2007-2009 Biennial Report: Invasive Species Tunicate Response in the Puget Sound Region

Category: Management Plans

Published: June 2009

Pages: 57

Author(s): Larry LeClair, Allen Pleus, and Jesse Schultz


There are seven non-native tunicates currently reported as established to some degree in Washington State waters

(Table 1). Three of these are of primary invasive concern to the Washington Department of Fish and Wildlife (WDFW) resource managers and local stakeholders and are the focus of the WDFW Tunicate Management Plan and this report. The remaining four are of secondary invasive concern as they have not demonstrated a high invasive threat.

Table 1. Known nonnative invasive tunicates in Washington State marine waters and their management priority.

Scientific Name

Common Name

Priority Level

Styela clava Solitary Club Tunicate High
Ciona savignyi Transparent Solitary Tunicate High
Didemnum vexillum Colonial Tunicate High
Botryllus schlosseri Colonial Star Tunicate Low
Botrylloides violaceus Colonial Sheath Tunicate Low
Ciona intestinalis  Solitary Tunicate Low
Molgula manhattensis Solitary Sea Grape Tunicate Low

The Puget Sound Partnership (PSP) has contracted with the WDFW Aquatic Invasive Species Unit (AISU) to provide a continued response to the threat of non-native tunicates in Puget Sound for the 2007-2009 biennium (Interagency Contract #200804). The work is to be conducted through consultation with the state Tunicate Response Caucus and the Tunicate Response Advisory Committee (TRAC). The agreement implements or addresses:

a) Unfinished elements of the 2006-2007 Interagency Invasive Species Rapid Response Plan.

b) The Aquatic Nuisance Species (ANS) Management Plan by minimizing the introduction of aquatic nuisance species; stopping them from spreading; and eradicating or controlling them to minimize impacts.

c) The Puget Sound Recovery Plan by protecting and preventing loss of habitat; restoring habitat functions and values; protecting ecosystem biodiversity; and building and sustaining capacity for action.

d) The WDFW Tunicate Management Plan.

Further, there are seven specific expected outcomes and results listed in the contract as follows:

1) Develop a statewide tunicate management plan that includes a priority system for managing invasive tunicates to include eradication objectives maximize the use of limited resources, and that identifies long-term strategies.

2) Implement a research and monitoring program for non-native tunicates.

3) Assist in the development of best management practice manuals for managing invasive marine organisms at sites such as marinas, boat yards, aquaculture operations, and hull cleaning services; and define clear strategies to implement these practices.

4) Survey a minimum of 50 high risk areas such as marinas, boat cleaning areas, and shellfish growing areas for the presence or absence of invasive tunicates.

5) Map locations of infestations, and make this information available to the legislature, resource agencies, and the public.

6) Post all management plans, best management practices manuals, management methods, and reports on the WDFW web page for public access.

7) Prepare cost estimates by June 30, 2009 of additional work needed to successfully eradicate invasive tunicates within Puget Sound. This report details AISU efforts toward meeting the goals and objectives of the contract and makes recommendations for further work into the 2009-2011 biennium.

Suggested citation

LeClair, L., A. Pleus, and J. Schultz. 2009. 2007-2009 Biennial report: Invasive species tunicate response. Prepared for the Puget Sound Partnership. Washington Department of Fish and Wildlife; Fish Program; Aquatic Invasive Species Unit.