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- Multispecies tracking reveals a major seabird hotspot in the North AtlanticPublication . Davies, Tammy E.; Carneiro, Ana P.B.; Tarzia, Marguerite; Wakefield, Ewan; Hennicke, Janos C.; Frederiksen, Morten; Hansen, Erpur Snær; Campos, Bruna; Hazin, Carolina; Lascelles, Ben; Anker‐Nilssen, Tycho; Arnardóttir, Hólmfríður; Barrett, Robert T.; Biscoito, Manuel; Bollache, Loïc; Boulinier, Thierry; Catry, Paulo; Ceia, Filipe R.; Chastel, Olivier; Christensen‐Dalsgaard, Signe; Cruz‐Flores, Marta; Danielsen, Jóhannis; Daunt, Francis; Dunn, Euan; Egevang, Carsten; Fagundes, Ana Isabel; Fayet, Annette L.; Fort, Jérôme; Furness, Robert W.; Gilg, Olivier; González‐Solís, Jacob; Granadeiro, J. P.; Grémillet, David; Guilford, Tim; Hanssen, Sveinn Are; Harris, Michael P.; Hedd, April; Huffeldt, Nicholas Per; Jessopp, Mark; Kolbeinsson, Yann; Krietsch, Johannes; Lang, Johannes; Linnebjerg, Jannie Fries; Lorentsen, Svein‐Håkon; Madeiros, Jeremy; Magnusdottir, Ellen; Mallory, Mark L.; McFarlane Tranquilla, Laura; Merkel, Flemming R.; Militão, Teresa; Moe, Børge; Montevecchi, William A.; Morera‐Pujol, Virginia; Mosbech, Anders; Neves, Verónica; Newell, Mark A.; Olsen, Bergur; Paiva, Vitor H.; Peter, Hans‐Ulrich; Petersen, Aevar; Phillips, Richard A.; Ramírez, Iván; Ramos, Jaime A.; Ramos, Raül; Ronconi, Robert A.; Ryan, Peter G.; Schmidt, Niels Martin; Sigurðsson, Ingvar A.; Sittler, Benoît; Steen, Harald; Stenhouse, Iain J.; Strøm, Hallvard; Systad, Geir H. R.; Thompson, Paul; Thórarinsson, Thorkell L.; Bemmelen, Rob S.A.; Wanless, Sarah; Zino, Francis; Dias, Maria P.The conservation of migratory marine species, including pelagic seabirds, is challenging because their movements span vast distances frequently beyond national jurisdictions. Here, we aim to identify important aggregations of seabirds in the North Atlantic to inform ongoing regional conservation efforts. Using tracking, phenology, and population data, we mapped the abundance and diversity of 21 seabird species. This revealed a major hotspot associated with a discrete area of the subpolar frontal zone, used annually by 2.9–5 million seabirds from ≥56 colonies in the Atlantic: the first time this magnitude of seabird concentrations has been documented in the high seas. The hotspot is temporally stable and amenable to site-based conservation and is under consideration as a marine protected area by the OSPAR Commission. Protection could help mitigate current and future threats facing species in the area. Overall, our approach provides an exemplar data-driven pathway for future conservation efforts on the high seas.
