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You are here: Home / Manager's Tool Kit / Early Detection and Rapid Response / The Early Detectives / Green Crab Early Detection Program
Manager's Tool Kit
Early Detection and Rapid Response

The Early Detectives: How to Use Volunteers Against Invasive Species, Case Studies of Volunteer Early Detection Programs in the U.S.

Green Crab Early Detection Program - New Release: Volunteers Needed to Help Spot Invasive Crab Species (Jul 20, 2000)/ Species Profile - Green Crab

Contacts: Jean Olson
E-mail: nnw2@fidalgo.net
Phone: (360) 766-6008


Originally a native of Europe, the European Green Crab, or Carcinus maenas, has been widely introduced around the world, and has populations in Australia, South Africa, Japan and much of the Atlantic seaboard of the U.S.. The green crab has since expanded its range to Northern California, Oregon, Washington State and British Columbia, Canada region. It has been postulated that green crabs were introduced to these new environments through ballast water discharge, live seafood shipments and ocean currents due to El Nino and La Nina events, which have been known to move the larvae of organisms on a global scale.

The Green Crab Detection Program was originally developed in 1999 to detect European Green Crabs (EGC's) in the Puget Sound and inland waters of Washington State in the event of an introduction to the Sound, which could have a severe impact on the region's shellfish farming and crabbing industries. Due to a tight budget, the state decided to implement the program using volunteers via the Adopt-a-Beach action group. While Adopt-a-Beach was in control of the monitoring EGC's, the program consisted of approximately 55 volunteers setting crab traps and monitoring for the presence of the green crabs.

The Adopt-a-Beach program disbanded in 2001, and the detection program was contracted to the Puget Sound Restoration Fund, which sub-contracted to Nahkeeta Northwest Wildlife Services, a local wildlife consulting business.


The biggest success thus far has been the increase in recruitment, recently on San Juan Island, Nahkeeta Northwest teamed with another non-profit, Friends of the San Juans which gained 5-6 new volunteers, and contacted with few more people who will begin monitoring. Another community group, The Friends of Camano Island, also were recruited to monitor for EGC's on their island.


Nahkeeta Northwest is currently in its third season of coordinating volunteers for the European Green Crab detection program, and thus far, no crabs have been detected within Puget Sound or the inland waters. At the end of 2001, Nahkeeta Northwest had 24 volunteers trapping in 30 different places, from April to September. In 2002, the program grew to approximately 100 volunteers monitoring in 93 separate locations.

Recruitment and Training

Nahkeeta Northwest's volunteer coordinator, Jean Olson, does the majority of the recruitment for the program through a variety of techniques. Most are introduced to the program through a series of workshops given by Nahkeeta Northwest, and others are drawn to the program by advertisements and word of mouth. Along with the volunteer programs, Nahkeeta Northwest has involved some area tribes in monitoring for EGC's, and have 5-6 that are now monitoring as well.

The training for the detection program lasts a couple of hours and is both easy and user-friendly. Most of the people interested in the program are familiar with shellfish, and have been trapping in the area for some time. At the workshops, volunteers are shown a video on invasive species or another on green crabs. The volunteers are then shown how to identify and sex European Green Crabs and distinguish them from native crabs using a plastic tub containing of native and exotic crab molts. The volunteers are then given an informational packet from the Washington State Department of Fish and Wildlife, and encouraged to sign a trapping pledge, thereby fostering a more serious work ethic towards the trapping protocol. The volunteers are then introduced to the crab traps, and educated on crab habitats and the areas where they should focus their trapping activity.

The volunteers are also asked to fill out state survey forms regarding trapping activity and the kinds of organisms caught. This is part of a state wide effort to get an idea of species concentrations in certain areas, to make it easier to assess damage when an invasive species like the Green Crab arrives, or to gauge the impact of some other ecosystem disruption such as oil spills. Some of the volunteers work in teams, but each must have an individual permit issued by the state. Some of the volunteers have tried to get a GPS location of a site, but due to lack of equipment by many of the volunteers, a paper map with an X showing the trapping spot is primarily used.

Recommendations for Beginning a Program

"When beginning a program, it is important to have everyone in a specific database, making it easy to keep track of your volunteers and their monitoring locations, Adopt-a-Beach was somewhat disorganized in its approach to the volunteer program. Having a map on where volunteers are monitoring, with labels that coincide with each entry in database will make this easy, Nahkeeta uses Microsoft Access, Excel and ArcView GIS."

"Email is another excellent way to keep in touch," people will be more inclined to read an email and respond on their own time than answer a phone call."

If the program is going to be monitoring a large area, try to coordinate with other organizations that have a volunteer base already. It is also important to keep track of volunteers and their monitoring locations, as disorganization will severely disrupt a program. Have volunteers monitor areas that are more crab-friendly habitat, and leave the fringe monitoring areas for biologists and state officials. Encourage the volunteers to monitor in convenient places, for if it is not convenient for them, they will not do it. "Explain to them what habitats are important, and let them make decisions."

Challenges of the Program

The two greatest difficulties are volunteer consistency and funding. For volunteer motivation, try to keep people involved, stay in touch, because keeping them involved is the way to combat volunteer dropout.

Quick Facts

Staffing: One volunteer coordinator, approximately 100 volunteers

Operating Budget: Partly from the Washington Department of Wildlife which funds the program because of the fear of shellfish farming collapse. A portion of the state fish and wildlife budget goes to invasive species, which funds the European Green Crab detection program. The program is not heavily funded, and has experienced heavy cuts within the last year.

Species Targeted: Green Crab/European Green Crab (Carcinus maenas)

Habitats Patrolled: Saltwater regions, shoreline and Sounds, Inland Saltwater areas (Puget Sound and inland waters of Washington State)

Location: USA, Nahkeeta Northwest, Washington

Report prepared by: Matthew Rose

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Last Modified: Jan 09, 2018
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