All Species

Invasive Tunicates

Didemnum vexillum; Botrylloides violaceus
An invasive colonial tunicate (Botrylloides violaceus), also known as a sea squirt, fouls a brick and line hanging in the water from a small boat dock in Ketchikan. Credit: Danielle Verna

Why is it a problem?

  • When conditions are right, rapid growth can occur and this tunicate can quickly outcompete native benthic organisms and shellfish
  • Can have a significant impact on local marine foodwebs
  • Can conceal food on the seafloor from predators due to smothering
  • Has extraordinary growth rates and populations can expand quickly

How do I manage it?

  • Monitor for invasive species as a citizen scientist with Kachemak Bay National Estuary Research Reserve
  • Report unusual sightings found on beach walks, fishing gear, growth/biofouling on boats, crab pots, or equipment
  • Before and after transport, clean, drain and dry (3 day minimum) boots, nets, fishing gear, pots (shrimp or crab), motors, docks, and any marine equipment. Clean above the high tide line AND ensure wash water doesn’t drain back into the ocean when it rains or is hosed down
  • Follow proper ballast water dumping procedures

More info on species biology