Molt Search

This program is designed to get more eyes on more shorelines to help managers detect new populations of green crab. For this reason, your surveys are most valuable on shorelines of Washington’s Salish Sea. Surveys from shorelines along Washington’s pacific coast may also help us compare known populations of green crab with molt patterns on shore. Molt Searches can be done on any shoreline where you have safe, legal access. Be aware of local collection and access regulations. Take a look at the map of where previous Molt Searches have been submitted. The more coverage, the better!

Note: Molt Searches are welcome on Washington State Park shorelines, too! Scientific Research Permit #230603 covers these activities.

Surveys are welcomed from any time of day or year. Because molts are a result of crabs outgrowing their shell, you’ll likely find more during warmer months (May-October) when crabs are growing more quickly. You are welcome to conduct Molt Searches as frequently or seldom as you’d like. A monthly survey from a shoreline near you would be a great contribution to the dataset!

Yes! Molt Searches can be done in teams of up to 4 people, and only one of those must be trained. To help us maintain our data integrity, anyone who hasn’t yet attended a volunteer monitoring workshop should rely on a trained volunteer to direct the search and submit the group’s report via their MyCoast account. Have fun working together to gather and identify all the molts you can find! 

If your friends want to do more molt searches on their own, help them find an upcoming training to learn how to submit their own data.

Because we’re interested in the presence or absence of Dungeness and green crabs, don’t fret too much about this distinction.

If you’re unsure, feel free to submit additional photos of the individual in question with your report and add any notes or observations in the Field Notes/Comments section on the last page of the MyCoast reporting form. Sometimes it can be tricky to tell if the shell in your hand is a molt or dead crab. To get to the bottom of it, we’ve outlined four questions you can ask yourself:

1. Is there any obvious trauma? Some predators will leave specific clues behind after munching on crab shells. Looking for these clues may help you distinguish between a molt or a dead crab that met an unfortunate demise.
2. How heavy is it? Molts are typically much lighter than dead crabs with tissue still in-tact.
3. Does it open? Because molting crabs essentially climb out the back of their shells, the shell of a molt should easily open on a hinge (much like a jewelry box). If it’s hard to open, it’s likely a dead crab.
4. What’s inside? Molted shells should be quite clean inside, while dead crabs may contain goo or crust of internal tissue. Remember that feathery gill tissue appears in molts too.

A molt (left) will have a clean shell interior, and open like a jewelry box hinging at the eyes. A dead crab (right) may be filled with “goo” of various colors in the middle section of the shell and attached to the inside of the carapace. Note that both crabs appear to have gills, while the molt actually only has the molted coverings of the gills. Photos Jeff Adams and Emily Grason

Curiosity piqued? Read even more in this WSG Crab Team blog post.

The Molt Search ID guide (above) has many of the species that we think you are likely to see in your molt surveys, but it doesn’t include everything and every beach is different. It also can take some practice to feel confident in your species identifications! 

If you find anything you can’t identify, make sure the molt is in your collection photo and leave us a note in the Field Notes/Comments section on the last page of the MyCoast reporting form. You can also include an additional, close-up photo of your mystery molt.

You can edit or delete reports from your computer via the MyCoast website. From there, log in to your MyCoast account and then use the top menu bar to navigate to “My Account” > “My Reports” to view, edit, and delete your submitted reports. If you have trouble, feel free to send us an email (crabteam@uw.edu) with any notes or amendments.

Each and every report you submit gets monitored by Washington Sea Grant staff for reports for European green crab findings. Visit https://mycoast.org/wa/crab to view all the new reports coming in.

Whether or not a report includes green crab, the locations of Molt Searches will be included in annual planning conversations where Washington Sea Grant works with WDFW and local partners to best distribute limited monitoring resources across the region. It’s important to know where searches have yielded no evidence of green crab presence, so that search effort can instead be focused on locations that have yet to be explored.

All confirmed detections of European green crabs in a new water body will be directly communicated to WDFW and relevant local partners. From there, managers may initiate a follow-up trapping effort to determine the extent of the location population. Based on the outcome of that assessment, managers and scientists discuss what ongoing efforts may be appropriate for the site—ranging from continued monitoring, repeated assessments, or intensive control trapping. Learn more about how European green crabs are managed in Washington at WDFW’s European Green Crab Hub.

We are currently developing our plans to further expand our workshop offerings. There are currently two ways your group can hold a local Molt Search training. 

1. Send a representative to our annual train-the-trainers workshop, where they’ll learn how to organize a public-facing Molt Search workshop and teach these protocols in your local community. Workshops given by facilitators who attend a “train-the-trainers” are supported by Molt Search advertising and materials.
2. On a limited basis and with some date coordination, Molt Search staff can send a trainer to your group’s meeting.

Start a planning conversation by sending us an email: crabteam@uw.edu