University of Wisconsin - Extension

It might seem like just another fish story, but it's a common perception these days that bluegill fishing just isn't what it used to be.

According to Bill Swenson, University of Wisconsin-Superior/Extension fishery specialist, evidence supports this claim. "Evidence accumulated during the last few years suggests intensive fishing and removal of the largest bluegills, particularly during spawning, may be resulting in development of genetic strains which grow much slower," Swenson says.

"Just as in the breeding of domestic animals, by removal of the larger individuals and allowing only the small ones to reproduce, we have inadvertently developed smaller breeds of panfish."

In response to a request by the Bayfield County Iron River Lakes Association, Swenson's fish population biology class at UW-Superior measured age and growth of bluegills collected from two generally similar lakes with very different levels of fishing pressure. The project was designed to determine if abundance of older fish and growth rates were being reduced by intensive sport fishing.

"Comparison of the two lakes demonstrated that bluegills averaged one year younger in the intensively fished lake," explains Swenson. "Length and weight of bluegills of the same age also indicated that growth was much slower. Bluegills averaged 15 to 21 percent smaller in length and 39 to 57 percent less in weight at the same age in the intensively fished lake."

Sports persons have expressed concern about over-harvest of panfish in general for several years, Swenon adds. "Other recent studies in both Wisconsin and Minnesota support our findings. One study conducted cooperatively by Wisconsin and Minnesota Department of Natural Resource biologists used a computer model. It showed that restricting the take during spawning probably represents the only way to rebuild the kind of faster growing panfish populations which people enjoyed in the past."

Reducing the bag limit to 10 fish per day also would stimulate improved growth and abundances of larger fast-growing fish, adds Swenson.