The ongoing story of the European green crab invasion offers us
scientific, social and even psychological drama, which I would like
to update by mentioning four new developments:
The somewhat mysterious finding of a partially eaten green crab
on the Bellingham waterfront,
A “story map” that spells out much of what we know about
European green crabs in Puget Sound, including maps, photos and
videos.
Information about Harper Estuary in South Kitsap and other
areas where groups of citizen scientists are on the lookout for
green crabs, and
Reports of a new breed of European green crab in Maine that
attacks people and may prove to be more destructive than the green
crabs that have lived in the area for a very long time.
The war against the invasive European green crab continues in
Puget Sound, as this year’s Legislature offers financial support,
while the Puget Sound Crab Team responds to crabs being caught for
the first time in Samish Bay in North Puget Sound and at Kala Point
near Port Townsend.
In other parts of the country where green crabs have become
established, the invaders have destroyed native shoreline habitat,
diminished native species and cost shellfish growers millions of
dollars in damages. See
Environmental Protection Agency report (PDF 1.3 mb).
European green crab trapping
sites in Puget Sound.
Map: Washington Sea Grant
In Puget Sound, it’s hard to know whether the crabs are being
trapped and removed rapidly enough to defeat the invasion, but so
far humans seem to be holding their own, according to Emily Grason,
who manages the Crab Team volunteer trapping effort for Washington
Sea Grant.
“The numbers are still in line with what we saw the past two
years,” Emily told me. “Since the numbers have not exploded, to me
that is quite a victory. In other parts of the world, they have
been known to increase exponentially.”
The largely volunteer Crab Team program is focused on placing
baited traps at 56 sites in Puget Sound, as shown in the first map
on this page. About 220 trained volunteers are involved in that
work, with various federal, state and tribal agencies adding about
40 additional people.
Dungeness Spit on the Strait of Juan de Fuca near Sequim remains
a hot spot for the invasive European green crab, which first showed
up in Puget Sound during the fall of 2016.
This small male crab is one of
the European green crabs caught last year in traps at Dungeness
Spit.
Photo: Allen Pleus
The green crab, one of the most dreaded invasive species in the
world, brings with it the potential to destroy shellfish beds and
disrupt key habitats essential to native species in Puget
Sound.
Thankfully, except for the Dungeness Spit, new findings of green
crabs have been almost zero since a massive volunteer trapping
effort resumed in April throughout most of Puget Sound.
I do have some additional news about green crabs to share, so
please read on for a discussion of these topics:
Contractors are putting the final touches on two new bridges in
Kitsap County, both of which are expected to improve the local
environment.
A new bridge over the Carpenter
Creek Estuary near Kingston helps to restore the upper salt
marsh.
Photo; Stillwaters Environmental Center
One is a 150-foot bridge that crosses the Carpenter Creek
Estuary on West Kingston Road near Kingston. The other is a 50-foot
bridge that crosses Big Anderson Creek on Seabeck-Holly Road near
Holly.
Among local residents, the Carpenter Creek bridge may best be
known as the bridge that blocked traffic and forced a detour near
Kingston for more than a year — much longer than originally
planned. (Recall reporter Nathan Pilling’s story in the
Kitsap Sun.) While contract issues remain in dispute, the
environmental benefits are clear, according to Joleen Palmer of the
nearby Stillwaters Environmental Center.
An invasion of the European green crab, which started last
summer in northern Puget Sound, appears to be continuing this
spring with 16 green crabs caught in traps at one location on
Dungeness Spit near Sequim.
European green crab
Photo: Gregory C. Jensen, UW
The new findings are not entirely unexpected, given that
invasive green crabs have established a viable population in Sooke
Inlet at the southern end of Vancouver Island in Canada. From
there, young crab larvae can move with the currents until they
settle and grow into adult crabs. Last summer and fall, green crabs
were found on San Juan Island and in Padilla Bay.
The big concern now is that a growing population of invasive
crabs could spread quickly to other parts of Puget Sound, causing
damage to commercial shellfish beds and disrupting the Puget Sound
ecosystem.
“It knocks the wind out of your sails for sure,” said Emily
Grason when I asked how she felt about the latest discovery. “You
feel kind of powerless, and you want to get out there and start
doing things.”
A European green crab invasion may be taking place in Puget
Sound, and Washington Sea Grant intends to enhance its Crab Team
this summer with more volunteers looking in more places than ever
before.
The second European green crab
identified in Puget Sound was found in Padilla Bay, where three
others were later trapped.
Photo: Padilla Bay Reserve
Training is about to get underway, and anyone with an interest
in furthering science while being exposed to the wonders of nature
may participate. It’s not always good weather, but I’ve been
inspired by the camaraderie I’ve witnessed among dedicated
volunteers.
The work involves going out to one or more selected sites each
month from April into September with a team of two to four other
volunteers. It is helpful to have folks who can carry the crab
traps, plastic bins and other equipment. For details, check out the
Washington Sea Grant website.
