Feb 18, 2015

Invasive Species


Aside from adverse weather, strict regulations, fluctuating environmental conditions and unpredictable gas prices, there is yet another enemy compromising the health of our local fishery, and the problem isn’t a new one.  When the first ships sailed over to New England from Europe, the people weren’t the only passengers on-board:  from these early colonial days, invasive species were introduced into our local waters.  This problem has only intensified as the world has become increasingly globalized.

By definition, an invasive species is any plant or animal that is not native to a geographical area, usually brought over unintentionally, that has a tendency to take root and spread in such a way that is harmful to native species and the local environment.  Sea creatures are often spread this way by travelling as stowaways on the bottom of boats or unknowingly in cargo hauls.  Some foreign species are also introduced intentionally, for example as part of aquaculture projects.  Regardless of the route they take to get here, these foreign invaders compete for natural resources, prey on local species, and have the potential to contaminate local waters with bacteria and toxins that are not normally found in the area.

There have been countless examples of invasions by foreign in New England’s history.  Invasive species of notability in New England’s history include Asian red seaweed (Grateloupia turuturu)dungeness crabs (Cancer magister), and periwinkle snails (Littorina littorea) from Europe. MIT’s SeaGrant program has a great website dedicated to invasive species of the northeast.  On it they note, “Introduced species are an international problem. There are extensive campaigns around the world to control invasive species and the damage that they cause. Controlling invasive species and preventing their introduction in the first place, can save taxpayers and marine-based businesses hundreds of millions of dollars each year.” You can check out this website and learn more by clicking here. 


Source: MIT SeaGrant
Source: MIT SeaGrant

A recent Boston Globe Magazine article takes an in-depth look at one of the most prominent invasive species to hit New England in recent history.  To say that the European green crab (Carcinus maenas), has taken over our local shorelines is a gross understatement.  In his article, “Green Crabs are Multiplying, Should we Eat the Enemy?” Globe staff writer Roger Warner investigates whether or not this highly invasive species might be of some culinary value.  He collaborates with a local food writer and a local chef to investigate the possibility that there may be something we can do with this overabundance of green crab, which is posing a serious environmental issue in our local waters.  In regards to the environmental impact, Warner explains:

“For their size, green crabs have ferocious appetites. Their favorite foods include tiny seed clams (baby clams of any species) and mussels. In coastal Maine, according to Beal, who teaches ecology at the University of Maine at Machias, there will be few clams shipped commercially this year and next, because the green crabs have wiped out so many of the clam beds. On Massachusetts’s North Shore, the clam harvest fell by more than half between 2012 and 2013, and green crabs get most of the blame. The crabs are the prime suspects in the disappearance of a mussel colony of several acres that I used to visit in Ipswich, as well as the near destruction (by 90 percent in the last year) of another, smaller colony nearby. Mind you, I’m just an amateur shellfisherman who likes to get away from his computer screen every once in a while to indulge his inner hunter-gatherer instincts. But I had my own reasons for buying a crab trap: These critters were eating my lunch.

But coastal protectionists have another worry. When green crabs run out of baby shellfish to devour, they mow down underwater beds of eelgrass, which provide habitat for juvenile saltwater fish. Some veteran clammers and fishermen around here fear green crabs have accelerated a downward-spiraling feedback loop. They imagine a coastal apocalypse: waters with little in them, except for hordes of green crabs running amok like extras in an underwater zombie movie.”

As it turns out, these little invaders might be edible after-all.  The Boston Globe Magazine is well worth a read.  From a sustainability standpoint, it’s important we think outside the box in terms of this issue of invasive species in the name of protecting out local resources and preserving the rich bounty the ocean has to offer. You can read the whole Boston Globe article by clicking here.