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Henri Weimerskirch – One of the best experts on this subject based on the ideXlab platform.

  • Illegal fishing bycatch overshadows climate as a driver of Albatross population decline
    Marine Ecology Progress Series, 2017
    Co-Authors: Pamela E. Michael, Henri Weimerskirch, Karine Delord, Christophe Barbraud, Robin Thomson, Sophie De Grissac, Alistair Hobday, P. G. Strutton, Geoffrey N. Tuck, Chris Wilcox

    Abstract:

    Effective management of Albatross populations requires understanding the impacts of environmental factors on Albatross demographics. An integrated modeling approach, incorporating multiple data sources, can further the understanding of Albatross demographics by incorporating error from all components of modeling and distinguishing between variability related to one factor (e.g. environment) from that of another factor (e.g. density-dependence). We apply such an integrated, spatially-explicit population model to quantify the impact of environmental conditions (sea-surface temperature: SST), fisheries, and density-dependence on a black-browed Albatross (Thalassarche melanophris) population breeding on Kerguelen Island, southern Indian Ocean for the period 1950-2011. The model is structured by sex, age-class, and breeding stage, with a 5 × 5 spatial scale and monthly temporal scale. All parameters are estimated within a maximum-likelihood framework. This includes estimation of the seabird bycatch rates of each of five fishing super-fleets, grouped by gear-type and reported bycatch rates: (i) Japanese pelagic longline, (ii) other pelagic longline, (iii) legal demersal longline, (iv) trawl, and (iv) illegal, unreported and unregulated (IUU) demersal longline. A decline in the Kerguelen black-browed Albatross population occurred between the mid-1990s through the mid-2000s. Our analysis attributes the majority of modelled bycatch to the IUU demersal longline super-fleet operating near Kerguelen for this period. Including SST during the incubation period indicated that warm SST favors high breeding success. These results indicate that effective management requires an integrated understanding of the impacts of the environment, illegal, and legal fishing activities on vulnerable populations

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  • High occurrence of jellyfish predation by black-browed and Campbell Albatross identified by DNA metabarcoding
    Molecular Ecology, 2017
    Co-Authors: Julie C. Mcinnes, Rachael Alderman, Mary-anne Lea, Ben Raymond, Bruce E. Deagle, Richard A Phillips, Andrew Stanworth, David R. Thompson, Paulo Catry, Henri Weimerskirch

    Abstract:

    Gelatinous zooplankton are a large component of the animal biomass in all marine environments, but are considered to be uncommon in the diet of most marine top predators. However, the diets of key predator groups like seabirds have conventionally been assessed from stomach content analyses, which cannot detect most gelatinous prey. As marine top predators are used to identify changes in the overall species composition of marine ecosystems, such biases in dietary assessment may impact our detection of important ecosystem regime shifts. We investigated Albatross diet using DNA metabarcoding of scats to assess the prevalence of gelatinous zooplankton consumption by two Albatross species, one of which is used as an indicator species for ecosystem monitoring. Black-browed and Campbell Albatross scats were collected from eight breeding colonies covering the circumpolar range of these birds over two consecutive breeding seasons. Fish was the main dietary item at most sites, however cnidarian DNA, primarily from scyphozoan jellyfish was present in 42% of samples overall and up to 80% of samples at some sites. Jellyfish was detected during all breeding stages and consumed by adults and chicks. Trawl fishery catches of jellyfish near the Falkland Islands indicate a similar frequency of jellyfish occurrence in Albatross diets in years of high and low jellyfish availability, suggesting jellyfish consumption may be selective rather than opportunistic. Warmer oceans and overfishing of finfish are predicted to favour jellyfish population increases and we demonstrate here that dietary DNA metabarcoding enables measurements of the contribution of gelatinous zooplankton to the diet of marine predators.

