Otago fishermen have formed a working party to write their formal response to Port Otago's plans to dump more than seven million cubic metres of sand and silt off Taiaroa Head.
Port Otago will soon apply for resource consent to widen the Otago Harbour shipping channel and dump 7.2 million cubic metres of dredge material 6.5km out to sea.
The Port Chalmers Fishermen's Co-operative fears the sand and silt may create a "dead zone" along the coast, threatening fishing stocks and their income.
About half the co-operative's 40 members attended a meeting on Thursday night to discuss the issue.
President Steve Little said the unanimous view was that Port Otago needed to commission more research on the effect of tides on the sand and silt, where the dumped material might move to and what impact the material would have on the sea floor and kelp beds which sustained marine life.
"We are unconvinced enough research has been done . . . on the risk management side of the proposal.
"This could potentially threaten the $6 million-$12 million crayfish industry right along the Otago coast."
The scale of the proposal had escaped people, Mr Little said, suggesting this was because the material was to be dumped at sea, rather than on land.
"Seven million cubic metres of material is a colossal amount.
"If it was about to be top-dressed on to the Taieri Plain, I am sure dairy farmers would have something to say about it."
The meeting elected four people to a working party, which will write a submission on the proposal.
Its members are Mr Little, Otago crayfish industry executive officer Simon Gilmour, fisherman Neil McDonald and Karitane taiapure fishery and customary fishing management area representative Alan Anderson.
Port Otago has said it plans to lodge its consent application in May or June after it has finished consulting affected parties.
