Page 28 - aruba-today-20170130

A28 SCIENCE
Monday 30 January 2017

Study says grass carp have invaded 3 of the Great Lakes

JOHN FLESHER ing five in Lake Ontario at
AP Environmental Writer Toronto, said Becky Cud-
TRAVERSE CITY, Mich. (AP) more, Asian carp program
— Invasive grass carp manager for Canada’s
have reached three of the fisheries and oceans agen-
Great Lakes and pose a cy and the report’s primary
significant environmental author.
risk there, but time remains “Right now, the sterile fish
to prevent them from get- outnumber the fertile fish,”
ting out of hand, accord- Cudmore said. “This isn’t
ing to a scientific analysis game over, but we are
released Friday. finding more of these fertile
The voracious grass carp fish.”
is among four Asian carp The analysis said it is “very
species threatening to likely” that grass carp will
reach the world’s largest become established in
surface freshwater system. Lakes Erie, Huron, Michigan
Bighead and silver carp, and Ontario within 10 years
the most feared, would unless effective steps are
compete with native fish taken to stop them. The risk
that eat microscopic is lower in frigid Lake Supe-
plants and animals, while rior, which offers less food.
grass carp feast on aquat- In an Aug. 2, 2012 photo, Asian carp species, from top, silver, bighead, and grass lay alongside An established popula-
ic vegetation that provides each other prior to being prepared at Carters Fish Market in Springfield, Ill. tion is one that reproduces
crucial habitat and spawn- Associated Press over multiple generations.
ing grounds. Researchers are study-
Grass carp have been have a binational, peer- Commission. “They’ve just been hum- ing how to prevent that,
found in Lakes Erie, Michi- reviewed study by some Grass carp were intro- ming in the background,” Gaden said.
gan and Ontario, although of the best minds and duced to the U.S. in the Gaden said. Tougher enforcement of
it’s uncertain how many practitioners in the field early 1960s to control weed “They haven’t gotten a laws against bringing them
there are or how widely who have a consensus on growth in waterways. Like lot of attention. Once in a into the region would help,
they have spread, U.S. what the risk is to the Great other Asian carp, some es- while one would get cap- along with greater care to
and Canadian researchers Lakes from grass carp, and caped into the Mississippi tured.” prevent release of fertile
said. At least some are re- it’s pretty substantial,” said River and have migrated But they have turned up fish from hatcheries.
producing. Marc Gaden, spokesman northward toward the more often in recent years Another possibility would
“For the first time, we for the Great Lakes Fishery Great Lakes. and the threat of a full- be using nets to block their
It has long been known fledged invasion appears path to spawning areas
that at least a small num- to be rising, he said. A during times when they re-
ber of grass carp were particularly ominous sign is produce, Cudmore said.
in the lakes, Gaden said. that some of those caught Asian carp are known to
Some may have slipped have been fertile. Grass spawn later than native
into Lake Michigan through carp reared in hatcheries, fish.
a Chicago-area waterway which some states allow, “Our assessment is saying
network before electric are supposed to be steril- that yes, they were show-
barriers were erected to ized before being released ing up before, but now
block fish migration. Peo- into the wild. they’re starting the inva-
ple might have released Twenty-three grass carp sion process,” she said.
others, intentionally or by have been caught in Can- “They have arrived. Now is
accident. ada since 2012, includ- the time to act.”q