Captura incidental de la raya pelágica dasyatis violacea por la flota palangrera uruguaya y aspectos de su distribuciòn en el atlàntico sudoccidental

La presencia de la raya pelágica Dasyatis violacea (Bonaparte, 1832) en aguas uruguayas ha sido detectada desde el comienzo del Programa Nacional de Observadores a bordo de la Flota Atunera Uruguaya (PNOFA) en abril de 1998. Este es el primer informe sobre esta especie para el Atlántico Sur, frente a las costas de Uruguay. Se analiza su distribución dentro del área, sobre la base de 13 viajes realizados entre abril de 1998 y septiembre de 2001, entre los 26º y 37º S. Durante dicho período se capturaron quinientos veinticinco ejemplares. La presencia de esta especie parecería estar estrechamente relacionada con los valores más altos de temperatura superficial del agua, con una CPUE relativamente baja por debajo de los 20º C. La frontera sur de distribución de la especie estaría alrededor de los 36º S. Dasyatis violacea integra una fauna de agua templada bien determinada, que alcanza las aguas uruguayas y del norte de Argentina, siguiendo corrientes subtropicales templadas. La captura incidental de D. violacea en dicha área alcanza cifras significativas. Esta especie es siempre descartada. Sugerimos que esta captura fortuita es importante y debería ser analizada, a efectos de generar medidas que permitan su conservación.The presence of the pelagic ray Dasyatis violacea (Bonaparte, 1832) in uruguayan waters has been monitored since April 1998, the beginning of the National Observer Programme on board of the uruguayan tuna fleet (PNOFA). These are the first records of the species for the South Atlantic off Uruguay. Its distribution within the area is analysed, based on 13 trips made from April 1998 to September 2001 from 26 to 37ºS. Five hundred and twenty five specimens were caught during this period. The presence of the species appears to be closely associated with the highest values of surface water temperature, with CPUE being relatively low belowr 20ºC. The southern border of its distribution is around 36ºS. Dasyatis violacea is part of a well defined warm water fauna that reaches Uruguayan and northern Argentinean waters following warm subtropical waters. The incidental capture of D. violacea in the area reaches significant levels; the species is always discarded. We suggest that this bycdatch is important and should be monitored from a conservation point of view.Fil: Domingo, Andrés. Direccción Nacional de Recursos Acuáticos; UruguayFil: Menni, Roberto Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados; ArgentinaFil: Forselledo, Rodrigo. Direccción Nacional de Recursos Acuáticos; Urugua

Marine mammal bycatch by the industrial bottom trawl fishery at the Río de la Plata Estuary and the adjacent Atlantic Ocean.

Fisheries interactions with non-target marine vertebrates are a worldwide problem. The impact of coastal bottom trawl fisheries on marine mammals has never been evaluated before in the Río de la Plata Estuary and the adjacent Atlantic Ocean. Our aim was estimating the bycatch per unit effort (BcPUE) and incidental mortality rates of marine mammals caused by the industrial coastal bottom trawl fisheries fleet. We evaluated the mortality of three species (i.e., franciscana dolphin Pontoporia blainvillei, South American sea lion Otaria flavescens, and the South American fur seal Arctocephalus australis); these species are facing conservation problems either at the regional or local scale. We conducted an onboard data collection program of marine mammals’ bycatch involving crew members of 10 vessels (30%) of the Uruguayan coastal bottom trawl fleet between January 2009 and April 2012. A total of 102 marine mammal individuals were bycaught during 490 fishing trips involving 2,398 fishing days. Mortalities estimated for franciscana dolphin were the highest among the species affected, with values adding up to ~100 individuals for year (with scenarios of population decline in the area), followed by South American sea lion with ~77 individuals by year (0.8% of local population) and the South American fur seal with an annual mortality estimate of ~25 individuals (~0.02% of local population). BcPUE showed significant temporal variation, with franciscana dolphin BcPUE varying seasonally and those of otariids according to their breeding season. Our estimates of marine mammal bycatch by bottom trawl fisheries should constitute an important input for the sustainable management of fisheries and the conservation of marine biodiversity in the southwestern Atlantic Ocean

Brief update on the satellite tagging of Atlantic swordfish

This paper provides a brief update of the study on habitat use for swordfish, developed within the working plan of the Swordfish Species Group of ICCAT. A total of 9 miniPAT tags have been deployed by observers on Portuguese and Spanish vessels and the Uruguayan research cruise in the North and South Atlantic. Data from eight tags/specimens are available, four specimens suffered from post-release mortality and one individual tag pop-up date has not occurred yet. These preliminary results showed swordfish moved in several directions, travelling considerable distances. Swordfish spent most of the daytime in deeper waters, being closer to the surface during night-time. The main plan for the next phase of the project is to continue the tag deployment during 2020 in several regions of the Atlantic Ocean and Mediterranean Sea

BRIEF UPDATE ON THE SATELLITE TAGGING OF ATLANTIC SWORDFISH

This paper provides a brief update of the study on habitat use for swordfish, developed within the working plan of the Swordfish Species Group of ICCAT. A total of 9 miniPAT tags have been deployed by observers on Portuguese and Spanish vessels and the Uruguayan research cruise in the North and South Atlantic. Data from eight tags/specimens are available, four specimens suffered from post-release mortality and one individual tag pop-up date has not occurred yet. These preliminary results showed swordfish moved in several directions, travelling considerable distances. Swordfish spent most of the daytime in deeper waters, being closer to the surface during night-time. The main plan for the next phase of the project is to continue the tag deployment during 2020 in several regions of the Atlantic Ocean and Mediterranean SeaEn prens

