The Sitka Sound Science Center has a lot of irons in the fire when it comes to scientific research- in addition to their fisheries work, they’re conducting cutting edge landslide research and running a hatchery. One of the organization’s most recent endeavors may sound a little spooky, but for some of the ocean’s crustiest critters it’s an exciting development.
“This is just a salt water flow through tank, so there’s a little bit of movement to mimic what would be happening in the ocean” Callie Simmons says over the loud hum of pumps and running water behind the Sitka Sound Science Center. She gestures to a nondescript box tucked away in a corner, with holes poked in the sides that allow water to circulate.
“There’s a little bit of movement to mimic what would be happening in the ocean,” she says.
She’s showing me a project she’s monitoring, but the tank isn’t full of fish like you might expect. It’s full of hinges.
“We have two different types of hinges, kind of suspended in the water,” she says, lifting the lid to the tank to show me the rows of hinges. “We’re just seeing how long it takes them to biodegrade.”
Why? A research team at the science center wants to see if biodegradable hinges can prevent “ghost fishing” in Alaska. While that may sound a little spooky, it’s actually pretty straightforward.
“Okay so ghost fishing is when you put a crab pot out, and for some reason the crab pot becomes un-retrievable. So then it can continue to fish,” explains Ron Heintz. He’s the research director at the science center- he’s been on the job since March. He recently retired from NOAA and has done a lot of work with fisheries biology.
“It was a lot of grinding fish up and setting them on fire to see how many calories were in them,” he laughs.
The science center is doing a wide variety of research- but recently they’ve been studying crab pots- big round, sometimes square, wire traps used for crabbing.
“There’s a funnel that the crab goes into and at the end there’s a little gate. And the crab pushes the gate open and goes inside the pot and gets stuck,” Heintz explains.
And if a crab pot gets lost on the ocean floor, there’s a safety mechanism in place. “There’s a cotton cord that you put on the top of a crab pot, on a big flap, on one of the sides of the crab pot,” Heintz says. “That cotton cord will rot eventually. And then that flap can open up and presumably the crabs can escape.”
That is unless the pot happens to be sitting flap side down on the bottom of the ocean, or the pot gets heavily fouled with other organisms weighing it down. Then the crabs are stuck and they die of starvation.
So the center partnered with colleagues at the Virginia Institute of Marine Science who have developed crab pots with biodegradable hinges. They’ve been using them for the blue crab fishery in the Chesapeake Bay.
“The idea is that these hinges would degrade and then the bar that prevents the crab from escaping from the pot would fall to the bottom of the pot and then the crab could run away.”
This isn’t the first time the science center has looked into a solution for ghost fishing.
“We tried an experiment like this several years ago, where we wanted to sew a biodegradable panel into the side of the pots, and the panels never degraded,” Heintz says.
Why? Southeast Alaska waters are too cold. And this recent experiment hasn’t been without its hang ups. They gave several test crab pots with biodegradable hinges to sports fishermen.
“The first thing we learned was that the hinges failed almost immediately,” says Heintz.
So the researchers in Virginia sent them new hinges, and Heintz says those seem to be working out well. But then they came up against another problem.
“The Alaska crabs seem to be a little meaner and more hardcore than the blue crabs in Chesapeake Bay,” he says. “The Dungeness crabs, what they like to do, is when they get stuck is they grab that little gate with their claw and they just yank on it and break the hinges off.”
Heintz calls this the “crab effect”. Dungies just cannot be contained.
So what’s the solution? Keep testing the hinges. Those being tested behind science center are different thicknesses. They will be in the water for 120 days. Simmons says the sweet spot is about four months of use before the hinges begin to degrade. She and Heintz hope to walk away from the project with more information on how to reduce ghost fishing in cold Alaska waters where mean crustaceans abound.
It’s doubtful any crabs will say “boo” to that.
