ABSTRACT
OBJETIVO: avaliar os fatores associados aos oÌbitos e ataques de tubaraÌo no Brasil. MÉTODO: trata-se de um estudo transversal, quantitativo, realizado mediante acesso virtual ao website do Global Shark Attack File. A análise foi realizada no programa R, a partir de estatística descritiva e dos testes de Qui-quadrado de Pearson e Teste Exato de Fisher. RESULTADOS: ocorreram 86 ataques, dos quais 26 (30,2%) resultaram em óbito. Foi encontrada associação entre a ocorrência de ataque com o ano, estado, região, dia da semana, turno e espécie do tubarão, além da faixa etária, sexo da vítima e local do corpo acometido. Nenhuma variável apresentou associação com o óbito. O estado de Pernambuco computou o maior número de ataques (83,7%) e óbitos (96,2%). CONCLUSÃO: os ataques de tubarão estiveram associados com nove variáveis: três de caracterização da vítima e seis do perfil do acidente. Os óbitos não apresentaram associação significativa. Pernambuco sobressaiu como estado com maior ocorrência de ataque e óbitos.
OBJECTIVE: to evaluate the factors associated with shark attacks and deaths in Brazil. METHOD: this is a cross-sectional and quantitative study, carried out through virtual access to the Global Shark Attack File website. The analysis was performed in the R program, using descriptive statistics and the Pearson's chi-square and Fisher's exact tests. RESULTS: there were 86 attacks, of which 26 (30.2%) resulted in deaths. An association was found between occurrence of the attacks and year, state, region, day of the week, shift and shark species, in addition to the victim's age group and gender and to the part of the body affected. No variable was associated with death as outcome. The state of Pernambuco accounted for the largest number of attacks (83.7%) and deaths (96.2%). CONCLUSION: shark attacks were associated with nine variables: three related to the victim's characterization and six to the profile of the accident. The deaths did not present a significant association. Pernambuco stood out as the state with the highest occurrence of attacks and deaths.
OBJETIVO: evaluar los factores asociados con las muertes y los ataques de tiburones en Brasil. MÉTODO: se trata de un estudio transversal, cuantitativo, realizado a través del acceso virtual al sitio web Global Shark Attack File. El análisis se realizó mediante el programa R, utilizando estadística descriptiva y chi-cuadrado de Pearson y prueba exacta de Fisher. RESULTADOS: hubo 86 ataques, de los cuales 26 (30,2%) resultaron en muerte. Se encontró que hay asociación entre el ataque y el año, estado, región, día de la semana, turno y especie de tiburón, además del rango etario, sexo de la víctima y parte del cuerpo afectada. Ninguna variable se asoció con la muerte. El estado de Pernambuco tuvo el mayor número de ataques (83,7%) y muertes (96,2%). CONCLUSIÓN: los ataques de tiburones se asociaron con nueve variables: tres de la caracterización de la víctima y seis del perfil del accidente. Las muertes no mostraron una asociación significativa. Pernambuco se destacó como el estado con mayor número de ataques y muertes.
Subject(s)
Humans , Animals , Male , Female , Infant, Newborn , Infant , Child, Preschool , Child , Adolescent , Adult , Young Adult , Sharks , Death , Bites and Stings/mortality , Brazil/epidemiology , Cross-Sectional Studies , Risk FactorsABSTRACT
Resumen En México, la captura del recurso pesquero tiburón-cazón (RTC) ocupa el décimo lugar de las 22 pesquerías más representativas del país, con un volumen anual promedio estimado en 29 772 T, y una derrama económica de 437 millones de pesos mexicanos. La captura máxima que se puede obtener sin agotar el recurso en ningún plazo, se denomina rendimiento máximo sostenible (RMS), y es uno de los principales puntos de referencia en la evaluación de pesquerías. El objetivo del presente estudio fue estimar el rendimiento máximo sostenible del recurso pesquero tiburón-cazón, agrupándolo en 26 regiones (México, océano Pacífico, golfo de México, 6 regiones de la NOM-029-PESC-2006 y 17 estados costeros). Se utilizaron series de tiempo de captura (STC), en toneladas por año de captura reportada (Cr) y captura total (Ct) (captura reportada + captura no reportada) del periodo de 1976 a 2014, y se aplicaron modelos empíricos que relacionan la captura máxima de la STC con el RMS. No hubo diferencias significativas entre los modelos. Con base en la Ct y el RMS estimados (T x 103) se evidencia una sobreexplotación del RTC en México (Ct = 51 417, RMS = 29 040), en el océano Pacífico (Ct = 38 654, RMS = 20 840) y en el golfo de México (Ct = 15 737, RMS = 14 540); en la Región 2 (golfo de California) (Ct = 22 664, RMS = 14 330) y Región 5 (línea costera de Tamaulipas, Veracruz y Tabasco) (Ct = 9 202, RMS = 8 510), y en la costa de los estados de Baja California (Ct = 5 781, RMS = 4 880) y Baja California Sur (Ct = 5 950, RMS = 5 510). Es necesario atender de forma urgente la problemática del aprovechamiento de este recurso pesquero en la república mexicana.
Abstract In Mexico, shark catch ranks 10th place out of the 22 most representative fisheries in the country, with an estimated annual average number of 29 772 T and an economic income of approximately MXN 437 million. The maximum sustainable yield (MSY), which means the maximum catch that can be obtained without the depletion of the fishing resource at any given time is one of the main points of reference in the evaluation of fisheries. In this study, the MSY of sharks in Mexico was estimated for 26 coastal areas (Mexico, Pacific ocean, gulf of Mexico, 6 regions of the NOM-029-PESC-2006 and 17 coastal States). Catch time series (CTS) were used in tons per year of reported catch (Rc) and total catch (Tc) (reported catch + non-reported catch) over the 1976 to 2014 period. In addition, empirical models that relate the maximum catch of the STM to the MSY were applied. There were no significant differences between the models applied. Based on the estimated Tc and MSY (T x 103) there is an over-exploitation of sharks in Mexico (Tc = 51 417, MSY = 29 040), in the Pacific ocean (Tc = 38 654, MSY = 20 840) and in the gulf of Mexico (Tc = 15 737, MSY = 14 540); in Regions 2 (gulf of California) (Tc = 22 664, MSY = 14 330) and 5 (coastal line of Tamaulipas, Veracruz and Tabasco) (Tc = 9 202, MSY = 8 510) and on the coast of the States of Baja California (Tc = 5 781, MSY = 4 880) and Baja California Sur (Tc = 5 950, MSY = 5 510). It is recommended to urgently address the problem of using this fishery resource in the Mexican Republic.
