Around 50,000 small-sized Atlantic salmon escaped from the nets of Australia's Petuna Aquaculture farm in Macquaria Harbour, The Advocate reported.

The fish escaped when a pen broke from its mooring due to adverse weather conditions, Petuna's Strategy Manager Richard Miller said.

This is the second loss the company reported in the past year, both involving small-sized fish of about 250 grams each, Miller said.

The salmon that escaped are not expected to live long in the wilds of Macquarie Harbour since they were never exposed to predators in the farm, according to Devonport Angling Club President Peter Coventry.

In May, Petuna announced plans to double production at an offshore farm site in Tasmania's ominously named Storm Bay.