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The behavior of the Argentine shortfin squid (Illex argentinus) in reaction to a trawl net is reported from images obtained during one fishing tow operated by a commercial trawler in May 2015 in slope grounds off southern Brazil (depth 370-361 m; 33°37'S, 50°49'W). Video analysis utilized criteria to classify the horizontal and vertical distribution of squid in the field of view of the camera, posture (pitch and yaw), squid color patterns, escape reaction, swimming time and use of the tail fin. The monitored bottom trawl operation intercepted dense and patchily distributed schools of I. argentinus that could be observed for brief periods of time swimming ahead of the mouth of the trawl. Individuals were evenly distributed in the water column but concentrated on the center and right sectors of the trawl mouth. Most squids in the path of a trawl tended to swim by jet-propulsion for 10-20 s, tail-first and with regularly spaced fin flaps. Estimated speed (1.24 m s-1) was higher than cruise speed recorded for other ommastrephid squids in nature (0.3 m s-1), possibly reflecting an emergency escape reaction. After a period of sustained swimming ahead of the trawl, squid reacted in different ways including: a) slowing down and swimming into the net tunnel, b) shifting directions to escape through the trawl mouth sides, and c) swimming up, trying to escape over the top trawl panel, sometimes turning around pointing the tail towards the trawl mouth. [ABSTRACT FROM AUTHOR]

A nivel internacional, paralelo a la declinación y al colapso de pesquerías de gran escala, surgió un interés creciente por el estudio de las interacciones entre mamíferos marinos y pesquerías. El golfo San Matías (Patagonia, Argentina) es considerado un ecosistema pesquero independiente de las aguas de la Plataforma Continental Argentina, con condiciones oceanográficas y biológicas particulares. La condición de sistema semi-cerrado podría generar escenarios particulares para la interacción entre la flota pesquera de arrastre de fondo y la población de lobos marinos de un pelo Otaria flavescens. En el presente trabajo se caracterizó la dieta del predador y la composición de las capturas pesqueras a fin de evaluar el solapamiento trófico entre ambos componentes. A partir de este análisis y la comparación de las tallas de las presas consumidas, se encontró que la posibilidad de una interacción competitiva entre la flota pesquera y los lobos marinos, a partir de la utilización de recursos similares, sería baja en el ecosistema del golfo San Matías.As world fisheries began to decline and massive collapses were observed, the competition between marine mammals and fisheries became an issue of growing concern. San Matías Gulf (Patagonia, Argentina) is considered to be a fishery ecosystem independent of the Argentine Continental Shelf waters, with particular oceanographic and biological properties. As a semi-enclosed ecosystem, this gulf may generate particular scenarios for interactions between the demersal trawl fishery fleet and the population of South American sea lions Otaria flavescens. In this paper, the diet of the top predator and the composition of fishery catches were characterized in order to assess the trophic overlap between these two components. This analysis and a comparison of the sizes of prey consumed revealed a low probability of competition for similar resources between the fishing fleet and the marine mammals in the San Matías Gulf ecosystem.