ABSTRACT
El estudio morfológico de la dentadura de chondrichthyes representa un carácter taxonómico importante empleado para la clasificación e identificación de diferentes especies. Se diafanizaron dientes de cuatro especies distintas de selacimorfos (Carcharhinus leucas, Galeocerdo cuvier, Rhizoprionodon longurio y Sphyrna sp.) con la finalidad de estandarizar una técnica dental para su transparentación. Estandarizando la técnica de Okumura-Aprile aplicada para la diafanización dental de humanos, se obtuvo una diafanización óptima en las cuatro especies en tratamiento con HCl al 7 % donde se podía observar con claridad la cámara pulpar, por lo que podemos concluir que la técnica de Okumura-Aprile es eficiente en la diafanización dental de tiburones.
The morphological study of the chondrichthyes teeth represents an important taxonomic characteristic used for the classification and identification of different species. The teeth of four different species of selacimorphs (Carcharhinus leucas, Galeocerdo cuvier, Rhizoprionodon longurio and Sphyrna sp.) were diaphonized in order to standardize a dental technique for their transparency. By standardizing the Okumura-Aprile technique applied for the dental diaphonization of humans, an optimal diaphonization was obtained in the four species treated with 7 % HCl where the pulp chamber was clearly observed. Therefore, we may conclude that the OkumuraAprile technique is efficient in shark dental diaphonization.
Subject(s)
Animals , Sharks/anatomy & histology , Tooth/anatomy & histology , Decalcification Technique/methods , Sharks/classificationABSTRACT
Introduction: Mustelus higmani is one of the shark species most commonly caught in the Northeastern region of Venezuela; however, this species has been poorly studied. Objective: To evaluate the age and growth of M. higmani on the basis of the optical analysis of vertebrae. Methods: Between August 2016 and July 2017, the vertebral samples were collected in the fishing port of Juan Griego, Margarita Island. The growth study was based on a sample of 238 individuals, 86 males (24.1-59.5 cm TL) and 152 females (24.4-69.5 cm TL) and the use of VBGF modeling approach. Results: The RMI analysis suggested an annual periodicity for the deposition of growth rings. Ages assigned varied between 0 and 5 years in males, and between 0 and 6 years in females. The estimates of VBGF parameters were L ¥ = 60.4 cm TL, k = 0.53 years-1 and t 0 = -1.02 years in males; and L ¥ = 71.1 cm TL, k = 0.38 years-1 and t 0 = -1.17 years in females. The ages at maturity and longevities resulted respectively in 2.6 and 6.6 years for males; and in 2.1 and 9.0 years for females. Conclusions: In general, results indicate that M. higmani has a rapid growth, early maturity, short longevity, and annual reproductive cycle, characterizing it as a biologically productive species.
Introducción: Mustelushigmani es una de las especies de tiburones más comúnmente capturadas en el nororiente de Venezuela; sin embargo, ha sido poco estudiada. Objetivo: Examinar la edad y crecimiento de M. higmani con base en el análisis óptico de las vértebras. Métodos: Entre agosto 2016 y julio 2017, se recolectaron muestras de vertebras en el puerto pesquero de Juan Griego, Isla de Margarita. La asignación de las edades se realizó con base en 238 ejemplares, 86 machos (24.1-59.5 cm LT) y 152 hembras (24.4-69.5 cm LT). Resultados: El análisis de RMI sugiere una periodicidad anual en la formación de los anillos de crecimiento. Las edades estuvieron comprendidas entre 0 y 5 años en los machos, y entre 0 y 6 años en las hembras. A su vez, los valores de los parámetros VBGF fueron L ¥ = 60.4 cm LT, k = 0.53 años-1 y t 0 = -1.02 años en los machos, y L ¥ = 71.1 cm LT, k = 0.38 años-1 y t 0 = -1.17 años en las hembras. Las edades medias de madurez y las longevidades resultaron respectivamente en 2.6 y 6.6 años para los machos, y en 2.1 y 9.0 años para las hembras. Conclusiones: En general los resultados indican que M. higmani presenta un crecimiento rápido, madurez temprana, corta longevidad y ciclo reproductivo anual, caracterizándola como una especie productiva desde el punto de vista biológico.
ABSTRACT
The nurse shark, Ginglymostoma cirratum (Bonnaterre, 1778) is one of the most studied species of elasmobranchs. However, the knowledge of their reproductive biology is still relatively rare, particularly in the western South Atlantic. This study aimed to describe the morphology of the uterus and the ovary of G. cirratum, based on specimens caught off at the Fortaleza/CE coast, northeast Brazil. Samples were collected from September 2012 to June 2013, from regular landings of artisanal fishing, which commercialize this species freely. A total of ten females were collected. The methodologies followed for analyzing the ovaries and uterus of those females included both macroscopic and histological analysis. G. cirratum has internal type ovary morphology, with invaginations of connective tissue, which defines compartments and separate oocyte groups in ovigerous lots. The epithelium lining the ovary changes from simple columnar ciliated in the area without ovigerous lots, which turns into a simple cubic epithelium in the coating portion of the epigonal organ where ovarian tissue is absent. The uterine mucosa has secretory cells denoted by Alcian Blue staining, indicating the production of mucopolysaccharides, even in immature individuals. This lecithotrophic shark has a uterine vascularized mucosa that is one characteristic of viviparous elasmobranch species.(AU)
O tubarão-lixa, Ginglymostoma cirratum (Bonnaterre, 1778) é uma das espécies mais estudadas de elasmobrânquios. O conhecimento de sua biologia reprodutiva, no entanto, ainda é relativamente raro, particularmente no Oeste do Atlântico Sul. Este estudo objetivou a descrição morfológica do útero e ovário de G. cirratum, baseado em espécimes capturados na costa de Fortaleza/CE, no Nordeste do Brasil. Um total de dez fêmeas foi coletado de setembro de 2012 a junho de 2013, nos desembarques regulares da pesca artesanal, que comercializam essa espécie livremente. A metodologia foi de acordo com as analises macroscópica e histológica dos ovários e útero. G. cirratum tem o tipo de morfologia de ovário interno, com invaginações de tecido conjuntivo, que define compartimentos e separa grupos de oócitos em lotes ovígeros. O epitélio que reveste o ovário varia de epitélio simples colunar ciliado na área que não apresenta lotes ovígeros para epitélio simples cúbico na porção de revestimento do órgão epigonal, onde o tecido ovariano é ausente. A mucosa uterina possui células secretoras, evidenciadas pela coloração em Alcian Blue, indicando a produção de mucopolissacarídeos, mesmo em indivíduos imaturos. Este tubarão lecitotrófico apresenta a mucosa uterina vascularizada, sendo esta uma característica de espécies de elasmobrânquios vivíparos.(AU)
Subject(s)
Animals , Female , Ovary/anatomy & histology , Sharks/anatomy & histology , Uterus/anatomy & histologyABSTRACT
Abstract A review and update to the shark and ray species recorded for the marine waters of Colombia was carried out. A total of 206 species had been recorded in the literature, of which 138 species (76 sharks and 62 rays) could be confirmed from museum records, catches, photographs, and videos. No evidence was found for 25 species, but their distribution included neighboring countries, and they were therefore classified as possible based on distribution. Thirty- six species were classified as improbable based on distribution and seven more were considered as misidentifications. The inventory of confirmed species includes 57 genera (30 shark and 27 batoid genera) and 34 families (18 shark and 16 batoid families). There was notably an addition of 26 confirmed species since 2007 as well as numerous modifications to group systematics and taxonomy, especially for batoids. The total number of confirmed elasmobranchs represented 12.1% of species known worldwide, and could even reach 14.5%, indicating that Colombia has one of the richest cartilaginous fish faunas in Latin America, behind Mexico and Brazil. This demonstrates that although Colombia cannot be considered an elasmobranch biodiversity hotspot or site of elasmobranch endemism globally, it does have good representativity of these species' biodiversity at the regional level, especially regarding amphi-American species.
