Wildlife and Habitat Management
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We hypothesised that New Zealand sea lions from Campbell Island/Motu Ihupuku of various sex and age classes would utilise the water column differently due to differing physiological constraints and therefore have different accessibility to prey resources. We tested whether sea lion diving behaviour varied in relation to (i) age and sex class, (ii) time of day and (iii) water depth. We also hypothesized that the proportion of benthic/pelagic diving, and consequently risk of fisheries interaction, would vary in relation to age and sex. Satellite telemetry tags were deployed on 25 NZSL from a range of age/sex classes recording dive depth, duration and location. Adult females and juveniles used inshore, benthic habitats, while sub-adult males also utilised benthic habitats, they predominantly used pelagic habitat at greater distances from the island. Adult females and juveniles exhibited shorter dives than the same age/sex classes at the Auckland Islands, suggesting a lower dive effort for these age/sex classes at Campbell Island.
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In this study, 34 fledgling Fairy Prions (Pachyptila turtur) recovered during a wreck event in south-eastern Tasmania in 2022 were examined for ingested plastics (number, mass, type, colour, and particle size) and body condition (e.g., wing chord length).
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Data to accompany publication on wild diet of southern rock lobster on the east coast of Tasmania. In this study we collected 64 lobsters and analysed the diet of each individual using stomach contents, stable isotope analysis and DNA identification of prey species in faecal samples.
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This record provides an overview of the NESP Marine and Coastal Hub project "Aerial survey of the Southern Right Whale ‘western’ sub-population off southern Australia". For specific data outputs from this project, please see child records associated with this metadata. -------------------- Southern right whales are listed as Endangered under the EPBC Act and are a species of national conservation significance. Monitoring of their recovery is guided by the Southern Right Whale Conservation Management Plan, which aims to improve the population’s conservation status through regular assessment of population size, calving intervals, and spatial trends. This project continued the long-term aerial survey program of southern right whales along the southern Australian coast, spanning from Perth (WA) to Ceduna (SA). Annual surveys have been conducted since 1993, providing a continuous long-term dataset for the 'western' population and supporting national assessments of connectivity with the smaller ‘eastern’ population. The surveys contribute essential data on population trends, calving rates, and movements of individuals. The August 2022 aerial survey ensured an uninterrupted time series in the long-term population trend data. This is particularly important given the species' non-annual breeding cycle (typically every three years). Annual surveys are essential to maintain an acceptable level of precision in estimating population trends and key life history parameters. A total of 526 whales were recorded, including 247 cow–calf pairs, 31 unaccompanied adults and one yearling. Based on long-term models, this equated to a population estimate of approximately 2,675 individuals, with an average annual growth rate of ~5.3%. While this represents a continued population growth, results suggest a possible slowing in the rate of growth over the past 13 years (from 7.5% in 2009). The 2022 survey also recorded the lowest number of unaccompanied animals in the entire time series, extending a five-year trend of low sightings in this group. Continued monitoring of the population is needed to assess whether these changes represent longer-term shifts in population dynamics and calving intervals, and to inform adaptive management for this long-lived, slow-recovering species. Outputs • Estimate of relative abundance and population trend compared to long-term aerial survey sightings [dataset] • Individual whale photo-identification data - 2021-22 season [imagery - published to ARWPIC] • Final technical report detailing overall numbers of southern right whales observed within the survey region, their gender (and life stage where possible) and spatial distribution of individuals [written]
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Invasive mammal eradications are widely used for managing island ecosystems. However, tracking the outcomes of such large-scale, whole ecosystem projects is challenging and costly, and monitoring all components of an ecosystem is near impossible. Instead, indicators of ecosystem change may provide more practical and integrated measures of ecosystem response to eradications. As high-order marine predators, seabirds subsidise island ecosystems with nutrients isotopically enriched in nitrogen. Invasive mammals have caused a global decline of seabirds on islands, reducing this nutrient subsidisation. Following eradications, nitrogen stable isotope analysis may provide a useful and resource-efficient indicator of ecosystem functional change on eradicated islands. However, isotope ratios are affected by a myriad of factors, with potential sources of variation being introduced by spatial and temporal variation in sampling, and within and between different taxa and ecosystem components. To correctly attribute isotopic change to post-eradication ecosystem function change, these confounding variables need to be understood. To address this need, we analysed stable isotopes of nitrogen in soil, plant, spider, and seabird guano samples collected at different distances from seabird colonies and at different stages of the short-tailed shearwater breeding cycle on six island sites around south-eastern Tasmania, Australia. Across these cool, temperate islands we detected no temporal variability in δ15N throughout the breeding season. However, there was notable spatial variability in δ15N values. The effects of seabird-derived nutrient subsidisation were highly localised with high δ15N values found inside seabird colonies and then rapidly decreasing from the colony boundary. Higher δ15N values also occurred in areas of higher burrow density within a colony. Variability in δ15N values also existed both within and between ecosystem components. Our results highlight the importance of context dependency when using ecological indicators and have important implications for the design, implementation and interpretation of studies employing stable isotopes as indicators for ecosystem change. We provide recommendations for designing future stable isotope studies on seabird islands.
