Aquatic Aliens Attack
By Traci Watson, USA TODAY
This is not the summer of the shark.
That was last year. This is the summer of the northern
snakehead, the Asian swamp eel, the lionfish and the Asian
carp - foreign invaders that can poison divers,
kill off native wildlife and shrink the catches of fishermen.
The northern snakehead seems to have
stirred the most alarm. Since a fisherman hooked one in
a pond in Maryland last month, state biologists have been
trying to figure out how to deal with the invader, which
has a bottomless appetite and the ability to wriggle across
dry land to other bodies of water.
A man has admitted dumping two snakeheads
in the pond in the town of Crofton. He had tired of feeding
them, so he gave them their freedom.
Last week, experts decided that chlorine
and nets would not be enough to get rid of the snakehead,
and they recommended that the state poison the whole pond.
Today, Interior Secretary Gale Norton
plans to propose a ban on the import and shipment of the
northern snakehead and 27 other snakehead species, except
by special permit. No federal rule bars their import now,
though 13 states prohibit possessing them.
Despite efforts to tighten borders
against waterborne creatures from abroad, such animals
continue to sneak into the USA.
Among other monster fishes that have
recently turned up or spread in U.S. waters:
- The lionfish, native to the western Pacific
Ocean. First reported earlier this year, this striped
fish has been spotted off the East Coast from Florida
to Long Island. It wields its long, poison-tipped spines
to impale and paralyze small fish and crustaceans, but
its venom is strong enough to be a danger to humans.
Fisheries experts worry that the
lionfish will gobble the prey of native groupers and snappers.
- The Asian swamp eel, native to tropical Asia.
The eel has a collection of tricks to rival the snakehead's.
It can breathe air if necessary, can shrug off poison
and explosives and can slither across dry land. Its
secret weapon: a coating of slime that allows it to
Its voracious appetite would be catastrophic
for native fish if it reaches Florida's Everglades National
Park. A federal survey this month found it swimming along
the park's eastern boundary.
- The Asian carp, native to East Asia. It escaped
from fish farms in the South and swam up the Mississippi
River. Now it has been found only 25 miles from Lake
Michigan. Two weeks ago, experts begged Congress for
money to shore up barriers between the carp and the
The fish can grow to 110 pounds and
4 feet in length. When startled, it can leap 8 to 10 feet
into the air and can knock over or injure boaters by hitting
them. It's so effective at sucking up plankton and vegetation
that it could virtually eliminate other fish species from
the Great Lakes by destroying their food supply.
Federal scientists calculate that
from 1850 to 1900, several dozen foreign fish species
flopped into the USA. From 1951 to 1996, it was several
"On a monthly basis, we get reports
of new invasive species we haven't known about before,"
says Dianna Padilla of the State University of New York-Stony
Brook. "Not all species will cause huge damage, but we
can't really predict ahead of time which ones will."
Many of these invaders hitchhike
into the USA in ballast water that ships take on in foreign
ports for stabilization. Others escaped from American
Some, such as the snakehead in Maryland,
were released or spread by routine, seemingly harmless
activities. A population of swamp eels in Georgia probably
began when somebody dumped the contents of a home aquarium
into a stream. The lionfish is also a suspected escapee
from a fish tank.
State and federal officials are trying
to erect defenses against these invaders. Earlier this
year, for example, North Dakota banned bait imports, to
cut the chance that an angler tossing leftover bait into
a lake would introduce a monster fish.
"It's startling. The public can so
easily introduce an invasion," says James Carlton, director
of the maritime studies program at Mystic Seaport in Connecticut.
"A few of these things successfully reproduce and spread,
and there's our nightmare."