Resumen Se llevó a cabo una revisión y actualización de los registros de especies de tiburones y rayas de aguas marinas colombianas. En la literatura se había registrado un total de 206 especies, de las cuales 138 (76 tiburones y 62 rayas) se habian podido confirmar con registros de museo, capturas, fotografías y videos. No se encontró evidencia de 25 especies, pero su distibución incluye países vecinos, por lo que fueron clasificadas como "posible basada en la distribución". Treinta y seis especies se clasficaron como "improbable basada en la distribución" y siete más se consideraron identificaciones erróneas. El inventario de especies confirmadas incluye 57 géneros (30 tiburones y 27 géneros batoideos) y 34 familias (18 tiburones y 16 familias batoideas). De modo notable, hubo una adición de 26 especies confirmadas desde 2007, así como numerosas modificaciones de la sistemática y taxonomía del grupo, especialmente para batoideos. El número total de elasmobranquios confirmados representó el 12.1 % de las especies conocidas en el mundo, y podría aún alcanzar el 14.5 %, lo cual indica que Colombia tiene una de las faunas de peces cartilaginosos más ricas de Latinoamérica, después de México y Brasil. Esto demuestra que, aunque Colombia no puede ser considerada un punto caliente de biodiversidad de elasmobranquios o un sitio de endemismo de elasmobranquios a nivel global, sí tiene una buena representatividad de la biodiversidad de estas especies a nivel regional, especialmente respecto a especies anfi-americanas.
Resumo Realizou-se uma revisão e atualização dos registros de espécies de tubarões e arraias de água marinha colombianas. Na literatura se encontrava registro de um total de 206 espécies, das quais 138 (76 tubarões e 62 arraias) foram possíveis de confirmação por meio de registros de museus, capturas, fotografias e vídeos. Não se encontrou evidencia de 25 espécies, mas suas distribuições incluem países vizinhos, sendo então classificadas como "possível com base na distribuição". Trinta e seis espécies se classificaram como "improváveis com base na distribuição" e outras sete se consideraram identificações errôneas. O inventário de espécies confirmadas inclui 57 gêneros (30 tubarões e 27 gêneros de batóides) e 34 famílias (18 tubarões e 16 famílias batóides). Notavelmente, houve uma adição de 26 espécies confirmadas desde 2007, assim como numerosas modificações da sistemática e taxonomia do grupo, especialmente para batóides. O número total de elasmobrânquios confirmados representou um 12.1 % das espécies conhecidas no mundo, e poderia ainda alcançar 14.5 %, o que indica que Colômbia tem uma das faunas mais rica da América Latina em peixes cartilaginosos, depois de México e Brasil. Isto mostra que Colômbia, ainda que possa não ser considerada um ponto de referência de biodiversidade de elasmobrânquios ou um local de endemismo de elasmobrânquios a nível global, possui uma boa representatividade da biodiversidade de estas espécies a nível regional, especialmente com respeito a espécies anfi-americanas.
ABSTRACT
El tiburón martillo (Sphyrna zygaena (Linnaeus, 1758)) es una de las especies de elasmobranquios más utilizada para consumo humano en el Perú. Sin embargo, se desconoce los niveles de mercurio que contiene su carne. Este trabajo tuvo como objetivo evaluar los niveles de mercurio hallados en el músculo del tiburón martillo y su posible implicancia en la salud humana. Además, determinar si existe una correlación entre el tamaño del tiburón y los niveles de mercurio. Analizamos 27 muestras de músculo de neonatos y juveniles capturados en el norte del Perú. La concentración de mercurio varió entre 0.13 - 0.85 mg kg-1 peso húmedo. Se encontró una relación negativa y significativa entre el tamaño corporal del tiburón y los niveles de mercurio. Este trabajo representa el primer estudio que evalúa los niveles de mercurio de tiburones en el Perú. Si bien los valores hallados fueron menores a lo recomendado por la Organización Mundial de la Salud (< 1 mg kg-1), se recomienda ampliar este tipo de estudios en individuos adultos de tiburón, así como en otros recursos hidrobiológicos de consumo humano.
The smooth hammerhead shark Sphyrna zygaena (Linnaeus, 1758) is one of the elasmobranch species most used for human consumption in Peru. However, the level of mercury in hammerhead muscle tissue is unknown. This study assessed the level of mercury found in the muscle of hammerhead sharks and its relation with human health. Moreover, we evaluated the relationship between shark body size and mercury levels. We analyzed 27 muscle samples of neonates and juveniles captured in northern Peru. Mercury concentrations varied between 0.13 and 0.86 mg kg-1 wet weight. Moreover, we found a negative and significant relationship between shark body size and mercury levels. This study represents the first evaluation of mercury levels of sharks in Peru. Although the values found do not exceed levels recommended by the World Health Organization (< 1 mg kg-1), we recommend expanding this study to include other size classes of sharks as well as other marine resources used for human consumption.
