US weighs costs of fighting invasive species
WASHINGTON - Invasive species - long the cause of environmental hand-wringing - have been raising more unwelcome questions recently, as the expense of eliminating them is weighed against the mounting liability of leaving them be.
Which is worse? Closing two locks on a critical waterway that is used to ship millions of dollars’ worth of goods from the Great Lakes to the Mississippi basin? Or allowing a voracious Asian carp to chow down on the native fish sustaining a Midwestern fishing industry that nets $7 billion a year?
And how do you put a price tag on the damage caused by the Burmese python and other constrictor snakes that are strangling the precious ecology of the Everglades? Questions like those became more urgent last week, when a team of scientists led by the University of Notre Dame disclosed that silver carp dominating stretches of the Mississippi River and its tributaries had infiltrated Lake Michigan.
The federal government had spent $22 million on electric barriers in the Chicago Sanitary and Ship Canal to keep carp out, but it clearly was not enough. An additional $33 million is going into the effort next year.
A coalition of six Great Lakes states and the Canadian province of Ontario have sought a preliminary injunction from the Supreme Court to shut down two major locks immediately on the grounds that an Asian carp invasion would cause “irreparable harm.’’
The court declined to grant the injunction last month, but it will accept briefs soon on the broader question of whether to close them at all.
Army Corps of Engineers officials say it is too early to shut down the locks. They are focused on building a third electrical barrier to provide yet another obstacle to Asian carp infiltrating Lake Michigan.
“It’s not a silver bullet, but it’s a good tool to impede the movement of the silver and bighead carp,’’ said Colonel Vincent Quarles, commander of the Army Corps’ Chicago District.
But the barriers are not surefire, and specialists say it is difficult to say how many Asian carp would have to make it through to establish a viable population.
US officials have been fighting invasive species for many years, but efforts have intensified in recent years as the impact has become clear. For instance, zebra and quagga mussels that were once restricted to the Great Lakes have moved west, clogging systems at critical dams.