OzCast

In this episode of OzCast, marine scientist Dr David Harasti explains why the Greynurse Shark is one of Australia's most vulnerable ocean species, and how simple changes in the way we fish can have a serious impact on their survival. He also explains the role these sharks play in the ocean's ecosystem and how fishers, scientists and conservation groups can work together to protect these important predators.   https://ozfish.org.au/ozcast/episode-15/

In this episode of OzCast, Troy Gaston dives beneath the surface of the often-overshadowed marine habitat of Saltmarsh. Being the unassuming heros of our coast, Troy explains that saltmarshes are in fact ecological powerhouses playing a pivotal role in coastal ecosystems. After spending over 25 years looking into their role, Troy uncovers his most pivotal research and findings in respect of saltmarshes impact on the food chain, their role in the reproduction of marine species and protecting coastal erosion. Saltmarshes, the unassuming heroes of our coasts, are more than just wetlands. They are biodiversity hotspots and crucial buffers against coastal erosion. Troy's work uncovers their role in carbon sequestration and as a nursery for myriad marine life, highlighting their global environmental impact. 

Join us on this episode of OzCast as we look beneath the surface at the often-overlooked realm of small-bodied threatened fish species in Australian waterways with Dr. Nick Whiterod, a seasoned marine ecologist with over twenty years of dedicated research and conservation efforts.  Dr. Nick Whiterod holds a PhD from Charles Sturt University, assessing the bioenergetic implications of large impoundments on Murray cod. His career has been marked by a profound commitment to the conservation of Australia's freshwater ecosystems, particularly focusing on small-bodied fish and crayfish species. His work extends beyond mere research; he has played a pivotal role in the national conservation listing of more than 50 freshwater species. Dr. Whiterod's expertise is not limited to conservation alone; he is widely recognised for his skill in species reintroduction and managing complex ecosystems. His approaches and methods in reintroducing species to their native habitats have contributed significantly to the recovery of threatened species like the Southern Purple Spotted Gudgeon, Southern Pygmy Perch, Yarra Pygmy Perch, and Murray Hardyhead. During the podcast, Nick explains the role these species have as vital indicators of ecosystem health and the concerning implications of their decline. The conversation extends to how the restoration of these fish populations can benefit the basin's overall health, and what their presence, or absence, reveals about water quality and environmental management. A focus of the discussion is the rediscovery of certain fish species in the Murray-Darling Basin, particularly the Southern Purple Spotted Gudgeon. Dr. Whiterod shares how these species, once common, have become rare in certain areas, with occasional surprising reappearances. The impact of habitat changes due to events like the Millennium drought and human efforts in conservation, including captive breeding and reintroduction, are examined. He also touches on the intriguing presence of northern fish species, like Barramundi, in southern waterways, raising questions about their survival and adaptation in unfamiliar habitats. In looking to the future, the podcast delves into the threats posed by introduced species on native fish populations, focusing on the predatory habits of Redfin Perch and Trout. Dr. Whiterod discusses the threat to native species such as the Purple Spotted Gudgeon and Pygmy Perch, their dwindling numbers, and the factors contributing to their decline, which includes habitat destruction and disease.  Throughout the episode, Nick provides an insight into the work he has completed in this area, speaking on the importance of maintaining 'insurance populations' to safeguard against potential losses down the track. Emphasising the importance of local conservation efforts, Dr. Whiterod underscores the role of individuals and community groups in protecting vulnerable populations, encouraging listeners to support threatened species in their local waterways.  An underlying theme in the interview is the bridging of the gap between scientific research and community involvement. Dr. Whiterod stresses the importance of translating scientific knowledge into actionable strategies that individuals and communities can undertake. He emphasises that conservation is not just the responsibility of scientists and policymakers but is a collective effort that requires widespread community engagement. Dr. Whiterod expresses cautious optimism about the future of Australia's aquatic ecosystems. He acknowledges the challenges posed by climate change and habitat loss, but remains hopeful due to increasing awareness and ongoing conservation efforts. His message underscores the importance of continued research, public education, and dedicated conservation actions to protect these vital ecosystems.

In this episode of OzCast, fisheries scientist Craig Boys dives beneath the surface of the Hexham Swamp, a Ramsar-listed wetland with ecological and cultural significance. Craig highlights the intricate relationship between aquatic ecosystems and human interventions, particularly focusing on the impact of floodgates installed for flood mitigation.  Throughout the episode, we explore the consequential shifts in fish and prawn populations, the resurgence of native species, and the broader implications for fishery productivity.  This episode is not only an educational journey through the swamp's history and transformation but also a celebration of community involvement in environmental stewardship.   Hailing from New South Wales, Australia, Dr Craig Boys is a Principal Research Scientist for the NSW Department of Primary Industries (Fisheries). Craig brings an extensive 20-year career to the forefront of fish ecology and fisheries conservation. His expertise is not only recognised nationally but also holds international acclaim. Craig's academic journey includes a position as an Adjunct Associate Professor of Research at Charles Sturt University. His research portfolio spans across continents, including Australia, Southeast Asia, Europe, and America, demonstrating his global impact in the field. A leader in screening technology, Craig has dedicated his career to bridging the gap between primary industries and fisheries outcomes.  Throughout the episode, Craig dives beneath the surface on the significance of Hexham Swamp. Once thriving with biodiversity, the installation of floodgates in the 1970s drastically altered the swamps ecological balance. Craig explains how these gates, designed to protect urban developments, inadvertently stifled the wetland's ecological heartbeat by disrupting the natural flow of water. His insights offer a compelling story about the intersection of human intervention and natural ecosystems, emphasising the impact of seemingly minor infrastructural changes on waterway health.  The floodgates led to decreased water quality, acidification, and a significant drop in aquatic life. These changes not only impacted the immediate area but also had cascading effects on the broader ecosystem, including local fish productivity. The swamp's transformation from a vibrant wetland to a near-barren landscape starkly illustrated the unintended consequences of human interference in natural systems.  A turning point in Hexham Swamp's story came through advocacy, particularly by local commercial fisher, Jeff Hyde. Craig's recount of Jeff's relentless efforts to reopen the floodgates is a testament to the power of individual voices in driving change. Change was slow but steady. The gradual reopening of the gates marked the beginning of the swamp's recovery, with notable improvements in water quality, fish, and prawn populations.  Craig's team meticulously tracked the ecological changes post the reopening of the gates. Their research employed a comprehensive approach, comparing the changes in Hexham Swamp to similar ecosystems, both with and without floodgates. This method provided a clear evidence, underpinning the importance of scientific data in environmental decision-making.  The success story of Hexham Swamp goes beyond its boundaries, the long-term environmental benefits, including the resurgence of native species and the recovery of vital habitats. This case serves as a crucial lesson in environmental stewardship, highlighting the potential for change when human interventions are thoughtfully managed.  The Hexham Swamp story is one of hope and resilience, demonstrating that with informed decisions and community involvement, we can aid in the recovery and preservation of our natural environments. 

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.