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Resumen:A pesar de la gran importancia ecológica, evolutiva y económica de los condrictios, su diversidad ha sido escasamente estudiada en México. En este estudio se describe la diversidad de especies de condrictios que se han registrado hasta el momento para México, la cual se compone de 214 especies (111 tiburones, 95 rayas y 8 quimeras) y representa el 17.3 % de las registradas a nivel mundial. Las familias con mayor diversidad de especies son Rajidae (14.5 %), Carcharhinidae (12.1 %), Pentanchidae, Triakidae y Urotrygonidae (5.1 %). En términos de su distribución geográfica, la diversidad del litoral del Pacífico mexicano contiene el 56.1 % del total de aquellas que habitan en las aguas marinas y salobres de México (120 spp., 62 géneros, 37 familias y 14 órdenes); porcentaje muy similar a las que habitan en el litoral del Atlántico con el 55.1 % de las especies (118 especies, 59 géneros, 35 familias y 13 órdenes). Las afinidades biogeográficas de la fauna de condrictios mexicanos son complejas, pues 19.7 % de las especies son circunglobales, 9.9 % trasatlánticas, 1.9 % transpacíficas y 9.4 % son endémicas de la zona económica exclusiva. Además, el 36.6 % de las especies son endémicas del Pacífico oriental, presentan mayor afinidad a la provincia de Cortés (27.7 %), seguida de la de California (20.7 %), Panamá (19.3 %), Galápagos (5.6 %) y Peruano-Chilena (8.9 %). Así mismo, el 33.3 % de las especies son endémicas del Atlántico occidental donde tienen mayor afinidad con la provincia Caribeña (31.9 %), seguido por la Caroliniana (24.4 %) y Brasileña (6.6 %).
Abstract:The diversity of chondrychthyans in Mexico is described. The fauna is composed by 214 species (111 sharks, 95 rays and 8 chimaeras) and represents 17.3 % of the total number of species recorded worldwide. The families with the highest diversity comprise: Rajidae (14.5 %), Carcharhinidae (12.1 %), Pentanchidae, Triakidae, and Urotrygonidae (5.1 %). In terms of geographical distribution, the diversity on the Mexican Pacific slope reaches up to 56.1 % of those species inhabiting Mexican marine and brackish waters (120 species, 62 genera, 37 families and 14 orders); the diversity in the Atlantic slope resulted similar to that on the Mexican Pacific with 55.1 % of the species (118 species, 59 genera, 35 families and 13 orders). The biogeographical affinities of the Mexican chondrychthyan fauna are complex with 19.7 % of the species being circumglobal, 9.9 % transatlantic, 1.9 % transpacific, and 9.4 % endemic to the exclusive economic zone. Additionally, 36.6 % of the species recorded so far are endemic to the Eastern Pacific coast where the species are similar to those found in the Cortez biogeographic province (27.7 %), followed by the Californian (20.7 %), Panamanian (19.3 %), Galapagos (5.6 %) and Peruvian-Chilean (8.9 %). Likewise, 33.3 % are endemic of the Atlantic coast, where species are similar to those found in the Caribbean province (31.9 %), followed by the Carolinean (24.4 %) and the Brazilian (6.6 %). Rev. Biol. Trop. 64 (4): 1469-1486. Epub 2016 December 01.
Subject(s)
Animals , Sharks/classification , Skates, Fish/classification , Chordata/classification , Biodiversity , Animal Distribution , Sharks/physiology , Species Specificity , Atlantic Ocean , Pacific Ocean , Skates, Fish/physiology , Chordata/physiology , MexicoABSTRACT
During 1995, 2001, 2003, 2004 and 2007; we studied the temporal variation in the structure of the elasmobranch assemblage along the Colombian Pacific coast using: the community index of diversity, heterogeneity, equitability, species composition, average catch sizes, and mean trophic levels. A total of 1711 specimens from 19 species (7 sharks and 12 rays) were collected during the 90 trawling operations. The number of species captured varied between 7 (1995) and 12 (2007) demonstrating a trend towards an imbalance in the assemblage attributes. In 1995, the mean trophic level (TLm) of the assemblage was 3.60, but in 2007 it decreased to 3.55 when the functional level of large predators was absent (TL > 4). These results suggest changes in species composition, structural attributes, and a reduction of the highest functional level. Alterations to the catch proportions were also found: i.e. a greater abundance of rays of lower trophic levels. This study suggests an effect of trawling on the stability of this tropical coastal ecosystem.
Durante 1995, 2001, 2003, 2004 y 2007 estudiamos la variación temporal en la estructura de un ensamblaje de elasmobranquios a lo largo de la costa pacífica colombiana. Para ello utilizamos los índices de diversidad, heterogeneidad, equitatividad y composición de especies, así como el tamaño promedio de capturas y los niveles tróficos promedio. Se colectó un total de 1711 especímenes de 19 especies (7 tiburones y 12 rayas) durante 90 operaciones de pesca de arrastre. El número de especies capturadas varió entre 7 (1995) y 12 (2007), lo cual demuestra una tendencia hacia un desbalance en los atributos del ensamblaje. En 1995 el nivel trófico promedio (TLm) del ensamblaje fue de 3.60, pero en 2001 disminuyó a 3.55, cuando estuvo ausente el nivel funcional de grandes predadores (TL > 4). Estos resultados sugieren cambios en la composición de especies y en los atributos estructurales, y una reducción del nivel funcional superior. Se encontraron también alteraciones en las proporciones de captura, como una mayor abundancia de rayas de niveles tróficos inferiores. Este estudio sugiere un efecto de la pesca de arrastre en la estabilidad de este ecosistema tropical costero.
Durante 1995, 2001, 2003, 2004 e 2007 estudamos a variatilo temporal na estrutura da comunidade de elasmobranquios ao longo da costa pacífica colombiana usando o índice comunitário de diversidade, heterogeneidade, equidade, composic. So de espécies, tamanho médio das capturas e níveis tróficos médios. Um total de 1711 espécimes de 19 espécies (7 tubarões e 12 raias) foram coletadas durante as 90 operações de pescas de arrasto. O número de espécies capturadas variou entre 7 (1995) e 12 (2007), demonstrando uma tendencia ao desequilibrio nos atributos da comunidade. Em 1995, o nível trófico médio (TLm) da comunidade era de 3,60, mas em 2007 decresceu para 3,55 quando o nível funcional de grandes predadores estava ausente (TL ≥ 4). Estes resultados sugerem alterações na compostilo das espécies, em atributos estruturais e uma redução do mais alto nível funcional. Também foram encontradas alterações na propongo de capturas, ou seja, uma maior abundancia de raias de níveis tróficos mais baixos. Este estudo sugere um efeito da pesca de arrasto na estabilidade de este ecossistema costeiro tropical.
