June 20, 2008 in Keepers Log, More Logbook

Mitten Crab Alert!

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Less than three miles downstream of the lighthouse, along the creek feeding Tivoli Bays, an invasive species of crab was spotted. The presence of the Chinese mitten crab in the Hudson River Estuary is alarming because of the potential for the crab to disrupt the ecosystem and displace native species.

Excerpted from the Hudson River Almanac:

6/3 – Saw Kill, HRM 98.5: At the fish ladder on the Saw Kill I spotted
several small eels in the holding tank. I drained the tank and removed
the four eels. Then I noticed something hiding under the drain plug on
the side of the tank. A little prodding produced a small (21.0 mm
carapace width) female Chinese mitten crab. This eel ladder is on the
first dam of the Saw Kill on the Bard College campus and is located
upstream of a substantial waterfall. It looks like mitten crabs can
overcome such obstacles.
– Bob Schmidt

[The Chinese mitten crab (Eriocheir sinensis) is native to the
estuaries of China where it is highly regarded in the market. Mitten
crabs are catadromous, meaning that they spend much of their life in
freshwater, then return to higher salinities in the lower estuary (15-20
parts-per-thousand salt) to reproduce. The salinity gradients of east
coast estuarine systems like the Chesapeake Bay, Delaware Bay, and the
Hudson River are nearly ideal for them. Adult mitten crabs have a
carapace width of about 3″, but 6 of its 8 legs are almost twice as
long, giving them an almost “spider crab” look. Unlike the native blue
crab, a swimming crab, mitten crabs are burrowing crabs, similar to our
mud crabs only many times larger. Visit the DEC website at
http://www.dec.ny.gov/animals/35888.html for more information.

If you catch a Chinese mitten crab, do not release it back to the
water. Keep it and freeze it (preserve in alcohol if you can’t freeze
it). Note date and location caught (GPS coordinates preferred but
pinpointed on a map is acceptable) and how you caught it. If possible,
take close-up photos, top and bottom views. You may e-mail photo to
SERCMittenCrab@si.edu for identification.

The Mitten Crab Network, a partnership among several state, federal and
research organizations, is collecting data to determine the status,
abundance and distribution of this species. DEC’s Division of Fish,
Wildlife and Marine Resources has agreed to collect and hold specimens
for genetics testing to determine the origin of individuals caught in
the Hudson River. DEC is seeking the public’s assistance in collecting
any specimens that may exist in NY. Persons collecting and holding
chinese mitten crabs for the sole purpose of turning the crab over to
DEC must, within 48 hours of collecting the animal, contact one
following individuals:

Long Island Sound, New York Harbor and Hudson River below George
Washington Bridge: Kim McKown, NYS DEC Division of Fish Wildlife and
Marine Resources Crustacean Unit, 631-444-0454

Hudson River above George Washington Bridge: Mark Dufour, NYS Division
of Fish, Wildlife and Marine Resources Hudson River Fisheries Unit,
845-256-3171 or 845-256-3071; Hudson River Estuary Research Reserve,
845-889-4745 or e-mail r3hrf@gw.dec.state.ny.us ]

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