Fish Surveys Show New Fishways Have Opened Up 100km+ Of Waterways  

Fishways are helping fish species, including barramundi and mangrove jack, to breed up in local waterways.

Six fishways built in the Ingham region, and in other places between Tully and Crystal Creek, have removed barriers for juvenile fish. Together, they’ve opened up more than 100 kilometres of creek and river systems – and recent surveys at these sites have shown they are fish highways.

More than 1000 fish were recorded moving through one of the fishways – at Insulator Creek north of Townsville - in one day. And in more recent surveys, over 4500 fish were caught and released during monitoring work at four rock ramp fishways.

“Sixteen native species, including juvenile barramundi, empire gudgeon, rainbow fish, tarpon and long-finned eels, were recorded,’’ Terrain NRM’s Deb Bass said.

“Of the 80+ species of native fish we have in the Wet Tropics region, up to half need to move between salt and freshwater habitats to complete their lifecycles. Barriers like weirs, pipes, culvert crossings and weed chokes can stop these species from thriving.

“In recent surveys at our fishways, eight of the 16 native species recorded are species that need that movement - from their beginnings in saltwater to safer freshwater nursery grounds as juveniles and then back downstream to the saltwater to breed as adults. So we can see the fishways are providing access for these species, from barramundi and mangrove jack to shrimps.”

Terrain NRM has been working with OzFish Unlimited, Catchment Solutions and Australasian Fish Passage Services on the ‘Fish Homes and Highways’ project, which is funded by the Australian Government’s Reef Trust. Fishways are a relatively new solution in the region – a series of underwater stairs for fish, with deep pools between each one for resting.
Catchment Solutions fishery ecologist Matt Moore said rocks were placed strategically, sometimes in S-bend and sometimes a straight line, to achieve the right gradient to create a slower flow while also being able to withstand floods.

“To pull in our monitoring traps and see all the fish – a lot goes into the design of these structures, so we love seeing a result like this,’’ he said.

A ‘nursery slot’ is a new feature, trialled in one of the fishways, to help super small juveniles move upstream.

“It needs 20mm or less of water going through it to create the right conditions for weaker-swimming juvenile fish,” Matt said. “We recently recorded the smallest snakehead gudgeon ever documented in Australian fishway studies travelling through the slot. It was 16mm long.”

Oz Fish Unlimited’s Geoff Collins, an aquatic ecologist and Adjunct Research Fellow at James Cook University’s TropWATER, said the new fishways had been monitored for five days to assess the diversity and size of fish moving through. Results showed they would make an impact on the health of fish species and the waterways themselves.

“We are opening up habitat that many juvenile fish haven’t been able to access, particularly in low-flow situations, for decades in some cases,’’ he said.

“These structures are enabling migration for tens of thousands of fish. And the more habitat we can give fish access to, the more productive our fish stocks will be. Freshwater wetlands, creeks and rivers are important nursery grounds with abundant food resources that will help our native fish to grow fast, and to travel back downstream and breed in the tropical wet season.”

The ‘Fish Homes and Highways’ project began with extensive survey work in the Herbert and Murray River catchments between Crystal Creek near Paluma and Tully, where more than 3,500 potential fish barriers were identified, leading to on-ground inspections of over 300 sites.

The fishways were built at barriers like causeways and, in other places, bed-level crossings were built to replace causeways, or creek crossings were completely removed.

“We’ve also removed aquatic weeds and there has been revegetation in an area where fish passage works were completed,’’ Terrain NRM’s Deb Bass said.