ABSTRACT
The protection of the habitats used by juvenile sharks is a management strategy that has recently caught the attention of fishery biologists. In the present study, we evaluated the population of the lemon shark (Negaprion brevirostris) from Los Roques Archipelago in order to identify the nursery area, describe the size composition, and examine the variation in nocturnal activity of the juvenile individuals. The data analysed came from three different sources: commercial shark fishery, tag-recapture sampling, and visual records. A total of 375 lemon sharks with total lengths between 55 and 281 cm were recorded during the study period. Overall data showed that the area occupied by juvenile lemon sharks was clearly partitioned into primary and secondary nurseries. Additionally, nighttime activity seemed to change according to the size of sharks in the primary nursery, suggesting a reduction of time activity overlapping among juveniles of distinct size/age. Results suggest that the strategy of utilization of the primary nurseries by the lemon shark may lead to important ecological benefits by reducing the competition, predation and natural mortality.
La protección de los hábitats utilizados por tiburones juveniles es una estrategia de manejo que ha capturado recientemente la atención de los biólogos de pesquerías. En el presente estudio se evaluó la población del tiburón limón (Negaprion brevirostris) del Archipiélago Los Roques con el fin de identificar su zona de cría, describir su composición de tamaño y examinar la variación en la actividad nocturna de los juveniles. Los datos analizados provienen de 3 fuentes distintas: pesquería comercial de tiburones, muestreo de captura-marcaje-recaptura y registros visuales. Durante el período de estudio se registró un total de 375 tiburones limón, con longitudes totales entre 55 y 281 cm. En general, los datos mostraron que el área ocupada por los tiburones limón estaba claramente dividida entre zonas de cría primarias y secundarias. Adicionalmente, la actividad nocturna parecía cambiar de acuerdo con el tamaño de los tiburones en la zona de cría primaria, lo cual sugiere una reducción de la coincidencia entre juveniles de distinto tamaño/edad. Los resultados sugieren que la estrategia de utilización de la zona de cría primaria por el tiburón limón puede conducir a importantes beneficios ecológicos por la reducción de competencia, predación y mortalidad natural.
A protecao dos habitats utilizados pelos tubaroes jovens é uma estratégia de manejo que recentemente tem chamado á atenção dos biólogos pesqueiros. No presente estudo avaliamos a populacao do tubarao limao (Negaprion brevirostris) no Arquipélago de Los Roques, com o propósito de identificar a área de berçário, descrever a composição de tamanhos, e examinar a variação da atividade noturna dos individuos jovens. Os dados analisados foram originados a partir de tres fontes diferentes: Foram analisados dados da pescaría comercial de tubaroes, trabalhos de marcação e recaptura, e registos visuais. Um total de 375 tubaroes limáo com comprimento total entre 55 e 281 cm foi registado durante o período de estudo. Os dados mostram que a zona ocupada pelos tubaroes limao jovens se encontra claramente dividida em áreas de berçários primaria e secundária. Adicionalmente, a atividade noturna dentro da área de berçário primaria pareceu mudar de acordo com o tamanho dos tubaroes, sugerindo uma separação desta atividade por grupos de idade. Os resultados sugerem que a estratégia de utilizacao da área de berçário primaria do tubarao limao poderia oferecer importantes benefícios ecológicos, como a reducao da competicao, predacao e mortalidade natural.
ABSTRACT
Para conocer los patrones zoogeográficos de los elasmobranquios marinos de Colombia, la riqueza de especies de Pacífico y Caribe y sus subáreas (Pacífico costero, Pacífico oceánico, Caribe costero y Caribe oceánico) fue analizada. Las áreas compartieron 10 familias, 10 géneros y 16 especies de tiburones y ocho familias, tres géneros y cuatro especies de batoideos. Carcharhinidae tuvo la mayor contribución a la riqueza de tiburones mientras que Rajidae y Urotrygonidae tuvieron la mayor contribución a la riqueza de batoideos en el Caribe y el Pacífico, respectivamente. La mayoría de los elasmobranquios estuvieron asociados con hábitats bénticos y costeros. El análisis de similitud permitió la identificación de cinco grupos de familias que caracterizan la riqueza de elasmobranquios en ambas áreas. La diversidad beta indicó que el mayor recambio de especies se produjo entre el Pacífico costero y las dos subáreas del Caribe. La diferencia en la riqueza y composición de especies entre las áreas puede ser debida a eventos vicariantes tales como el surgimiento del Istmo de Panamá. Es poco probable que la diversidad de elasmobranquios en Colombia se originara de un único evento de colonización. Eventos locales de diversificación/especiación, dispersión desde las regiones templadas de América, del Pacífico y del Atlántico son orígenes posibles que no se excluyen entre sí.
In order to investigate zoogeographical patterns of the marine elasmobranch species of Colombia, species richness of the Pacific and Caribbean and their subareas (Coastal Pacific, Oceanic Pacific, Coastal Caribbean, Oceanic Caribbean) was analyzed. The areas shared 10 families, 10 genera and 16 species of sharks, and eight families, three genera and four species of batoids. Carcharhinidae had the highest contribution to shark richness, whereas Rajidae and Urotrygonidae had the greatest contribution to batoid richness in the Caribbean and Pacific, respectively. Most elasmobranchs were associated with benthic and coastal habitats. The similarity analysis allowed the identification of five groups of families, which characterize the elasmobranch richness in both areas. Beta diversity indicated that most species turnover occurred between the Coastal Pacific and the two Caribbean subareas. The difference in species richness and composition between areas may be due to vicariant events such as the emergence of the Isthmus of Panama. It is unlikely that the Colombian elasmobranch diversity originated from a single colonization event. Local diversification/speciation, dispersal from the non-tropical regions of the Americas, a Pacific dispersion and an Atlantic dispersion are origin possibilities without any of them excluding the others.