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  • Tracking reveals limited interactions between Campbell Albatross and fisheries during the breeding season
    Journal of Ornithology, 2017
    Co-Authors: Lisa A. Sztukowski, Henri Weimerskirch, David R. Thompson, Mariëlle L. Van Toor, Leigh G. Torres, Paul M. Sagar, Peter A. Cotton, Stephen C. Votier

    Abstract:

    Fisheries-related mortality has been influential in driving global declines in seabird populations. Understanding the overlap between seabird distribution and fisheries is one important element in assessing bycatch risk, and may be achieved by tracking the movements of individual birds and fishing vessels. Here, we assess the spatiotemporal overlap between the vulnerable Campbell Albatross Thalassarche impavida and large (>28 m) commercial fishing boats in New Zealand’s Exclusive Economic Zone (EEZ). We used a novel analytical approach, bivariate Gaussian bridge movement modelling, to compute spatiotemporal utilization distributions of bird-borne global positioning system (GPS) loggers and data from the Vessel Monitoring System. We tracked birds for 28,815 h during incubation and chick brooding, with half of this time spent within New Zealand’s EEZ, utilizing 6.7% of the available area. However, there was no evidence that Albatrosses and fishing vessels were in the same location simultaneously. We accounted for the broader ecological footprint of fishing vessels by calculating the distance between GPS-fix locations for Albatrosses and fishing vessels, revealing that Albatrosses were within 30 km of fishing vessels in 8.4% of foraging trips. This highlights differences in estimated fine-scale spatiotemporal overlaps which may be due to the distance between Albatrosses and vessels or the methods used. Overall, the low levels of spatial overlap could be a result of Campbell Albatross’ preference for foraging in areas without fishing activity or competitive exclusion by other species. Our results reinforce the importance of multi-scale, temporally explicit, and multi-national approaches to risk assessment, as Campbell Albatrosses spend approximately half of their time foraging outside New Zealand’s EEZ. Besenderung zeigt limitierte Interaktionen zwischen Campbell Albatrossen und der Fischerei während der Brutzeit Die durch Fischfang verursachte Sterblichkeit hat einen entscheidenden Einfluss auf die globalen Rückgänge von Seevogelpopulationen. Ein wichtiges Element zur Abschätzung des Beifangrisikos ist das Verständnis der Überschneidung von Seevogelverbreitungen und Fischerei. Ein solches Verständnis kann erlangt werden durch die Verfolgung der Bewegungen einzelner Seevogelindividuen und der von Fischereibooten. In der vorliegenden Studie untersuchen wir die räumlich-zeitliche Überschneidung zwischen dem gefährdeten Campbell Albatross Thalassarche impavida und großen (> 28 m) kommerziellen Fischereischiffen in der neuseeländischen Ausschließlichen Wirtschaftszone (AWZ) ab. Dazu nutzten wir einen neuen Analyseansatz, „Bivariate Gaussian Bridge Movement“-Modelle, um aus den GPS-Loggerdaten der Vögel und Daten des Schiffsmonitorings die räumlich-zeitliche Nutzungsverteilung zu berechnen. Wir verfolgten besenderte Vögel über 28.815 Stunden während der Inkubations- und Huderphase. Die Hälfte dieser Zeit verbrachten die Vögel in der neuseeländischen AWZ, wobei sie 6,7% der insgesamt verfügbaren Fläche nutzten. Jedoch gab es keine Belege dafür, dass sich Albatrosse und Fischereiboote gleichzeitig im selben Gebiet aufhielten. Wir berücksichtigten auch den breiteren ökologischen Fußabdruck der Fischerei durch die Berechnung der Distanz zwischen den GPS-Punkten der Albatrosse und den Fischereibooten. Es zeigte sich, dass sich die Albatrosse in 8,4% ihrer Nahrungsflüge in einem 30 km Radius um die Fischereiboote aufhielten. Dies zeigt die Unterschiede zwischen den berechneten feinskaligen räumlich-zeitlichen Überschneidungen auf, die wahrscheinlich auf die Distanzen zwischen Albatrossen und Schiffen oder auf die angewendeten Methoden zurückzuführen sind. Die geringe räumliche Überschneidung kann die Folge davon sein, dass die Albatrosse Nahrungsgebiete präferieren, in denen nicht gefischt wird, oder von Konkurrenzausschluss durch andere Arten. Unsere Ergebnisse bekräftigen die Wichtigkeit mehrskaliger, zeitlich expliziter und multinationaler Ansätze der Gefährdungsabschätzung, da Campbell Albatrosse schätzungsweise die Hälfte der Zeit zur Nahrungssuche außerhalb der neuseeländischen AWZ verbringen.

