The Perfect Storm - What is causing Australia's fish kills?

What's behind the horrifying phenomenon of fish kills in Australian inland waterways? Join us as we unearth the many fish kills that have taken place recently with Prof. Lee Baumgartner – the leading scientists who is involved in the government enquiry investigating the events. Throughout the episode, Lee sheds light on the environmental culprits behind these disasters, stressing the importance of responsible river management going forward. From dissecting blackwater events, hydrology, bacteria and algae, river infrastructure and flow, the ‘perfect storm’ that leads to a fish kill is discussed so you can better understand what is happening to our native fish throughout the Murray-Darling Basin.  

Prof. Lee Baumgartner 

Prof. Lee Baumgardner stands as a revered figure in the realm of applied research, best known for his groundbreaking contributions to the intricate interplay of food, water, and energy. His work is particularly pivotal in regions where water serves as a lifeline for sustenance and economic activities, playing a crucial role in irrigation and hydropower. Lee directs his focus to communities reliant on fish, a cornerstone of biodiversity, nutrition, and income. However, these aquatic populations face a dangerous decline due to extensive river development, prompting Lee's active involvement in government inquiries into fish kills. 

Lee Baumgardner is no stranger to the corridors of power, having contributed to parliamentary inquiries and been appointed to prime ministerial advisory panels. His outreach extends to international and national media, where he tirelessly promotes the cause of healthy rivers. A recipient of prestigious awards, including the NSW Crawford Medal, Lee holds a Ph.D. in applied ecology from the University of Canberra (2005). Having only recently completed his commitments on the government panel enquiring into the fish kills, Lee offers insight into how environmental enquiries work. The transparency, which is important for the rec fishing community gaining trust in our respective state fisheries managements, leads the discussion to looking below the surface at what actually happened in the 2018 and 2023 fish kills.

Collaborating with a diverse spectrum of professionals—engineers, functional ecologists, social scientists, policy experts, and water professionals—Lee addresses the multifaceted challenges confronting these communities. Passionate about nurturing healthy rivers, his mantra, "A healthy river is an economic and environmental engine," encapsulates the essence of his recent research and advocacy. 

Beyond the realms of science and advocacy, Lee reveals a more personal facet—a passionate fisherman with a love for Port Phillip and Corio Bay. Whether chasing snapper, whiting, or flathead, he finds solace in the waters, embodying a harmonious connection between his professional pursuits and personal pleasures. 

Understanding Fish Kills  

Fish kills are complicated. Understanding them requires dissection of blackwater events, hydrology, stratification, bacteria and algae, river infrastructure and flow. Interestingly, both the 2018 and 2023 events were caused from different catalysts. As Lee explains on the episode, both fish kills were due to a lack of oxygen, yet how we came to that was due to different preceding weather events.  

In looking beneath the surface at these ‘environmental culprits’, Lee dives into the science behind blackwater events and breaks down this complex phenomenon. He explains how these occurrences, exacerbated by specific environmental conditions such as flood and drought, lead to drastic reductions in water quality and oxygen levels, culminating in mass fish deaths.  

Importantly, Lee highlights that blackwater alone is not the culprit for fish kills. A key component in this story is the process of stratification – the turning of water in a weir pool. As explained by Lee, the water at weir 32 in Menindee throughout 2018 and 2023 was divided into two layers; one warm layer full of algae, and one starved of oxygen. In both events, fish could tolerate the conditions in the bottom layer, before the water turned and conditions became unbearable.  

The discussion takes a historical turn, examining how changes in river management practices over the years have contributed to this current crisis. Lee underscores the absence of large-scale fish kills in Australia's history, contrasting it against recent events driven by human intervention. Australian rivers have always faced droughts and floods, but what has changed?  In comparing to other countries, Lee explains that fish kills are natural in places like Europe and the Americas, however the ones we see in Australia is purely due to how humans have manipulated the rivers.  

In a unique approach, Lee discusses how studying the ear bones of dead fish offers insights into their age, life history and the water conditions they experienced. This analysis helps unravel the broader implications of fish kills and the interconnectedness of different parts of the river system. Interestingly, Lee finds a positive news story to come from these events.  

The episode doesn't just highlight problems; it also explores potential solutions. Lee talks about the importance of early warning systems, technology like aerators and bubblers, and the need for strategic fish relocation to prevent future fish kills. For Lee, this is one the major recommendations he made to the government enquiry this year.  

The conversation culminates in a compelling call to action. Lee emphasizes the need for community involvement, policy change, and continued scientific research to safeguard the health of Australia's rivers and aquatic life for future generations.