The Tasmanian salmon producer Tassal is crediting a boost in domestic sales for a 22 per cent increase to its half-year profit.

Tassal has recorded a profit of almost $16 million for the six months to December, up from about $13 million a year earlier.

The company's domestic marketing campaign helped sales in Australia to climb 20 per cent during the period.

But the value of salmon exports plunged 94 per cent, from $11 million to just $650,000.

That is in line with the company's decision to scale down export because of growing international competition.

Tassal has said it is cutting the cost of feeding salmon farmed in Tasmania's south-east and in Macquarie Harbour.

The company will pay an interim dividend of four-and-a-half cents per share.