Honolulu Star-Advertiser © Susan Scott
Friday, November 7, 2008
I’ve just returned from a trip to the Lake Michigan area where carp has become wildlife enemy number one.
What’s so bad about carp? I wondered. Those fish have been there for ages.
But the common carp we saw in creeks when we were kids, aren’t the ones in the news. The recent trouble-makers are giants known as Asian carp.
People have introduced seven species of carp native to Asia into U.S. waters, but the Asian carp in the news are two relatively recent introductions.
One is the silver carp, a native of China, Russia and North Vietnam. Silver carp grow to 3 feet long and weigh up to 60 pounds, although 40 pounds is more common.
In 1973, an Arkansas aquaculture farmer imported some silver carp to control algae in his ponds. Before long, state, federal and private organizations were raising these exceptional algae eaters to clean up polluted bodies of water, including city sewage lagoons. Some silver carp were transported across the country.
Over time, the fish escaped from their hatcheries and thrived. They now live in the wild in 12 mainland states.
Currently, the fish in the Illinois River are working their way toward Lake Michigan, which would be an environmental catastrophe for the linked Great Lakes.
These fish are bad in two ways. Also called flying carp, silvers leap up to 10 feet from the water when motorboats disturb them, and sometimes crash into the occupants. When a 40-pound airborne fish hits a person or vessel, bones get broken as well as boats. One federal biologist compared it to being hit by a bowling ball.
Also, what was once silver carp’s finest gift to waterways is now a management nightmare. These fish gobble algae like mad, eating the aquatic plants other fish larvae need to survive. The resulting lack of food leaves some native species in dire straits.
The other Asian carp causing trouble is called bighead carp, and its story is similar to the silver: native to China; imported by an aquaculture farmer; raised for algae control; escaped during flooding; now a pest like its silver cousin.
Bighead carp have become a favorite prey of Illinois bowfishermen. Anglers pursue bigheads, which can grow to about 80 pounds, with bows and arrows from boats.
But such hunting doesn’t control their numbers, because both silver and bighead carps are Darwinian poster fish. They’re adaptable, outcompete smaller fish, grow fast, big and reproduce like mad. That’s fine in their native habitat, but causes problems elsewhere.
Two years ago, the U.S. Army Corps of Engineers built a $9 million electric fish fence in Illinois to keep these Goliaths out of Lake Michigan, but the project stalled. The fence is finished, but officials worry that the high electrical charge in the water could ignite flammable material on barges and electrocute workers who fall overboard.
In the meantime, at least one Illinois fish distributor is buying and selling smoked bighead carp. The species is a delicacy in China, but Americans need a little coaxing to eat carp. OK, a little trickery. The distributor markets the carp under several other names.
If I see noble fish, speckled armur, lake fish, tongsan, Chinese fish or just plain carp on a menu, I’m ordering it. If we can’t beat them, we might as well eat them.