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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. Resumo Dados 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.

This study estimates and analyses the reproductive parameters and cycle of Sympterygia bonapartii in San Matías Gulf, northern Patagonia, Argentina. A total of 827 males and 1,299 females were analysed. Males ranged from 185 to 687 mm of total length (TL) and females from 180 to 742 mm TL. Sexual dimorphism was detected; females were larger, heavier, exhibited heavier livers, wider discs and matured at lager sizes than males. Immature females ranged from 180 to 625 mm TL, maturing females from 408 to 720 mm TL, mature ones from 514 to 742 mm TL and females with egg capsules from 580 to 730 mm TL. Immature males ranged from 185 to 545 mm TL, maturing ones from 410 to 620 mm TL and mature males from 505 to 687 mm TL. Size at which 50% of the skates reached maturity was estimated to be 545 mm TL for males and 594 mm TL for females. According to the reproductive indexes analysed, S. bonapartii exhibited a seasonal reproductive pattern. Mating may occur during winter-early spring and the egg-laying season, during spring and summer. RESUMEN El presente estudio estima y analiza los parámetros reproductivos y el ciclo reproductivo de Sympterygia bonapartii en el Golfo San Matías, Patagonia norte, Argentina. Se analizaron 827 machos y 1.299 hembras. Los machos midieron entre 185 y 687 mm de largo total (LT) y las hembras entre 180 y 742 mm LT. Se detectó dimorfismo sexual; las hembras fueron más grandes y pesadas que los machos y presentaron anchos de disco, pesos de hígado y tallas de madurez sexual mayores a los de los machos. Las hembras inmaduras midieron entre 180 y 625 mm LT, las hembras en maduración entre 408 y 720 mm LT, las maduras entre 514 y 742 mm LT y las hembras con cápsulas entre 580 y 730 mm LT. Los machos inmaduros midieron entre 185 y 545 mm LT, los machos en maduración entre 410 y 620 mm LT y los maduros entre 505 y 687 mm LT. La talla media de madurez sexual fue estimada en 545 mm LT para los machos y 594 mm LT para las hembras. De acuerdo con los índices reproductivos analizados, S. bonapartii se reproduce estacionalmente. El apareamiento ocurriría durante el invierno y la primavera y la temporada de puesta durante la primavera y el verano.

This study quantifies and describes the diet composition and variability, and the trophic ecology of Sympterygia bonapartii (Batoidea: Arhynchobatidae) in the San Matías Gulf, northern Patagonia, Argentina. A total of 1,047 stomachs were analyzed and 98 % of them contained food. The low proportion of empty stomachs recorded and the presence of prey in different stages of digestion suggested that this skate was a continuous feeder. A total of 81 prey items were identified. However, the diet was mainly composed of crabs. Other important groups in its diet were teleost fishes, shrimps and prawns, bivalves and worms. At the species level, the crab Peltarion spinosulum accounted for the highest contribution and the anchovy Engraulis anchoita ranked second in importance. By analyzing its diet composition, it was possible to classify S. bonapartii as a benthic predator, as are other skates reaching a similar maximum size. In addition, it was placed in the functional group of species that mainly feeds on decapod crustaceans. Trophic level was estimated at 3.61, indicating that the species was a secondary consumer. Significant differences were found in the diet according to sex, size class and season. These differences may be due to extrinsic and intrinsic factors that could be operating together. Fil: Estalles, María Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Perier, María Raquel. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; Argentina Fil: Di Giacomo, Edgardo Ernesto. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; Argentina

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 Matias 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.

The San Matias 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.

Sexual dimorphism and morphometric relationships of Atlantoraja platana (Gunther, 1880) in San Matias gulf waters, Patagonia.The skate Atlantoraja platana, commonly known in Argentina as “raya platana”, is endemic to the Southwest Atlantic. It is distributed from Brasil (24°S) to north Patagonian waters (42°11’S). In this study the morphometric aspects of this skate were described. In the San Matias gulf (41°-42°S y 64°-65°W), a total of 778 females and 709 males were sampled from different sources between 2004 and 2006. The total length ranged was 19 to 89 cm for females and 19 to 79 cm for males. Atlantoraja platana was sexually dimorphic in total length-weight and total length-disc width relationships. Since 41 cm onwards the females are being heavier than males. The total length-weight relationship was Pt= 0.0132 x Lt2.91 for females and Pt= 0.0222 x Lt2.77 for males. The total length-disc width relationship was DW= 7.27 + 0.762Lt for females and DW= 7.768 + 0.798Lt for males. This is the first report of morphometric relationships of this species in the Argentinean Sea and they should be used for comparison purpose between different latitudinal localizations of this skate.