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Rosemary Gales – One of the best experts on this subject based on the ideXlab platform.

  • global population status of shy Albatross and an assessment of colony specific trends and drivers
    Wildlife Research, 2011
    Co-Authors: Rachael Alderman, Rosemary Gales, Geoff Tuck, J D Lebreton

    Abstract:

    Context. Monitoring the status of Albatross populations and identifying the factors driving observed trends remain international conservation and management priorities. The shy Albatross is endemic to Australia and breeds only on three Tasmanian islands. Aims.ToprovideareliabletotalpopulationestimateforshyAlbatross,includinganassessmentofdemographictrendsfor each of the three populations where possible. We consider also key drivers of population trends for each population, particularly the potential role of fisheries by-catch, with an overall aim of determining the status of the species. Methods.Aerialphotographyandgroundsurveyswereusedtoestimatethenumberofannualbreedingpairsandtrendsin adultandjuvenilesurvivalrateswerecalculatedusingmark–recapturemethods.At-seadistributiondatawasusedtoidentify populationspecifictrendsintheoverlapofshyAlbatrossand fisheriestoevaluatethepotentialinfluenceof fisheriesby-catch on the populations. Key Results. The Albatross Island population increased post-harvesting but has recently stabilised at around 5200 breeding pairs, less than half its estimated historic size. This trajectory change appears driven by a decrease in juvenile survival. The small (170 breeding pairs) Pedra Branca population has recently declined, probably due to reduced breeding success associated with the increasing population of Australasian gannets (Morus serrator) on the island. The largest population (on Mewstone) comprises at least 9500 breeding pairs. Trends for this population are unknown. However, this paperdemonstratesthatthesebirdshavegreateroverlapwithtrawlandlongline fishingeffortandareconsequentlyathigher risk of fishing-related mortality. Conclusions.Giventheextentof fisheriesoverlap,survivalratesforMewstoneindividualsarelikelytobelowerthanthe AlbatrossIslandpopulation.CombinedwithrecenttrendsonPedraBrancaandAlbatrossIsland,wesuggestthatthecurrent status of the shy Albatross is likely to be stable at best and quite possibly decreasing. Implications. The concerns raised about the conservation status of shy Albatross reinforce the importance of continued population monitoring focussed particularly on establishing the trend of Mewstone. A thorough assessment of interactions with trawl fishing operations also is a management priority for this species.

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  • foraging movements of the shy Albatross diomedea cauta breeding in australia implications for interactions with longline fisheries
    Ibis, 2008
    Co-Authors: Rosemary Gales, April Hedd, Graham Robertson

    Abstract:

    Satellite telemetry was used to identify the foraging zones of Shy Albatrosses Diomedea cauta breeding at two sites off Tasmania, Australia (Albatross Island in western Bass Strait and Pedra Branca to the south) to assess their level of interaction with longline fisheries. Adult birds from both colonies fed locally both in and outside the breeding season. Breeding birds from Albatross Island foraged over the Australian continental shelf or slope waters off northwest Tasmania, while those from Pedra Branca foraged between the colony and the southeastern edge of the continental shelf. The distances travelled by the birds and the duration of their foraging trips varied during the breeding cycle and tended to decrease as eggs approached hatching. Adults which were tracked near the end of the breeding season (March-April, n = 7 birds) deserted their chicks prematurely, and while dispersing further than incubating or brooding birds, they remained over the continental shelf and slope waters off southeast Australia. Home range analyses indicated 41% overlap between foraging zones of birds during successive breeding stages. Dispersal during the postbreeding period extended the foraging zones with less overlap between individuals (10% for Albatross Island and 19% for Pedra Branca). The recent contraction of the Japanese Southern Blue fin Tuna longline fishery to the south and east coasts of Tasmania has resulted in extensive overlap with adult Shy Albatrosses from Pedra Branca, but appears to pose a minimal threat to adult birds from Albatross Island. Coupled with the concomitant increase in the Australian domestic tuna longlining industry, adult Shy Albatrosses from southern Tasmania (Pedra Branca and the Mewstone) are vulnerable to incidental capture throughout their annual cycle.

