Intensive breeding programs, vital river restoration, and strategic restocking initiatives are proving crucial in the fight to save the endangered Mary River cod. Specialist fish breeder Darren Knowles described the fierce territorial nature of the male cod during breeding season, noting the challenges of retrieving eggs from their nests, often guarded aggressively within large plastic pipes.

These powerful fish can be intimidating, even dislodging a diver’s mask, but Mr. Knowles, who also works as a firefighter, dedicates his efforts to protecting this critically threatened freshwater species. His involvement began at just 14 years old, volunteering to help hatchery pioneer Gerry Cook with restocking efforts in the Mary River and its tributaries.

The Mary River, a significant waterway flowing from the Sunshine Coast hinterland to Hervey Bay, has faced severe ecological pressures. Habitat destruction and historical overfishing decimated the cod population, which plummeted to as few as 600 individuals in its natural environment by the late 1990s, according to Tom Espinoza, chief executive of the Burnett Mary Regional Group (BMRG).

Historically, the abundance of Mary River cod was so great that they were used as pig feed, and at one point, fishing methods even included explosives. Early settlers, influenced by outdated advice, removed essential habitat features like hollow logs and log-jams, which are vital for cod nesting. Furthermore, the removal of riverbank vegetation led to increased erosion, silting up deep waterholes.

A recent workshop, organized by Mr. Espinoza, brought together a diverse group of stakeholders, including traditional owners, recreational fishing groups, scientists, and conservation experts. The aim was to update a 25-year-old recovery action plan, fostering a collaborative approach to research and securing necessary funding to prevent the species’ extinction.

Collaboration is recognized as a cornerstone of successful conservation efforts for the cod. Mark Kennard, deputy director of the Australian Rivers Institute, emphasized the long-term commitment required from all parties involved to work together and pursue funding opportunities. This united front is seen as essential for the species’ future.

Encouraging progress has already been observed, with a fishing ban implemented during the cod’s breeding months of August, September, and October in the upper Mary River and its tributaries. This measure helps prevent accidental catches of the protected species. Genetic testing is also being employed to guide the sourcing of wild broodstock, aiming to minimize inbreeding and enhance genetic diversity.

Restoration efforts include installing pile fields along the riverbanks to slow water flow during floods and mitigate erosion. The Mary River Catchment Coordinating Committee and BMRG have assisted landowners in reshaping and replanting riverbanks to prevent significant land loss. Scientists are also actively deploying hollowed-out logs into the river, providing much-needed nesting sites for the cod.

While many challenges remain, there is growing optimism regarding the Mary River cod’s survival. Mr. Knowles, reflecting on the outcomes of restocking programs, expressed hope. He noted that anecdotal evidence and research-driven results suggest a stabilization, and in some areas, an increase in cod numbers, indicating a promising future if critical conservation steps are maintained.

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Keywords: Mary River cod, endangered species, fish conservation, river restoration, restocking programs, habitat protection, Burnett Mary Regional Group, Australian Rivers Institute