10 documents found, page 1 of 1
Effects of gear modifications in a North Atlantic pelagic longline fishery: A m...
Lima, Françoise; Parra, Hugo; Alves, Rita B.; Santos, Marco A. R.; Bjorndal, Karen; Bolten, Alan B.; Vandeperre, FredericThe threat of population declines caused by pelagic longline fisheries in the Atlantic has increased the concern to find strategies that minimize the bycatch and mortality of non-target marine animals. Gear modification, such as the use of circle hooks instead of conventional J-hooks, has been identified as an effective bycatch reduction strategy in different pelagic longline fisheries around the world. This st...
Size-based differences in isotopic niche width (delta C-13 and delta N-15) of g...
Ferreira, Rogério L.; Ceia, Filipe R.; Borges, Teresa C.; Ramos, Jaime A.; Bolten, Alan B.Within the same population, nesting green turtles (Chelonia mydas) might exploit different niches by exhibiting polymorphic foraging strategies and/or inhabiting geographically distinct foraging areas. This is crucial information for the conservation of this species. Here, we used stable carbon and nitrogen isotope ratios (delta C-13 and delta N-15) to test for differences in a population of green turtles nesti...
Hawksbill (Eretmochelys imbricata) and Green Turtle (Chelonia mydas) Nesting an...
Ferreira, Rogério L.; Martins, Helen R.; Bolten, Alan B.Hawksbills (Eretmochelys imbricata) and green turtles (Chelonia mydas) are the predominant nesting sea turtle species on the beaches of Príncipe Island in the Gulf of Guinea. The extent of nesting has been largely unknown, but such information is essential for management and conservation. Our study is the first island-wide nesting assessment. Results from the survey, conducted from 1 December 2009 to 18 January...
Sea turtles : University of Florida – University of the Azores connection 1984 ...
Martins, Helen R.; Bjorndal, Karen A.; Ferreira, Rogério L.; Parra, Hugo Alexandre Esteves; Pham, Christopher K.; Rodríguez, Y.; Santos, M. R.The loggerhead (Caretta caretta) is the most common sea turtle in the Azores. Since they do not nest in the area, a tagging program was started in the 1980’s to try to discover their origin. The result based on size distribution, suggested that they mainly are coming from beaches in SE United States. A collaboration between University of Florida and the University of the Azores began in 1984 in order to proceed...
Foraging niche segregation between juvenile and adult hawksbill turtles (Eretmo...
Ferreira, Rogério L.; Ceia, Filipe R.; Borges, Teresa C.; Ramos, Jaime A.; Bolten, Alan B.Hawksbill sea turtles are the most tropical sea turtle species with one of the last remaining aggregations in West Africa found on Príncipe Island (1° 37′ N; 7° 23′ E). Here we present for the first time, data on the trophic and foraging ecology of both juvenile and adult hawksbill turtles found in the shallow waters of Príncipe, using stable isotope analyses of carbon (δ13C) and nitrogen (δ15N), and assess any...
Plastic ingestion in oceanic-stage loggerhead sea turtles (Caretta caretta) off...
Pham, Christopher K.; Rodríguez, Yasmina; Dauphin, Axelle; Carriço, Rita; Frias, João Pedro Garcez Luís de; Vandeperre, Frederic; Otero, VanessaJuvenile oceanic-stage sea turtles are particularly vulnerable to the increasing quantity of plastic coming into the oceans. In this study, we analysed the gastrointestinal tracts of 24 juvenile oceanic-stage loggerheads (Caretta caretta) collected off the North Atlantic subtropical gyre, in the Azores region, a key feeding ground for juvenile loggerheads. Twenty individuals were found to have ingested marine d...
Compensatory growth in oceanic loggerhead sea turtles: response to a stochastic...
Bjorndal, Karen A.; Bolten, Alan B.; Dellinger, Thomas; Delgado, Cláudia; Martins, Helen R.Compensatory growth (CG, accelerated growth that may occur when an organism that has grown at a reduced rate as a result of suboptimal environmental conditions is exposed to better conditions) is considered an adaptation to variable en vironments. Although documented thoroughly under captive conditions, CG has rarely been studied in wild populations. In their first years of life, oceanic-stage loggerhead sea tu...
Impact of swordfish fisheries on sea turtles in the Azores.
Ferreira, Rogério L.; Martins, Helen R.; Silva, Alexandre A.; Bolten, Alan B.The surface longline fishery around the Azores targets swordfish (Xiphias gladius). Bycatch from this fishery includes loggerhead sea turtles (Caretta caretta) and occasionally leatherback sea turtles (Dermochelys coriacea) that are either hooked or entangled in the lines. Hooks are generally set at depths of 15-50 m and baited with squid, mackerel, or sometimes with shark meat. The size classes of loggerhead s...
Transatlantic developmental migrations of loggerhead sea turtles demonstrated b...
Bolten, Alan B.; Bjorndal, Karen A.; Martins, Helen R.; Dellinger, Thomas; Biscoito, Manuel J.; Encalada, Sandra E.; Bowen, Brian W.Molecular markers based on mitochondrial (mt) DNA control region se quences were used to test the hypothesis that juvenile loggerhead sea turtles (Caretta caretta) in pelagic habitats of the eastern Atlantic are derived from nesting populations in the western Atlantic. We compared mtDNA haplotypes from 131 pelagic juvenile turtles (79 from the Azores and 52 from Madeira) to mtDNA haplotypes observed in major ne...
Size distribution of pelagic-stage loggerhead sea turtles (Caretta caretta) in ...
Bolten, Alan B.; Martins, Helen R.; Bjorndal, Karen A.; Gordon, JonathanAs tripulações de navios atuneiros marcaram e mediram 731 tartarugas-caretas (Caretta caretta) durante as safras de 1990, 1991 e 1992. Os comprimentos curvos das carapaças das tartarugas variaram de 10 a 82 cm. A distribuição interanual de tamanhos não foi significativamente diferente. O tamanho médio de 45 tartarugas marcadas na Madeira foi significativamente maior do que o das tartarugas dos Açores. Os result...