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  • foraging strategies of shy Albatross thalassarche cauta breeding at Albatross island tasmania australia
    Marine Ecology Progress Series, 2001
    Co-Authors: April Hedd, Rosemary Gales

    Abstract:

    The foraging zones and behaviour of shy Albatross Thalassarche cauta were studied at Albatross Island, Tasmania, Australia, during the 1995/96 and 1996/97 breeding seasons, using a combination of archival recorders and satellite telemetry. Birds foraged exclusively in the neritic zone, at a maximum distance of 200 km from the colony, making wide use of continental shelf waters off northwest Tasmania. The duration of foraging trips, the distances traveled and the activity ranges of the birds (i.e. 95% isopleths from Kernel home range analyses) were greatest during incubation (2.8 d, 754 km, 24 667 km 2 ), least during chick-brood (1.1 d, 273 km, 19 067 km 2 ), and intermediate during early chick-rearing (1.8 d, 426 km, 19 400 km 2 ). At the population level, the foraging zones of the birds (i.e. the 50% home range isopleths) were highly consistent between years, overlapping by 43% during both the incubation and chick-brooding stages across 3 breeding seasons. Overall, the foraging zones of males and females were similar in both size and location. Individual birds did not return to the same locations to feed from 1 trip to the next; however, their foraging was not random. On successive trips birds maintained a constant heading from the colony, repeatedly searching the same broad patches of ocean, a degree of site fidelity maintained within a single breeding stage. They flew for 72% of the daytime and 39% of the night, and their rate of travel was significantly higher during the day. Combined with a diet predominated by prey found at or near the surface dur- ing the day, these data suggest that shy Albatross are largely diurnal feeders. Nocturnal activity was strongly influenced by moon phase, with increased time spent flying and increased flight speed dur- ing full moon. Consistent traveling speeds, foraging trip durations and foraging locations across years suggest relatively stable prey availability and/or accessibility for shy Albatross breeding off the northwest coast of Tasmania.

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Rachael Alderman – One of the best experts on this subject based on the ideXlab platform.

  • telemetry reveals existing marine protected areas are worse than random for protecting the foraging habitat of threatened shy Albatross thalassarche cauta
    Diversity and Distributions, 2018
    Co-Authors: Claire Mason, Rachael Alderman, Jennifer Mcgowan, Hugh P Possingham, Alistair J Hobday, Michael D Sumner, Justine D Shaw

    Abstract:

    Aim
    To assess the efficacy of marine reserves in Australia for shy Albatross, using long‐term tracking data.

    Location
    Albatross Island, Tasmania, and south Australian waters.

    Methods
    We integrated a tracking dataset consisting of 111 individuals collected over 23 years and generated Brownian bridge kernel density estimations to identify important habitat. We quantified the overlap between the foraging distribution of early incubating adults and post‐fledgling juveniles with management boundaries and marine reserves. We compared the extent of coverage of Albatross foraging areas by Marine Protection Areas (MPAs) relative to a randomly designed network of the same size to determine whether the spatial protection measures are likely to be effective.

    Results
    Incubating adults consistently foraged in waters to the northwest of Tasmania while post‐fledglings occupied shelf waters around Tasmania and South Australia. We show that our sample of 99 incubating adults adequately represented the population but that our sample of 12 post‐fledgling birds was insufficient, thereby limiting the confidence in our results for this life stage. The Commonwealth Government has the majority of management responsibility for shy Albatross at‐sea, containing 88% and 90% of the area occupied most intensively by adult and post‐fledgling shy Albatross, respectively. Randomly designed reserve networks outperformed the current MPA network for both life stages, such that the mean protection by a random reserve system was 30% and 12% higher than the actual protection for adults and juveniles in Commonwealth waters.

    Main conclusions
    Important foraging habitat of shy Albatross from Albatross Island is mostly within Commonwealth‐managed waters. The current MPA network, the only spatial protection measure for shy Albatross, provides less coverage for this species than a randomly placed network. An increase in the representation of productive shelf waters in MPA networks would benefit the conservation of shy Albatross through reducing fisheries interactions and protecting habitat in these regions.

