously reported for most coastal areas, especially those species that are subject to fishing, however, little is known on the species from deep sea zones, due to sampling cifficulties. We studied the deep sea fishes collected with trawl nets during three research surveys in the Gulf of California, Mexico in 2004-2005. We provide a systematic checklist and some notes on biogeographical aspects. For this, 74 fishing hauls were done, and a total of 9 898 fishes were captured, belonging to two classes, 15 orders, 35 families, 53 genera and 70 species. The best represented families in number of species were: Paralichthyidae (eight), Serranidae (six), and Scorpaenidae and Triglidae with five species each one. The typical families from deep waters were: Ophidiidae, Moridae, Lophiidae, Scorpaenidae, Triglidae, Paralichthydae, Pleuronectidae and Cynoglossidae. Size range varied from 13cm for the Splinose searobin (Bellator xenisma) to 234cm in the Pacific Cutlassfish (Trichiurus nitens). The biogeographical affinity showed that species with affinity to the East Tropical Pacific (ETP) dominated, followed by species from San Diego-Panamic, San Diego-Panamic-Peruvian-Chilean and Oregonian-Cortes provinces, respectively. A biogeographic overlap was found in the fauna, which reflects the Gulf of California’s geographical position, with distribution limits of species from temperate, tropical and warm-temperature transition affinities, divisions that characterize the Gulf of California. Taxonomic status of fish with a focus on composition, location, characterization and zoogeography are fundamental to any subject of biodiversity and fisheries management actions.

El Golfo de California tiene una alta variedad de ecosistemas que permiten obtener diferentes servicios y los peces juegan un papel prominente en la ecología, evolución y economía de este. De los peces, las especies costeras han sido reportadas previamente para la mayoría de las zonas litorales, especialmente aquellas especies que son sujetas a explotación pesquera, sin embargo, poco se conoce de las especies que habitan en zonas marinas profundas, debido a lo difícil de su muestreo. Se presenta el listado sistemático y la afinidad biogeográfica de los peces recolectados en tres cruceros de investigación en el Golfo de California con red de arrastre. Se efectuaron 74 lances exploratorios y se capturó un total de 9 898 peces, integrados por dos clases, 15 órdenes, 35 familias, 53 géneros y 70 especies. Las familias mejor representadas en número de especies son: Paralichthyidae (ocho especies), Serranidae (seis), Scorpaenidae y Triglidae (cinco cada una). Las familias típicas de aguas profundas son: Ophidiidae, Moridae, Lophiidae, Scorpaenidae, Triglidae, Paralichthydae, Pleuronectidae y Cynoglossidae. El intervalo de tallas encontrado varió de 13cm en la vaca doble hocico (Bellator xenisma) a 234cm en el sable del Pacífico Trichurus nitens. La afinidad biogeográfica muestra que dominaron las especies de afinidad al Pacífico Oriental Tropical (POT), seguidos por las especies de las provincias de San Diego-Panámica; San Diego-Panámica-peruano-chilena y provincias Oregoniana-de Cortés respectivamente. Se encontró un traslape biogeográfico de la fauna, la cual es reflejo de la posición geográfica del Golfo de California en los límites de distribución de los elementos en donde se manifiestan especies de afinidades templadas, tropicales y de transición templado-cálido, divisiones que caracterizan al Golfo de California. Los estatus taxonómicos en peces con un enfoque de composición, ubicación, caracterización y zoogeografía son fundamentales ...

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Shrimp trawling fishery in the Gulf of California captures a wide variety of non-target species of fish, crustaceans, and mollusks that are relatively unknown. The Pacific flagfin mojarra Eucinostomus currani is a frequently found species in these catches, nevertheless, nothing is currently known about its population dynamics. To contribute to the knowledge on this fish species, we studied the size structure, growth, mortality, and the recruitment pattern during the 2004-2005 seasons. A total of 6,078 mojarra were captured from 350 samples, with minimum and maximum lengths of 4.5 cm and a maximum of 21.0 cm. The average total length of the four major cohorts was 11.4, 13.7, 15.6 and 18.0 cm, corresponding to ages 0.9, 1.2, 1.6 and 2.2 years, respectively, being the most abundant the 1.2 year-old group. The instant growth coefficient indicated moderate growth rates (K(s) = 0.81/year, K(E) = 0.85/year), corresponding to individuals living between 3.5 to 3.7 years. The estimated asymptotic lengths was L (infinity) = 21.8 cm. In general, the population could be considered healthy: natural mortality (M = 1.53/year); total mortality (Z = 2.73/year); condition factor (K = 0.01072); fishery mortality (F = 1.2/year) and exploitation rate (E = 0.43/year). The maximum reproduction period almost coincided with the closed season for shrimp fishing (March to August), thus we concluded that survival of the species is ensured because reproduction is indirectly protected.

