Walleye appearance varies from Great Lake to Great Lake, but within any one lake, the fish look very similar, regardless of where they hatched. So ecologists have to use other means to identify a fish's river of origin.
Analyzing otoliths is a technique that has gained acceptance over the last decade. Mangel Pflugeisen used a statistical method that will help ecologists make the most of the limited information they can get.
She explained how her results could apply to fishery management.
"Almost no walleye stray from other sites to spawn at the Maumee," she said. "So if the Maumee is ever overfished, it is unlikely to recover, since fish won't be coming in from other sites to replenish the population. However, since so many fish from other sites stray to the Sandusky to spawn, the Sandusky is less vulnerable to overfishing. Officials would have a little more flexibility in the management of that river."
Her advisor, Catherine Calder, associate professor of statistics, explained the larger significance.
"While this research was motivated by the need to better understand particular Lake Erie walleye populations, the statistical techniques in Bethann's thesis are general enough to be directly applicable in studies of other fish species in different regions of the world," Calder said.
Mangel Pflugeisen decided to pursue the project after taking an aquatic ecology course from Elizabeth Marschall, associate professor of evolution, ecology, and organismal biology at Ohio State.
Marschall provided Lake Erie walleye data collected by one of her former graduate students, Jennell Bigrigg, who just earned her doctorate in veterinary medicine.<
|Contact: Catherine Calder|
Ohio State University