- Working the day or the night shift? Foraging schedules of Cory’s shearwaters vary according to marine habitatPublication . Dias, Paulo Sousa; Granadeiro, J. P.; Catry, PauloThe diel vertical migration of zooplankton and many other organisms is likely to affect the foraging behaviour of marine predators. Among these, shallow divers, such as many seabirds, are particularly constrained by the surface availability of prey items. We analysed the atsea activity of a surface predator of epipelagic and mesopelagic prey, Cory’s shearwater Calonectris diomedea, on its several wintering areas (spread throughout the temperate Atlantic Ocean and the Agulhas Current). Individual shearwaters were mainly diurnal when wintering in warmer and shallower waters of the Benguela, Agulhas and Brazilian Currents, and comparatively more nocturnal in colder and deeper waters of the Central South Atlantic and the Northwest Atlantic. Nocturnality also correlated positively with bathymetry and negatively with sea-surface temperature within a single wintering area. This is possibly related to the relative availability of epipelagic and mesopelagic prey in different oceanic sectors, and constitutes the first evidence of such flexibility in the daily routines of a top marine predator across broad spatial scales, with clear expression at population and individual levels
- Coastal waters of a marine protected area of the Bijagós Archipelago, West Africa, shelter juvenile fishes of economic and ecological importancePublication . Correia, Edna; Granadeiro, J. P.; Regalla De Barros, Aissa; Catry, PauloIn many marine ecosystems small pelagic fish exert a crucial role in controlling the dynamics of the community, mainly due to their high biomass at intermediate levels of the food web. These fish use coastal marine ecosystems as nursery areas, but also to forage and to avoid predation or competition. We studied spatial, seasonal, lunar and diel variations in a coastal fish community from a marine protected area of the Bijagós Archipelago, Guinea-Bissau. Fish were sampled with 46 beach seine net sessions in 2015 and 2016. A total of 35 fish species of 25 families were captured. Fish abundance varied between years and seasons, with a higher abundance in the dry season, but not by lunar tide. Nonetheless, the community composition was broadly similar over the seasons, among islands and between lunar tides. Clupeidae, Haemulidae and Gerreidae were the most abundant fish families. Sardinella maderensis highly dominated the captures throughout the year, with catches much higher than any other species. The differences in abundance between seasons and years may be related with movements to or from the shore due to feeding activity or to avoid predation, or else to differences in recruitment between years. There were no significant diel differences in species richness and diversity, although higher numbers of fish were captured during daytime. For most species the majority of individuals captured were immature, highlighting the importance of the archipelago as nursery area for several species. These small pelagics, and particularly Sardinella maderensis, represent the main prey for several marine predators. Thus, the conservation of such fish species may be key for the management of the Bijagós Archipelago.
- Trace elements’ reference levels in blood of breeding black-browed albatrosses Thalassarche melanophris from the Falkland IslandsPublication . Furtado, Ricardo; Granadeiro, J. P.; Campioni, Letizia; Silva, Mónica; Pereira, Eduarda; Catry, PauloTrace elements' concentration in the ocean is fast growing and is a source of major concern. Being charismatic and at the top of food chains, seabirds are often used as biological monitors of contaminants. We studied the concentration of trace elements in blood of black-browed albatross from the Falklands Islands, which we here show, by tracking with geolocators, forage over most of the Patagonian Shelf. Levels of trace elements were measured in males and females from two different islands. Blood concentrations of trace elements were not significantly different between islands, which is consistent with observations from foraging behavior revealing that birds from both islands foraged in broadly the same areas in the months before sampling. Arsenic and selenium concentrations in females were higher than in males. Sex-related differences in the concentration of these elements may be related to unknown slight differences in diet or to differences in assimilation between sexes. These results provide reference values for monitoring elemental contamination in the Patagonian Shelf Large Marine Ecosystem using black-browed albatrosses, one of the most abundant top predators and a suitable sentinel for the region's environmental health.