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Shrimp trawling fishery in the Gulf of California captures a wide variety of non-target species of fish, crustaceans, and mollusks that are relatively unknown. The Pacific flagfin mojarra Eucinostomus currani is a frequently found species in these catches, nevertheless, nothing is currently known about its population dynamics. To contribute to the knowledge on this fish species, we studied the size structure, growth, mortality, and the recruitment pattern during the 2004-2005 seasons. A total of 6 078 mojarra were captured from 350 samples, with minimum and maximum lengths of 4.5cm and a maximum of 21.0cm. The average total length of the four major cohorts was 11.4, 13.7, 15.6 and 18.0cm, corresponding to ages 0.9, 1.2, 1.6 and 2.2 years, respectively, being the most abundant the 1.2 year-old group. The instant growth coefficient indicated moderate growth rates (K S=0.81/year, K E=0.85/year), corresponding to individuals living between 3.5 to 3.7 years. The estimated asymptotic lengths was L∞=21.8cm. In general, the population could be considered healthy: natural mortality (M=1.53/year); total mortality (Z=2.73 /year); condition factor (K=0.01072); fishery mortality (F=1.2/ year) and exploitation rate (E=0.43/year). The maximum reproduction period almost coincided with the closed season for shrimp fishing (March to August), thus we concluded that survival of the species is ensured because reproduction is indirectly protected. Rev. Biol. Trop. 59 (2): 887-897. Epub 2011 June 01.

La pesquería de camarón del Golfo de California captura una amplia variedad de especies incidentales, relativamente no conocidas que incluye peces, crustáceos y moluscos. La mojarra bandera del Pacífico Eucinostomus currani es frecuentemente encontrada en las capturas del camarón y no hay información sobre su dinámica poblacional. La estructura de tallas, crecimiento, mortalidad y patrón de reclutamiento fueron determinados durante la temporada 2004-2005. De manera que se recolectaron 6 078 organismos de esta especie en 350 muestras, las tallas mínima y máxima fueron 4.5cm y 21.0cm. La talla media de las cuatro cohortes presentes fueron 11.4, 13.7, 15.6 y 18.0cm, correspondiendo a edades de 0.9, 1.2, 1.6 y 2.2 años. El coeficiente instantáneo de crecimiento indica un crecimiento moderado (KS=0.81/año, KE=0.85/año), con una longevidad de 3.5 años. La longitud asintótica estimada fue L∞=21.8cm. En general, la población se mostró saludable, con una mortalidad natural (M=1.53/año); factor de condición (K=0.01072); mortalidad total (Z=2.73 /año); mortalidad por pesca (F=1.2/año) y tasa de explotación (E=0.43/año). El periodo de máxima reproducción coincide con la temporada de veda de la pesca de camarón (marzo a agosto). Concluimos que la sobrevivencia de la especie se encuentra indirectamente protegida.

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Bycatch fish species from shrimp industrial fishery in the Gulf of California, Mexico. The shrimp fishery in the Gulf of California is one the most important activities of revenue and employment for communities. Nevertheless, this fishery has also created a large bycatch problem, principally fish. To asses this issue, a group of observers were placed on board the industrial shrimp fleet and evaluated the Eastern side of the Gulf during 2004 and 2005. Studies consisted on 20kg samples of the capture for each trawl, and made possible a systematic list of species for this geographic area. Fish represented 70% of the capture. A total of 51 101 fish were collected, belonging to two classes, 20 orders, 65 families, 127 genera, and 241 species. The order Perciformes was the most diverse with 31 families, 78 genera, and 158 species. The best represented families by number of species were: Sciaenidae (34) and Paralichthyidae (18) and Haemulidae and Carangidae (16 each). The best represented genera in number of species were Symphurus (nine) and Diplectrum and Cynoscion (six); other important genera were Larimus and Porichthys with five species each. The best represented species in number were Syacium ovale, Pseudupeneus grandisquamis, Haemulopsis nitidos, Diplectrum pacificum, Synodus scituliceps, Balistes polylepis, Eucinostomus currani, Eucinostomus gracilis, Porichthys analis, Chloroscombrus orqueta, Selene peruviana, Orthopristis reddingi, Etropus crossotus, Scorpaena sonorae and Urobatis halleri. The number of recorded species is notably high, compared with demersal fauna of other areas of the Mexican Pacific, such as Gulf of Tehuantepec (178), Nayarit, Michoacán, Guerrero (174, 120 and 166), Jalisco and Colima (161 species), and those of the Western coast of the Baja California Peninsula (220 species). Rev. Biol. Trop. 58 (3): 925-942. Epub 2010 September 01.

