-Argentina is one of the countries with the largest overall landings of skates and rays (24 000 t/year). As a consequence of high levels of exploitation and deficient management tools, many of these species are threatened with extinction. In the bottom trawl fishery of San Matías Gulf, northern Patagonia, skates and rays are caught as bycatch and all have historically been recorded in the fishery logbook under the category "rays". Therefore, species composition and their characteristics were unknown. The aim of this study was to characterize the commercial exploitation of batoid species in this fishery. Our results indicate that commercial landings include nine species of skate, six of which are common. Among these, Atlantoraja platana, Sympterygia bonapartii and Dipturus chilensis were considered the main species of this fishery. Their combined relative abundance and weight made up about 90% of the batoid catch throughout the year. Sexual segregation was detected in four species in which individuals of one sex dominated commercial landings. The commercial fraction was composed of individuals with a wide range of sizes. Immature individuals could represent 90% of the individuals landed for some species. At present, lack of data prevents us from quantifying the impact that this fishery is having on these species, but our findings highlight the importance of conducting research surveys to assess the abundance and geographic extent of these populations. The information presented here provided the basis for the proposal of a new logbook format incorporating species-level identification. The new logbook was implemented on 1 January 2010.

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Abstract:The San Matías Gulf (SMG; 41°-42° S; 64°-65° W) is the largest gulf in Northern Patagonia, Argentina. Up to date, the chondrichthyan fauna of this area has not been reported. Therefore, the aim of this work is to provide a list with species presence and biological characteristics of the chondrichthyans recorded in SMG during the last 30 years. A total of 13 sharks distributed in 11 families, 19 skates and rays distributed in six families, and one holocephalan have been so far recorded in SMG. From the zoogeographical point of view, this chondrichthyan fauna is a mixed assemblage of species typically found in the Argentinean and Magellanean Provinces. The holocephalan Callorhinchus callorynchus is the most landed chondricthyan of the local fishery. With it, five sharks and seven skates are also exploited.Key words: Holocephali, Elasmobrachii, Batoidea, Southwest Atlantic, Patagonia.Resumen: Los condrictios del Golfo San Matías, Patagonia, Argentina. El Golfo San Matías (SMG; 41°-42° S -64°-65° O) se encuentra ubicado en el norte de la Patagonia, Argentina. Hasta la fecha no se cuentan con reportes de la fauna de condrictios de esta zona. Por lo tanto, el objetivo de este trabajo es proporcionar una lista de la presencia y las características biológicas de los condrictios registrados en el SMG durante los últimos 30 años. Un total de 13 tiburones distribuidos en 11 familias, 19 batoideos distribuidos en seis familias y un holocefalo han sido reportados para la zona. Desde el punto de vista zoogeográfico, el SMG presenta un ensamble de especies pertenecientes a las Provincias Magallánica y Argentina. El holocefalo Callorhinchus callorynchus es el condrictio más desembarcado de la pesquería local. Con menor importancia son explotadas comercialmente, cinco especies de tiburones y siete de rayas.

Standardized catch rate of cockfish, Callorhinchus callorynchus, in a bottom trawl fishery of Patagonia: Is it possible its use as a predictor of abundance trend?The catch per unit of effort (CPUE) data of cockfish, Callorhinchus callorynchus, during 1986-2011 was evaluated for the bottom trawl fishery of the San Matías gulf (Patagonia, Argentina). The objective of this work was to detect what are the factors related to fishery dynamic that affect catch rate of cockfish and to assess standardized CPUE by General linear models (GLMs) and General linear mixed models (GLMMs) as a relative abundance index. The annual trend of the catch rate indicated an increase during the evaluated period. The nominal CPUE and the indices standardized by the Delta-GLM and Delta-GLMM showed the same annual trend, with increases of 57%, 61.1% and 60.7%, respectively. The LogNormal models have the best-fit model and explained 23.5% of the total variability. The factors year, month, depth and hake CPUE explained the highest variability. The analysis of the models indicated that the catch rate of cockfish is subject to the lack of an homogeneous distribution of the fishing effort during different years, months and vessels. This was related to the fleet dynamic searching the targets species. The increasing trend of CPUE and landings would be indicating an increase in effort directionality to the cockfish in the last decade. Descriptors: Standardized CPUE, Holocephali, Chondrichtyans bycatch, GLM, GLMM, Chimaeroids. AbstrActDados de captura por unidade de esforço (CPUE) do peixe-galo Callorhinchus callorynchus foram avaliados para a pesca de arrasto de fundo no Golfo de San Matías (Patagonia, Argentina), durante o período 1986-2011. Os objetivos do trabalho foram identificar quais os fatores relacionados à dinâmica pesqueira que afetam a taxa de captura do peixe-galo e verificar a viabilidade em utilizar dados de CPUEs padronizadas pelos Modelos Lineares Gerais (GLM) e Modelos Lineares Gerais Mistos (GLMMs) como índices de abundância relativa. A tendência anual da taxa de captura indicou um aumento durante o período avaliado. A CPUE nominal e os índices padronizados pelo Delta-GLM e Delta-GLMM apresentaram a mesma tendência anual, com aumentos de 57%, 61.1% e 60.7%, respectivamente. Os modelos LogNormal foram os de melhor ajuste e explicaram 23,5% da variabilidade total dos dados. Ano, mês, profundidade e "hake" CPUE foram os fatores mais explicativos. A análise dos modelos indicou que a taxa de captura do peixe-galo está ligada à falta de distribuição homogênea do esforço de pesca durante os diferentes anos, meses e navios. Este fato esteve relacionado à dinâmica das frotas na busca das espécies alvo. A tendência crescente no aumento das CPUE e descargas em terra estaria indicando a mudança do esforço de pesca direcionado ao peixe-galo na última década.