Green Crab Monitoring and Management


huge crab from bmsInvasive European green crabs (Carcinus maenas) are threatening the economies and ecosystems of the Kennebec Estuary.  Green crabs have been linked to decreases in clam populations, erosion of salt marshes and loss of eelgrass.  Populations of green crabs have exploded within the last year and have been seen in very high numbers across the Kennebec Estuary’s intertidal zone.

KELT is partnering with groups throughout the region to monitor and manage green crabs in order to increase understanding about:

  • green crab populations in the region
  • methods that can be used to decrease crab populations
  • methods that can be used to protect other species from predation by green crabs

Green Crab Projects Across the Estuary

Bath Middle School Green Crab Population Study – 2013

Bath Middle School Green Crab Study – 2014

Woolwich Central School Green Crab and Clam Study – 2014-2015

Green Crab Identification

BMS Green Crab crop

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.




female 2 cut
Female: Rounded, ‘beehive’ shape on underside
male cut
Male: Pointed, ‘obelisk’ shape on underside


Green Crab Trap Types Used in the Kennebec Estuary

Eel Trap – Minnow Trap – Modified Lobster Trap – Shrimp Trap – Acer Crab Trap

Kennebec Estuary Green Crabs in the News

Bath Middle School Green Crab Population Study




Green Crab Resources

Thank You To Our Green Crab Project Sponsors!

mohflogo              The Margaret E. Burnham Charitable Trust