Comparative histological analysis of cerebellum of representative species of elasmobranchii

SUMMARY: In elasmobranch fishes, variations in gross structural organization of cerebellum has been extensively explored. The basic histological features of cerebellum although conserved in the group but the comparative account on subtle cellular variations is largely underestimated. The present study aims to explore the histological and cellular variations in different layers of cerebellar cortex of the representative elasmobranchs' species belonging to different habitat. Our findings showed that the histological architecture of cerebellar granular layer between the examined species varies noticeably. By and large increase cellular density were observed in all the layers of cerebellum in the representative species of shark compared to ray. The findings were then compared and discussed with reference to their habitat and behavior.

En los peces elasmobranquios, las variaciones en la organización estructural general del cerebelo se han explorado ampliamente. Las características histológicas básicas del cerebelo, aunque se conservan en el grupo, pero la descripción comparativa de las variaciones celulares sutiles es limitada. El presente estudio tiene como objetivo explorar las variaciones histológicas y celulares en diferentes capas de la corteza cerebelosa de las especies representativas de elasmobranquios pertenecientes a diferentes hábitats. Nuestros hallazgos mostraron que la arquitectura histológica de la capa granular del cerebelo entre las especies examinadas varía notablemente. Se observó un gran aumento de la densidad celular en todas las capas del cerebelo en las especies representativas de tiburón en comparación con la raya. Luego, los hallazgos se compararon y discutieron con referencia a su hábitat y comportamiento.

Residency of bull sharks, Carcharhinus leucas (Carcharhiniformes: Carcharhinidae), at San Pedrillo Islet in Islas Murciélago, North Pacific of Costa Rica

Introduction: The bull shark, Carcharhinus leucas, is particularly vulnerable to anthropogenic actions because of its permanence in coastal ecosystems; populations depletion is registered in different places around the world. Aggregations of bull sharks have been reported in the North Pacific of Costa Rica, at Islas Murciélago, within the Guanacaste Conservation Area. Objective: To study the residency of bull sharks at San Pedrillo islet, Islas Murciélago. Methods: During the study period (June 2013 to February 2015) we used passive telemetry to tag 10 bull sharks. Results: All the sharks tagged were females, they were detected on 59 798 occasions by the acoustic receiver deployed in San Pedrillo. Acoustic signals from tagged sharks were received for a total period of 1 to 229 days (mean = 73.9 ± 71.3 days), with the last detections occurring on 9 January 2015. The Residency Index for each tagged shark across the entire monitoring period ranged from 0.41 to 1.00. The bull shark activity showed a significant pattern throughout the day at the receiver that specifically corresponded with the daily light cycle. Conclusions: This study concludes that San Pedrillo is an aggregation site (cleaning station) for bull sharks (C. leucas), possibly related to reproduction and not feeding behaviors.

Introducción: El tiburón toro (Carcharhinus leucas) es una especie tropical y subtropical que habita ríos, estuarios y aguas costeras. Objetivo: Estudiar la residencia del tiburón toro en San Perdillo, Islas Murciélago, Área de Conservación Guanacaste. Métodos: Durante el período de estudio (junio de 2013 a febrero de 2015) se marcaron 10 tiburones toro con telemetría acústica en San Pedrillo. Resultados: Los tiburones marcados fueron todos hembras y fueron detectados en 59 798 ocasiones por el receptor acústico desplegado en San Pedrillo. Las señales acústicas de los tiburones marcados se recibieron durante un período total de 1 a 229 días (media = 73.9 ± 71.3 días), y las últimas detecciones ocurrieron el 9 de enero de 2015. El índice de residencia de cada tiburón marcado durante todo el período de seguimiento osciló entre 0.41 y 1.00. La actividad del tiburón toro mostró un patrón significativo a lo largo del día en el receptor que se corresponde específicamente con el ciclo de luz diario. Conclusiones: Este estudio concluyó que San Pedrillo es un sitio de agregación (estación de limpieza) para el tiburón toro, posiblemente relacionado con comportamientos de reproducción y no de alimentación; y es un sitio crítico para la especie. Se necesitan más estudios para identificar áreas de alimentación y cría en el Área de Conservación de Guanacaste y áreas circundantes.