The development of a deep-sea fishery for aristeid shrimps off Brazil is reviewed from its early days in 2002. Descriptive data were collected by observers on board 75 directed fishing trips conducted in the study period, with a total of over 15,000 monitored trawls. An incipient fishing phase took place between No-vember 2000 and October 2002, when aristeid shrimps were occasionally reported in the bycatch of operations mostly targeting the Argentine hake (Merluccius hubbsi). After that, a directed fishery was established for these resources. All nine vessels involved in this fishery (one national and eight chartered) concentrated on 11 limited grounds between 700 and 800 m deep and 18°S and 34°S. The main species caught between November 2002 and May 2007 was the "carabinero" Aristaeopsis edwardsiana (456,710 kg), followed by the "moruno" Aristaeomorpha foliácea (121,497 kg), and then the "alistado" Aristeus antillensis (27,919 kg). The trawlers operate in conjunction, such that the total area of each fishing ground was swept at least twice. This harvest pattern substantially reduced "carabinero" catch rates from 14 kg hour-1 in the first sampled trimester to 4 kg hour-1 in the last. Despite the inferred biomass reduction of this species, the fishery has continued without a formal management plan.Se revisa el desarrollo de una pesquería en aguas profundas dirigida a gambas aristeideas en Brasil. Desde su inicio, en 2002, los datos descriptivos fueron obtenidos por observadores a bordo de 75 viajes de pesca realizadas en ese período que resultaron en más de 15.000 arrastres monitoreados. Una fase incipiente de la pesquería se estableció entre noviembre de 2000 y octubre de 2002, cuando gambas aristeideas fueron registradas en la captura accidental de operaciones de pesca dirigidas principalmente a la merluza-argentina (Merluccius hubbsi). A ésta sobrevino una fase dirigida en que participaron nueve arrastreros (uno nacional y ocho arrendados). Estos buques concentraron sus operaciones en 11 fondos de pesca angostos entre 700 y 800 m de profundidad y los paralelos 18°S y 34°S. Las principales especies capturadas entre noviembre de 2002 y mayo de 2007 fueron el "carabinero" Aristaeopsis edwardsiana (456,710 kg), seguido del "moruno" Aristaeomorpha foliácea (121,497 kg), y el "alistado" Aristeus antillensis (27,919 kg). Los arrastreros operaran de forma agregada y esto hace que el area total de cada zona de pesca haya sido arrastrada al menos dos veces. Este patrón de explotación ha producido reducciones substanciales en las tasas de captura del "carabinero" que varió de 14 kg hora-1 en el primer trimestre de monitoreo a 4 kg hora-1 en el último. A pesar de la aparente reducción de biomasa de esta especie, la pesquería ha continuado sin un plan formal de manejo.

The use of the turtle excluder device (TED) has been mandatory in Brazil since 1994. In spite of the importance of sea turtle bycatch reduction, TED effectiveness to maintain target species capture had never been evaluated in shrimp fisheries off southern Brazil. For this purpose, a test was carried out in November 2013 with the TED installed with two different configurations, top or bottom opening under the supervision of a technician of the National Oceanic and Atmospheric Administration (NOAA). Absolute catch and fishery yields were simultaneously monitored in 10 fishing hauls of a double-rig trawler by an onboard observer in one net equipped with a TED and the other without a TED. Although a Bayesian hypothesis test demonstrated no significant differences through the simultaneous comparison of absolute capture considering the use and non-use of the TED, the credibility interval of posterior beta distributions intercepted almost its minimum limit which weakens the hypothesis of equality. In terms of orientation, the model mounted with the top opening showed no differences in absolute catches of the target species in respect to control. [ABSTRACT FROM AUTHOR]

As world fisheries began to decline and massive collapses were observed, the competition between marine mammals and fisheries became an issue of growing concern. San Matías Gulf (Patagonia, Argentina) is considered to be a fishery ecosystem independent of the Argentine Continental Shelf waters, with particular oceanographic and biological properties. As a semi-enclosed ecosystem, this gulf may generate particular scenarios for interactions between the demersal trawl fishery fleet and the population of South American sea lions Otaria flavescens. In this paper, the diet of the top predator and the composition of fishery catches were characterized in order to assess the trophic overlap between these two components. This analysis and a comparison of the sizes of prey consumed revealed a low probability of competition for similar resources between the fishing fleet and the marine mammals in the San Matías Gulf ecosystem. [ABSTRACT FROM AUTHOR]

The development of a deep-sea fishery for aristeid shrimps off Brazil is reviewed from its early days in 2002. Descriptive data were collected by observers on board 75 directed fishing trips conducted in the study period, with a total of over 15,000 monitored trawls. An incipient fishing phase took place between November 2000 and October 2002, when aristeid shrimps were occasionally reported in the bycatch of operations mostly targeting the Argentine hake (Merluccius hubbsi). After that, a directed fishery was established for these resources. All nine vessels involved in this fishery (one national and eight chartered) concentrated on 11 limited grounds between 700 and 800 m deep and 18°S and 34°S. The main species caught between November 2002 and May 2007 was the "carabinero" Aristaeopsis edwardsiana (456,710 kg), followed by the "moruno" Aristaeomorpha foliacea (121,497 kg), and then the "alistado" Aristeus antillensis (27,919 kg). The trawlers operate in conjunction, such that the total area of each fishing ground was swept at least twice. This harvest pattern substantially reduced "carabinero" catch rates from 14 kg hour-1 in the first sampled trimester to 4 kg hour-1 in the last. Despite the inferred biomass reduction of this species, the fishery has continued without a formal management plan. [ABSTRACT FROM AUTHOR]