Marine mammal bycatch by the industrial bottom trawl fishery at the Río de la Plata Estuary and the adjacent Atlantic Ocean

Fisheries interactions with non-target marine vertebrates are a worldwide problem. The impact of coastal bottom trawl fisheries on marine mammals has never been evaluated before in the Río de la Plata Estuary and the adjacent Atlantic Ocean. Our aim was estimating the bycatch per unit effort (BcPUE) and incidental mortality rates of marine mammals caused by the industrial coastal bottom trawl fisheries fleet. We evaluated the mortality of three species (i.e., franciscana dolphin Pontoporia blainvillei, South American sea lion Otaria flavescens, and the South American fur seal Arctocephalus australis); these species are facing conservation problems either at the regional or local scale. We conducted an onboard data collection program of marine mammals' bycatch involving crew members of 10 vessels (30%) of the Uruguayan coastal bottom trawl fleet between January 2009 and April 2012. A total of 102 marine mammal individuals were bycaught during 490 fishing trips involving 2,398 fishing days. Mortalities estimated for franciscana dolphin were the highest among the species affected, with values adding up to ~100 individuals for year (with scenarios of population decline in the area), followed by South American sea lion with ~77 individuals by year (0.8% of local population) and the South American fur seal with an annual mortality estimate of ~25 individuals (~0.02% of local population). BcPUE showed significant temporal variation, with franciscana dolphin BcPUE varying seasonally and those of otariids according to their breeding season. Our estimates of marine mammal bycatch by bottom trawl fisheries should constitute an important input for the sustainable management of fisheries and the conservation of marine biodiversity in the southwestern Atlantic Ocean.Fil: Franco Trecu, Valentina. Universidad de la República; UruguayFil: Szephegyi, María Nube. Universidad de la Republica; UruguayFil: Doño, Florencia. Universidad de la Republica; UruguayFil: Forselledo, Rodrigo. Universidad de la Republica; UruguayFil: Reyes, Federico. Universidad de la Republica; UruguayFil: Passadore, Cecilia. Universidad de la Republica; Uruguay. Flinders University; AustraliaFil: Crespo, Enrique Alberto. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Inchausti, Pablo. Universidad de la República; Urugua

UPDATE ON THE SATELLITE TAGGING OF ATLANTIC AND MEDITERRANEAN SWORDFISH

This paper provides an update of the study on habitat use for swordfish, developed within the working plan of the Swordfish Species Group of ICCAT. A total of 26 miniPAT tags have been deployed so far in the North (n=13) and South Atlantic (n=9) and the Mediterranean (n=4). Data from eight tags was analysed for horizontal and vertical habitat use. These preliminary results showed swordfish moved in several directions, travelling considerable distances in both the North and South stocks. Swordfish spent most of the daytime in deeper waters with a mean of 540.8 m, being closer to the surface during nighttime (mean=78.3 m). The deepest dive recorded was of 1480 m. Regarding temperature, swordfish inhabited waters with temperatures ranging from 3.9ºC to 30.5ºC with a mean of 11.3ºC during daytime and 21.7ºC during nighttime. The main plan for the next phase of the project is to continue the tag deployment during 2022 in several regions of the Atlantic Ocean and Mediterranean Sea. Currently 11 tags are with the participating CPCs and nine tags are still to be attributed.En prens

Distributional and reproductive aspects of the bigeye thresher shark (Alopias superciliosus) in the Atlantic ocean

Captura asociada a la pesquería de palangre de superficie dirigida a pez espadaThe bigeye thresher shark, Alopias supercilious is sometimes caught as bycatch in pelagic longline fisheries targeting tunas and swordfish in the Atlantic Ocean. As part of an ongoing cooperative program for fisheries and biological data collection, fishery observer data from various fishing nations and projects were compiled and analyzed. Those data sets include information on geographic location of the observations, as well as size, sex and in some cases maturity stage. A total of 4371 bigeye threshers were recorded throughout the Atlantic Ocean between 1992 and 2013, with the sizes ranging from 70 to 305 cm FL (fork length). Considerable variability was observed in the catchat- size, with particular emphasis on the tropical region where the mean sizes tended to be smaller than in the other regions. The expected distribution of juvenile and adult specimens also showed considerable variability, and the sex-ratios varied between regions and size classes. Maturity ogives were fitted to data from 642 specimens, with the median sizes at maturity estimated at 208.6 cm FL (corresponding to 349.1 cm TL) for females and 159.2 cm FL (corresponding to 269.8 cm TL) for males. In addition, a segmented regression model (SRM) was used for males, and two breakpoints (Bk1: 122.5cm FL, Bk2: 173.3cm FL) estimated, identifying transitions between the three different maturity stages for male sharks (immature, maturing and mature). Only a few pregnant females were recorded, always with the presence of two embryos (one per uterus), and were distributed predominantly in the tropical northeast Atlantic closer the African continent, and in the southwest region, with those regions possibly serving as nursery areas for this species. These reproductive parameters, and especially the estimated median sizes at maturity and low fecundity, highlight the vulnerability of this species, reinforcing that the bigeye thresher tends to mature at a larger size than the other species of the Alopiidae family. The biological and distributional patterns presented can help managers adopt more informed and efficient conservation measures for this species.En prensa0,000