Mairs, a naturalist, says in his article about the Great Pond mudpuppies that insects and crayfish have been identified as their primary food elsewhere, though small fish and fish eggs, worms, leeches, snails and other salamanders also are part of their diet. Mairs concluded that the significance of Belgrade's introduced mudpuppies on fish populations, either through competition or predation, hasn't been studied conclusively. "There are just so many questions," he said of the interaction among aquatic species. "Nobody's doing any research because there's no money for research on the subject."
As a lifelong resident of the area who lives near the stream where mudpuppies were introduced, Mairs says he's unfazed by the intruders. "I think they're great," he said, though he admitted it may be a creature only a herpetologist could love. Which is not to say he is unconcerned about introduced species. "Native biodiversity usually suffers," he said.
Mike Little, watershed steward of the Belgrade Regional Conservation Alliance, who has a degree in environmental management and a lifelong interest in "herps," started a conversation about mudpuppies with "I've got a couple in my freezer"explaining that he's collecting samples to try to see what they've eaten. "They probably eat some fish eggs, but they're about as benign an invasion as you can get," was his preliminary conclusion. (This from one of the leaders of a mobilization to stop the spread of invasive aquatic plants, particularly variable milfoil, in central Maine lakes.)
Woodward added: "There have been other changes in the whole biological system that's made it [the effect of mudpuppies on fisheries] hard to track." Most prominent was the introduction of northern pike to the watershed 35 years ago. But a broader history of aquatic fauna puts the introduction of the mudpuppies in a different perspective. Nature isn't what it used to be. Those bass E.B. White caught, practically all of the game fish, most of the minnows and even crustaceans in the Belgrade Lakes, it turns out, are introduced species, scientists say.
It took about 20 or 30 years to eliminate the unwanted walleyed pike from the Belgrades, but soon after that was accomplished the northern pike was illegally introduced. A game fish prized by some for its size, strength and fighting ability, big northern pike can run four feet long. The Maine record, caught in North Pond, adjacent to Great Pond, weighed more than 31 pounds. It's a top-of-the-food-chain predator, so it comes to a body of water at a price, and that price is paid by other species including brook trout, landlocked salmon and white perch.
Woodward said he heard a reliable account that an out-of-state land developer connected with a notoriously shady land deal west of Long Pond who was seen deliberately dumping a tub of northerns into Little North Pond in 1969. Anglers started catching pike in all of the downstream Belgrades during the 1970s ("We thought they were pickerel at first," said Boulette), and by the 1980s they were part of annual fishing derbies. Year after year, the winning fish got bigger.
"We get so used to having these things that it's old news," Woodward said of introduced species. "This is the way it is with pike now. We knew we couldn't get rid of them, so we started managing them." Some fishermen would argue that the pike could stand more heavy-handed management. While the Belgrade chain is the only lake system in Maine with an established pike population, a mature pike was found in Sebago Lake last summer, prompting concerns about the storied landlocked salmon fishing there.