Squishy, blobby and alien-looking, some varieties of sea squirts — so called because they squirt water when they’re disturbed — have been in Maine for hundreds of years.
But with the Gulf of Maine warming rapidly due to climate change, it has created a more hospitable habitat for new hangers-on from elsewhere: invasive sea squirts.
For those who work in aquaculture, these invaders can be a constant source of annoyance and stress throughout the fishing and growing season. And some years, they can be a major hindrance to doing business.
Troy Carter, dock manager at Community Shellfish in Bremen, says for lobstermen, invasive sea squirts have gotten out of control in the past four or five years. Squirts foul up gear, and in extreme cases, make traps so heavy they’re hard to pull out of the water.
“A trap that weights, 30, 40, pounds now weighs 100 pounds. And you do that 200 times in a day,” he says.
And if you’re not constantly hauling up and rotating the traps, it can become a problem pretty quickly.
“They won't be very big, like half an inch, and within a week, within a week, they're an inch and a half, two inches big,” said Scott Poland, another lobsterman from Bremen.
Sea squirts are tenacious little animals. Once they’ve glommed onto something, it’s really hard to shake them. If you cut them off, they’ll grow back. But they can’t withstand high temperatures, so many lobstermen, and oyster farmers, leave their gear out in the sun to dry them out over several days.
Poland said he keeps 20 or 25 traps out of the water drying out at all times.
“So in doing that, you've got your trap out of the water when the lobsters are there and you aren't fishing with it,” he said.
Some lobstermen "cook" their traps in boiling water to remove biofouling organisms, like squirts. This means submerging each trap in a giant vat of boiling water that's between 160 and 180 degrees. That's a lot of extra work.
Sea squirts — formally named tunicates, because of the tunic-like covering over their siphons — were particularly bad last year, according to several oyster and mussel farmers who spoke to Maine Public. Bangs Island Mussels in Portland had to change their entire operations flow as a result of biofouling from sea squirts. And Evan Young of Blue Hill Bay Mussels says they crowded out underwater surface area where mussels should have been able to grow.
You’d pull up a seeded line, he said, and “at any time half that line could be solid squirts,” said Young.
For a small business, it was labor intensive, to say the least.
"We were spending probably 30% of our time taking squirts off and trying to get rid of them before they went through our equipment," he recalled.
Now, he orders lines from the Downeast Institute hatchery that already have seeds attached, rather than setting out bare lines to attract wild mussels.
"My farm is 100% hatchery seed, and we get our seed from the hatchery at DEI in April, and Mother Nature doesn't get her seed until July. We get a good 3-month head start."
And Young says he tries to grow more mussels per foot of line so there is less room for the sea squirts to attach themselves.
But as fishermen are toiling to free their gear from these pests, Christina Cota is having the opposite problem: she can't get enough sea squirts.
"We study the development of these organisms, and specifically the cellular processes that are associated with that development," says Cota, a biologist and professor at Colby College.
Sea squirts are a valuable model organism for scientists. Their embryos are completely transparent, which means researchers can see into them and watch how the cells interact. And, genetically, they're closely related to humans.
"Intriguingly, as we're starting to see these guys become more and more of a problem in the Gulf of Maine, researchers are beginning to find them more and more exciting," said Cota.
Cota buys over a hundred sea squirts to be shipped to her lab from California each week. But lately, she's been hanging pipes off docks and trying to catch them herself.
But as a busy university professor, she doesn't have a lot of time to collect them herself. She says she's hoping Maine fishermen can start to harvest the squirts themselves and sell them to scientists.
"It's a lemons-out-of-lemonade situation, right?" she said.
It's not yet clear if there's enough demand from researchers to make a real dent in the population. The Department of Marine Resources doesn't specifically track the growth of invasive sea squirts, so most of what's known comes from other related studies of underwater species.
But the reality of climate change means that as waters warm and temperatures change, animals and organisms are moving. Cota says, if the tunicates are going to be here anyway, and demand is growing from the scientific community, why shouldn't it help bolster Maine's fishing industry?
"We all have to deal with changing climate," Cota said. "And the reality is that the distributions of these populations globally are changing. As waters warm, as temperatures change, the animals are moving."
But what is known is that the invasive sea squirt is here to stay, and that the shellfish and lobstering industries will have to continue to adapt.
