Don't blame cormorants for walleye decline: researcher

Jodie Sinnema, Edmonton Journal
March 21, 2006

A flourishing cormorant population is not responsible for the decline of walleye in Lac La Biche, says a University of Alberta researcher.

Walleye make up less than one per cent of the water birds’ diet, says Suzanne Earle, who was dive-bombed by gulls, splattered with excrement and pecked by nesting chicks, all in an effort to collect regurgitated food left by cormorants nesting near the lake in central Alberta.

“I felt like the cormorants were getting a bit of an unfair rap for contributing to the decline of walleye,” said Earle, a graduate student in biological sciences whose project was funded in part by Alberta Sustainable Resources, Alberta Conservation Association and Alberta Sport, Recreation, Parks and Wildlife Foundation. “Nobody knew what they were eating, but they were an easy target to blame."

Earle and her supervisor became interested in doing a study on the cormorants’ diets after the provincial government began to destroy eggs in cormorant nests on the shores of Lac La Biche in June 2003.

More than 20,000 cormorants live in the Lac La Biche area, but colonies are also flourishing around Ontario’s Great Lakes and by New York’s Oneida Lake.

Not so the walleye. An estimate from 2003 suggests only 2,800 adult walleye are swimming in Lac La Biche. That’s about five per cent of the minimum 50,000 adult walleye that are needed to sustain the fish’s population in the lake.

But biology professor Cindy Paszkowski, Earle’s supervisor, said the province’s management plan for the lake wasn’t backed by strong science, since the province didn’t know exactly what the cormorants were eating and whether or not they were contributing to the disappearance of the walleye.

“Shoot first, ask questions later: that’s kind of the approach they used,” Paszkowski said.