Recreational shellfish collectors are being warned not to eat shellfish from Hobsons Bay after a marine algal bloom was detected off Port Melbourne beach.

Blooms are concentrations of miniscule marine plants varying in colour, sometimes mistaken for oil pollution.

The Department of Environment, Land, Water and Planning (DELWP) on Friday said routine water sampling had detected high levels of the potentially toxic algae, Alexandrium minutum.

The naturally-occurring algae can cause toxins to build up in shellfish such as mussels, pipis, oysters and scallops and, to a lesser extent, fish.

“While there are already restrictions on collecting shellfish in this area, as a precaution we want to let the community know that it may not be safe to eat them,” regional manager Bernard Barbetti said.

“We are also advising anglers that any fish caught in the Hobsons Bay area should be cleaned and washed in clean water and the internal organs removed of before eating.

“DELWP advises people to avoid contact with algae-affected water, which may look murky or discoloured. If contact occurs, wash with clean water.”

He said it was safe to eat shellfish and fish from shops or commercial fisheries.

DELWP will conduct further water sampling on Friday and continue to monitor the situation.