D. vex grows in dense colonies. Although each individual is microscopic, together they form a slimy mat resembling a sponge. (KCAW photo/Robert Woolsey)
Gov. Bill Walker has declared June 20-26 to be Invasive Species Awareness Week. Although invasives are a statewide problem, much of the concern over invasives is directed toward Sitka, where an infestation of D.vex is now in its sixth year.
KCAW’s Robert Woolsey caught up with one of the state’s top invasive-fighters, Tammy Davis, as she coordinated a dive team in Sitka’s Whiting Harbor.
I guess it’s going to be one of those interviews.
“So, Robert we’re working with divers and we’re trying to guide them on transects, and if they get off we have noise making apparatus that we use. But it wasn’t as loud as I thought it might be.”
The 105-foot Kestrel is one of two research vessels operated by the state in Southeast waters. It visits Sitka every spring to support the renown sac-roe herring fishery. (KCAW photo/Robert Woolsey)
Tammy Davis is making one of her now-regular visits to Sitka, aboard the state research vessel Kestrel. She’s the coordinator of the Invasive Species Program for the Alaska Department of Fish & Game.
She’s taking it all in stride: communicating with divers on the bottom, and with a reporter over a sketchy cell phone connection.
Davis – I’m sorry, you cut out a little bit there.
KCAW – How much of your energy are you spending on the d.vex issue in Sitka?
Davis – Oh, it’s one of my main focus areas. You know, I’m also interested in recreational watercraft movement into the state. There are freshwater invasives like zebra and quagga mussels.
Zebra and quagga mussels are Asian species that have found their way into a number of freshwater systems in the lower 48. Davis and the US Department of Fish & Wildlife work to stop them at the Canadian border, by quarantining and cleaning suspect boats.
D.vex is a different kind of challenge. It’s a microscopic organism called a tunicate, that colonizes the ocean floor with millions of its brethren in a dense, smothering mat.
Last summer, a team from the Smithsonian Institution developed and tested several methods of killing D.vex, using chlorine, salt, or cement powder. Their report to the state won’t be ready until this fall.
If it’s practical, Tammy Davis and the state might try to eradicate D.vex in Sitka. If not, they’ll do what’s been done for similar invasions in California, Washington, and British Columbia.
“If it’s deemed financially not feasible to eradicate the tunicate, then we’re really in a position to ask the public not to spread it around.”
Davis says that several other invasive tunicates have been identified in Sitka, but they don’t present the same extreme hazard as D.vex. She recommends that anyone who’s had a boat in the water for a long time clean it off, “especially before going to a remote area.”
