Eastern Freshwater Cod given a lifeline in the Clarence River
23 Nov 2023
Innovative cod hotels or ‘nest’ boxes - first trialled in 2022 - are continuing to demonstrate their success, helping produce a new generation of Eastern Freshwater Cod on the NSW North Coast for the second time in two seasons.
Following preliminary trials at the NSW Department of Primary Industries (NSW DPI) Grafton Fisheries Centre last year, a partnership project developed a purpose-built ‘nest box’ with the goal to increase breeding sites for this iconic fish.
North Coast Local Land Services General Manager, Louise Orr, said this project targeted the key recovery needs of the Eastern Freshwater Cod.
“The success of the cod nest boxes has been a step in the right direction for a species that is unique to our region,” Ms Orr said.
This project is supported by North Coast Local Land Services and NSW DPI Fisheries through funding from the Commonwealth Government’s Bushfire recovery package for wildlife and their habitat.
Eastern Freshwater Cod are currently only found in the Clarence and Richmond River Catchments in Northern NSW. They are listed as Endangered under both NSW and federal legislation.
Senior Land Services Officer, Shaun Morris, said habitat modification had reduced river features such as bankside vegetation, in-stream woody habitat (snags), undercut banks and deep holes – all of which are crucial to this species reproduction and long-term survival.
“This project aimed to identify how this species is going following the bushfires of 2019-2020 and support their recovery with our successfully trialled nest boxes,” Mr Morris said.
NSW DPI Senior Research Scientist Gavin Butler said surveys supported by this project have revealed spawning sites are limited for Eastern Freshwater Cod in the Clarence River Catchment following years of drought, fire and flood.
“These nest boxes mimic the preferred nesting habitat of Eastern Freshwater Cod, which is a dark cave where the father fans and guards the eggs and larvae during the springtime. It’s pretty much like a private room in a maternity ward - just for fish,” Dr Butler said.
“We have designed these nest boxes to be easily transported and placed in the river where we know Cod persist, but suitable spawning habitat is missing.
“At the start of spring last year, we placed 30 nesting boxes in the upper Clarence catchment and obtained the first definitive evidence of a completely successful nesting event through to larval fish.
“In an exciting development, we have confirmed that one more spawning event has taken place this breeding season in one of last year’s boxes,” Dr Butler said.
Using this concept, North Coast Local Land Services is also looking to install large hollow logs as part of their riverbank erosion control on the Orara River.
“We have engaged contractors from Victoria to trial an innovative drilling technique in large timber logs, which bores out suitably sized hollows in the woody habitats which are then placed in the river for Eastern Freshwater Cod to spawn,” Mr Morris said.
“We will be incorporating these hollow logs into our erosion control works as part of an ongoing partnership program with Coffs Harbour City Council to protect Eastern Freshwater Cod populations.”
This project complements recent conservation and recovery stocking efforts by NSW DPI including the breeding and release of more than 5,000 Eastern Freshwater Cod fingerlings in the area.
For more information on this project, visit the Marine Estate Management Strategy page on our website.
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