• Gabe Wilson and Mikey Walsh

Invasive Green Crabs Vs. Soft-Shelled Clams In The Gulf of Maine


Introduction

“They just boil out of the water”- Maine Clammer Clint Goodenow [1] speaks for many clammers across the Gulf of Maine. The growing population of the Carcinus maenas or green crab along the coast of the Gulf of Maine has created many new issues for native marine species as well as people. C. maenasis an invasive species which found its way into the Gulf of Maine. At first, the crabs were not a problem in the Gulf of Maine. With the long cold winters, green crab populations were in check. However, three major factors have contributed to their population explosion: rising water temperatures, lack of natural predators, and their incredible fecundity.

Green crabs settled into Maine’s waters and found the perfect food source; the softshell clam. The clam industry is important to many people in Maine. It employs over 1,000 harvesters and brings in millions of dollars every year for Maine’s economy. The softshell clam harvest in Maine has recently seen the lowest numbers in decades. One green crab can consume 40 half-inch juvenile clams in just one day. With thousands of crabs on the hunt, the damage happens very fast. “It’s not that there’s not clams, it’s that they don’t survive.” said clammer Chad Coffin

Freeport, Maine [2]. If the clam population continues to decline at this rate, Gulf of Maine clam

harvesters will be negatively affected. The green crab could be the end of a northeast business and a family tradition for many.

Background

There are many factors contributing to a thriving population of green crab in the Gulf of Maine waters. The green crab found their way into the Gulf during the mid-1800s on sailing ships from western Europe, and by the 1870s the green crabs had spread all the way from the Chesapeake Bay to Cape Cod.

The first factor is rising ocean temperatures and milder winters have allowed crabs to survive through traditionally cold winters. Maine’s previous long and cold winters helped prevent the omnivore from rapidly reproducing and gaining in population. The quick rise of ocean temperatures and a string of mild winters over the past several years has caught many off-guard, making it difficult to find solutions for a continually growing green crab population which negatively impact commercially important species such as soft-shell clams.“In 2016, clam landings fell 21 percent, from 9.3 million to 7.3 million pounds, the lowest total reported since 1991, according to the state Department of Marine Resources” [3] with clam landings dropping in millions of pounds each year, the number of clam harvesters is following a similar path. “The clams are still readily available to consumers, but the number of harvesters digging for them has slipped to about 1,600 in Maine. It was more than 2,000 as recently as 2015.” [4] says Patrick Whittle from the Portland Press Herald in summer 2016. The downside is that hundreds of clammers are losing their jobs. On the other hand, this allows remaining clammers to still make a living with the remaining clams. Green Crabs pose a huge threat to the softshell clam business and culture of Maine clammers.