Fish scientists who wrote a paper released Friday, “First evidence of grass carp recruitment in the Great Lakes Basin,” say they are confident they’ve proved that four year-old grass carp caught last year in the Sandusky River reproduced locally.
There are several kinds of Asian carp, including grass carp, bighead carp and silver carp. Most of the attention has been focused on the bighead and silver carp, which have overrun the Mississippi River and threaten to get into the Great Lakes. It’s feared that if they got into Lake Erie, they would gobble up lots of plankton, threatening the yellow perch and walleye populations.
While grass carp are not as feared as their cousins, they could create problems of their own, said Duane Chapman, a federal fish scientist in Columbia, Mo., and the lead author of the new paper.
Grass carp don’t eat plankton but prefer vegetation, which means if they reproduced in large numbers in Lake Erie, they’d threaten shoreline wetlands that are important to ducks and certain fish species.
Scientists have been arguing about whether Asian carp can reproduce in Lake Erie. Chapman, one of the country’s top Asian carp researchers, said he sees no reason why bighead and silver carp couldn’t reproduce in the same river as a grass carp.
Chapman said the findings don’t prove the battle against Asian carp has been lost, as the fish would only become a problem if they reproduced in large numbers. Since those four grass carp were found, only two more have been found, he said.
“Six fish are not the end of the world,” he said.
Three grass carp have been found in the Lake Erie basin so far this year — one in the Maumee River, one in the Cuyahoga River and one in Lake Erie, said Rich Carter, fish administrator for the Ohio Division of Wildlife. None have been found in the Sandusky River this year.
Bones in the heads of the fish, called otoliths, show the unique chemistry of the Sandusky River, a high ratio of strontium to calcium. That’s why the paper’s authors believe the four fish lived in the Sandusky watershed their entire lives.
Much of the work on the otoliths was done by Jeremiah Davis, 32, a Sandusky native who just obtained a master’s degree in biology from Bowling Green State University.
“It was a really rewarding experience to do something on the Sandusky River,” said Davis, a 1999 graduate of Sandusky High School.