Groups reject clean salmon farming claim

Environmentalists have hit back at Tasmania's salmon farmers, insisting the booming industry is linked to increased pollution levels.

The Senate's environment committee has held public hearings in Hobart, where on Thursday Environment Tasmania's Rebecca Hubbard gave evidence in contrast to that provided by salmon growers and the state government.

"Clearly, things are not fine and we hope that the inquiry would reveal that there is a disconnect between the reality and the message from government," she told reporters outside the hearing.

Ms Hubbard cited water quality data that showed worrying results in areas near salmon farms, including in Macquarie Harbour on Tasmania's west coast.

"The rapid expansion, the doubling of production, in the harbour has coincided with an outbreak or bacteria mats, of pollution species and of dissolved oxygen crashes - effectively the creation of dead zones," she said.

"That cannot just be a coincidence."

Ms Hubbard hopes the committee will recommend a formal review of the regulation of the aquaculture industry.

"It needs direct and immediate research ... and response," she said.

Her comments come a day after the state's Liberal government revealed the results of an independent scientific review of salmon farming that found there was no evidence to suggest the practice is having a negative impact on waterways.

The Tasmanian Salmonid Growers Association, representing the state's three major producers, insists its members adhere to world-leading regulatory measures and rejects that they are causing pollution.

Abalone and mussel growers have reported a drop in growth rates near salmon farms, with an unknown sludge forming on their stock and particles in the water.

Tasmanian Abalone Council boss Dean Lisson told the committee that while he could not prove salmon farming was responsible for the pollution, private research suggested that it was the case.

"Divers over the past 15 or 20 years started to notice evidence of this sludge ... and we have video footage," he said.

The committee will adjourn to consider the evidence and may request further public hearings if more information is needed.