P.N. Trathan results 27
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Marine megafauna species are affected by a wide range of anthropogenic threats. To evaluate the risk of such threats, species’ vulnerability to each threat must first be determined. We build on the existing threats classification scheme and ranking system of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species by assessing the vulnerability of 256 marine megafauna species to 23 at‐sea threat...
Scaling up ocean conservation through recognition of key biodiversity areas in the Southern Ocean from multispecies tracking dataNARA Subscribed
Biodiversity is critical for maintaining ecosystem function but is threatened by increasing anthropogenic pressures. In the Southern Ocean, a highly biologically productive region containing many endemic species, proactive management is urgently needed to mitigate increasing pressures from fishing, climate change, and tourism. Site‐based conservation is one important tool for managing the negative impacts of human activities o...
The west Antarctic Peninsula is an important breeding and foraging location for marine predators that consume Antarctic Krill ( Euphasia superba ). It is also an important focus for the commercial fishery for Antarctic krill, managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Aiming to minimise ecosystem risks from fishing, whilst enabling a sustainable fishery, CCAMLR has recently en...
This study was performed to aid the management of the fishery for Antarctic krill Euphausia superba . Krill are an important component of the Antarctic marine ecosystem, providing a key food source for many marine predators. Additionally, krill are the target of the largest commercial fishery in the Southern Ocean, for which annual catches have been increasing and concentrating in recent years. The krill fishery is managed by...
Un-crewed aerial vehicle population survey of three sympatrically breeding seabird species at Signy Island, South Orkney IslandsNARA Subscribed
Surveying seabirds in polar latitudes can be challenging due to sparse human populations, lack of infrastructure and the risk of disturbance to wildlife or damage to habitats. Counting populations using un-crewed aerial vehicles (UAVs) is a promising approach to overcoming these difficulties. However, a careful validation of the approach is needed to ensure comparability with counts collected using conventional methods. Here,...
Unravelling the relative roles of top‐down and bottom‐up forces driving population change in an oceanic predatorNARA Subscribed
In the open ocean ecosystem, climate and anthropogenic changes have driven biological change at both ends of the food chain. Understanding how the population dynamics of pelagic predators are simultaneously influenced by nutrient‐driven processes acting from the “bottom‐up” and predator‐driven processes acting from the “top‐down” is therefore considered an urgent task. Using a state‐space demographic model, we evaluated the po...
Climate change and Southern Ocean ecosystems I: how changes in physical habitats directly affect marine biotaNARA Subscribed
Antarctic and Southern Ocean ( ASO ) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This article reviews current and expect...
Genetic tagging reveals extreme site fidelity in territorial male Antarctic fur seals Arctocephalus gazellaNARA Subscribed
Genetic tagging, the identification of individuals using their genotypes, provides a powerful tool for studying animals that are difficult to observe or identify using conventional techniques. However, despite being widely adopted by conservation biologists, the full potential of this approach has yet to be realized. Here we used genetic recapture data to quantify male site fidelity at a colony of Antarctic fur seals where an...
Contrasting population changes in sympatric penguin species in association with climate warmingNARA Subscribed
Climate warming and associated sea ice reductions in Antarctica have modified habitat conditions for some species. These include the congeneric Adélie, chinstrap and gentoo penguins, which now demonstrate remarkable population responses to regional warming. However, inconsistencies in the direction of population changes between species at different study sites complicate the understanding of causal processes. Here, we show tha...
Foraging ecology and interactions with fisheries of wandering albatrosses ( Diomedea exulans ) breeding at South GeorgiaNARA Subscribed
Knowledge about the areas used by the foraging wandering albatross, Diomedea exulans , its prey and overlap with longline fisheries is important information not only for the conservation of this species but also for furthering our understanding of the ecology of its prey. We attached satellite‐tracking devices and activity recorders to wandering albatrosses between May and July of 1999 and 2000 (years of differing food availab...
Synchronicity in southern hemisphere squid stocks and the influence of the Southern Oscillation and Trans Polar IndexNARA Subscribed
Squid are short lived, with highly labile populations that respond rapidly to changes in environmental conditions. This makes them a good model for studying the response of recruitment processes to environmental signals. This study examines the influence of the Southern Oscillation Index (SOI) and Trans Polar Index (TPI) on the environment and abundance of six species of commercially important squid from the southern hemispher...
Oceanographic variability and changes in Antarctic krill ( Euphausia superba ) abundance at South GeorgiaNARA Subscribed
Oceanographic data collected to the north of South Georgia were examined for three consecutive summers (1996/97, 1997/98, 1998/99). The results show the existence of a shelf break front during each period. The most reliable means of defining the front was the potential density anomaly at the near‐surface potential temperature minimum. In each year, off‐shelf waters were separated from on‐shelf waters by water with a potential...