Cutting-Edge Dolphin Research Happening in Mandurah
Dolphins are at the heart of Mandurah, and understanding them is essential. Our inland waterways are home to a thriving community of Indo-Pacific Bottlenose Dolphins, vital not just to our hearts but to the health of the whole ecosystem. Researcher Dr. Krista Nicholson has dedicated her career to studying these amazing creatures, discovering why they’re so important, how their community thrives, and what impacts them the most. In this blog, we dive into Dr. Nicholson’s ongoing research on Mandurah’s dolphins and explore why it’s so crucial for both the dolphins and our waterways.
Dr Krista Nicholson
Dr. Krista Nicholson, population ecologist at Murdoch University, is the driving force behind the Mandurah Dolphin Research Project. For years, she has been dedicated to understanding the lives of Mandurah’s dolphins; how they interact, form social bonds, and thrive within our waterways. Her work goes far beyond counting dolphins though, it reveals the behaviours that keep their community strong and the factors that influence their survival.
Since completing her PhD on Indo-Pacific bottlenose dolphins in the Peel-Harvey Estuary, Dr. Nicholson has continued her research through the Murdoch University Marine Mammal Research Lab, using photo ID capture-recapture methods to monitor and study these incredible animals. Her standard monitoring in the field is detailed and consistent. For every sighting, she collects high-quality photographs of each individual, particularly of the dorsal fin, which acts like a fingerprint for identification. Alongside imagery, she records precise data including location, water depth, behavioural observations, start and end times of the sighting, whether a calf is present, whether the calf is in the protective “baby position”, the identification and sex of individuals, and notes on any new markings or injuries. This long-term dataset allows her to track individuals over time and build a clear picture of the population’s health and dynamics.
Her studies have examined population trends, social structures, and the dolphins’ role in maintaining estuary health. Most recently, her research focuses on identifying the biggest threats to the dolphins and finding ways to minimise these impacts, ensuring the community can thrive for years to come.
Recognising the critical importance of this research, Mandurah Cruises has invested $50,000 to support Dr. Nicholson’s work and the Mandurah Dolphin Research Project. This partnership will extend vital fieldwork through to 2028, helping to ensure Mandurah’s dolphin community, and the waterways they call home, remain healthy for generations to come.
Population Dynamics
Dr. Krista Nicholson’s previous population assessments have shown a slight decline in Mandurah’s dolphin population, but nothing alarming. Overall, the population remains stable, with a healthy age structure: around 40% adults, 30% juveniles, and 20% calves. This balance ensures that the community has a strong foundation for growth and resilience.
The population is also at reproductive capacity. Female dolphins typically have calves back-to-back, with a new calf born once the previous one has been weaned at around three years old. Interestingly, there are slightly more females than males, at a 2:1 ratio, giving the population a perfect operational sex ratio. This means that each mating season, there are enough females available to maintain consistent reproduction, an essential factor for long-term population stability.
While the population is stable, careful management is still necessary to prevent future declines. Dr. Nicholson’s research has identified that losing more than one adult female per year on average could have a significant impact. Protecting adult females and supporting calf survivorship, ensuring that calves reach independence, is crucial for maintaining high population numbers and the health of the dolphin community.
Through ongoing research, Dr. Nicholson and the Mandurah Dolphin Research Project continue to monitor the population, understand what impacts it most, and work to minimise those threats. Their efforts help ensure that Mandurah’s dolphins continue to thrive in the Peel–Harvey Estuary for generations to come.
ecological impact
Mandurah’s dolphins are intrinsically connected to the health of the estuary, relying almost entirely on its rich and productive waterways for food. Through Dr. Krista Nicholson’s research using stable isotope analysis, we now have a clearer understanding of just how dependent they are on these estuarine resources. Stable isotope analysis is a scientific technique that measures the natural ratios of non-radioactive isotopes in organic and inorganic materials, primarily through isotope ratio mass spectrometry, to trace nutrient pathways through food webs. In simple terms, it allows researchers to identify where animals are feeding and how energy moves through the ecosystem.