- Combined spatio-temporal impacts of climate and longline fisheries on the survival of a trans-equatorial marine migrantPublication . Ramos, Raül; Granadeiro, J. P.; Nevoux, Marie; Mougin, Jean-Louis; Dias, Maria P.; Catry, PauloPredicting the impact of human activities and their derivable consequences, such as global warming or direct wildlife mortality, is increasingly relevant in our changing world. Due to their particular life history traits, long-lived migrants are amongst the most endangered and sensitive group of animals to these harming effects. Our ability to identify and quantify such anthropogenic threats in both breeding and wintering grounds is, therefore, of key importance in the field of conservation biology. Using long-term capture-recapture data (34 years, 4557 individuals) and year-round tracking data (4 years, 100 individuals) of a trans-equatorial migrant, the Cory's shearwater (Calonectris diomedea), we investigated the impact of longline fisheries and climatic variables in both breeding and wintering areas on the most important demographic trait of this seabird, i.e. adult survival. Annual adult survival probability was estimated at 0.914±0.022 on average, declining throughout 1978-1999 but recovering during the last decade (2005-2011). Our results suggest that both the incidental bycatch associated with longline fisheries and high sea surface temperatures (indirectly linked to food availability; SST) increased mortality rates during the long breeding season (March-October). Shearwater survival was also negatively affected during the short non-breeding season (December-February) by positive episodes of the Southern Oscillation Index (SOI). Indirect negative effects of climate at both breeding (SST) and wintering grounds (SOI) had a greater impact on survival than longliner activity, and indeed these climatic factors are those which are expected to present more unfavourable trends in the future. Our work underlines the importance of considering both breeding and wintering habitats as well as precise schedules/phenology when assessing the global role of the local impacts on the dynamics of migratory species.
- The diet of two opportunistic seabirds (Caspian and Royal Terns) confirms the importance of Sardinella spp. in West African coastal food websPublication . Correia, Edna; Granadeiro, J. P.; Regalla, Aissa Said; Monteiro, Hamilton; Catry, PauloDespite their importance for fisheries, livelihoods and biodiversity conservation, shelf ecosystems in West Africa are poorly known. Caspian Tern (Hydroprogne caspia) and Royal Tern (Thalasseus maximus) are two of the most numerous and widespread nesting seabirds in the region, and an understanding of the diet of these opportunistic predators may throw light on important elements of the local food webs. This study describes and compares the prey consumed by these two species in Guinea and Guinea-Bissau collected from 2013 to 2015. Our results show that both tern species feed mostly on pelagic fish from which Clupeidae (mostly Sardinella maderensis) dominated the diet at all locations and seasons. Pristigasteridae and Polynemidae were the next most frequent prey in the diet of these two tern species. Our findings strengthen the recent suggestion of a wasp-waist ecosystem for our study area, with sardinella as the key prey for several predators, including seabirds and pelagic fishes, and potentially influencing their distribution and abundance. Moreover, our results show a higher diversity in the diet of the Caspian Tern, with this species preying on a greater range of benthopelagic fishes (e.g. Gerreidae; Mugilidae) which fits with observations of inshore foraging that seems rarer in Royal Terns. We further show that prey identification based only on otoliths from pellets, as opposed to the use of all hard structures (e.g. otoliths, vertebrae, scales), seriously underestimates the occurrence of species with fragile and small otoliths, including clupeids and other small pelagics.
- Diet and trophic position of two mackerel species in the archipelago of Madeira, PortugalPublication . Romero, Joana; Vieira, Carolina; Garrido, Susana; Hermida, Margarida; Catry, Paulo; Faria, Graça; Granadeiro, J. P.The Atlantic chub mackerel Scomber colias and the Blue jack mackerel Trachurus picturatus are two abundant species in the Macaronesia region which include the archipelago of Madeira, Portugal. Both are key species in the trophic web, being important prey for several local top predators, such as seabirds and marine mammals. However, little is known about their feeding ecology in oceanic environments. In this study, we describe the seasonal variation of the diet of S. colias and T. picturatus in the oceanic region of Madeira throughout a year. Visual inspection of stomach contents revealed that S. colias fed on a broader range of prey groups than T. picturatus, but for both species, zooplankton (particularly calanoid copepods) and fish were the most important food items. The diet of S. colias included a higher proportion of fish, namely Atlantic saury Scomberesox saurus and S. colias, than that of T. picturatus, that included mostly the Longspine snipefish Macroramphosus scolopax. Trachurus picturatus consumed a higher proportion of decapods and other copepods. Seasonal variation was found in the diet of both species, with zooplanktonic species being more important in colder months (February to April) for S. colias and during warm months (May to October) for T. picturatus. Their diet in other seasons were dominated by fish. Despite consuming similar prey, Carbon and Nitrogen stable isotope analysis of muscle of S. colias and T. picturatus showed little overlap in their diets, and T. picturatus showed higher δ15 N and a narrower isotopic niche.
