West Vancouver resident Blair Calkins was prawn fishing on the weekend during an excursion to Bowen Island when he came across an unexpected creature in one of his traps: A large Atlantic female lobster, stuffed with eggs.

Not knowing whether he should release the alien species back into the Pacific, Blair said he called the Department of Fisheries and Oceans on Saturday for direction, but by Tuesday was still waiting for someone to return his call.

The lobster is sitting in a tank, and Blair said he will likely release it back on the south end of Bowen Island within the next couple of days, in hopes that it will survive.

"The eggs look pretty ripe," he said. "We were all shocked. We had a couple of people who work in the fish industry on our boat and they were shocked too."

UBC marine biologist and professor of zoology Christopher Harley said occasionally someone will find an Atlantic lobster in the Pacific, but the sightings are rare, and whether there are established populations here remains a mystery.

"Since there are no native lobsters here, they must have been released by somebody," he said. "When you have a combination of live seafood markets and members of the public who feel that it's not fair to the animals, then you have people buying them to set them free."

After studying the photo sent by Blair, Harley said it was very interesting and rare to see an Atlantic lobster full of eggs, although he noted the eggs would have to survive a complicated larval development to establish a new generation of lobsters.

"This species from the Atlantic doesn't have a problem with temperature," he said. "But there are a lot of native species that could act to stop that invasion. Maybe these lobsters can survive the temperature, but all of their babies get eaten by Dungeness crab, or something like that."

He said that throwing lobsters into the sea may seem like a good idea, but there are always risks that an invading species could damage the ecosystem.

"It makes me nervous when people start letting these things go, because you never know what will happen. I don't imagine it's legal to release them in an attempt to establish a fishery on this coast."

A spokeswoman for the DFO said she would look into the claim.

Several thousand Atlantic lobsters were dumped into B.C. waters during at least half a dozen experimental transplants by either private industry or the federal government during a 70-year period ending in the mid-1960s.

But Calkins said it is unlikely there would be any lobsters left from those experiments. It is more likely they are being dumped by animal rights activists, a common occurrence in other cities on the Pacific coast such as Seattle and San Francisco.

ticrawford@vancouversun.com

With a file from Larry Pynn