Scientists are reporting a sharp decline in the number of young lobsters settling off the coast of Maine and in the waters southwest of Nova Scotia.

For two decades researchers in Maine have been tracking the number of baby lobsters at 11 locations in the Gulf of Maine.

On the American side, their sampling of baby lobster has fallen by more than half of their 2007 levels.

Bob Bayer, executive director of the Lobster Institute at the University of Maine, says it takes about eight years for baby lobsters to be big enough to harvest — meaning it's likely the end to the United States' unprecedented catches.

"We were going along a 20 million pound harvest for many, many years. Now this last year we're up over 120 million pounds. This probably isn't a sustainable level," he said.

A concern for the Maritimes

Scientists at the Bedford Institute of Oceanography are also participating in the lobster settlement index. They are noting declines in the Bay of Fundy and off the southwest coast of Nova Scotia.

Fisheries and Oceans Canada scientist John Tremblay says landings off of Nova Scotia will be impacted.

"I expect that we will see a decline perhaps in three to four years. But I'm not sure how large it will be," he told CBC News.

Tremblay is cautious about drawing conclusions from the data, adding the Canadian samples came from small areas and were collected over a shorter period than the studies out of Maine. The only zone bucking the trend is Prince Edward Island's north shore.

"We want to follow through and we are doing that. It is a concern when we see these kinds of declines," Tremblay said.

Scientists say it's not clear what caused the recent boom in landings nor can they explain the decline in baby lobsters they are now seeing.

The Nova Scotia government says the province exports $400 million worth of lobster each year.