Study: Asian carp DNA may not signal live fish

By JOHN FLESHER

TRAVERSE CITY, Mich. (AP) — Live Asian carp don’t nec­es­sar­ily have to be present for their DNA to turn up in the envi­ron­ment, accord­ing to a gov­ern­ment study released Wednes­day that could inten­sify the debate over how to pre­vent the aggres­sive, hun­gry invaders from reach­ing the Great Lakes and other vul­ner­a­ble waters.

DNA is found in excre­ment, slime and scales from live fish. But the report by three fed­eral agen­cies iden­ti­fies six other pos­si­ble means through which genetic fin­ger­prints from big­head and sil­ver carp could find their way into loca­tions such as the Chicago water­way sys­tem and west­ern Lake Erie, where it has been detected in dozens of sam­ples taken in recent years.

Those poten­tial path­ways include storm sew­ers, fish­eries sam­pling gear, fish-eating birds, dead fish car­casses, barges and sed­i­ments, the U.S. Army Corps of Engi­neers said in a state­ment accom­pa­ny­ing the report. It said carp DNA attached to any of those sources could remain for days before disintegrating.

Sci­en­tists with the corps, the U.S. Fish and Wildlife Ser­vice and the U.S. Geo­log­i­cal Sur­vey are con­duct­ing a three-year study designed to answer ques­tions raised by the repeated dis­cov­ery of Asian carp DNA in rivers and canals in the Chicago area — includ­ing loca­tions beyond an elec­tric bar­rier intended to block the carp’s north­ward march toward Lake Michi­gan. Their DNA also has been found in the Mis­sis­sippi River beyond Minneapolis.

“The pur­pose … is to improve the under­stand­ing and inter­pre­ta­tion of Asian carp envi­ron­men­tal DNA results, so we can refine and make this rel­a­tively young mon­i­tor­ing tool the most effec­tive to detect live Asian carp pres­ence,” said Kelly Baer­waldt, an Army corps fish­eries biol­o­gist and Asian carp pro­gram man­ager. Addi­tional reports are planned as the study continues.

Big­head and sil­ver carp escaped into the Mis­sis­sippi River from sewage treat­ment ponds and fish farms in the Deep South decades ago and have migrated north­ward, invad­ing numer­ous trib­u­tary rivers. The fil­ter feed­ers gob­ble mas­sive vol­umes of plank­ton — micro­scopic plants and ani­mals cru­cial to aquatic food webs.

Sci­en­tists say if allowed to infest the Great Lakes, the carp even­tu­ally could crowd out native species, endan­ger­ing the region’s $7 bil­lion fish­ing indus­try. Sil­ver carp, which spring from the water when star­tled and have col­lided jar­ringly with boaters, pose a threat to tourism.

Some state and local offi­cials in the Great Lakes region want struc­tures placed in the Chicago water­ways to seal off Lake Michi­gan from the Mis­sis­sippi water­shed. Busi­ness and gov­ern­ment lead­ers in Chicago say that would dev­as­tate ship­ping in the area, and some have ques­tioned whether the DNA find­ings are suf­fi­cient evi­dence that the carp have evaded the elec­tric barrier.

Just one live carp has been found beyond the bar­rier net­work, which is in a canal 37 miles south­west of the city.

Posted by Rob Treynor on Feb 21 2013. You can follow any responses to this entry through the RSS Feed. Both comments and pings are currently closed.