Mission: Crayfish

Research Question


Where are native and invasive crayfish in the northeast? How will their ranges shift as our climate changes?

You're invited

Dr. Karen Wilson, University of Southern Maine, invites the Vital Signs community to join her crayfish survey. She put her mission invite and instructions on this VIDEO. Check it out! Karen is interested in documenting what kinds of crayfish are found in the northeast, what habitats they are found in, and how abundant they are. Gathering detailed observations and submitting them to Vital Signs will help piece together a picture of where crayfish are and how they are adapting to climate change.

Mission steps

1. Pick a time in early fall or late spring to conduct your investigation (when the water is warm and the crayfish are movin’).

2. Gather your materials for fieldwork, including the crayfish species ID card and the Freshwater Species & Habitat Survey datasheet and head to a local pond, lake, stream, or river.

3. To look for crayfish, flip over rocks and look under logs (be sure to replace anything that you move). Scoop up any crayfish you find with a small net or with your hands. Be prepared - crayfish swim backwards with a flip of their tail. Search for at least 10 minutes. Record evidence of what you found (or did not find) on the Freshwater Species & Habitat Survey datasheet.

4. In your field notes, record the amount of time you spent searching, the habitat type (rocky, sandy, or mucky), and the abundance of the crayfish (rare, common, abundant).

5. For each crayfish you found, determine whether it is male or female and find the length of the carapace (that’s the main body of the crayfish, measured from the tip of the rostrum--the point that sticks out between the eyes--to the beginning of the tail).

6. If you find a male crayfish, send it to Karen!

  • Freeze the specimen
  • Place it in a sealed container with alcohol
  • Label the container with your VS username, date collected, coordinates, habitat type & abundance level
  • Contact Karen to let her know you'll be sending it

7. Post your data to Vital Signs.

*Joining from outside of Maine? Post your photo and written evidence to our Project Bank (How do I do that?).*

Orconectes virilis, native!

Why this Mission matters

Invasive crayfish, like the rusty crayfish, pose a real threat to Maine’s native crayfish and trout populations, as well as aquatic plants and bottom nesting fish. Relatively little is documented on the whereabouts of native and invasive crayfish in Maine. Dr Karen Wilson has been heading up a statewide crayfish survey in Maine to help determine population distributions. There are a few different crayfish species that live in the northeast and some have more specific habitat preferences than others. As our climate warms and species adapt, what will these mean for the native crayfish and the species they interact with? Be a part of Karen’s effort to help document where these crayfish are living in and around the northeast and how that may be changing over time.

Teacher Resources

Find important information for conducting this investigation with your class on the Mission: Crayfish Teacher Resources page.


Hi, I live on the Pleasant River in Gray and today I took my 6 year old son for a walk in the stream/river to catch critters. We brought a net and a bucket not knowing what we'd find and the crawfish were everywhere...some were quite large and about 8cm long. There are holes in the silt bottom of the stream all over the place. There are so many of them in there that I'm considering having a crawfish boil like I did when I lived in Mississippi, as they are similar in size to the Red Swamp Crayfish. I took a picture of our bucket with about 20 of them that we caught and I took a closeup of one of the larger ones. Is there a way I can send you a picture? They are on my phone so it is easy to email or text them. I can get more pics too if you're interested. Or if I can even find a way to post them to this site...the only reason I joined this site is because I Googled invasive crayfish species in Maine and your page came up. Hope to hear from you soon.



You can definitely post your observation to Vital Signs. The species expert will get a notification when you do. Here's a helpful how-to guide to help you: http://vitalsignsme.org/how-citizen-scientists-collect-data-and-put-it-w...

You will need an evidence photo, site photo, sampling method photo, and your location data. Once you have those things you can go to your "My Vital Signs" page (see the link in the top right?) and publish your data.

Thanks for sharing!

-The VS Team

My son and I would like to study crawfish in Northern Maine waters. How do we collect the voucher samples humanly for you? How do we send them to you?

We are excited to help you in your project.

Thank you.

Last summer I found 2 crayfish at a stream a few hundred feet from my house, but I'm not sure if they were invasive or not. I will look into it, though I haven't seen any more since.

i might do crayfish too

Hi, where have you found the crayfish in Maine?

Click on "Explore Data" and then do a Species Search for crayfish. If you click "Map It," you'll get a map of all the places where crayfish have been looked for in Maine.

Are you planning to add another crayfish observation to the map soon? Hope so!



im doing crayfish also.