At the second day of hearings into finfish farming in Tasmania, Lonnavale resident Geoffrey Swan said he and his wife had been bullied on social media, which included threats of lynching and having their home burned down.

"For the first time in 10 years, my wife and I have had to lock our doors for fear of our lives," he said.

"In this industry, there are bullies and they are connected to people I know who are bad so this is very real terror.

"We are frightened."

Trish Baily from Tasman Peninsula Marine Protection and representatives from the Tasmanian Alliance for Marine Protection also made comments about abuse directed towards them on social media.

The two groups told of situations where major salmon companies Tassal and Huon Aquaculture had engaged with them until challenges to provide information mounted up.

Ms Baily said community groups were made to jump through hoops just to get simple answers.

Tasmanian Alliance for Marine Protection representative Sheenagh Neill said the industry's zero-tolerance approach to marine debris was failing as there were not enough people managing it.

She said companies disputed ownership of some debris while yachts and boats suffered thousands of dollars worth of damage.

"It is only a matter of time before death," Ms Neill said.

"[Companies] have improved, they have listened in some cases, but zero tolerance in my opinion should be zero.

"The fines are not big enough, they fight them, and there are not enough penalties."