Commercial fisherman Bart Butson first noticed signs of the harmful algal bloom near the head of the Gulf St Vincent in Port Wakefield back in early June, following a significant storm.
"We went out onto the sea, and it was a different colour — it was a horrible greeny, grey colour," Mr Butson said.
"There was hundreds and hundreds of dead cuttlefish floating on top of the water.
" It was from that moment that I thought to myself, 'Oh my goodness, we're all in a bit of trouble here.' "
Mr Butson said within two weeks of the weather event, calamari had virtually disappeared from the waters.
"The catches dropped rapidly within a two-to-three-week period, and we haven't seen the calamari for 10 weeks," he said.
"It's like they never existed."
Mr Butson outlined his concerns at a publ