Fishermen in Maine’s coastal waters are facing challenges due to the increase in populations of small, blob-like animals brought on by warming ocean temperatures.
Numerous invasive species of minute invertebrates are attaching themselves in enormous quantities to lobster traps and aquaculture equipment, which can often cause harvesters a great deal of trouble as they attempt to tend to their equipment.
Sea squirts, also known as tunicates, are abundant in September. Hilton Turner, a lobsterman and chair of Stonington’s port committee, described them as “coming on like gangbusters.”
He said, “Every year gets a little worse.”
More direct in his criticism of the animals was marine biologist Brian Beal, who oversees the Down east Institute, an organization dedicated to aquaculture research on Great Wass Island, and teaches at the University of Maine’s Machias campus.
Beal remarked, “They’re a pain in the ass.”
According to him, they can grow so large on oyster cages and mussel ropes that they endanger the animals that sea farmers are attempting to raise.
Around ten years ago, sea squirt populations in the Gulf of Maine skyrocketed, according to Beal. “They’re just a major annoyance.”
Scientists believe that climate change and an overall rise in the gulf’s water temperature are the primary causes of the critters’ growing presence in the Gulf of Maine, one of several changes in species observed off Maine’s coast.
The shifting gulf population is causing havoc for Maine’s fishing sector in addition to the growing threat of increasingly powerful storms.
While other native Maine species like cod, northern shrimp, and herring are disappearing, invasive species like black sea bass and green crabs are becoming more prevalent.
The largest and most profitable fishery in the state, lobstering, is not immune to the shifting circumstances in the gulf.
Landings have decreased by 30 percent statewide since the industry peaked in 2016 with 132 million pounds of lobster carried ashore.
There are about a dozen different species of tunicates in the Gulf of Maine, where Emily Lancaster conducted her graduate research.
She is a marine science teacher at Eckerd College in Florida. She stated that about half of them are thought to be alien invading species.
Certain species, like one that resembles pancake batter and is occasionally referred to as “sea vomit,” are colonial in nature, the speaker stated. Other non-colonial forms that grow on fixed fishing gear include ascidiella aspersa, a European variety, and Coinatia intestinalis, sometimes known as “sea vases.”
For fisherman, they pose a serious issue, according to Lancaster. “There is no doubt that climate change is a factor.”
Sea squirt populations, according to Turner, vary with the seasons and reach their zenith when the hectic fall lobstering season gets underway.
He stated that they are more likely to be discovered in shallower water, where they can clog traps’ mesh and netting and even attach themselves to the ropes that link the traps to surface buoys.
Turner remarked of towing tunicate-encrusted traps to the surface, “It makes them wicked heavy.” According to him, the sea squirts can quadruple a trap’s weight, making it harder to lift them out of the water and reducing the amount that can be brought aboard securely.
Lobstermen use different techniques to try to remove the squirts. Some people try submerging the traps in salt-saturated water, others blast them with a power washer (which can take a while), and Turner noted that some people set the traps in boiling hot water tanks on their boats.
“It would be great if we could find a predator for those things,” the fisherman remarked.
According to Beal, having to remove tunicates from fishing gear on a regular basis may be quite costly and time-consuming. In order to help prevent tunicate epidemics, scientists have collaborated with mussel farmers to figure out how to extensively seed grow ropes with mussel larvae through trial and error, he said.
“They are out-competing them for food,” Beals said of grow sites where sea squirts have proliferated. “To prevent these things from getting on their gear, most farmers are pulling out their hair.”
Although it has a webpage devoted to information about tunicates, the Department of Marine Resources, which oversees Maine’s commercial fisheries, does not currently have any initiatives focused on tunicate study or management. The EPA claims that while spraying them with white vinegar will kill some species, it won’t harm others.
According to the webpage, “Since tunicates cannot withstand drying out, the best method of getting rid of them from gear is to take the gear out of the water and scrape off the tunicates after they have dried.” “Leaving equipment outside in the rain may also lessen their presence, as they will not withstand prolonged periods of precipitation.”
Lancaster issued a warning, noting that it is not an easy task to stop the spread of sea squirts.
When the traps they are tied to are dragged to the surface, certain types are known to spawn in response to stress, she said. Furthermore, removing tunicates from gear and returning them to the water is not fatal—especially for colonial varieties—and may even increase the distribution of sea squirts on the ocean bottom.
“You could potentially make the problem worse,” she said. “There probably won’t be a solution that works for everyone.”
Sea squirt management will be difficult as long as Gulf of Maine water temperatures rise or even remain at current levels, according to Beal.
Beal remarked, “If only we could get a winter like 1963,” which was particularly chilly and snowy in a large portion of the Northern Hemisphere. However, I don’t think that will occur anytime soon.