- Evidence for trophic differences between live and bycatch oceanic juvenile loggerhead sea turtlesPublication . Raposo, Cheila; Patrício, Ana Rita; Catry, Paulo; Dellinger, Thomas; Granadeiro, J. P.The loggerhead sea turtle Caretta caretta is a vulnerable migratory species that spends its first years of life in the open sea. During this developmental phase, loggerheads can be found foraging in the epipelagic zone of the waters surrounding the Madeira Archipelago, providing a rare opportunity to gather information on the ecology of its oceanic developmental stage. In this study, we characterized the isotopic niche of these juveniles, using stable isotope analysis. We assessed two groups of turtles, turtles captured alive (n = 24) and turtles captured as bycatch on local longlines (n = 12), and explored whether animals caught in the local fishing gear represented a random sample of the population, or whether there is some evidence for a specialized foraging behaviour. We found that turtle bycatch had a significantly higher mean stable nitrogen isotope value in whole blood (δ15N = 8.5 ± 0.6‰ SD) compared to the group of turtles captured alive in the same period (δ15N = 7.6 ± 0.5‰ SD), indicating that they had a different diet. While there was a tendency for turtle bycatch to be slightly larger, we found no effect of body size on δ15N values. We propose a distinct foraging behaviour strategy hypothesis, with a group of turtles being more susceptible to interactions with fisheries and thus having a higher mortality risk, which should motivate the implementation of existing guidelines to reduce sea turtle bycatch.
- Global political responsibility for the conservation of albatrosses and large petrelsPublication . Beal, Martin; Dias, Maria P.; Phillips, Richard A.; Oppel, Steffen; Hazin, Carolina; Pearmain, Elizabeth J.; Adams, Josh; Anderson, David J.; Antolos, Michelle; Arata, Javier; Arcos, José Manuel; Arnould, John P. Y.; Awkerman, Jill; Bell, Elizabeth; BELL, Mike; Carey, Mark; Carle, Ryan; Clay, Thomas A.; Cleeland, Jaimie; Colodro, Valentina; Conners, Melinda; Flores, Marta Cruz; Cuthbert, Richard; Delord, Karine; Deppe, Lorna; Dilley, Ben J.; Dinis, Herculano; Elliott, Graeme; De Felipe, Fernanda; Felis, Jonathan; Forero, Manuela G.; Freeman, Amanda; Fukuda, Akira; González-Solís, Jacob; Granadeiro, J. P.; Hedd, April; Hodum, Peter; Igual, Jose Manuel; Jaeger, Audrey; Landers, Timothy; Le Corre, Matthieu; Makhado, Azwianewi; Metzger, Benjamin; Militão, Teresa; Montevecchi, William A.; Pujol, Virginia Morera; Herrero, Leia Navarro; Nel, Deon; Nicholls, David; Oro, Daniel; Ouni, Ridha; Ozaki, Kiyoaki; Quintana, Flavio; Ramos, Raül; Reid, Tim; Reyes-González, José Manuel; Robertson, Christopher; Robertson, Graham; Romdhane, Mohamed Salah; Ryan, Peter G.; Sagar, Paul; Sato, Fumio; Schoombie, Stefan; Scofield, Richard; Shaffer, Scott; Shah, Nirmal Jivan; Stevens, Kim L.; Surman, Christopher; Suryan, Robert M.; Takahashi, Akinori; Tatayah, Vikash; Taylor, Graeme; Thompson, David R.; Torres, Leigh; Walker, Kath; Wanless, Ross; Waugh, Susan M.; Weimerskirch, Henri; Yamamoto, Takashi; Zajkova, Zuzana; Zango, Laura; Catry, PauloMigratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.