It's a cool August morning, and Amanda Laliberte is helping sort through bags of crayfish outside the office at Rangeley Lakes Heritage Trust.
Laliberte helps contestants sort the crayfish into piles of males and females, showing them how to identify each. She points to the tiny legs on the underside of the males, and the small spot on the belly of the females.
And then they carefully count the numbers of each sex, and weigh the entire catch.
The idea for the contest came from the land trust's Julia Morin who had seen green crab derbies in other states. She thought it could be a creative way to educate residents about an invasive species that they otherwise might not know existed in local waters.
"Because there aren't any other aquatic invasive species in the Rangeley Lakes Region, like, including plants and everything," Morin said. "So that you know, they just assume that everything is where it's supposed to be."
But to enter the contest, participants have to be able to distinguish the rusty crayfish from native species.
And the differences are subtle. Rusty crayfish typically have two rust-colored spots on either side their body — hence the name. They also have black bands and orange tips on their claws, which have an oval shaped gap even when closed.
"It's important to know that crayfish are omnivores, that is they eat everything — they're like people," said Karen Wilson. "So they'll eat plants, they'll eat animals, they'll eat insects, they'll eat snails"
Wilson teaches environmental science and policy at the University of Southern Maine. She studied rusty crayfish in Wisconsin, where the species is much more widespread and she's now tracking invasive crayfish here.
"So the best thing you can do with crayfish, invasive crayfish, is just to not have them show up in the first place," she said.
Wilson says the rusty crayfish cause a variety of problems in Maine lakes and streams. They disrupt habitats, pushing natives out of their protective hiding places, and compete for their natural sources of food.
They have spread from their native waters in the Ohio river basin, arriving in Maine in the 1960s, most likely as bait — and Wilson says that's still the primary way they continue to be spread.
"One of the really most important things I tell people about crayfish is never move them from one lake to another because you just don't know if you're accidentally introducing a species that might suddenly start to reproduce rapidly and cause problems for lake," Wilson said.
At this year's Rangeley lakes contest, the three team members known as the "Hunter Cove Crayfish Killers" won by a landslide after catching 70 rusty crayfish. Twelve-year-old Hanna Pitkin, 10-year-old Mae Derrig and 14-year-old Micah Derrig used one trap but caught most of the crayfish with nets baited with pieces of bread. Derrig says they plan to come back again to hunt for rusty crayfish next summer.
"I think this is the last week we're gonna be here, but next year, definitely," he said. "It was super fun."
To date, rusty crayfish have only been found in the Rangeley lakes and Belgrade lakes regions of Maine, but conservationists are seeking the help of volunteers to watch for the appearance of the species in other inland waters.
Support for Deep Dive: Invasives is provided by Maine Audubon, Friends of Acadia and Coastal Maine Botanical Gardens.
