NEW GLOUCESTER – Fish species not native to Maine’s lakes are becoming a threat to native species, including Sabbathday Lake’s cold-water trout, members of the Sabbathday Lake Association were told on Wednesday.

Fisheries biologist Francis Brautigam of Maine’s Department of Inland Fisheries and Wildlife addressed roughly 40 people attending the group’s annual meeting at the Sabbathday Lake Grange.

A link exists between invasive plants and illegal fish stocking that is threatening Maine’s trout and salmon fishery and water quality.

And, the illegal fish stocking limits food and space and may depress or altogether displace desirable native trout and salmon species. Sabbathday Lake’s trout fishery could be threatened by white pike, large mouth bass, crappie and cusk, for example.

Illegal stocking of private and public waters represents one of the largest threats facing fisheries managers and traditional anglers. Without the support and cooperation of the angling public in addressing this invasion, said Brautigam, this invasion will cause many popular stocking and management programs to be destroyed.

“Fish that have been moved from its native habitat to a new location even nearby cause significant harm to the new environment,” said Brautigam, who works in the Gray office.

For example, between 1980 and 2000, 613 lakes and ponds had a 47 percent increase in the number of bass. And northern pike that were only in nine water bodies in the 1980s are now in 30 lakes this year.

Black crappie, which were found in 13 water bodies in 1985, have increased 392 percent and were found in 64 lakes by 2000. New fish species recently discovered include rock bass in the Androscoggin, and channel catfish, white catfish, muskellunge and carp in the Kennebec River.

Egg production is high among these populations. For example, brook trout lay 100 to 5,000 eggs, while northern pike average 32,000 and white perch 71,000 eggs.

In response to this growing threat, new emergency legislation was adopted increasing penalties up to $10,000 for stocking without a permit, or even for possession of live fish, excluding bait fish, without necessary permits.

Operation Game Thief, under the jurisdiction of the Maine Department of Inland Fisheries and Wildlife, offers a $2,000 reward for information leading to the apprehension of anyone responsible for illegal introduction of fish into any Maine water. People may call Operation Game Thief at 800-253-7887.

“Recreational fishing is worth $300 million in Maine,” said Brautigam. “Be vigilant and report suspicious activity to Operation Game Thief.”