A remarkable comeback story is unfolding in the Brisbane River catchment, where an endangered apex predator, the Mary River cod, is thriving once again. This is a century after its close relative, the Brisbane River cod, sadly went extinct in the area.
The Brisbane River catchment, an expansive region stretching from Brisbane to Ipswich and the Somerset area, was once home to the now-extinct Brisbane River cod. However, its cousin, the Mary River cod, is making a strong comeback, five years after the introduction of thousands of fingerlings.
Ecologist and Ipswich City Council waterway health officer Jack McCann explains that the Brisbane River cod's extinction occurred sometime in the 1920s or 1930s. He highlights that early settlers relied on this large fish, which could grow up to 20 kilograms and a meter in length, as a valuable source of protein and even used it as fodder for piggeries.
The decline of the Brisbane River cod can be attributed to overfishing and habitat destruction, with extensive logging and clearing of riparian zones contributing to its demise. The loss of this apex predator had a significant impact on the river's ecosystem, disrupting the natural balance and food web.
But here's where it gets controversial... The Mary River cod, an endangered species itself, has been reintroduced to the catchment, and it's thriving. This successful reintroduction is part of a species recovery plan implemented in its native environment, which spans from the Sunshine Coast to Hervey Bay.
The endangered status of the Mary River cod was a key factor in the controversial decision to scrap the Traveston Crossing Dam project near Gympie. There is a possibility, and even a likelihood, that the Brisbane River cod and the Mary River cod are genetically the same species, though genetic samples of the former are not available.
Since 2020, approximately 30,000 Mary River cod fingerlings have been released into the catchment as part of a collaborative effort between local councils, fish stocking associations, and state government organizations. This initiative has also involved the construction of a fish ladder at a weir on the Bremer River, allowing the species to migrate more freely.
In September, a significant milestone was reached when a Mary River cod was observed using the fishway for the first time. This marked the first formal recapture, and plans are underway to tag the fish for monitoring its movement and growth.
Somerset and Wivenhoe Fish Stocking Association president Garry Fitzgerald expressed his excitement, stating that seeing fingerlings grow into adults is incredibly rewarding and gives real hope for the species' recovery.
Mr. McCann added that there is evidence suggesting the species is spawning in the catchment for the first time, which is the next crucial phase of the recovery plan. This phase involves restoring riparian habitats, benefiting not only the Mary River cod but also other native species like platypus.
The Mary River cod is protected, and any local fishers who catch one must release it unharmed.
This story of conservation and the successful reintroduction of an endangered species is a testament to the power of collaborative efforts and the potential for positive change. It offers a glimmer of hope for the future of our ecosystems and the species that call them home.
What do you think? Do you find this story inspiring? Are there similar conservation efforts in your area that you'd like to share? We'd love to hear your thoughts and experiences in the comments below!
