Diet and habitat use of New Zealand fur seals at the western margin of their population expansion

Ana Hara

    Research output: ThesisMaster's Thesis

    113 Downloads (Pure)

    Abstract

    New Zealand (NZ) fur seals (Arctocephalus forsteri) are now increasing their population size and expanding their number of breeding colonies and the extent of their range, as they recover from past exploitation from commercial sealing. This is particularly evident on the southwest coast of Western Australia (WA), which is the western margin of their distribution. While there has been significant effort directed towards researching the recovery of NZ fur seals, our understanding of how the expansion is unfolding in Western Australia is limited. The aim of this study was to help fill this gap by exploring the diet and habitat use of NZ fur seals in WA. Scats and regurgitates of NZ fur seals at Rottnest Island were examined to investigate the main prey species throughout the year, and to determine whether this marginal group displays differences in its dietary composition compared with other populations in the core of the range. The main species recovered from the scats and regurgitates were southern calamari (Sepioteuthis australis), beaked salmon (Gonorynchus greyi) and arrow squid (Nototodarus gouldi), suggesting a different diet composition from other populations. These differences are likely to be influenced by the location of Rottnest Island, on the margin of the species’ distribution. The population increase at the western edge does not seem to follow the same pattern as in the core of the Australian distribution to the east, and is unusual in that the breeding range is expanding northwards. Using data collected from three population surveys and GIS mapping tools, habitat use by fur seals was investigated to test the influence of physical characteristics of the ocean on the location of the colonies in WA.
    Original languageEnglish
    QualificationMasters
    Publication statusUnpublished - 2012

    Fingerprint

    seals
    fur
    Western Australia
    habitats
    diet
    calamari
    Arctocephalus
    breeding
    squid
    salmon
    population growth
    population size
    biogeography
    oceans
    coasts
    testing

    Cite this

    @phdthesis{42e5917a10d14117bbb820d29af9aefd,
    title = "Diet and habitat use of New Zealand fur seals at the western margin of their population expansion",
    abstract = "New Zealand (NZ) fur seals (Arctocephalus forsteri) are now increasing their population size and expanding their number of breeding colonies and the extent of their range, as they recover from past exploitation from commercial sealing. This is particularly evident on the southwest coast of Western Australia (WA), which is the western margin of their distribution. While there has been significant effort directed towards researching the recovery of NZ fur seals, our understanding of how the expansion is unfolding in Western Australia is limited. The aim of this study was to help fill this gap by exploring the diet and habitat use of NZ fur seals in WA. Scats and regurgitates of NZ fur seals at Rottnest Island were examined to investigate the main prey species throughout the year, and to determine whether this marginal group displays differences in its dietary composition compared with other populations in the core of the range. The main species recovered from the scats and regurgitates were southern calamari (Sepioteuthis australis), beaked salmon (Gonorynchus greyi) and arrow squid (Nototodarus gouldi), suggesting a different diet composition from other populations. These differences are likely to be influenced by the location of Rottnest Island, on the margin of the species’ distribution. The population increase at the western edge does not seem to follow the same pattern as in the core of the Australian distribution to the east, and is unusual in that the breeding range is expanding northwards. Using data collected from three population surveys and GIS mapping tools, habitat use by fur seals was investigated to test the influence of physical characteristics of the ocean on the location of the colonies in WA.",
    keywords = "New Zealand fur seal, Diet, Habitat use, Western Australia, Population expansion, Marginality, Arctocephalus forsteri",
    author = "Ana Hara",
    year = "2012",
    language = "English",

    }

    TY - THES

    T1 - Diet and habitat use of New Zealand fur seals at the western margin of their population expansion

    AU - Hara, Ana

    PY - 2012

    Y1 - 2012

    N2 - New Zealand (NZ) fur seals (Arctocephalus forsteri) are now increasing their population size and expanding their number of breeding colonies and the extent of their range, as they recover from past exploitation from commercial sealing. This is particularly evident on the southwest coast of Western Australia (WA), which is the western margin of their distribution. While there has been significant effort directed towards researching the recovery of NZ fur seals, our understanding of how the expansion is unfolding in Western Australia is limited. The aim of this study was to help fill this gap by exploring the diet and habitat use of NZ fur seals in WA. Scats and regurgitates of NZ fur seals at Rottnest Island were examined to investigate the main prey species throughout the year, and to determine whether this marginal group displays differences in its dietary composition compared with other populations in the core of the range. The main species recovered from the scats and regurgitates were southern calamari (Sepioteuthis australis), beaked salmon (Gonorynchus greyi) and arrow squid (Nototodarus gouldi), suggesting a different diet composition from other populations. These differences are likely to be influenced by the location of Rottnest Island, on the margin of the species’ distribution. The population increase at the western edge does not seem to follow the same pattern as in the core of the Australian distribution to the east, and is unusual in that the breeding range is expanding northwards. Using data collected from three population surveys and GIS mapping tools, habitat use by fur seals was investigated to test the influence of physical characteristics of the ocean on the location of the colonies in WA.

    AB - New Zealand (NZ) fur seals (Arctocephalus forsteri) are now increasing their population size and expanding their number of breeding colonies and the extent of their range, as they recover from past exploitation from commercial sealing. This is particularly evident on the southwest coast of Western Australia (WA), which is the western margin of their distribution. While there has been significant effort directed towards researching the recovery of NZ fur seals, our understanding of how the expansion is unfolding in Western Australia is limited. The aim of this study was to help fill this gap by exploring the diet and habitat use of NZ fur seals in WA. Scats and regurgitates of NZ fur seals at Rottnest Island were examined to investigate the main prey species throughout the year, and to determine whether this marginal group displays differences in its dietary composition compared with other populations in the core of the range. The main species recovered from the scats and regurgitates were southern calamari (Sepioteuthis australis), beaked salmon (Gonorynchus greyi) and arrow squid (Nototodarus gouldi), suggesting a different diet composition from other populations. These differences are likely to be influenced by the location of Rottnest Island, on the margin of the species’ distribution. The population increase at the western edge does not seem to follow the same pattern as in the core of the Australian distribution to the east, and is unusual in that the breeding range is expanding northwards. Using data collected from three population surveys and GIS mapping tools, habitat use by fur seals was investigated to test the influence of physical characteristics of the ocean on the location of the colonies in WA.

    KW - New Zealand fur seal

    KW - Diet

    KW - Habitat use

    KW - Western Australia

    KW - Population expansion

    KW - Marginality

    KW - Arctocephalus forsteri

    M3 - Master's Thesis

    ER -