Invasive Green Crabs: Implications & How to Utilize Them

Invasive Green Crabs: Implications & How to Utilize Them

This blog post was written by Mary Parks, Founder & Director of


Green crabs were first spotted in Casco Bay in the early 1900s after moving northward from Massachusetts waters where they were introduced a century before. In recent years, green crabs have become Maine’s most common crab species, wreaking havoc on some of the state’s most valuable fisheries and vulnerable ecosystems. Cold winters that historically kept green crab populations in check are no longer common and as climate change continues to warm the Gulf of Maine, green crab populations could increase. This invasive species has singlehandedly destroyed the soft-shell clam fishery (a single green crab can eat up to 40 clams in a day), compete with local crabs and lobster for food, and destroy important eelgrass habitats. Many have launched diversified efforts to monitor green crabs, control their populations, prevent predation of clams, and spread awareness of their invasive impact. 

Wolfe’s Neck Center has been utilizing green crabs as compost for years, collecting them from coastal waters to utilize as a nutrient source and educating visitors on the impact of green crabs. Last year alone, Wolfe’s Neck Center’s farm team composted 12,000 pounds (about twice the weight of an elephant) of green crabs.

In this post, we will go over a basic recipe for cooking with green crabs and tips for using the remaining shells as compost in your garden, so you can be part of the solution at home! 


Green Crab Stock – the perfect base for seafood soups and bisques! 


  • 3 pounds whole green crabs 
  • 1 onion unpeeled, halved crosswise 
  • 1 head garlic, unpeeled, halved crosswise 
  • 3 celery ribs 
  • 1 fennel bulb, halved lengthwise, fronds left attached 
  • 3-inch knob ginger, roughly chopped 
  • 1 tsp whole black peppercorn 


  1. Rinse the crabs in a colander and add to a stockpot. They do not need to be defrosted first. 
  2. Add the onion, garlic, celery, fennel, ginger, and peppercorns. Cover the contents of the pot with water by one or two inches.  
  3. Bring the pot to a simmer. After about an hour, periodically crush the green crabs to release their flavor into the stock.  
  4. Skim off the foam that rises to the surface (this is a foamy stock).
  5. Cook until your desired flavor is reached, then strain the stock through a fine-meshed sieve. 
  6. Stock can be stored in the freezer for up to 3 months. 

Make sure to keep your shells for the next step! 


How to Compost with Green Crab 

Green crabs can be a great source of nitrogen for your compost pile! However, before transporting, be sure that green crabs are not alive. These pesky crabs can survive on land for weeks without water and can become a biosecurity issue.  

To ensure they are not alive before transporting, you can place them in a closed container with fresh water or pulverize them. Pulverizing the crabs also ensures that they will break down quicker in your compost pile and that pests will not be tempted to take this important source of nutrients from your compost! Once you break down the green crab, mix it in with your existing compost pile.  

If you are interested in learning more about at-home composting, we recommend checking out this tutorial for creating your own stable green crab fertilizer. 

This June in partnership with, Wolfe’s Neck Center is hosting their first-ever green crab derby with the goal of collecting as many green crabs as possible from surrounding waters and educating community members on how to utilize the crabs in the kitchen and the garden. If collecting green crabs on your own, we encourage you to familiarize yourself with the crabs so as not to displace native species. 

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