The commercial fisherman said he was fishing off Blueskin Bay when he hauled up the net, which looked as if it had been deliberately dumped, with several tonnes of old rope weighing it down.

"I could have cut it, but these are the fishing grounds where I fish all the time."

He believes the dumped rope and net - a potential environmental and shipping hazard - may have come from one of the foreign-owned fishing vessels which visited Dunedin and were known to anchor in the area.