The Electric ray Discopyge tschudii is distributed form southern Brazil to Peru. The main threat to this species is fishing. Discopyge tschudii is noncommercial and individuals caught are discarded on board. The present study analyzes the distribution and the morphological and reproductive characteristics of this ray in San Matías Gulf (SMG). A total of 1087 individuals were analyzed. The species presented an aggregated distribution with the main concentrations in the northern and eastern areas of SMG at depths below 100 m. Males ranged from 9 to 43 cm and females from 11 to 38 cm. The species presented sexual dimorphism. Males were larger and heavier than females and they also matured at larger sizes. Size at 50% of maturity was estimated at 30 cm for males and 21 cm for females. A total of 199 embryos were sampled and the proportion of sexes showed no significant differences from the expected 1:1. The number of embryos per female varied from 1 to 12. The most frequent values were 2 and 5. Length at birth was estimated at 82.17 ± 3.87 mm. According to our findings we hypothesizes that the electric ray D. tschudii completes its reproductive cycle in SMG. La raya eléctrica Discopyge tschudii se distribuye, en el Atlántico Sudoccidental, desde el sur de Brasil hasta el sur de Argentina y en el Pacifico Sudoriental desde Perú al sur de Chile. La principal amenaza para la especie es la pesca. Es una especie sin valor comercial y debido a esto los ejemplares capturados por las embarcaciones pesqueras son descartados a bordo. En el presente estudio se analizan la distribución espacial y las características morfológicas y reproductivas de la especie en el Golfo San Matías (GSM), Argentina. Un total de 1087 ejemplares fueron analizados. La especie presentó una distribución agregada, encontrándose las principales concentraciones en el sector norte y este del GSM a profundidades menores a los 100 m. Los machos midieron entre 9 y 43 cm de largo total y las hembras entre 11 y 38 cm. La especie exhibió dimorfismo sexual, siendo los machos más grandes, más pesados y presentando mayores tallas de madurez que las hembras. La talla de madurez a la cual el 50% de la población alcanzó la madurez sexual fue estimada en 30 cm en machos y 21 cm en hembras. Se analizaron 199 embriones. Las proporciones de sexos de los embriones no mostraron diferencias significativas de lo esperado 1:1. El número de embriones por hembra varió de 1 a 12, siendo los valores más frecuentes 2 y 5. La talla de nacimiento fue estimada en 82,17 ± 3,87 mm. De acuerdo a nuestros resultados se hipotetiza que D. tschudii completa su ciclo reproductivo en el golfo. Fil: Estalles, María Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biologia Marina y Pesquera Almirante Storni; Argentina Fil: Coller, Nidia Marina. Universidad Nacional del Comahue. Instituto de Biologia Marina y Pesquera Almirante Storni; Argentina. Universidad Nacional del Comahue; Argentina Fil: Di Giácomo, Edgardo Ernesto. Universidad Nacional del Comahue. Instituto de Biologia Marina y Pesquera Almirante Storni; Argentina. Universidad Nacional del Comahue; Argentina Fil: Perier, María Raquel . Universidad Nacional del Comahue. Instituto de Biologia Marina y Pesquera Almirante Storni; Argentina. Universidad Nacional del Comahue; Argentina

From 1971, a small scale bottom trawl fishery has developed in the San Matias Gulf (41°–42° S; 64°–65°W) of the Argentinean Sea, targeting the hake (Merluccius hubbsi Marini). The dynamics of a spawning aggregation of hake in the gulf were analyzed based on changes in sex ratio and the proportions of different stages of sexual maturity. It was concluded that the northern part of the gulf is the main spawning zone. While males are concentrated there, mature females come to the area, spawn, and then move back to the west zone. The presence of a spawning aggregation and the occurrence of all stages of the life cycle in the San Matśas Gulf, suggests that the hake population in the Gulf constitutes a stock unit separate from the continental shelf stocks. Further support for this hypothesis is provided by the oceanographic characteristics of the Gulf.