Composición taxonómica de peces integrantes de la fauna de acompañamiento de la pesca industrial de camarón del Golfo de California, México. La pesquería de camarón es la más importante en el Golfo de California y también la más problemática con respecto a las capturas incidentales en México. Dentro de la fauna de acompañamiento del camarón (FAC), el grupo de mayor abundancia son los peces. Se presenta listado sistemático de las especies de peces presentes en la FAC de la pesquería industrial de camarón en la costa oriental del Golfo de California. Durante 2004-2005 se implementó un sistema de observadores a bordo de la flota camaronera de Guaymas, Sonora, que recolectaron muestras de 20kg de la captura. Los peces representaron 70% de las capturas en número. Se recolectó un total de 51 101 ejemplares de peces, pertenecientes a dos clases, 20 órdenes, 65 familias, 127 géneros y 241 especies. El orden Perciformes fue el más diverso (31 familias, 78 géneros y 158 especies). Las familias mejor representadas en número de especies fueron: Sciaenidae y Paralichthyidae con 34 y 18 especies, Haemulidae y Carangidae aportaron 16 especies. Los géneros mejor representados fueron Symphurus con nueve y Diplectrum y Cynoscion con seis especies, otros géneros importantes fueron Larimus y Porichthys con cinco especies. El número de especies registrado es alto, comparado con la fauna demersal de otras áreas del Pacífico Mexicano. Esta alta riqueza de especies se puede atribuir a los sistemas de corrientes, surgencias, remolinos, topografía y batimetría únicas, que en conjunto originan un ecosistema dinámico con un amplio régimen térmico y una gran variedad de hábitats. Los resultados aqui presentados ponen de manifiesto que esta región del Golfo de California presenta una gran riqueza de especies, lo que abre diversas expectativas desde el punto de vista ecológico, pesquero, alimenticio y de manejo.

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Bycatch fish species from shrimp industrial fishery in the Gulf of California, Mexico. The shrimp fishery in the Gulf of California is one the most important activities of revenue and employment for communities. Nevertheless, this fishery has also created a large bycatch problem, principally fish. To asses this issue, a group of observers were placed on board the industrial shrimp fleet and evaluated the Eastern side of the Gulf during 2004 and 2005. Studies consisted on 20kg samples of the capture for each trawl, and made possible a systematic list of species for this geographic area. Fish represented 70% of the capture. A total of 51 101 fish were collected, belonging to two classes, 20 orders, 65 families, 127 genera, and 241 species. The order Perciformes was the most diverse with 31 families, 78 genera, and 158 species. The best represented families by number of species were: Sciaenidae (34) and Paralichthyidae (18) and Haemulidae and Carangidae (16 each). The best represented genera in number of species were Symphurus (nine) and Diplectrum and Cynoscion (six); other important genera were Larimus and Porichthys with five species each. The best represented species in number were Syacium ovale, Pseudupeneus grandisquamis, Haemulopsis nitidos, Diplectrum pacificum, Synodus scituliceps, Balistes polylepis, Eucinostomus currani, Eucinostomus gracilis, Porichthys analis, Chloroscombrus orqueta, Selene peruviana, Orthopristis reddingi, Etropus crossotus, Scorpaena sonorae and Urobatis halleri. The number of recorded species is notably high, compared with demersal fauna of other areas of the Mexican Pacific, such as Gulf of Tehuantepec (178), Nayarit, Michoacán, Guerrero (174, 120 and 166), Jalisco and Colima (161 species), and those of the Western coast of the Baja California Peninsula (220 species).