Depletion of trophy large-sized sharks populations of the Argentinean coast, south-western Atlantic: insights from fishers' knowledge

Abstract Globally, sharks are impacted by a wide range of human activities, resulting in many populations being depleted. Trophy large-sized sharks of the Argentinean coast, the sand-tiger Carcharias taurus , the copper Carcharhinus brachyurus and the sevengill shark Notorynchus cepedianus are under intense sport and artisanal fishing since the 50's decade. However, the current and historical information for the assessment of its populations status is scarce. The aim of this work was to analyze the status of conservation of these species through the gathering of expert fishermen knowledge (FK) on semi-structured interviews. Abundance variation perception between the beginning and the end of fishermen careers revealed a critical status for the species study (means variation between -77 and -90 %). Furthermore, a best day's catch analysis reinforce this result in the case of the sand tiger shark. The school shark Galeorhinus galeus was included on this work with the objective of contrast FK with formal information available of catch-per-unit-effort (CPUE) time series. Both sources of information, despite are not comparable, shows declines ~ - 80%. The critical conservation situation of study species needs urgent management action, particularly for the san tiger shark which could became regionally extinct before the reaction of stakeholders occurs.

Resumen A escala global, los condrictios se encuentran severamente afectados por un amplio rango de actividades antrópicas. Actualmente una gran proporción de poblaciones se encuentran diezmadas y algunas especies son consideradas en peligro de extinción. Los tiburones de gran tamaño y de interés pesquero de la costa Argentina, el escalandrún Carcharias taurus , el bacota Carcharhinus brachyurus y el gatopardo Notorynchus cepedianus se encuentran bajo una intensa presión de pesca desde la década del 50. Sin embargo, la información actual o histórica sobre el estado de conservación de estas especies es muy escasa. El objetivo de este trabajo fue analizar el estado de conservación de estas especies a través de la colecta de conocimiento de pescadores expertos mediante entrevistas semi-estructuradas. La precepción de los pescadores sobre la variación en abundancia entre el principio de sus carreras y el final de las mismas, mostró un estado crítico de las especies de estudio (variación media entre -77 y -90%). Además, un análisis sobre el mejor día de capturas revela un estado particularmente crítico para el eslandrún. El cazón Galeorhinus galeus fue incluido en este trabajo con el objetivo de contrastar los resultados de la percepción de los pescadores con información formal disponible basada en información de Captura por Unidad de Esfuerzo. En ambas fuentes de información, si bien no son comparables, se obtuvo una declinación del 80 % en la abundancia. Adicionalmente, en este trabajo se recabo información sobre los patrones estacionales de ocurrencia de las especies (adultos y neonatos). El crítico estado de conservación de las especies de estudio requiere la aplicación de mediadas de manejo urgentes, especialmente para el escalandrún que podría extinguirse regionalmente antes de que reaccionen usuarios u organismos de manejo.

Concentración de Hg, Pb, Cd, Cr y As en hígado de Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae) capturado en Veracruz, México

Concentration of Hg, Pb, Cd, Cr and As in liver Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae) captured in Veracruz, Mexico. Pollution by heavy metals in marine ecosystems in the Gulf of Mexico is one of the hardest conservation issues to solve. Sharks as top predators are bioindicators of the marine ecosystem health, since they tend to bioaccumulate and biomagnify contaminants; they also represent a food source for local consumption. Thus, the objective of this study was to study the possible presence of heavy metals and a metalloid in livers of Carcharhinus limbatus. For this, a total of 19 shark livers were taken from animals captured nearby Tamihua, Veracruz, Mexico from December 2007 to April 2008. 12 out of the 19 captured sharks were males, one was an adult female, three were juvenile males, and three juvenile females. Four heavy metals (Hg, Pb, Cd, and Cr) and one metaloid (As) were analyzed in shark livers using an atomic absorption spectrophotometry with flame and hydride generator. Our results showed that the maximum concentrations found were: Hg=0.69mg/kg, Cd=0.43mg/kg, As=27.37mg/kg, Cr=0.70mg/kg. The minimum concentrations found were: As=14.91mg/kg, Cr=0.35mg/kg. The Pb could not be determined because the samples did not have the spectrophotometer minimum detectable amount (0.1mg/kg). None of the 19 samples analyzed showed above the permissible limits established by Mexican and American laws. There was a correlation between shark size and Cr and As concentration (Pearson test). The concentration of Cr and As was observed to be higher in bigger animals. There was not a significant difference in heavy metals concentration between juveniles and adults; however, there was a difference between males and females. A higher Cr concentration was found in females when compared to males. None of the samples exceed the maximum limit established by the laws of Mexico and the United States of America. Much longer studies are needed with C. limbatus and other species caught in the region, in order to determine the degree of contaminants exposure in aquatic ecosystems and to identify potential health risks to consumers.

