Green Crab Monitoring

Why Monitor Green Crabs?

Green crabs are an invasive species that threaten clam populations, eelgrass beds, and local marshes.  To find out more about these crabs, KELT purchased green crab traps with the help of a grant from the Maine Outdoor Heritage Fund in 2014. Since then, these traps have helped to gather information about crab populations in our region.  KELT used them to work with students at Bath Middle School to trap green crabs and document information about their populations each fall.

Get Involved!

Bath Middle School 7th grade students and teachers spend their fall exploring information about local fisheries.  This exploration includes learning about invasive green crabs and trapping them to find out information about their population and how it changes over time. 

If you are interested in supporting an in-classroom exploration or fieldtrip, reach out to Ruth Indrick (rindrick@kennebecestuary.org or 207-442-8400).

What Have We Learned?

BMS Green Crab Population Study

Sponsors

Maine Outdoor Heritage Fund

The Margaret E. Burnham Charitable Trust

Resources for Volunteers

  • Maine DMR – Green Crab Webpage

  • Maine DMR – Green Crab 1 Day Trapping Survey Report

  • Maine Green Crab Summit – information and presentations from the December, 2013 Green Crab Summit

  • Green Crab Trap Types Used in the Kennebec Estuary

    • Eel Trap

    • Minnow Trap

    • Modified Lobster Trap

    • Shrimp Trap

    • Acer Crab Trap

  • What's a Green Crab?

    • Green Crabs have 5 spines on each side of their eyes

    • Their carapace (shell) is roughly pentagon shaped

    • The crabs can be green, brown or red

    • Green crabs rarely grow larger than 3 1/4 inches

    • The size measured is the width of the crab at the widest part of its carapace – from the tip of one spine to the other

    • Females have a rounded “Beehive” shape on underside, while males have a pointed “obelisk” shape