Figures obtained by  The Weekend Australian  under right to information laws showed Tasmanian ocean salmon and trout farming was responsible for the death of 144 protected seals over the past four years, as well as a number of dolphins and several hundred seabirds.

Most of the affected animals were said to have drowned from being stuck in underwater netting of the circular fish pens, while others died during relocation programs, or were euthanased because they were a danger to workers. 

Greens primary industries spokesman Kim Booth said that if the reported number of animals killed was accurate, the industry needed to declare how it was going to improve its record in light of expansion.

The consensus among the state's biggest salmon farming companies was that tougher cages and nets were needed to prevent animals from getting trapped, with brands such as Tassal and Huon Aquaculture already investing in predator-proof pens and nets. 

Alastair Scott, head of government resource management and conservation, said a seal interaction forum and marine predator working group was also working with the industry to identify safer and more effective protocols.

``The department recognises that this issue is about managing human health and safety as well as wildlife issues,'' Mr Scott said. 

``Fish farm operators have raised concerns over the safety of their staff when trying to manage seals which have accessed their pens.

``There is a requirement for industry to report seal mortalities . ?. ?. and follow-up action, such as identifying measures to reduce the potential for wildlife impacts, can result from these investigations.''

The Tasmanian Salmonid Growers Association said sales of Tasmanian salmon were about 43,000 tonnes per annum and worth about $500 million.