Mathew Butcher said the seal was sleeping on the Portland boat ramp near the fishing club when he saw someone get dropped off from a boat.

"Someone got dropped off at the pontoon from a boat, but it wasn't going to let anyone pass," he said. "They went and got back on the boat."

Mr Butcher said he had witnessed the seal get grumpy when people approached it.

He believes Glenelg Shire Council should consider moving fish cleaning tables further away from the water.

Department of Environment, Land, Water and Planning program manager compliance operations Mark Bregeut said the authority was investigating options to manage the seal.

"The seal has become increasingly aggressive in seeking out discarded fish scraps from anglers."

Mr Bregeut said signage had been installed to warn visitors about the seal.

Feeding a seal carries a $242 on the spot fine and a maximum fine of up to $3223.80.

Mr Bregeut said despite the large and cumbersome appearance of seals, the mammals could be unpredictable and cover short distances quickly.

"For this reason, members of the public are urge to keep their distance," he said.

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