Written by Melissa Wood
Thursday, 25 July 2013
I remember seeing green crabs on the beach when I was a kid. They were tiny and tended to scamper under rocks when I reached into tidepools to scoop up a starfish or a snail, which I always wanted to catch out before they shrank into their shells.
Green crabs were faster, and I couldn't always catch them. Sometimes I'd shift the rock to see where a crab had gone and it would disappear into the the whirls of sand. Someone told me they were an invasive species, which sounded exotic (I grew up in Maine), but I didn't think much of it. Apparently, no one else thought much of green crabs either.*
Now they've become a threat to mussels and clams, Maine's third largest fishery, and there are concerns that lobster will be next. Green crabs came from Europe reportedly riding over in the ballast water on ships. Though they've been here for more than 100 years, a couple of warm winters combined with warming water temperatures have caused populations to explode in Maine. Green crabs may be small, but as I saw, they can burrow down into the sand and eat tiny clam spat.
The state is taking action to limit green crabs, which you can read about here. Although there's no commercial fishery for the crabs, among the efforts is a private-sector initiative to grind them up into a protein that can be used for aquaculture feed. But the priority is to get rid of them. (Such initiatives are also of interest to those on the West Coast where they're a growing threat to shellfish populations there as well.)
How much it will take remains to be seen, but our track record for fighting invasive fish species is not good. Yesterday, a federal plan with a $50 million price tag was released in the latest fight against Asian carp's reaching the Great Lakes. The plan includes strengthening barriers as well as some alternative methods that include the use of water guns and hormonal fish love potions.
It's a lot of money, but that's just a fraction of what is being spent in the Asian carp battle. Including the $50 million, in four years the Obama administration will have spent $200 million. Plus there's no plan to get rid of these harmful invaders, which continue to spread in the Mississippi. They're just trying to keep them out of the Great Lakes, and no one's sure if it will be successful.
Will Maine's action be enough and in time to stem the green crab tide? I hope so. But it seems like too much of management is waiting until a problem becomes so great that it is often too late to solve.
*A historical note: Green crabs have gotten some attention through the years during other spikes in their populations. I found a 1959 article from National Fisherman's archives that reported a jump in green crab populations that were threatening Maine's soft-shell clams. Warming water temperatures were blamed for the increase then too.
NMFS recently released a draft action plan for fish discard and release mortality science, creating a list of actions that they hope can better inform fisheries.
We know that fishermen have to deal with bycatch by discarding or releasing unwanted catch overboard, but there is a data gap regarding how those fish survive.Read more...
A new study has identified a set of features common to all ocean ecosystems that provide a visual diagnosis of the health of the underwater environment coastal communities rely on.
Together, the features detail cumulative effects of threats -- such as overfishing, pollution, and invasive species, allowing responders to act faster to increase ocean resiliency and sustainability.Read more...