Subject(s)
Animals , Sharks/growth & development , Biodiversity , PhylogeographyABSTRACT
Sexual dimorphism is a widespread feature in several groups of vertebrates. Chondrichthyans differ sexually due to the presence of the clasper, a structure for internal fertilization, and other sexual differences in secondary characteristics. Nevertheless, studies assessing these variations are fairly rare. The main goal of this study is to identify differences in sexual dimorphism in three species of sharks from the Carcharhinidae family (Rhizoprionodon porosus, Carcharhinusporosus and Isogomphodon oxyrhynchus) using morphometric tools. A total of 213 specimens were captured in the Amazonian Equatorial Coast and analyzed using 65 morphometric characters. Discriminant analysis and The Student's t-test were used to demonstrate the morphological differences among sexes. Sexual dimorphism was reported at different levels for the three species. This study suggests that the most likely explanation for the presence of these variations is related to their reproductive characteristics and mating behavior.
El dimorfismo sexual es una característica presente en diversos grupos de vertebrados. Machos y hembras de Chondrichthyes se identifican fácilmente por la presencia de una estructura para la fertilización interna, el clasper, y otras pequeñas diferencias en las características secundarias. Sin embargo, los estudios que evalúan estas variaciones en la morfología entre los sexos son poco frecuentes. El objetivo de este trabajo es identificar el dimorfismo sexual en tres especies de tiburones de la familia Carcharhinidae (Rlhizoprionodon porosus, Carcharhinus porosus y Isogomphodon oxyrhynchus) con el uso de herramientas morfométricas. Se capturaron un total de 213 ejemplares en la costa Ecuatorial Amazónica y fueran analizados utilizando 65 caracteres morfométricos. Fueran aplicadas análisis discriminantes y prueba t-student para mostrar las diferencias morfológicas entre los sexos. Se observó dimorfismo sexual en diferentes niveles para las tres especies. Sugerimos que la explicación más probable para la presencia de estas variaciones está relacionada con las características reproductivas y el comportamiento de cópula.
O dimorfismo sexual é uma característica presente em vários grupos de vertebrados. Machos e fèmeas de Chondrichthyes são facilmente identificados pela presenca de uma estrutura para a fertilização interna, o clasper, além de outras diferencas em características secundárias. No entanto, estudos que avaliam estas variacóes na morfologia externa entre os sexos são raros. O principal objetivo deste estudo é identificar dimorfismo sexual em très espécies de tubarão da familia Carcharhinidae (Rhizoprionodon porosus, Carcharhinus porosus e Isogomphodon oxyrhynchus) através do uso de ferramentas morfométricas. Um total de 213 espécimes foi capturado na costa Equatorial Amazónica e analisado através de 65 caracteres morfométricos. Análises discriminantes e teste t-student foram aplicados para evidenciar as diferencas morfológicas entre os sexos. Nós observamos dimorfismo sexual, em diferentes níveis, para as très espécies estudadas e sugerimos que a causa mais provável para a presenca de tais variacóes está relacionada a características reprodutivas e comportamentos copulatórios.
ABSTRACT
Resumen De mayo 2010 a mayo 2011 se recolectó información referente a 67 faenas pesqueras artesanal con línea de fondo (44.8% observaciones abordo y 55.2% observaciones de descargas en centros de acopio) realizadas en Golfo Dulce, Pacífico Sur de Costa Rica. Durante las 67 faenas de pesca se analizaron en total 609 tiburones pertenecientes a diez especies. De estas, sobresalen S. lewini (más de 51.8% del total de tiburones analizados), M. lunulatus (23.5%), R. longurio, (13.8%) y C. limbatus (8.9%). Otras especies G. cirratum, G. cuvier, N.velox, S. tiburo y H. mexicanus fueron muy esporádicas ya que aportaron cerca del 2.0% del total. La condición de captura, el bajo valor comercial y la disponibilidad de los pescadores, permitió liberar con vida y sin anzuelos un total de 65 tiburones y 111 rayas, de las cuales 75.7% fueron rayas látigo (D. longa), 12.6% rayas gavilana (A. narinari), 5.4% rayas nariz de vaca (R. steindachneri), 5.4% rayas guitarra (R. leucorhynchus), 2.7% rayas de puntos (U. chilenis), 0.9% rayas mariposa (G. marmorata) y 0.9% mobula (Mobula sp.). Los análisis de CPUE en Golfo Dulce revelaron las mayores CPUE de tiburones en julio-agosto, mientras las mayores capturas de rayas se presentaron en enero-febrero.
Abstract Since May 2010 until May 2011 biological and fishery information regarding 67 artisanal fishing operations were collected in different areas of Golfo Dulce. A total of 30 (44.8%) onboard operations and 37 (55.2%) landings were observed. During onboard operations, a total of 872 fish were caught: 345 (39.6%) were sharks (Sphyrnidae, Carcharhinidae, Heterodontidae, Ginglymostomatidae and Triakidae), 228 (26.1%) "bait" fish (Aridae), 112 (13.1%) rays (Dasyatidae, Myliobatidae, Rhinobatidae and Mobulidae) and 111 (12.7%) commercial fish (Lutjanidae, Serranidae Sciaenidae). The capture condition (dead or alive), the low commercial value and the availability of fishermen, allowed us to release 65 sharks and 111 rays, all of them were alive and without hooks. Of these 75.7% were stingrays (D. longa), 12.6% eagle ray (A. narinari), 5.4% cownose rays (R. steindachneri), 5.4% guitar fish (R. leucorhynchus), the spoited ray 2.7% (U. chilenis), 0.9% butterfly ray (G. marmorata), and 0.9% mobula (Mobula sp.). The CPUE rate shows that the sharks and rays contributed more than 50% of the total catch of fishing operations. However, the months when the fishermen caught more sharks, the rays were not abundant. July and August were the months with the highest shark CPUE, while January-February were the months with the highest ray catches. Regarding the 37 landings observations, a total of 264 sharks were analyzed, being the scalloped hammerhead shark the most abundant (S. lewini, n=163), with 61.7%, followed by the common soothhound shark (M. lunulatus, n=48) (18.2%), the blacktip shark (C. limbatus, n=27) (10.2%) the pacific sharpnose shark (R. longurio, n=24) (9.1%), whitenose shark (0.4%) (Nasolamia velox, n=1) and the bonnethead shark (0.4%) (Sphyrna tiburo, n=1). The fusion of biological and fishery data from onboard observations and landings made it possible to analyze a total 609 sharks belonging to ten species. Of these, S. lewini represented more than 51.8% of total sharks analyzed; M. lunulatus, 23.5% R. longurio, 13.8% and C. limbatus, 8.9%. Other species G. cirratum, G. cuvier, N. velox, shovel head shark (S. tiburo) and the horn shark H. mexicanus were very sporadic since they contributed only 2.0% of the total. Analyses of length of S. lewini showed that they are mostly juveniles (74.31±17.4cm). Similar situation was found with individuals of R. longurio, M. lunulatus and C. limbatus whose mean total lengths were of 65.22±14.04cm, 94.08±23.64cm 4.44cm respectively 76.65cm. Rev. Biol. Trop. 63 (2): 183-198. Epub 2015 June 01.