La contaminación de los ecosistemas marinos y costeros por metales pesados en el Golfo de México es uno de los problemas que afectan a los recursos naturales del medio acuático. Los tiburones por situarse en niveles tróficos superiores de la red alimenticia acumulan y magnifican cantidades considerables de contaminantes. Por esta razón, el objetivo de este trabajo fue determinar la concentración de cuatro metales pesados (Hg, Cd, Pb y Cr) y un metaloide (As) en el tiburón punta negra (Carcharhinus limbatus) por medio de espectrofotometría de absorción atómica con flama y generador de hidruros. Se muestrearon 19 hígados de tiburones capturados cerca de Tamiahua, Veracruz entre noviembre 2007 y marzo 2008, de los cuales 12 fueron machos adultos, una hembra adulta, tres machos jóvenes y tres hembras jóvenes. Las concentraciones máximas registradas para cada metal fueron: Hg=0.69mg/ kg, Cd=0.43mg/kg, As=27.37mg/kg, Cr=0.35mg/kg. El Pb no fue detectado, no al menos la cantidad mínima de detección requerida por el espectrofotómetro de absorción atómica (0.1mg/kg). Ninguna de las muestras analizadas rebasó los límites máximos permisibles por las leyes mexicanas y americanas.

First record of the blacktip reef shark Carcharhinus melanopterus (Carcharhiniformes: Carcharhinidae) from the Tropical Eastern Pacific / Primer registro del tiburón punta negra Carcharhinus melanopterus (Carcharhiniformes: Carcharhinidae) del Pacífico Oriental Tropical

The blacktip reef shark Carcharhinus melanopterus, is one of the most common Indo-Pacific reef sharks. On April 29, 2012, a juvenile male blacktip reef shark measuring 89 cm total length (TL), was incidentally caught during a research expedition in Chatham Bay, Isla del Coco National Park, Costa Rica, located in the Tropical Eastern Pacific. This is the first record of the species from Isla del Coco National Park, Costa Rica, and from the Tropical Eastern Pacific.

El tiburón punta negra de arrecife, Carcharhinus melanopterus, es uno de los tiburones de arrecife más comunes del Indo-Pacífico. Durante una expedición científica al Parque Nacional Isla del Coco, Costa Rica, Pacífico Tropical Oriental, un tiburón punta negra de arrecife fue capturado en Bahía Chatham, Parque Nacional Isla del Coco, el 29 de abril 2012. El espécimen capturado era un macho juvenil de 89 cm. Este es el primer informe de esta especie para el Parque Nacional Isla del Coco, Costa Rica y para el Pacífico Tropical Oriental.

Análisis de abundancia, distribución y tallas de tiburones capturados por pesca artesanal en el parque nacional archipiélago los roques, Venezuela / Analysis of abundance, distribution and length of sharks caught by artisanal fishery in the los roques archipelago national park, Venezuela / Análise de abundância, distribuição e tamanhos de tubarões capturados mediante pesca artesanal no parque nacional arquipélago los roques, Venezuela

Se analizó la abundancia relativa, distribución y estructura de tallas de tiburones en el Parque Nacional Archipiélago Los Roques, Venezuela. La información fue obtenida a través del monitoreo de la pesca artesanal local dirigida a los tiburones durante 2001-2002. Fueron registradas un total de 13 especies de tiburones, de las cuales Carcharhinus limbatus (47,9%) y C. perezi (37,7%) dominaron la composición de la captura. Las especies Ginglymostoma cirratum, C. falciformis y Negaprion brevirostris obtuvieron conjuntamente un valor de importancia de 10,7%. El esfuerzo pesquero se concentró principalmente en el tercer trimestre en ambos años y a su vez a profundidad <10m. C. limbatus y C. perezi obtuvieron un promedio general en el índice de abundancia relativa (CPUE ±desv. estándar) de 2,76 ±2,43 y 2,35 ±2,17 ind 100-anz-1, respectivamente. Los ejemplares de C. limbatus midieron 53-218cm LT y el 96,5% resultaron ser juveniles capturados en la laguna central del archipiélago. En el caso de C. perezi, la captura estuvo conformada por individuos 67-270cm LT y el 82,6% fueron juveniles capturados en áreas poco profundas cercanas a las islas. Este estudio muestra que el Archipiélago Los Roques funciona como área de criadero para C. limbatus y C. perezi. La protección de las áreas de criadero, como estrategia de conservación, contribuiría directamente con el proceso natural del reclutamiento y mantenimiento del tamaño de las poblaciones y debe ser promovida en ese Parque Nacional.

