Giving endangered Eastern Freshwater Cod a helping hand

The male Eastern Freshwater Cod have been guarding and fanning their eggs with fierce dedication through Spring, defending their nests vigorously from predators and intruders. This unique behaviour is critical to the species’ survival, but across much of their historic range suitable nesting sites such as undercut banks and hollow logs have been lost to land clearing, sedimentation, floods and bushfires. Without secure nesting places, populations can struggle to rebuild, leaving the species highly vulnerable.

A new research paper, Blueprints for Riverine Cod Nest Boxes, published in Aquaculture, Fish and Fisheries, details how scientists are addressing this urgent problem. Fisheries Researchers tested modified hatchery boxes and trialled a triangular field nest box designed to withstand the powerful flows of northern NSW rivers. The design mimics natural cavities while remaining practical for transport, installation and long-term monitoring.

The results are highly encouraging. At DPIRD’s Grafton Fisheries Centre, hatchery trials showed spawning success increased from 3–5 events to as many as 18 in a single season. In the wild, at least five active nests were recorded inside triangular boxes deployed in the Mann–Nymboida system. These findings provide proof of concept that artificial structures can help replace missing habitat and give Eastern Freshwater Cod new opportunities to breed successfully.

The work demonstrates the importance of collaboration. North Coast LLS supported project delivery, while DPIRD Fisheries scientists designed and tested the nest boxes with input from local tradespeople, landholders and community members. Cabinet makers and builders in the Clarence Valley provided vital skills in turning sketches into robust prototypes that could survive in extreme river conditions.

The project was funded through the Australian Government’s Bushfire Recovery Package for Wildlife and their Habitat, with additional support from the NSW Recreational Fishing Trust

Shaun Morris, Senior Land Services Officer with North Coast Local Land Services, has been a passionate advocate of preserving the Eastern Freshwater Cod habitat since the project’s inception. “Restoring rivers for Eastern Freshwater Cod is about more than a single structure – it’s about blending science, community effort and practical design. These nest boxes give us new tools to help this iconic fish recover.”

The study also shows how innovative tools such as nest boxes can act as catalysts for wider habitat restoration. By engaging local communities in design, construction and monitoring, the project has built stronger connections between people and their rivers. It demonstrates how targeted conservation actions can sit alongside broader efforts like riparian planting, re-snagging and waterway rehabilitation, multiplying benefits for fish, farmers and the environment.

NSW DPIRD Senior Fisheries Scientist Dr Brendan Ebner said, “The nest boxes are not a silver bullet, but they are a vital step in rebuilding lost habitat and engaging communities in conservation. By improving breeding opportunities during this crucial season, we can give Eastern Freshwater Cod a better chance to thrive.”

The nest box project is helping reconnect communities with their local rivers, while also safeguarding one of the region’s most treasured species.

The research paper is available to view online.

Media Contact:
For more information, please contact Michelle Gapes, Regional Communications Advisor, North Coast/Hunter via email michelle.gapes@lls.nsw.gov.au or 0467 291 890.