New fishways to help boost populations

FISH HOMES AND HIGHWAYS

NEW FISHWAYS TO BOOST POPULATIONS

22 JANUARY 2024

A fishway close to Ingham’s town centre is the newest addition in a project that’s helping more than 100 species of fish – including barramundi, mangrove jack and jungle perch – to breed up in Wet Tropics waterways.

Terrain NRM and Catchment Solutions recently completed the 250 metre fishway at Gedges Crossing which will help fish to move through a weir. The structure is one of five fishways that have recently been built and one of 18 projects removing barriers to fish in the Murray and Herbert river catchments between Tully and Ingham.

Terrain NRM’s Deb Bass said other solutions have included bed-level creek crossings to replace causeways, culvert modifications and the removal of several creek crossings.

“We’ve also been working on invasive weed and feral pig control in these areas, and revegetation in an area where fish passage works were completed.

“This newest fishway is a curved rock ramp that’s at the side of Gedges Crossing on Pump Station Road, and is designed for lower flow conditions when smaller fish can’t get over the weir.

“It’s opening up more than 50km of upstream habitat to many different fish species.

“Fishways slow the water and create resting pools. The idea is juvenile fish can move upstream a couple of metres, then take a rest, then move up further and rest and so on.”

Terrain NRM has partnered with Catchment Solutions and OzFish Unlimited on the Fish Homes and Highways project, which is funded by the Australian Government’s Reef Trust program.

All the fishways were constructed in the dry season and the last one was completed just weeks before Cyclone Jasper crossed the Far North Queensland coast, bringing flooding rain.

“We’d already seen hundreds of empire gudgeons and shrimp species using the fishway at Lagoon Creek, moving up with the tide,” Deb said.

“OzFish Unlimited will be monitoring the fishways over the next six months to see the number and type of native fish moving through them.”

The construction phase followed extensive surveying in the Herbert and Murray River catchments. More than 3500 potential fish barriers were identified, leading to short-listing and on-ground inspections of over 300 sites to prioritise work based on the landscape, landholder willingness, accessibility, cost and development approvals.

Connecting Fish Habitat: Barriers that Prevent Fish Passage
This video explains what fish barriers are, how they affect fish habitat and what we can do to fix them. Many Australian fish species spawn in estuaries and then migrate upstream to freshwater habitats as juveniles. This means that barriers like causeways, weirs, dams and even weed chokes can prevent fish from completing their life cycles, which impacts on fish stocks.

The design phase was also comprehensive.

“Rocks need to be large enough to withstand flood events and to be placed precisely to create the right flow conditions. Each fishway is built to purpose. They’re engineered and approved. Some have an S-bend, others are a straight line and some are longer to achieve the right gradient.”

The Wet Tropics has the highest diversity of fish in Australia, with over 80 recorded species. Up to 50 per cent of them need to move between salt and freshwater habitats to complete their lifecycles, spawning in the estuaries and maturing into adults in freshwater wetlands.

“Barriers like weirs, drains and culverts, as well as aquatic weeds, are a threat to fish populations and diversity,” Deb said.

“Free passage is critical to allow these fish to breed, spread upstream, find waterholes in drier times, repopulate areas after dry periods, and access food and different habitats.”