Gizzard shad reduction successful at Lake Everett

Indiana DNR Release:

ARCOLA – Application of a fish toxicant to Lake Everett last fall has sharply reduced the number of unwanted gizzard shad in the 43-acre northwest Allen County lake, based on the results of a survey conducted by the Department of Natural Resources.

Biologists caught only four adult shad in 30 minutes of sampling on June 9 with an electrofishing boat, down from 137 shad captured with the same amount of sampling effort a year ago.

Ten additional gizzard shad were caught in gill nets and traps this year compared to 97 last year.
Gizzard shad, a silver-colored fish that grows up to 17 inches long, had overrun Lake Everett since the late 1990s. Shad competed for food with popular sport fish and were not sought by anglers.

Small shad, less than 6 inches long, are often eaten by predator fish, such as largemouth bass. But shad in Lake Everett had grown too large. Most shad were more than 10 inches long.

To reduce the number of shad, DNR biologists applied 21 gallons of rotenone to the lake in mid-September. Rotenone blocks a fish’s ability to breathe. When applied in low concentrations, it can be used to primarily target shad.
Although some small bluegills and bass were killed during the project, the DNR restocked 4,300 bass last November.

“We are pleased with the result of the rotenone treatment,” said Jed Pearson, DNR biologist. “It should ultimately lead to better bluegill and bass fishing.”

During the June survey, Pearson and his crew caught 82 bluegills, including some more than 8 inches long. They also caught 38 bass that were 12 to 15 inches long.

“This year, bass made up 44 percent and shad only 15 percent of our catch by weight,” Pearson said. “Last year, these figures were reversed. Bass comprised 11 percent and shad 63 percent.”

Reducing the number of shad may have also provided another benefit: cleaner water.
“Lake Everett is now the cleanest I’ve ever seen it,” Pearson said.

To measure water clarity, Pearson lowers a secchi disk, an 8-inch black-and-white plate, into the water until it disappears and records the depth

“From 1995 through 2008, the secchi disk disappeared between 2 and 6 feet and averaged 4 feet. This year I could still see it at 11 feet," he said.