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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

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

  • 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.

  • 167 individuals versus millions of hooks: bycatch mitigation in longline fisheries underlies conservation of Amsterdam Albatrosses
    Aquatic Conservation: Marine and Freshwater Ecosystems, 2016
    Co-Authors: Jean-baptiste Thiebot, Christophe Barbraud, Karine Delord, Cédric Marteau, Henri Weimerskirch
    Abstract:

    1. Industrial fisheries represent one of the most serious threats worldwide to seabird conservation. Death of birds in fishing operations (i.e. bycatch) has especially adverse effects on populations of Albatrosses, which have extremely low fecundity. 2. The single population worldwide of Amsterdam Albatross (Diomedea amsterdamensis) comprises only 167 individuals and risks considerable decline over the mid-term from additional mortality levels potentially induced by fisheries. The priority actions listed in the current conservation plan for this species included characterizing the longline fisheries operating within its range, dynamically analysing the overlap between Albatrosses and these fisheries, and providing fisheries management authorities with potential impact estimates of longline fisheries on the Amsterdam Albatross. 3. During all life-cycle stages and year quarters the birds overlapped extensively with fishing effort in the southern Indian and Atlantic oceans. Fishing effort, and consequently overlap score (calculated as the product of fishing effort and time spent by the birds in a spatial unit) was highest in July–September (45% of the hooks annually deployed). Just three fleets (Taiwanese, Japanese and Spanish) contributed to >98% of the overlap scores for each stage (72% from the Taiwanese fleet alone, on average). Daily overlap scores were higher for the non-breeding versus the breeding stages (3-fold factor on average). 4. Based on previous bycatch rates for other Albatross species, this study estimated that longline fisheries currently have the potential to remove ~2–16 individuals (i.e. ~5%) each year from the total Amsterdam Albatross population, depending on whether bycatch mitigation measures were or were not systematically employed during the fishing operations. 5. Recent bycatch mitigation measures may be instrumental in the conservation of the Amsterdam Albatross. This study suggests three further key recommendations: (1) to focus conservation efforts on the austral winter; (2) to require all operating vessels to report ring recoveries; and (3) to allocate special regulation of fishing operations in the areas of peak bycatch risk for the Amsterdam Albatrosses.

  • Atlas of top predators from French Southern Territories in the Southern Indian Ocean
    2014
    Co-Authors: K Delord, C Barbraud, C-a Bost, Y Cherel, C Guinet, Henri Weimerskirch
    Abstract:

    This Atlas of top predators from the French Southern Territories in the Southern Indian Ocean is a summary of information on the use of the southern Indian Ocean by 22 seabirds and seals species: king penguin, gentoo penguin, Adelie penguin, eastern rockhopper penguin, northern rockhopper penguin, macaroni penguin, Amsterdam Albatross, wandering Albatross, black-browed Albatross, Indian yellow-nosed Albatross, light-mantled Albatross, sooty Albatross, southern giant petrel, northern giant petrel, southern fulmar, Cape petrel, snow petrel, white-chinned petrel, grey petrel, brown skua, southern elephant seal and Antarctic fur seal. The distribution map of each species was obtained by the use of tracking methods that allow identifying important areas in the southern Indian Ocean. The determination of zones of high species richness suggests several important areas for top predators. First the breeding colonies and surrounding zones: Amsterdam and Saint Paul Islands, Marion and Prince Edward islands and the Del Cano Rise, Crozet Islands, Kerguelen Plateau and East Antarctica (Adlie Land sector). Second, the upwelling-current zones: Benguela and Agulhas Currents Systems and third several the oceanic zones: the Southwest Indian Ridge (East Bouvetya and the North Subtropical Front), the Mid-Indian Ridge (North of Kerguelen and the Eastern Indian Ocean, the Southeast Indian Ridge (Great Australian Bight and Tasmania, Ob and Lena Banks, and East Antarctica (Prydz Bay - Queen Maud Land sectors, Adlie Land sector). The analysis of distribution indicates that some pelagic species have a much wider foraging range outside the breeding season than during the breeding season (some disperse over very large areas, i.e. wandering Albatross). This highlights the urgent need to strengthen collaborations, namely between conservation and management organisms such as CCAMLR and the fisheries organisations (RFMOs), to ensure the protection of these species and the conservation of the ecosystem that will also be beneficial for many other species. In conclusion, although this inventory of areas of key importance is preliminary because of the lack of data on several keystone species such as burrowing petrels which could not be studied in this work, the results presented here show an unprecedented improvement in the identification of priority areas within the Southern Indian Ocean, which should be the primary targets of site-based conservation efforts in the near future. The Southern Indian Ocean is not pristine. The most serious threats are linked to industrial fishing activities, including fishery discards, bycatch of seabirds and marine mammals, as well as, in a lesser extent, degradation of marine environments through global and local pollution. On land, alien introductions and diseases are now the main threats. Despite much improvement in the conservation measures taken by several fisheries, especially in the southern part of the Indian Ocean, fisheries continue to exert an important negative influence on several seabirds, especially on the high seas. However climate change is now increasingly considered to have a negative impact on seabirds at some Antarctic and sub-Antarctic localities. The long-term monitoring programs on seabirds and seals are funded by the French Polar Institute Paul-Emile Victor (IPEV: programs n 109 ORNITHOECO: Oiseaux et mammifres marins sentinelles des changements globaux dans locan Austral, resp. H Weimerskirch; and n394 OISEAUX PLONGEURS: Stratgie nergtique des prdateurs marins et variabilit physique et trophique de locan Austral: tude en mer, resp : C-A Bost). The Atlas work was supported by the French Southern Territories (TAAF), the French Marine Protected Areas Agency through the program of bio-regionalisation en vue de ltablissement dun rseau daires marines protges dans locan Austral, les Kerguelen, Crozet, mer Dumont dUrville.

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.

  • 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.

  • 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.

  • Mercury and cadmium concentrations in the tissues of three species of southern Albatrosses
    Polar Biology, 1999
    Co-Authors: Mark A. Hindell, Rosemary Gales
    Abstract:

    Cadmium and mercury concentrations were measured in the tissues of 64 individual Albatrosses [23 wandering Albatrosses (Diomedea exulans), 9 royal Albatrosses (Diomedea epomophora) and 32 shy Albatrosses (Thalassarche cauta)] which were killed as by-catch in longline fishing activities between 1991 and 1994. Mercury concentrations were also determined for 33 shy Albatross eggs (excluding shells). The birds were all sexed and assigned to one of two age classes (immature and adult). The three species exhibited differences both in overall concentrations of cadmium and mercury, and also in the pattern of accumulation of metals with age and sex. Wandering Albatrosses exhibited the highest mercury concentrations with a mean concentration in adult liver samples of 920.0 ± 794.1 μg g−1 dry weight. Shy Albatrosses had the lowest mercury concentrations with mean concentrations in adult livers of 36.3 ± 21.4 mg g−1 dry weight. The highest mercury concentration was 1800 μg g−1 for an adult female wandering Albatross. Cadmium concentrations were less variable, with adult royal Albatrosses having the highest average concentrations (180.0 ± 165.0 in adult kidneys) and adult shy Albatrosses the lowest (40.1 ± 20.0 in adult kidney). The highest individual cadmium concentration was 287 μg g−1 for a juvenile wandering Albatross. There was no evidence of increased accumulation of cadmium with age in any of the species, but wandering Albatrosses showed higher mercury concentrations in adults than juveniles. Female wandering Albatrosses also had significantly higher mercury concentrations than males. The mercury contents of the shy Albatross eggs were very low, with a maximum concentration of 5.4 μg g−1. The results of this study are consistent with the findings of previous work on Albatrosses and support the notion that the life-history strategy of these species (i.e. long-lived with low reproductive output) may be an important determinant in the concentrations of some metals found in their tissues.

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.

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

  • 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.

Justine D Shaw - 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.

April Hedd - One of the best experts on this subject based on the ideXlab platform.

  • 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.

  • 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.