Subject(s)
Animals , Sharks/classification , Skates, Fish/classification , Fisheries/trends , Fishes/classification , Costa RicaABSTRACT
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.
Subject(s)
Animals , Female , Male , Liver/chemistry , Metals, Heavy/analysis , Sharks , Arsenic/analysis , Cadmium/analysis , Chromium/analysis , Lead/analysis , Mexico , Mercury/analysis , Spectrophotometry, Atomic , Water Pollutants, Chemical/analysisABSTRACT
Isla del Coco is an oceanic island 500km off the Pacific coast of Costa Rica. It is a National Park and its marine fauna has been relatively well protected. The island is famous for its elasmobranch (sharks, rays and skates) sightings in shallow waters. Here we present a catalogue of the deepwater elasmobranchs observed with the DeepSee submersible. Five species of sharks, six species of skates and one ray have been observed between 45 and 330m depth. Triaenodon obesus, the white tip reef shark, was commonly observed between 80 and 301m, but only in the afternoons. Sphyrna lewini, the scalloped hammerhead shark, was observed as deep a 303m, but commonly between 45 and 90m, and close to the island. Odontaspis ferox, the smalltooth sand tiger shark, was observed between 82 and 316m. Echinorhinus cookei, the prickly shark, was observed between 91 and 320m. Rhincodon typus, the whale shark, was observed only close to the island, between 77 and 80m. Taeniura meyeni, the marbled ray, was observed only close to the island, between 45 and 90m. A Dasyatis sp., similar to the the diamond stingray, was observed only once close to the island at 60m; this is the first report of this genus at Isla del Coco National Park. Manta birostris, the giant manta, was only observed close to the island at 90m. Mobula tarapacana, the sicklefin devil ray, was observed between 60 and 326m, extending its maximum depth almost 10 times what has been reported. Aetobatus narinari, the spotted eagle ray, was observed only close to the island between 60 and 82m. Torpedo peruana, the Peruvian torpedo ray, was observed only once at 313m, and is the first record of this species from Isla del Coco National Park.
La Isla del Coco es una isla oceánica a 500km de la costa Pacífica de Costa Rica. Es un Parque Nacional donde la fauna marina ha estado relativamente bien protegida. La isla es famosa por los elasmobranquios (tiburones y rayas) en aguas poco profundas. Aquí presentamos un catálogo de elasmobranquios observados con el sumergible DeepSee. Cinco especies de tiburones y siete especies de rayas han sido observadas entre 45 y 330m de profundidad. Triaenodon obesus, tiburón punta blanca de arrecifes o tiburón cazón coralero, observado comúnmente entre 80 y 301m pero solo en las tardes. Sphyrna lewini, el tiburón martillo o cornuda común, registrado hasta 303m, pero comúnmente entre 45 y 90m, y cerca de la Isla del Coco. Odontaspis ferox, tiburón solrayo, visto entre 82 y 316m. Echinorhinus cookei, tiburón negro espinoso, avistado entre 91 y 320m. Rhincodon typus, tiburón ballena, observado solamente cerca de la isla, entre 77 y 80m. Taeniura meyeni, raya moteada, vista solamente cerca de la isla, entre 45 y 90m. Dasyatis sp., parecida a la raya látigo, registrada solamente una vez, cerca de la isla a 60m; este es el primer informe de esta especie en el Parque Nacional Isla del Coco. Manta birostris, manta gigante, observada únicamente cerca de la isla a 90m. Mobula tarapacana, manta cornuda o manta moruma, vista entre 60 y 326m, extendiendo su profundidad máxima casi 10 veces a lo informado en la literatura. Aetobatus narinari, chucho pintado o raya águila, observada solamente cerca de la isla entre 60 y 82m. Por último, Torpedo peruana, raya torpedo eléctrico o raya peruana, solamente vista una vez a 313m y es el primer informe de esta especie en el Parque Nacional Isla del Coco.
Subject(s)
Sharks/anatomy & histology , Skates, Fish/classification , Elasmobranchii/classification , Biodiversity , Costa RicaABSTRACT
White-tip reef sharks are common inhabitants of the shallow waters surrounding the Galapagos Islands, where several known aggregation sites have become touristic attractions. With the aim to describe site fidelity and residency patterns of the white-tip reef sharks in a saltwater creek, we used the ultrasonic telemetry method. The study was undertaken in a saltwater channel South of Academy Bay, Santa Cruz Island, from May 2008-September 2009. A total of nine transmitters were attached to sharks and ultrasonic receivers were deployed at the inner and outside areas of the creek. From the total of fitted sharks, four lost their transmitters. The results obtained with the remaining sharks showed an elevated use of the inner area of the channel during the day, with more use of the external area during the night. However, none of the sharks were detected at the site every day, suggesting that they may have a number of preferred sites within their home range. More studies are needed to detail the home range and habitat use of this species, and to guide its protection level in the AcademyBay area. Rev. Biol. Trop. 60 (2): 735-743. Epub 2012 June 01.
Los tiburones punta blanca de arrecife son habitantes comunes de las aguas que rodean las Islas Galápagos, por lo que muchos de sus sitios de agregación se han convertido en atractivos turísticos. Con el objetivo de describir la fidelidad del sitio y los patrones de residencia de nueve tiburones desde mayo 2008-septiembre 2009, se utilizó telemetría ultrasónica en un canal de agua salada en el sur de Bahía Academia, Isla Santa Cruz. A pesar de que cuatro tiburones perdieron sus transmisores, los restantes tiburones monitoreados mostraron un uso elevado del interior del canal durante el día y del exterior durante la noche. Sin embargo, ninguno de los tiburones fue detectado en el sitio diariamente, lo cual sugiere que deben tener un número mayor de sitios preferidos dentro de su área de vida.