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This record provides an overview of the NESP Marine and Coastal Hub project "Mapping critical Australian sea lion habitat to assess ecological value and risks to population recovery". For specific data outputs from this project, please see child records associated with this metadata. -------------------- Australian sea lion populations have declined by more than 60% over the past four decades. Abundance and trends vary markedly across the species range, suggesting that localised risk profiles from threats - such as bycatch, marine pollution, and habitat degradation - vary at small spatial scales. Fine scale variation in habitat use is thought to underpin these differences, yet knowledge about Australian sea lion's dependency on key habitats and their vulnerability to human impacts is limited. This project deployed compact animal-borne cameras with GPS and motion sensors on eight adult female sea lions at two key colonies: Seal Bay (Southern Kangaroo Island Marine Park) and Olive Island (Western Eyre Marine Park). The devices recorded nearly 80 hours of footage over 560 km of seabed, identifying six distinct benthic habitat types, including previously unmapped rocky reefs and kelp forests. The footage was used to develop fine-scale habitat maps using machine learning models, providing a valuable baseline for assessing ecological value, foraging intensity, and the effectiveness of protected areas. This innovative approach complements traditional seafloor mapping and offers a scalable, cost-effective method for locating and monitoring critical habitats for endangered marine species. The results directly inform recovery planning, fisheries management, marine park design, and the identification of Biologically Important Areas. Ongoing camera deployments at Seal Bay and new sites along the western Eyre Peninsula will improve understanding of sea lion colony-specific behaviours and contribute to long-term monitoring of habitat change, diet, and emerging threats. Outputs • Tracking data from sea lion-deployed tags: location, depth, time, temperature, light, acceleration [dataset] • Timestamped video footage from sea lion-deployed cameras [dataset] • Final project report [written]
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Satellite linked data loggers collecting temperature, conductivity, depth, location and time using Sea Mammal Research Unit tags.
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We investigated the effects of seabird presence and seasonality on ground-active spider community structure (activity-density, family-level richness, age class and sex structure) and composition at the family-level across five short-tailed shearwater breeding islands around south-eastern Tasmania, Australia. Using 75 pitfall traps (15 per island), spiders were collected inside, near and outside seabird colonies on each island, at five different stages of the short-tailed shearwater breeding cycle over a year. 3. Pitfall traps were deployed for a total of 2,674 days, capturing 1,592 spiders from 26 families with Linyphiidae and Lycosidae the most common.
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To quantify the winter diving behaviour and vertical habitat use of adult female Antarctic fur seals (Arctocephalus gazella) we tracked females using Wildlife Computers Time-Depth Recorders (TDRs). Females were captured towards the end of the lactation period (March/April) and the TDR was attached dorsally to the fur approximately 10 cm anterior to the rump using a two-part epoxy. TDRs were retrieved just prior to or after giving birth the following season. Data files were extracted from the tags using the Wildlife Computers software Instrument Helper.
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The Maugean Skate Zearaja maugeana is a micro-endemic species known from only two isolated estuaries, Bathurst and Macquarie Harbours in southwestern/western Tasmania. This constitutes one of the most limited distributions of any known extant elasmobranch. As a result, the species is listed as ‘Endangered’ under the Threatened Species Protection Act (Tasmania) and the Environmental Protection and Biodiversity Conservation Act (Commonwealth). Even though it was first discovered in Bathurst Harbour, most of what is known about the species comes from the Macquarie Harbour population. Only four individuals have ever been reported in Bathurst Harbour, with the last known sighting occurring in 1992. This study used environmental DNA (eDNA) to determine the presence/absence of the Maugean skate in Bathurst Harbour on the southwest coast of Tasmania. Water samples were collected from the seafloor in Bathurst Harbour in November 2021 and February 2022, and in Macquarie Harbour (control samples) in December 2021. Samples were filtered using a self-preserving eDNA sampling system. Following each survey DNA from the samples was extracted and analysed through qPCR amplification. Mitochondrial primer pairs from two gene regions were used to detect the presence of Maugean skate DNA in the samples. Where possible, positive detections were sequenced, and their identity verified.
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