Category: Management Plans
Published: July 8, 2008
Author(s): Allen Pleus, Larry LeClair, and Jesse Schultz
The period of July 1, 2007 to June 30, 2008 has provided valuable information on the current distribution of invasive tunicate species and the significant challenges facing the state in addressing this threat. Recent management actions and data assessments by WDFW show that the extent of invasive tunicate population distribution is significant with 57 out of 102 sites1 having from one to four of the seven known species present. (Table 1). Of the 57 sites, 28 have at least one of the three priority invasive tunicate species.
WDFW has completed presence/absence surveys of 53 sites of which 35 were new locations and 18 were resurveys. A working draft of the statewide Tunicate Management Plan has been completed. Containment actions to remove tunicates from recreational watercraft hulls have been completed at six marinas: Blaine, Semiahmoo, Elliott Bay, Des Moines, Pleasant Harbor, and Homeport. A successful eradication action to remove a broad infestation of Didemnum vexillum was completed at the King County Dockton Park docks on Maury Island. Prior to the eradication action, multiple management tools and methods were tested at the Dockton site of which the use of acetic acid showed the greatest promise. Baseline monitoring is being implemented with full scientific assessments of tunicate densities and community structure at three sites to date. WDFW continues to work closely with PSP in their development of a "Clean Your Hull Clean" campaign. Quarterly Tunicate Response Advisory Committee (TRAC) meetings have been conducted and an annual review was provided earlier this month.
The conclusion of the TRAC annual review was that a greater effort needs to be implemented as the scale of the problem is greater than anticipated and cannot be effectively addressed at current contracting levels. Specific recommendations include the need for more dedicated WDFW staff and contract funding to rapidly:
1. Conduct a thorough baseline distribution and density survey of more Puget Sound and coastal sites;
1 Additional site data available, but not yet entered
2. Continue testing eradication techniques and acquiring necessary National Pollution Discharge Elimination System (NPDES) permits for use of aquatic biocides;
3. Implement a genetics research study;
4. Assess introduction and spread pathways and their management options; and
5. Fully assess the threat of invasive tunicates in Washington waters