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Se hace un análisis de la comunidad de los peces demersales del talud continental de la costa oriental del Golfo de California, México. Las muestras provienen de tres cruceros realizados con una red de arrastre a profundidades de 90-540m. Los diagramas de temperatura-salinidad (T-S) mostraron que a esas profundidades se encuentra la masa de agua del Golfo de California y por debajo de ella, la masa de agua sub-superficial del Pacífico. Se encontró que la temperatura y el O2 disuelto disminuyeron gradualmente hasta la profundidad máxima de muestreo (540m), siendo en esta última de 7°C y 0.1ml·l-1, respectivamente. Se registraron 71 especies pertenecientes a 35 familias. El valor de diversidad máxima y mínimo promedio (H’) fue 2,2 y 0,8 bits/ind, y la riqueza específica (D) fue de 3,6 y 0,2 Las especies Caelorinchus scaphopsis, Merluccius productus, Pleuronichthys verticals, Sebastes spinorbis, Microlephidium verecundum, Lepophidium prorates y Lophiodes spilurus fueron las dominantes de acuerdo al índice de importancia relativa. La comunidad de peces del talud se conformo de dos comunidades diferentes, la primera por especies de ambito costero que abarca de 90 a 270m, caracterizada por valores moderados y altos de diversidad y riqueza especifica, con la dominancia compartida entre un mayor número de especies, mientras que la segunda comunidad estuvo formada por especies típicas de profundidad, de baja diversidad, y la dominancia esta soportada en pocas especies. Se infiere que las variables ambientales juegan un papel importante en la conformación de esta estructura comunitaria.

An analysis of the demersal fish community of the eastern continental slope of the Gulf of California, México, was performed. Samples were obtained with a trawl net at 90-540m of depth by three separate research surveys. Temperature-salinity diagrams showed two main water masses, one represented by the Gulf of California water mass, down to a depth of 540m, and a deeper one corresponding to the sub-surface Pacific water mass. Depth profiles for temperature and dissolved O2 were obtained, and plots constructed from them. These profiles showed that temperature and O2 concentration decreased gradually along a smooth gradient to a minimun of 7°C and 0.1ml·l-1, respectively, at 540m deep. Seventy-one species belonging to 35 families were found. Average maximum and minimum overall diversity (H´) values were 2.2 and 0.8 bits/ind and the specific richness (R) index value were 3.6 and 0.2. Caelorinchus scaphopsis, Merluccius productus, Pleuronichthys verticals, Sebastes spinorbis, Microlephidium verecundum, Lepophidium prorates. and Lophiodes spilurus were the most dominant species, based on the relative importance index. The fish community structure suggests two different communities with two groups of species, one at 90-270m deep that shows strong associations with moderate to high diversity values and specific richness, with shared dominance by numerous species, and a second community made out of typical deep water species, with low diversity and dominance featured by a few species. The data suggests that environmental conditions play an important role in the distribution and the community structure of these species.

Faz-se uma análise da comunidade dos peixes demersais do talude continental da costa oriental do Golfo da Califórnia, México. As amostras provêm de três cruzeiros realizados com uma rede de arrasto a profundidades de 90-540m. Os diagramas de temperatura-salinidade (T-S) mostraram que a essas profundidades se encontra a massa de água do Golfo da Califórnia e por baixo dela, a massa de água subsuperficial do Pacífico. Encontrou-se que a temperatura e o O2 dissolvido diminuiram gradualmente até a profundidade máxima de amostragem (540m), sendo nesta última de 7°C e 0.1ml·l-1, respectivamente. Registraram-se 71 espécies pertencentes a 35 famílias. O valor de diversidade máximo e mínimo médio (H’) foi 2,2 e 0,8 bits/ind, e a riqueza específica (D) foi de 3,6 e 0,2. As espécies Caelorinchus scaphopsis, Merluccius productus, Pleuronichthys verticals, Sebastes spinorbis, Microlephidium verecundum, Lepophidium prorates e Lophiodes spilurus foram as dominantes de acordo ao índice de importância relativa. A comunidade de peixes do talude foi conformada a partir de duas comunidades diferentes, a primeira por espécies de âmbito costeiro que abrange de 90 a 270m, caracterizada por valores moderados e altos de diversidade e riqueza específica, com a dominância compartida entre um maior número de espécies, enquanto que a segunda comunidade esteve formada por espécies típicas de profundidade, de baixa diversidade, e a dominância está suportada em poucas espécies. Infere-se que as variáveis ambientais têm um papel importante na conformação desta estrutura comunitária.