A number of cetacean populations are currently threatened from multiple sources including pollution, prey source depletion, vessel traffic, entanglement in discarded fishing gear, anthropogenic noise and direct harvest. Monitoring the physiological condition of individual animals within these populations (i.e. health and reproductive parameters) is valuable for determining changes taking place at a sub-lethal level. Relatively little work has been undertaken to assess the physiological condition of wild cetaceans with the majority of research focusing on captive populations or post-mortem assessment of wild individuals. Novel approaches to obtain biological samples have now been developed for use on a range of free-ranging populations; however, in many cases, results obtained from these samples have failed to be validated within a biological or physiological context.
The Cetacean Ecology and Acoustics Laboratory focuses on studying the physiology of humpback whales and dolphins off the south-east Queensland coast. In particular, the rapid recovery of the E1 stock (East Australia) of humpback whales, since the end of commercial whaling, makes it an interesting model for studying the effects of health and reproductive rates on population trajectories. The ability of this species to undertake incredibly long annual migrations prior to reproducing, during a period of energy deficit (i.e. fasting), suggests the presence of some unique physiological adaptations. The high abundance (>20,000 individuals) and close proximity of their migratory corridor, make the east Australian humpback whales a prime candidate for research.
Endocrine monitoring as a tool for reproductive and adrenal assessment
This study was established to develop and validate non-lethal hormone-monitoring techniques to evaluate cetacean reproductive state and adrenal (i.e. stress) condition.
The aims of this project are to validate 'blow' and blubber hormone analysis techniques for monitoring changes to reproductive and adrenal state in cetaceans. In order to achieve this aim a comprehensive validation study on a captive population of bottlenose dolphins is currently underway. Examination of hormone levels, in different tissues and fluids, and with respect to social, demographic and reproductive contextual information, will allow us to determine how best to implement similar techniques in a wildlife setting.
The second part of this study involves applying equivalent sampling and analytical techniques to wild cetaceans. Humpback whales have been repeatedly sampled for skin/blubber (biopsies) since 2010, and since 2013, ‘blow’ samples. The analysis of reproductive and adrenal hormones is currently underway and will be examined with respect to spatio-temporal factors (i.e. season, location, year), health/condition (i.e. live, deceased, stranded) and social factors. The information generated will help in establishing indices for adrenal condition, which may be a useful sub-lethal indicator of stress in the population. Monitoring reproductive hormone variation, particularly between animals of different social and life history contexts (e.g. single females, cow-calf pairs), may help define how hormone concentration varies between reproductive states (e.g. non-pregnant and pregnant females). (Project leaders: Fletcher Mingramm and Rebecca Dunlop)