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Modelling the foraging ecology of the flesh-footed shearwater Puffinus carneipes in relation to fisheries and oceanography
thesisposted on 2023-05-26, 04:28 authored by Reid, TA
Increasing numbers of animal and plant species are under threat, often through human activity. To improve management of these species, it is important to understand the spatio-temporal nature of these interactions. In this thesis the threats to flesh-footed shearwater breeding on Lord Howe Island were explored, and methods that can be adopted for lowering them were investigated. A census of the population of flesh-footed shearwaters on Lord Howe Island indicated a continuing decline. Possible threats to the population that were identified as (i) offshore, in the form of fisheries by-catch and plastic pollution at sea, and (ii) onshore, with factors such as land clearance and road mortality on Lord Howe Island. Significant mortality was recorded on roads on Lord Howe Island. Offshore threats were examined by quantifying the regions of interactions between flesh-footed shearwaters and vessels operating in the Eastern Tuna and Billfish Fishery using data from fisheries observers, Australian Fisheries Management Authority logbook data and remote sensing data of oceanographic variables. Recent changes in the regions of interaction between the shearwaters and the ETBF were modelled, and how this affected the by-catch rate was examined. The effect these changes had on the by-catch rate was used to recommend the potential of area closures as a method of conservation. Using a novel statistical technique, the distribution of flesh-footed shearwaters and their interactions with the ETBF was further examined. Small scale oceanographic relationships between the shearwaters‚ÄövÑvº attendance of vessels operating in the fishery were quantified using an arrivals and departures multi-component model. For this the same data as that used in the previous section was used. By comparing the arrivals and departures for shearwaters behind vessels, finer scale attendance was examined and compared with the hypothesis that shearwaters were more likely to attend a vessel when it was operating in conditions that were likely to be more productive. Finally, the distribution of individual flesh-footed shearwaters during the breeding season was quantified using light based archival tags (GLS loggers). Discrete Choice Models were then used to examine if individuals returned to the same areas on successive trips. Flesh-footed shearwaters used experience to determine where they were foraging, returning to areas that they had visited during the previous two foraging trips, and returning to areas where they apparently were successful during those trips. This has rarely been demonstrated previously, especially for larger or oceanic animals.
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