According to the Maritime Union of Australia (MUA) the fleet of Australian registered and Australian crewed vessels has fallen to just 12 ships over the last eight years.

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That shortage saw Norwegian-flagged supply ship the Far Saracen being called on to deliver supplies to isolated South Coast communities during the Black Summer bushfires.

With a looming federal election, the MUA has launched a campaign to focus attention on the weakening domestic shipping sector, which places Australia at the end of a long supply chain.

"Australia is an island nation, and 99 per cent of our imports arrive by sea," MUA South Coast branch secretary Mick Cross said.

"We manufacture and produce less and less of what we consume locally, so our dependence on international shipping has only grown and grown."

The campaign launched on Thursday in Nowra with a documentary of the MV Portland, where Australian seafarers were removed from a ship plying a domestic route and replaced with a foreign crew.

South Coast Labour Council secretary Arthur Rorris said it was "absolutely imperative" that Australia's domestic shipping fleet was protected and bolstered "as an insurance policy against times of crisis or conflict".

"We want politicians in Canberra to sit up and listen to the warnings from seafarers," Mr Rorris said.

"We know better than anyone the strategic importance of our work, but we have seen local crew members marched off ships in the middle of the night by unscrupulous employers."

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