The United States is now requiring proof that its seafood imports are harvested in a way that minimizes harm to marine mammals like whales — and that has concerned some members of Atlantic Canada's fishing industry.

As of Monday, countries had to submit a list of fisheries measures in place to limit by-catch and gear entanglements with whales, turtles, porpoises and seals.

The U.S. wants standards comparable to those imposed on American fisheries.

Some Canadian fisheries may need to change

Nadia Bouffard, director general of external affairs with the Department of Fisheries and Oceans says it's too soon to know which fisheries in Canada will be affected.

The United States has not released the criteria it will use to evaluate management regimes in other countries.

"I expect there may be some fisheries [that] will need to look at changes in the ways they mitigate their operations on marine mammals across the country, but to tell you which ones will be required to make those changes is premature because we don't know what the U.S. will be doing to make that assessment," Bouffard said.

'Could be a big problem'

Later this year, the U.S. will release a country-by-country list of fisheries deemed acceptable and those deemed non compliant. The latter will have four years to satisfy American requirements.

"It could be a big problem," said Bernie Berry, president of the Coldwater Lobster Association, a group representing fishermen in Canada's most lucrative lobster fishing areas in southwest Nova Scotia.

Berry believes summer and fall lobster season closures, when whales are usually in the area, should satisfy the Americans. In Maine, lobster fishing is year round.

"I think we are compliant, but you have to meet their standards if they find us non-compliant that could mean a change of gear type ... so it would actually be costly," Berry says.

He said Canadian fishermen would have no choice but to comply.

What Canadian fishermen are doing to save whales 

Lobster fisherman Graeme Gawn with the Maritime Fisheries Union said his organization has been involved in marine mammal protection for 25 years, including creating safe zones and guidelines for removing gear from areas that whales habituate in the Bay of Fundy.

"We have also worked in conjunction with the whale-watching sector and the marine mammal disentanglement response networks to remove rope from whales that most often arrive in these waters already entangled," he said in an emailed response to CBC News.

Melanie Sonneberg of the Grand Manan Fishermen's Association in New Brunswick said lobster fishermen are also adding more traps per line, which reduces the number of vertical lines in the water. She fears the message may not get out.

"I think for everybody this is really concerning," she said. "We have not been privy to the actual ongoing discussions between the Department of Fisheries and Oceans and the U.S. government. What for us is uncomfortable is how these things are being viewed from office buildings."

Canada's most important seafood market

Two-thirds of all seafood caught in Canadian waters is exported to the United States, which is the world's largest importer of seafood.

According to Canadian government statistics, the top suppliers in 2014 were China, Canada, Indonesia, Chile and Vietnam.

Nova Scotia valued its seafood exports to the U.S. in 2015 at $958 million.

"The American market is really important to the seafood sector here in Canada, so meeting this requirement will be extremely important for them to maintain that trade into the U.S.," said Bouffard.

Environmentalist: We could do better 

Environmentalist Katie Schleit of the Ecology Action Centre in Halifax said there is room for improvement, especially in observing and monitoring.

The shortcomings were highlighted in a 2016 auditor general's report on the Department of Fisheries and Oceans.

"For example, observer coverage in some fisheries is at zero per cent or five per cent, which is far below what we might want for science monitoring," Schleit said.

"We've heard from the department already that they have some concern with the robustness of reporting. At the Ecology Action Centre it's really an opportunity for the fishing industry to get out ahead and show we do have good fisheries here. But without the right data, we are not able to show that."