Subject(s)
Animals , Behavior, Animal/physiology , Ecosystem , Sharks/physiology , Ecuador , Population Dynamics , Sharks/classification , TelemetryABSTRACT
One hundred seventeen specimens of sharks were caught along the coast of Pernambuco State, Northern Brazil, between May 2004 and May 2007, among which 86 were blacknose sharks, Carcharhinus acronotus, enabling a more detailed study of the species. Blacknose sharks were caught in the 2 study areas along the Boa Viagem/Piedade and Paiva beaches, accounting for the highest relative abundance among the species caught (73.5 percent of total). Potentially dangerous sharks, tiger and bull sharks, were also caught in the same areas, whereas hammerhead and blacktip sharks were only captured off Boa Viagem/Piedade. Concerning the blacknose shark, the total length (TL) ranged from 39.0 to 180.0 cm. Among the 38 females analysed, 32 were juveniles, 11 were maturing, 2 were pre-ovulatory and 21 were pregnant. Sexing was possible for 75 of the 83 embryos, 38 of which were males and 37 were females, with a sex proportion of 1:0.9 and total length ranging between 6.4 and 63.5 cm. Ovarian fecundity ranged from 5 to 10 and uterine fecundity from 1 to 3, with an estimated gestational period of 9 months. Among the 48 males, 6 were juveniles and 42 were adults. Both males and females seem to reach sexual maturity at about 105.0 cm TL. Among the 86 stomachs analysed, only 22.1 percent had contents, with teleosts as the most frequent item.
Entre maio de 2004 e maio de 2007, foram capturados 117 exemplares de tubarões na costa de Pernambuco. Desses, 86 eram tubarões-flamengo, Carcharhinus acronotus, possibilitando um estudo mais detalhado da espécie. Esta espécie foi capturada nas duas áreas estudadas, nas praias de Boa Viagem/ Piedade e Paiva, apresentando a maior abundância relativa entre os tubarões capturados (73,5 por cento do número total). Tubarões potencialmente perigosos (tigre e cabeça-chata) foram também capturados nas duas áreas, enquanto os tubarões-martelo e galha-preta foram capturados apenas em frente à Boa Viagem/ Piedade. O comprimento total (CT) dos tubarões-flamengo variou de 39,0 a 180,0 cm CT. Das 38 fêmeas analisadas, 32 eram jovens, 11 em maturação, 2 pré-ovulatórias e 21 prenhes. Dos 83 embriões, foi possível a sexagem de 75, dos quais 38 eram machos e 37 fêmeas, com proporção sexual de 1:0,9, e CT entre 6,4 e 63,5 cm. A fecundidade ovariana variou entre 5 e 10 e a uterina entre 1 e 3, com período gestacional estimado em 9 meses. Dos 48 machos, 6 eram jovens e 42 adultos. Tanto machos quanto fêmeas parecem alcançar a maturação sexual em torno de 105,0 cm CT. Dos 86 estômagos de tubarões-flamengo analisados apenas 22,1 por cento apresentavam conteúdo, com teleósteos sendo o item mais frequente.
Subject(s)
Animals , Female , Male , Pregnancy , Reproduction/physiology , Sharks/physiology , Brazil , Population Density , Seasons , Sexual Maturation/physiology , Sharks/anatomy & histology , Sharks/classificationABSTRACT
The ongoing decline in abundance and diversity of shark stocks, primarily due to uncontrolled fishery exploitation, is a worldwide problem. An additional problem for the development of conservation and management programmes is the identification of species diversity within a given area, given the morphological similarities among shark species, and the typical disembarkation of processed carcasses which are almost impossible to differentiate. The main aim of the present study was to identify those shark species being exploited off northern Brazil, by using the 12S-16S molecular marker. For this, DNA sequences were obtained from 122 specimens collected on the docks and the fish market in Bragança, in the Brazilian state of Pará. We identified at least 11 species. Three-quarters of the specimens collected were either Carcharhinus porosus or Rhizoprionodon sp, while a notable absence was the daggernose shark, Isogomphodon oxyrhyncus, previously one of the most common species in local catches. The study emphasises the value of molecular techniques for the identification of cryptic shark species, and the potential of the 12S-16S marker as a tool for phylogenetic inferences in a study of elasmobranchs.
ABSTRACT
El presente estudio es una contribución al conocimiento biológico de los peces cartilaginosos en la región norte del Caribe colombiano. Los ejemplares examinados se capturaron con una red demersal, se determinó su peso, longitud total y estado de madurez sexual. Adicionalmente se realizó la ubicación espacial de las capturas y la relación con las variables ambientales. Se capturaron un total de 21 individuos, colectando tres especies de rayas, Dasyatis americana, D. guttata y Rhinobatos percellens, dos de tiburones Mustelus minicanis y Rhizoprionodon porosus, la más común fue D. guttata con 56%, las tallas (longitud total) fluctuaron entre los 1760 -394 mm en rayas y 595 -585 mm en tiburones. Se obtuvieron más hembras que machos para todas las especies, con predominio de estados inmaduros y en maduración, solo se registró una hembra grávida de M. minicanis con dos embriones.
The present study is a contribution to the biological knowledge of cartilaginous fish from the north of Colombian Caribbean. The samples were obtained from a demersal net in the north of Colombian Caribbean, its weight, overall length and sexual maturity stage was determined. Additionally, spatial distribution and its relationships with environmental variables were explored. A total of 21 individuals were captured, three ray species were collected, Dasyatis americana, D. guttata and Rhinobatos percellens, two sharks Mustelus minicanis and Rhizoprionodon porosus, the most common was D. guttata with 56%, the sizes (total length) fluctuated between 1760 - 394 mm in rays and 595 -585 mm in sharks. More females were obtained than males in all the species, with predominance of immature and in maturation states, a single pregnant female of M: minicanis with two embryos was registered.
ABSTRACT
Sharks are suffering from intensive exploitation by worldwide fisheries leading to a severe decline in several populations in the last decades. The lack of biological data on a species-specific basis, associated with a k-strategist life history make it difficult to correctly manage and conserve these animals. The aim of the present study was to develop a DNA-based procedure to discriminate shark species by means of a rapid, low cost and easily applicable PCR analysis based on 5S rDNA repeat units amplification, in order to contribute conservation management of these animals. The generated agarose electrophoresis band patterns allowed to unequivocally distinguish eight shark species. The data showed for the first time that a simple PCR is able to discriminate elasmobranch species. The described 5S rDNA PCR approach generated species-specific genetic markers that should find broad application in fishery management and trade of sharks and their subproducts.