Relative abundance, distribution and length structure of sharks were examined based on specimens caught during 2001 and 2002 by the artisanal shark fishery from Los Roques Archipelago National Park. A total of 13 species of sharks were reported during the study period, in which Carcharhinus limbatus (47.9%) and C. perezi (37.7%) were the most common frequently caught. Ginglymostoma cirratum, C. falciformis and Negaprion brevirostris together comprised 10.7% of the shark catch. The fishing effort was primarily concentrated during the third quarter in both years of the study period, and in the depth strata of < 10 m. General mean CPUE showed that the most abundant species were C. limbatus (2,76 ind 100-anz-1 ± 2,43 DS) and C. perezi (2,35 ind 100-anz-1 ± 2,17 DS). C. limbatus catches were constituted by individuals measuring between 53 and 218 cm TL. However, 96.5% of those caught were juveniles captured within the central lagoon of the archipelago. The catches of C. perezi were represented by individuals with sizes between 67 and 270 cm TL, and the 82.6% of them were juveniles captured in shallow water zones near the islands. The present study showed that the Los Roques Archipelago is an important nursery area for the species C. limbatus and C. perezi. The protection of the nursery areas of sharks, as a conservation measure, should be promoted in the study area.

Analisou-se a abundância relativa, distribuição e estrutura de tamanhos de tubarões no Parque Nacional Arquipélago Los Roques, Venezuela. A informação foi obtida através do monitoramento da pesca artesanal local dirigida aos tubarões durante 2001-2002. Foram registradas um total de 13 espécies de tubarões, das quais Carcharhinus limbatus (47,9 %) e C. perezi (37,7 %) dominaram a composição da captura. As espécies Ginglymostoma cirratum, C. falciformis e Negaprion brevirostris obtiveram conjuntamente um valor de importância de 10,7%. O esforço pesqueiro se concentrou principalmente no terceiro trimestre de ambos os anos e na profundidade <10m. C. limbatus e C. perezi obtiveram uma média geral no índice de abundância relativa (CPUE ±desv. estándar) de 2,76 ±2,43 e 2,35 ±2,17 ind 100-anz-1, respectivamente. Os exemplares de C. limbatus mediram 53-218cm LT e 96,5% resultaram ser juvenis capturados na lagoa central do arquipélago. No caso de C. perezi, a captura esteve conformada por indivíduos 67-270cm LT e 82,6% foram juvenis capturados em áreas pouco profundas próximas às ilhas. Este estudo mostra que o Arquipélago Los Roques funciona como área de criadouro para C. limbatus e C. perezi. A proteção das áreas de criadouro, como estratégia de conservação, contribuiria diretamente com o processo natural do recrutamento e manutençãoo do tamanho das populações e deve ser promovida nesse Parque Nacional.

Fetal mummification in silky shark (Carcharhinus falciformis) from the Gulf of California, Mexico

The aim of this work was the description of fetal mummification in silky shark. During July of 2001 in Santa Maria fishing camp, Gulf of California Mexico, fourteen pregnant female of silky sharks were captured. In all of them the embryos were found to be dehydrated. However, total observations were possible in only two litters. Six embryos in each analyzed litters were found. All the embryos were mummified, complete and without maceration. Because the litters were totally mummificated in several females, it was suggested that fetal mummification was produced by the environmental condition.

A mumificação fetal é caracterizada pela desidatração de embriões mortos dentro do útero da mãe. A perda de embriões pode afetar a sustentabilidade da população explorada, tornando o estudo deste fenômeno de suma importância. Em Julho de 2001 quatorze femeas grávidas do tubarão lombo preto foram capituradas durante uma amostragem no campo pesqueiro de Santa Maria, Golfo de California, México. Todas as fêmeas capturadas apresentaram embriões mumificados. Infelizmente, observações detalhadas dos embriões foram possíveis em apenas duas fêmeas. Cada fêmea analizada apresentava seis embriões, todos completamente mumificados e sem maceração. Embriões completamente mumificados foram encontrados em muitas fêmeas, o que sugere que a mumificação fetal desses embriões pode ter sido causada por condições ambientais.

CONSTITUENT ANALYSIS AND CONTENT DETERMINATION OF FATTY ACIDS AND SQUALENE OF SHARK LIVER OIL / 中国海洋药物

Reported in this paper is the constituent analysis of shark Carcharhinus latistomus from China by gas chromatography/mass spectrometry. Squalene and fifteen kinds of fatty acids were identified,the contents of squaiene and fatty acids were determined.