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  • High occurrence of jellyfish predation by black-browed and Campbell Albatross identified by DNA metabarcoding
    Molecular Ecology, 2017
    Co-Authors: Julie C. Mcinnes, Rachael Alderman, Mary-anne Lea, Ben Raymond, Bruce E. Deagle, Richard A Phillips, Andrew Stanworth, David R. Thompson, Paulo Catry, Henri Weimerskirch

    Abstract:

    Gelatinous zooplankton are a large component of the animal biomass in all marine environments, but are considered to be uncommon in the diet of most marine top predators. However, the diets of key predator groups like seabirds have conventionally been assessed from stomach content analyses, which cannot detect most gelatinous prey. As marine top predators are used to identify changes in the overall species composition of marine ecosystems, such biases in dietary assessment may impact our detection of important ecosystem regime shifts. We investigated Albatross diet using DNA metabarcoding of scats to assess the prevalence of gelatinous zooplankton consumption by two Albatross species, one of which is used as an indicator species for ecosystem monitoring. Black-browed and Campbell Albatross scats were collected from eight breeding colonies covering the circumpolar range of these birds over two consecutive breeding seasons. Fish was the main dietary item at most sites, however cnidarian DNA, primarily from scyphozoan jellyfish was present in 42% of samples overall and up to 80% of samples at some sites. Jellyfish was detected during all breeding stages and consumed by adults and chicks. Trawl fishery catches of jellyfish near the Falkland Islands indicate a similar frequency of jellyfish occurrence in Albatross diets in years of high and low jellyfish availability, suggesting jellyfish consumption may be selective rather than opportunistic. Warmer oceans and overfishing of finfish are predicted to favour jellyfish population increases and we demonstrate here that dietary DNA metabarcoding enables measurements of the contribution of gelatinous zooplankton to the diet of marine predators.

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  • global population status of shy Albatross and an assessment of colony specific trends and drivers
    Wildlife Research, 2011
    Co-Authors: Rachael Alderman, Rosemary Gales, Geoff Tuck, J D Lebreton

    Abstract:

    Context. Monitoring the status of Albatross populations and identifying the factors driving observed trends remain international conservation and management priorities. The shy Albatross is endemic to Australia and breeds only on three Tasmanian islands. Aims.ToprovideareliabletotalpopulationestimateforshyAlbatross,includinganassessmentofdemographictrendsfor each of the three populations where possible. We consider also key drivers of population trends for each population, particularly the potential role of fisheries by-catch, with an overall aim of determining the status of the species. Methods.Aerialphotographyandgroundsurveyswereusedtoestimatethenumberofannualbreedingpairsandtrendsin adultandjuvenilesurvivalrateswerecalculatedusingmark–recapturemethods.At-seadistributiondatawasusedtoidentify populationspecifictrendsintheoverlapofshyAlbatrossand fisheriestoevaluatethepotentialinfluenceof fisheriesby-catch on the populations. Key Results. The Albatross Island population increased post-harvesting but has recently stabilised at around 5200 breeding pairs, less than half its estimated historic size. This trajectory change appears driven by a decrease in juvenile survival. The small (170 breeding pairs) Pedra Branca population has recently declined, probably due to reduced breeding success associated with the increasing population of Australasian gannets (Morus serrator) on the island. The largest population (on Mewstone) comprises at least 9500 breeding pairs. Trends for this population are unknown. However, this paperdemonstratesthatthesebirdshavegreateroverlapwithtrawlandlongline fishingeffortandareconsequentlyathigher risk of fishing-related mortality. Conclusions.Giventheextentof fisheriesoverlap,survivalratesforMewstoneindividualsarelikelytobelowerthanthe AlbatrossIslandpopulation.CombinedwithrecenttrendsonPedraBrancaandAlbatrossIsland,wesuggestthatthecurrent status of the shy Albatross is likely to be stable at best and quite possibly decreasing. Implications. The concerns raised about the conservation status of shy Albatross reinforce the importance of continued population monitoring focussed particularly on establishing the trend of Mewstone. A thorough assessment of interactions with trawl fishing operations also is a management priority for this species.

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