A catch of two Northern pike during a recent DNR fish survey at Crooked Lake near Columbia City is increasing concern that the predatory fish may harm the lake's fragile cisco population.
The Northern pike measured 27 and 29 inches long and marked the third time in four years that pike have been detected in the 206-acre natural lake.
Pike can grow more than 3 feet long and typically prey on suckers and perch. Ciscoes, where present, can make up an important part of their diet.
In Indiana, the cisco, a close relative to trout and salmon, is classified as a "species of special concern" due to a drastic decline in numbers. Only 13 Indiana lakes still contain ciscoes, down from more than 40 lakes in the 1950s.
Although most of the cisco decrease in Indiana lakes has been linked to declines in water quality, predator fish may play a role in limiting cisco numbers.
Crooked Lake still contains one of the largest remaining cisco populations in the state. Before 2009, however, no Northern pike were known to occur in the lake. Five pike have since been netted in the lake: two in September 2009, one in June 2010 and two this month.
Biologists speculate that anglers may have caught Northern pike elsewhere and illegally released them in Crooked Lake.
According to Indiana law (IC 14-22-9-8), anyone who stocks a fish in public waters under state control must first get a permit from the DNR. Catching fish in one lake and releasing them in another lake without an approved permit is a Class C misdemeanor.
Live-wells on boats filled with water make it easy for anglers to transport fish but difficult for conservation officers to control illegal stocking.
Although the current number of Northern pike in Crooked Lake is apparently low, they could reproduce and become a dominant cisco predator.
Biologists say it is too early to tell if pike are spawning in the lake. They won't know unless and until they begin to catch small, young pike.
Two illegally stocked Northern pike were also netted in 2009 at Loon Lake, located about two miles west of Crooked Lake. None were found at Loon Lake during a recent survey.