A benefactor has pledged to donate up to $50,000 to boost a green group's campaign against "big salmon" in Tasmania, but their identity is being kept secret.

Environment Tasmania announced a "very generous donor" had offered to match public donations to its salmon "consumer information campaign" which aims to "tell customers the full story of where their salmon comes from and the impact salmon farming is having on Tasmania's precious marine environment" ahead of the state election.

Spokeswoman Laura Kelly said the "well-known philanthropist" would match donations to Environment Tasmania dollar-for-dollar up to $50,000, meaning the group could have a $100,000 war chest to spend on its campaign against what is described as "big salmon".

Ms Kelly said while she would not reveal the donor's identity, she did not believe the secrecy comprised the integrity of the campaign.

"This person is a well-known philanthropist and has the interests of the Tassie marine environment at heart, so we're confident that that money aligns with our values and will be used solely for an education campaign," she said.

Environment Tasmania has urged people to throw their weight behind the campaign "protecting our voiceless, endangered marine life".

A series of environmental incidents have sparked concerns over intensive fish farming in Tasmania. ( Supplied: Huon Aquaculture )

In 2016, Tasmania's salmon industry came under the national spotlight following an ABC Four Corners report which highlighted the effects fish farming was having on the environment.

Ongoing concerns about the environmental impact sparked public protests and a Facebook advertising campaign by a group supported by Graeme Wood, businessman and founder of the travel and accommodation booking website Wotif.

Mr Wood, who sold Wotif in 2014 for a reported $140 million, made headlines in 2011 when he donated $1.6 million to the Australian Greens, the biggest political donation in Australian history at the time.

Tasmania's salmon producers Tassal and Huon Aquaculture declined to comment on the benefactor's $50,000 pledge.

Petuna did not respond to invitations to comment.