[MARMAM] New publication announcement
Dear Marmam Community, My co-authors and I are pleased to announce the publication of our paper on stomach content and stable isotope analysis of a population of bottlenose dolphins off the west coast of Australia. McCluskey, S.M., K.R. Sprogis, J.M. London, L. Bejder, and N.R. Loneragan. 2021. ‘Foraging Preferences of an Apex Marine Predator Revealed through Stomach Content and Stable Isotope Analyses’. *Global Ecology and Conservation* 25 (January): e01396. https://doi.org/10.1016/j.gecco.2020.e01396. Abstract Insights into the food habits of predators are essential for maintaining healthy predator populations and the functioning of ecosystems. Stomach content and stable isotope analyses were used to investigate the foraging habits of an apex predator, the Indo-Pacific bottlenose dolphin (*Tursiops aduncus*) in south-western Australia. A total of 2,594 prey items from 26 families were identified from the stomachs of 10 deceased stranded dolphins. Fish otoliths from stomach contents were used to identify fish to family or species level. Ninety-three percent of identified stomach contents were perciforme fishes, however, perciformes comprised only 30% of the catch during prey sampling. Gobiidae species, small fish generally <100 mm in total length, were the most prevalent family identified in dolphin stomachs, accounting for 82% of identified prey, yet Gobiidae accounted for 12.7% of the catch during prey sampling. For stable isotope analyses, tissue samples from 14 free-ranging dolphins were analyzed for nitrogen (δ15N) and carbon (δ13C) ratios. From stable isotope analyses and boat-based dolphin photo-identification surveys (n = 339, 2007–2011), results indicated niche differentiation between coastal and inshore (bay and estuarine habitat) dolphins. Carbon signatures showed that coastal dolphins had a more pelagic diet compared to a benthic diet observed in the inshore dolphins. Whereas, nitrogen signatures of inshore dolphins showed higher nitrogen levels than coastal dolphins, likely attributed to feeding on enriched prey typical of estuarian environments. Overall, these results indicated that bottlenose dolphins in the study area were selective foragers and that their foraging is specialized by the habitats most frequently used. The article is open-access and can be found here: https://www.sciencedirect.com/science/article/pii/S2351989420309379?via%3Dihub Thank you very much for sharing, Shannon ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] Publication on bottlenose dolphin prey availability and calorific value
Dear Colleagues, My co-authors and I are pleased to announce the recent publication of our paper titled "Dolphin Prey Availability and Calorific Value in an Estuarine and Coastal Environment". The paper is available for download FREE from Frontiers in Marine Science: http://journal.frontiersin.org/article/10.3389/fmars.2016.00030/full You can also find a link to the article and more information about the Murdoch University Cetacean Research Unit by going here: http://mucru.org/hot-off-the-press-dolphin-prey-availability-and-calorific-value/ You may also contact me directly with any queries. The abstract is below. Sincerely, Shannon McCluskey Murdoch University Cetacean Research Unit School of Veterinary and Life Sciences Murdoch University Perth, Western Australia Abstract Prey density has long been associated with prey profitability for a predator, but prey quality has seldom been quantified. We assessed the potential prey availability and calorific value for Indo-Pacific bottlenose dolphins (*Tursiops aduncus*) in an estuarine and coastal environment of temperate south-western Australia. Fish were sampled using three methods (21.5 m beach seine, multi-mesh gillnet, and fish traps), across three regions (Estuary, Bay, and Ocean) in the study area. The total biomass and numbers of all species and those of potential dolphin prey were determined in austral summers and winters between 2007 and 2010. The calorific value of 19 species was determined by bomb calorimetry. The aim of the research was to evaluate the significance of prey availability in explaining the higher abundance of dolphins in the region in summer vs. winter across years. A higher abundance of prey was captured in the summer (mean of two summer seasons 12,080 ± 160) than in the winter (mean of two winter seasons = 7358 ± 343) using the same number of gear sets in each season and year. In contrast, higher biomass and higher energy rich prey were captured during winters than during summers, when fewer dolphins are present in the area. Variability was significant between season and region for the gillnet (*p* < 0.01), and seine (*p* < 0.01). The interaction of season and region was also significant for the calorific content captured by the traps (*p* < 0.03), and between the seasons for biomass of the trap catch (*p* < 0.02). The dolphin mother and calf pairs that remain in the Estuary and Bay year round may be sustained by the higher quality, and generally larger, if lesser abundant, prey in the winter months. Furthermore, factors such as predator avoidance and mating opportunities are likely to influence patterns of local dolphin abundance. This study provides insights into the complex dynamics of predator—prey interactions, and highlights the importance for a better understanding of prey abundance, distribution and calorific content in explaining the spatial ecology of large apex predators. ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] Research Assistant Urgently Needed in Australia
Due to unforeseen circumstances, there has been an opening for a volunteer research assistant in Western Australia. A full-time assistant is needed from now until the end of September. Please see below for details. If interested contact: Shannon McCluskey shazza...@yahoo.com or s.mcclus...@murdoch.edu.au WHAT: Volunteer assistants are requested to partake in a PhD project investigating diet and foraging ecology of bottlenose dolphins. WHERE: Bunbury, South Western Australia (180 km south of Perth). A beautiful coastal town with easy access to Perth, the Margaret River wine region, surfing and bush walking. WHEN: June to September 2010. DUTIES:Relative composition and abundance of prey species in the Koombana Bay region will be sampled using beach seine nets, fish traps, and gillnets. Volunteers will be required to manually deploy and retrieve fish traps, seines and gillnets, assist in the operation of a research vessel, identify, count, weigh, and measure fish and invertebrate species. Stomach contents of stranded dolphins and scat samples will be analysed for prey content. This will involve separating and identifying hard parts in scat and stomach samples. Volunteers may also have the opportunity to assist with post mortem examinations of stranded dolphins. Spatial analysis to determine foraging “hot spots” will be carried out using point observational data. Assistants will be required to assist in the creation of data layers by entering data into an ArcGIS format and learn to use some basic GIS tools. Fish, invertebrate, and marine plant samples will be collected and prepared for stable isotope analysis. Volunteers may also be required to assist in the biopsying of dolphins for stable isotope work. Data entry and management, equipment maintenance, and other office and lab tasks will be required. QUALIFICATIONS: Mandatory -Primary requirement is a good attitude, work ethic, and ability to work in a physically demanding environment. This can include long hours in extreme weather conditions and long days on the water. Hauling fish traps and nets is physically demanding work. Volunteers must be able to repeatedly lift over 23 kg (~51 lbs). -Must be able to commit to a minimum of one month. People able to commit for longer periods will be preferred. Preferred, but not mandatory -Undergraduate degree in the biological sciences -Previous field work experience, specifically with fisheries or marine mammals -Experience using ArcGIS or similar spatial analysis software ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
