Congestion hits marine highways
OUR fish are facing a dilemma when it comes time to hit the open ocean, it seems.
A report commissioned by the Federal Government found that fish in the Mackay Whitsunday region are facing up to 4000 potential barriers to their migration patterns.
Catchment Solutions project officer Matthew Moore, who authored the report, said these blockages could cause native fish populations to decline sharply.
“What a lot of people don’t realise is that almost 48% of all fish species in the Mackay Whitsunday region are diadromous – meaning they are a truly migratory species and need to transit between freshwaters and the sea at various stages of their life cycle, including to breed,” he said.
Local fishing guru Bob Spees agreed that waterway barriers were a problem for fish populations in the Whitsundays.
“(Barramundi) come up to the freshwater to spawn, and what a lot of them will do is stay in the shallows and slowly grow,” he said.
“Each time they get a wet season, they’ll move down.”
The report makes special mention of the O’Connell River, which meets the ocean at Laguna Quays, as one of nine high-priority waterways in need of immediate action.
“By rebuilding fish passages at these sites, extensive areas of fish habitat will be opened up to migratory fish species,” Mr Moore said.
Mr Spees said the O’Connell River had large numbers of barramundi experiencing blockages.
“The O’Connell River has already got a lot of barramundi up there,” he said.
“There’s all these barrages and holes there already, and there’s barramundi right up there.
“But if they put little dams in there, you’re going to get even more barramundi.”
The local angler also made mention of the Thompson River.
“You only have to look at places like the Thompson River – all the fish that get caught up there,” he said.
“It’s nothing to get 100 fish a day off the road there.”
Mr Spees said overfishing was also proving a problem for fish stocks in the region, particularly in relation to barramundi, which must reach about 80cm long to undergo a sex change and become female.
“The big thing is that people have got to stop taking large barramundi that turn to female,” he said.
“If we keep taking the females out, we’re going to end up with no kids.”
The veteran angler said the region had “the worst barramundi laws in Australia”, with the bag limit at five barramundi.
“I’d like to see the bag limit change to two over 85cm,” he said.
BLOCKAGES: Reef Catchments coasts and biodiversity coordinator Stefanie Wabnik and Catchment Solutions aquatic ecologist Matt Moore investigate barriers to fish migration.