Predicting the distribution of a threatened albatross: The importance of competition, fisheries and annual variability

Abstract

a b s t r a c tThe ability to predict the distribution of threatened marine predators is essential to inform spatially explicit seascape management. We tracked 99 individual black-browed albatrosses Thalassarche melanophris from two Falkland Islands' colonies in 2 years. We modeled the observed distribution of foraging activity taking environmental variables, fisheries activity (derived from vessel monitoring system data), accessibility to feeding grounds and intra-specific competition into account. The resulting models had sufficient generality to make reasonable predictions for different years and colonies, which allows temporal and spatial variation to be incorporated into the decision making process by managers for regions and seasons where available information is incomplete. We also illustrated that long-ranging birds from colonies separated by as little as 75 km can show important spatial segregation at sea, invalidating direct or uncorrected extrapolation from one colony to neighboring ones. Fisheries had limited influence on albatross distribution, despite the well known scavenging behavior of these birds. The models developed here have potentially wide application to the identification of sensitive geographical areas where special management practices (such as fisheries closures) could be implemented, and would predict how these areas are likely to move with annual and seasonal changes in environmental conditions.

DNA Metabarcoding as a Marine Conservation and Management Tool: A Circumpolar Examination of Fishery Discards in the Diet of Threatened Albatrosses

“…For the main fish species (those contributing >10% of amplified sequences), the depth profile for each species during different age stages were compiled from the literature to determine which were likely to be naturally accessible to albatrosses (Table S1 in Supplementary Material). This study focused on the fishing zones adjacent to the breeding sites, as these are likely to be used more intensively than distant waters by foraging birds during chick-rearing (Phillips et al, 2004;Terauds et al, 2006;Catry et al, 2013;Arata et al, 2014), and secondly, the management of these areas is within the same national jurisdiction as the relevant breeding site. However, we acknowledge that birds may have also interacted with fisheries further from colonies, especially during incubation when BBA are foraging farther from the colony than during chick rearing (Phillips et al, 2004;Wakefield et al, 2011) …”

Biologically informed ecological niche models for an example pelagic, highly mobile species

“…Researchers have used these methods to address specific aspects of seabird distributional ecology such as habitat suitability (Ceia et al 2012;Oppel et al 2012;Catry et al 2013;Louzao et al 2013;McGowan et al 2013;Scales et al 2016), identification of hotspots in the present and past (Louzao et al 2013), selection of potential conservation areas and potential climate change impacts (Krüger 2017). But, many of the more recent applications use ensemble modelling (Scales et al 2016;Krüger 2017) or incorporate seabird movement data (Clay 2016;Quillfeldt 2017) that, whilst increasing in quantity and availability, is nowhere near as prevalent or accessible as point observation data.…”

“…Improved correlative modelling approaches, building on the baseline presented herein, can significantly enhance understanding of macroscale factors driving distributional dynamics of species, including pelagic seabirds and other highly mobile species, and provide crucial information to fill important information gaps necessary to project and explore the future distributional potential (Louzao et al 2011;Catry et al 2013). These insights, in combination with increasing knowledge of species' natural history and ecology, can inform conservation planners and offer information vital to the research priorities identified by Lewison et al (2012) including identification and mapping of movement corridors and foraging areas to understand impacts of global change on the distributions of pelagic seabirds and other highly mobile species.…”

“…Many pelagic seabird species appear to behave as generalists overall, whilst maintaining individual-or group-level specialisations (Ceia et al 2012). In view of their complex behavioural biology (Grecian et al 2012;Catry et al 2013), such as high individual variability (Phillips et al 2005), complex habitat partitioning and movement strategies (Phillips et al 2005;Weimerskirch et al 2006), and colonial nesting habits, available data for many of these species are highly biased towards breeding individuals. This information bias has left gaps in knowledge about at-sea distributions of non-breeding individuals (Weimerskirch et al 2003;Taylor et al 2011;Grecian et al 2012;Lascelles et al 2012).…”

Contribution of fishery discards to the diet of the Black-browed albatross (Thalassarche melanophris) during the non-breeding season: an assessment through stable isotope analysis

“…as it was previously stated, the overlapping between ice trawlers and BBas strongly suggests that the contribution of demersal fish to the diet of these birds during winter comes from the ice-trawl fleet. However, given the similitude between ice and freezer trawlers in the target species and by-products of the fishing operation, we understand that freezer trawlers should be regarded in the same way for conservation and management purposes, at least during moments of the annual cycle when BBas are distributed further south in the vicinity of breeding grounds (granadeiro et al 2011;Catry et al 2013). available information shows that the trawler fleet from Uruguay has the argentine hake as one of main target species (99.8 % of total landing for this species, DInara 2010) and this species is also discarded by shrimp-trawl fleet operating further south at the argentinean Continental Shelf, hence suggesting that BBas could be making use of discards from these fleets as well.…”