Crayfish are an invasive species that have been threatening a Kodiak Island lake for over two decades. Eradication efforts have been underway for years. But now the Sun’aq Tribe staff recently got a scuba certification to search for the freshwater shellfish in deeper water than ever before.
Buskin Lake is a serene scene near the island’s airport, surrounded by mountains and trees. But under the water, scientists have been trying to catch as many crayfish as possible to keep the invasive species’ population under control.
Daniel Smith is a biologist with the Sun’aq Tribe’s natural resources department. He’s been researching how the shellfish affect the lake’s ecosystem. He said they’ll eat anything, like underwater plants and even salmon eggs.
“They really are generalists in their foraging behavior – they basically eat what is accessible to them,” Smith said.
He said it’s hard to pin down a primary food source, meaning just about any aquatic animal in the lake could be threatened if a crayfish finds it.
But there’s good news – Smith and Matt Van Daele, the Tribe’s natural resources director, recently spent a week on the Kenai Peninsula getting scuba certifications to better study the invasive species.
Van Daele said that certification allows them to dive up to 60 feet, which is perfect for the team’s efforts.
“During high water events, Buskin Lake is only about 60 feet deep at the deepest,” he said. “So now with a certification, there is no place in the Buskin that crayfish can hide – we can access all points within the Buskin watershed.”
Smith and Van Daele previously were only able to dive to about 20 feet deep with snorkels.
He said there’s other good news, too. The local crayfish population could already be shrinking.
“We’re also seeing female crayfish with juvenile markings with eggs now,” Van Daele said. And that’s pretty substantial – a real indicator of a population under distress.
He said it implies that crayfish have fewer options for mates.
It's difficult to come up with population estimates; the pair suspect it’s somewhere in the tens of thousands in Buskin Lake. Smith said that even without exact numbers, they’re confident their efforts to limit crayfish are making a difference and helping protect native species.
“Our control efforts are definitely making a significant impact toward this population,” Smith said. “And we just want to reduce the population more so that the crayfish aren’t having as much of an impact as they already are.”
So far, they’ve been catching crayfish by hand and by setting traps.
The team is also trying to get the Kodiak community involved in their control efforts. There’s a friendly competition for who can design the best trap for crayfish. The Tribe doesn’t have any prizes so it’s just for bragging rights, but it will help keep crayfish counts as low as possible.
They’re also hoping to host derbies to catch as many crayfish as possible to have community crayfish boils. The first one of the year is set for June.
