SPRING LAKE SOUTH (northern pike) - In 1978, Spring Lake was divided into two distinct waters for the purpose of capital improvement and the restructuring of the fish population. Prior to 1916, Spring Lake was part of the Illinois River system as a lateral freshwater marsh. In 1916 it was separated from the river by a high levee and has remained a separate body of water. From 1916 until 1981, the quality of the fishery habitat and the fish population declined due to rough fish populations such as carp and bullheads. In 1986 the lake was treated with rotenone to remove the existing fish population and encourage the growth of aquatic vegetation. The key to the rehabilitation was the reestablishment of lush aquatic vegetation which had occurred by summer of 1986.

Always a shallow water, South Spring Lake today has an average depth of 2.9 feet. Of the 610 acres of water, at least 75 percent is covered with 13 different species of aquatic vegetation by late May of each year. The tremendous spring recharge from the bed of the lake amounts to 100 acre feet a day, creating very cold water temperatures under the insulating layer of vegetation for the majority of the summer months. This is a unique situation and only occurs in Spring Lake within the State of Illinois. The resulting temperature regime and water quality is excellent habitat for pike.

Because of its' proximity to the Jake Wolf Hatchery, South Spring Lake has been used as a brood source for northern pike the past 10 years and has provided most of the early northern stocks for statewide stocking of northern pike each year. In an effort to collect fish for egg production, extensive population assessment data has been gathered since 1994. We know quite a lot about the size structure and age of the population as well as growth. It appears that growth of female fish is excellent when compared to nation-wide populations. Growth of male northern is in the normal range when making a similar comparison. There is a big difference in the length at age between sexes! A 28 inch female is usually 4 years old, whereas a 25 inch male is 5 years old, on average.

In 2006 we were able to collect 245 northern pike in 4 days of trap netting effort. They ranged from 18 to 37 inches in length. All fish were processed for condition and sexual maturity. Female northern were spawned and males were collected for sperm.

Fishing for northern pike on South Spring Lake is a challenge. The water temperatures rise quickly and usually result in fish feeding actively in early March. Aquatic vegetation becomes thick and hard to fish no later than May 15th of each year and lasts until the lake closes for regular waterfowl season. The narrow window of opportunity between the first of March and mid-May results in some excellent fishing. The fish are then refuged by the thick vegetation until the following year. Sometimes fishing the holes in the vegetation in June is quite effective. There are a number of large fish in the population available to northern fishermen. Based on the size structure of the fish sampled during the spring of each year, it may be possible to catch northern up to 20 pounds in weight. Large white or yellow spinner baits are among the best choices early in the year with many larger fish caught by surface plugs and jerk baits later in the spring! A number of fish are caught in the winter in the large spring area located at the south end of the lake. State-wide regulations apply to the northern pike fishery at Spring Lake.