Invasive European Green Crab

Invasive Species Alert: European Green Crab (EGC)

European Green Crab (Carcinus maenas) is a highly destructive invasive species that impacts native ecosystems by destroying shellfish and eelgrass beds and feeding on and outcompeting native crab species.

EGC have an aggressive temperament and a pentagon-shaped shell. Many species of crabs are green, but only the European Green Crab has 5 spines.

Keep an eye out for this near-shore crab in shallow waters during shoreline and tide‑pool explorations.

If you think you’ve seen a European Green Crab don’t put it back in the water. Take a photo, record the location, date, and identifying features and contact Carla Skuce on 604-947-4255 ext. 244 or at cskuce@bimbc.ca.

Learn more about EGC here.

Illustrated educational poster showing how to identify an invasive European green crab. A large green-brown crab is centered with labels highlighting key features: three rounded bumps between the eyes, five spines on each side of the shell beside the eyes, orange or yellow colouring at the leg joints, and shell colours that can range from yellow, green, brown, and purple. The poster notes that shell size can reach up to 10 cm and emphasizes that not all European green crabs are green and not all green crabs are European. Below, comparison illustrations show a Dungeness crab with 10 spines beside the eyes and a hairy shore crab with three spines beside the eyes. A QR code and website for reporting sightings are included at the bottom.

Early Detection and Monitoring

Bowen Island Municipality has been running an early detection and monitoring program for European Green Crab since 2023 with support from community volunteers and the Department of Fisheries and Oceans (DFO).

So far, no live EGCs have been detected on Bowen Island. However, an empty shell was positively identified as belonging to an EGC on Sandy Beach in 2025 and a live specimen was discovered on Gambier Island in 2026.

Three people conduct European green crab monitoring on a tidal mudflat at low tide. One person in chest waders records observations on a clipboard, while two others examine specimens collected in a shallow white container. Crab traps and sampling equipment, including buckets and markers, are visible on the mudflat. Waterfront homes and trees line the shoreline in the background on a sunny day.
Two volunteers wearing high-visibility safety vests stand on a tidal mudflat during a European green crab monitoring survey. One volunteer holds a white container containing several crabs and identification tools, while the other records data on a field sheet attached to a clipboard. A seawall, culvert, forested shoreline, and exposed intertidal habitat are visible in the background at low tide.
Dorsal and ventral views of a European green crab specimen collected in Mannion Bay, Bowen Island on August 21, 2025. The crab and detached carapace are displayed on a white background inside a sample bag. A handwritten label reads: “Aug 21, 2025, European Green Crab, Found dead in Mannion Bay, Bowen Island.” The image shows the crab's claws, legs, and underside anatomy for identification and documentation purposes.
A hand holds a small fish above a white container filled with seawater during shoreline sampling. The fish has a dark back with silvery sides and a forked tail. Another fish rests in the water at the bottom of the container. A blue measuring tool and an orange marker line are visible in the container. The image documents marine species observed during intertidal monitoring and sampling activities.
Several aquatic species collected during intertidal monitoring are held in a white container filled with seawater.
Crabs in a bucket of seawater. Someone is holding a Purple Legs Dungeness Crab
Three children and an adult participate in shoreline monitoring on a gravel beach. The group kneels around white containers holding crabs collected during sampling, while crab traps and buckets are visible nearby. Shallow water and the exposed shoreline can be seen in the background. The image shows a hands-on community science activity focused on monitoring marine species in the intertidal environment.
Two shoreline monitoring volunteers stand on an exposed tidal flat beside a marina during low tide. The volunteers wear chest waders and are surrounded by crab traps, sampling buckets, and monitoring equipment. One volunteer holds a crab trap while the other stands beside several mesh traps placed on the ground. Sailboats, docks, forested hillsides, and coastal mountains are visible in the background. The image shows field monitoring activities in a marina intertidal area.
Three community members participate in shoreline monitoring on a rocky beach at low tide. The group kneels around a white sampling container and closely examines a small marine specimen held between two pairs of hands. Shallow water, exposed mudflat, and intertidal habitat are visible in the background. The image shows hands-on participation in marine monitoring and environmental stewardship activities.

For more information or to report a sighting please visit www.dfo-mpo.gc.ca.

Thank you for continuing to look, learn, and report what you see.

Last Updated on 2026-09-16 at 11:42 AM