An invasive crab species that first showed up in waters around Newfoundland five years ago has now been found in bays and coves all around the Burin Peninsula, causing concern for fisheries researchers.

"If you look at what it [green crab] was doing in just 2007, it was just in a few locations. Now it's pretty much spread through most of Placentia Bay," said Cynthia McKenzie, a scientist with the federal Department of Fisheries and Oceans.

Cynthia McKenzie is warning fishermen to keep an eye out for green crab. (CBC )

Experts say green crab can survive a wide range of water temperatures and saline levels, and a single female can lay up to 185,000 eggs.

"It's very aggressive in nature, it's a very general predator, so in terms of the aggression it's not going to back down from the native crabs, even if they are smaller," said Kyle Matheson, a DFO field researcher.

"They are what we call a generalist predator so they won't be very picky about what they eat."

Green crab destroys other species

Scientists say green crab devastated fishing grounds in the Maritimes. They crowded out native crab, ravaged lobster grounds and destroyed eel fishing areas.

The aggressive crab have also harmed habitat for young cod, herring and other species.

"Not only is it a risk to the juvenile lobster if there's an overlap, but the actual getting in and eating the bait before the lobster gets there," said McKenzie.

"And we've actually had reports of green crab in the lobster traps, eating the lobster that were trapped there."

Green crab have been able to survive out of the water for long periods of time, so they have been able to hitchhike to different bodies of water.

DFO asking locals for help

"I'd like for people to be aware of movement of gear and boats, within the bay and between the bays," said McKenzie.

"Because we certainly don't want to give them [the crabs] any more help then they've already got."

DFO officials have been urging people to help scientists in their study of green crab by reporting sightings of the invasive species in new areas.

Fish harvesters can also apply for a DFO licence to help destroy them.