The results of this work confirmed that Mandurah’s dolphins are true estuarine specialists. Rather than feeding widely outside the system, they rely heavily on fish species supported by the Peel-Harvey Estuary. Ecologically, their impact is substantial. Each year, the dolphins remove more than 200,000 kilograms of fin fish from the waterways. As apex predators, they play a crucial role in regulating fish populations, preventing imbalances and helping to maintain the overall stability of the ecosystem.
Their presence is not just symbolic of a healthy estuary, it is functionally important to it. By sitting at the top of the food web, the dolphins act as indicators of ecosystem health. Any significant change in their population or feeding patterns can signal broader environmental shifts within the waterways. Protecting the dolphins, therefore, also means protecting the ecological balance of the entire estuarine system they call home.
Incident research
Dr. Krista Nicholson’s current research is focused on incidents that directly impact Mandurah’s dolphins, particularly live strandings and fishing line entanglement. The Peel-Harvey Estuary is recognised as a live stranding hotspot in Western Australia, with many local dolphins having stranded at least once, and some on multiple occasions. During summer, dolphins often travel to the extremities of the waterways, moving into rivers and lakes connected to the estuary by shallow channels. These areas can provide valuable foraging grounds, but as tides recede, dolphins can become trapped between sandbars or left completely stranded in shallow pools.
Stranding presents serious risks. When dolphins are left lying on their stomachs, prolonged pressure on their internal organs can lead to organ shutdown if they are not assisted quickly. Even individuals that are partially submerged remain vulnerable, as sun exposure can cause severe sunburn. Dr. Nicholson’s research is examining how dolphins use these high-risk areas and how environmental factors, such as tidal states and water levels, may help predict when severe stranding events are likely to occur. The length of time an animal is trapped is critical; the faster a stranded dolphin can be relocated to deeper water, the greater its chance of survival. Encouragingly, findings so far suggest that dolphins that survive a stranding event typically return to normal behaviour and remain reproductively active. In many cases, the animals are otherwise healthy and appear to have stranded due to misadventure rather than illness, highlighting the importance of continuing to study the behavioural and environmental triggers behind these events.
Another major threat, both locally in Mandurah and globally, is fishing line entanglement, particularly from recreational fishing gear. Calves are especially vulnerable, and entanglement is considered one of the most significant risks to the population. Removing fishing line from a dolphin is extremely difficult and stressful for the animal, which is why prevention is far more effective than treatment. Research and education play a vital role here. Encouraging responsible fishing practices and the proper disposal of fishing line can significantly reduce the likelihood of entanglement, helping to protect Mandurah’s dolphins before harm occurs.
why the research is important
Education plays a vital role in protecting Mandurah’s dolphins, and it is strongly underpinned by the research led by Dr. Krista Nicholson and her team through the Mandurah Dolphin Research Project. The findings gathered in the field don’t stay in scientific journals, they are actively shared back with the community. Through volunteer groups, partnerships with Mandurah Cruises, public lectures presented by Dr. Nicholson, and ongoing outreach initiatives, research insights are translated into meaningful education that helps people better understand the dolphins that call these waterways home.
A collaborative approach ensures that all groups involved use the same name for each identified dolphin. This consistency is crucial. When new information is discovered about an individual, whether it relates to behaviour, reproduction, injury, or stranding, it can be added to extensive shared databases. Not only does this strengthen long-term research, but it also supports continuous visual monitoring across the estuary, with community members and operators able to recognise and report on specific dolphins.
For many of the challenges dolphins face, education and prevention are far more effective than treatment. By sharing research-backed knowledge, the goal is to foster understanding and connection. The more people learn about these individuals, their names, their stories, and their role in the ecosystem, the more likely they are to care, act responsibly, and become actively involved in protecting Mandurah’s dolphin community.
For more
We hope you’re enjoying learning about Mandurah’s dolphins and the research that helps us understand them. Keep an eye out for our third blog, coming soon in collaboration with Dr. Krista Nicholson, where we’ll take a closer look at the challenges and impacts these remarkable animals face.
Read more about our support for the Mandurah Dolphin Research Project here.
Delve deeper into Dr. Nicholson’s studies here.
If you’re feeling inspired, there are plenty of ways to get involved, from citizen science projects to volunteer programs and community initiatives, all making a real difference in protecting these iconic dolphins.
