After a recent visit to Gore for last month’s On The Fly Fishing festival, fly-fisherman, guide and writer Mike Weddell said he and other anglers were concerned by increasing river erosion and a perceived drop in fish numbers.
"I’ve fished the Mataura for 40 odd years. I’ve seen it move in some places more than 100 metres because of eroded banks," he said.
"A lot of places that used to be deep are now really shallow.
"There’s been people complaining recently about too much gravel in the rivers. It’s probably the same amount of gravel in the river all the time but it’s where it ends up," he said.
Mr Weddell acknowledged the issue was complicated but said it had major effects on the fishing spots around the river, exacerbated by the multiple flooding events throughout the years.
"Variations in depth are quite important from a fishing point of river. Brown trout are territorial. They need depth to escape to or go when the water is too warm. They need food production and cover.
"How wide and shallow the river is makes all the difference and either makes the fishing good or not so good, but it’s very complicated," he said.
"The most trout I’ve ever seen is off the bridge at the beginning of 2000 [when] I counted 54 just below the bridge. You’d be lucky to get 10 now, because the habitat’s not good. It’s too shallow," he said.
His comments echoed previous concerns brought up by Mataura Catchment Liaison Committee chairman Hugh Gardyne, who has been vocal about the gravel build-up within the Mataura River.
Mr Gardyne said, despite a public meeting last year with Environment Southland very little had been accomplished in terms of reducing the gravel issue in the river.
"The erosion is everywhere. We don’t think Environment Southland is getting on and keeping up with the essential maintenance.
"They’re treating it like a capital works programme, but it’s just deferred maintenance.
"You look at the bridge now it almost looks like the gravel’s reaching halfway across the river," he said.
Environment Southland general manager integrated catchment management Lucy Hicks said the organisation had received $14.9 million from the Regional Infrastructure Fund last year that would support work to reduce flood risk around Southland,
"As part of this programme, Environment Southland applied for a consent to remove gravel, sediment and vegetation from the bed of the Mataura River around and downstream of the Gore railway and State Highway bridges."
Other work looks to widen sections of the channel to improve flow through bridge opening and "reduce local river levels" with "no adverse downstream impacts identified in modelling", which is a targeted intervention specific to Gore.
Southland Fish & Game regional chairman Dave MacGregor said the organisation had data collected from drift dives suggesting "an overall increase in brown trout population" on the Mataura river over a 30-year period, with an average count of 20 fish per kilometre.
"But how long is a piece of string? This can be a touchy subject because we don’t drift by the whole river, we do sections. With flooding and everything, some sections can be good one year but might change.
"It’s a bit delicate trying to count a wild population in a moving river," he said.
Mr MacGregor said changes in habitat were an issue when it came to consistent fishing, calling flooding a major issue for river structures, but it was a question for Environment Southland to sort not F&G.
"Some sections are good, it may change, it might not hold as many fish, but a fisherman has probably got to adapt. Some sections are good fishing for years, a flood hits, then you have to keep moving and and keep looking for the fish," he said.
