1 April, 2008

Fisheries biologists are approached by an increasing number of anglers (fishermen) interested in harvest regulations for crappie.  In some cases these regulations are justified and in others they are not appropriate.  Minimum length limits have been widely applied to reduce crappie harvest and improve fishing quality.

Unfortunately, minimum length limits for crappie often result in increased catch rates with a reduction of overall harvest.  In addition, minimum length limits are only effective where crappie recruitment, the survival of fry, is poor and growth rates are high.  If recruitment is moderate to good and growth rates average to slow then crappie will “stack” up just under the size limit.  Crappie recruitment tends to be highly variable making the application of appropriate limits difficult over long periods of time.

Crappie recruitment on Lake Shelbyville has been highly variable, but on average has improved over recent years, especially for black crappie.  As a result growth rates and recruitment to legal size has slowed despite very high densities of gizzard shad, which crappie use for forage.  Analysis of crappie age and growth in spring 2007 indicates that the growth rates of all ages of black crappie are below state averages.  White crappie growth rates are higher than the state average for young fish, but slower than the state average for age 4+ and older crappie.

On Lake Shelbyville, a few anglers have reported good fishing results for crappie 10-inches or larger over the past several years.  However, the majority of crappie anglers have been catching high numbers of crappie just below the size limit, but few over the current length limit of 10 inches.  This has resulted in a lot of frustrated anglers and a reduction in the number of fishermen visiting Lake Shelbyville.  Since fishing is the number one recreational activity on Lake Shelbyville, the loss of anglers can have a significant effect on the local economy.

A new regulation has been approved on Lake Shelbyville for crappie and will take effect on April 1, 2008.  This regulation will be a little different than what anglers are used to seeing in mid-western states.  The new regulation will allow for the continued harvest of 10 crappie that are 10 inches or larger but will also allow the harvest of 5 crappie less than 10 inches.  The goal of this regulation is to thin the number of crappie under 10 inches slightly, giving them the slight nudge necessary to improve growth and recruitment to 10 inches and larger.

A wide variety of regulations and combinations of regulations were considered for crappie on Lake Shelbyville, but due to crappie population dynamics and fishing activity the proposed regulation was determined to likely produce the best results for over the longest period of time.  Although anglers catch a considerable number of black crappie on the lake, white crappie make up the bulk of anglers catch and harvest.  A large majority of the white crappie caught by anglers have been between 9.5 inches and 10 inches.  Because of this, the limit below 10 inches was set at only five fish to prevent potential overharvest of smaller white crappie and maintain good potential recruitment of white crappie to sizes 10 inches and larger.
Anglers are reminded that “culling” fish (replacing a kept fish with another caught later) is illegal unless they are in a bonafide fishing tournament.  Due to wide publicity of tournament fishing, where culling is legal, many anglers do not realize that this activity is illegal for non-tournament fishermen.  Only in bonafide tournaments with the fish kept in constantly aerated livewells, is culling legal.  Even in the best conditions, fish kept for any length of time and later released will suffer some mortality.  The death is usually delayed and often fishermen are unaware of the consequences of holding the fish for even an short period of time.  Therefore, any fish kept, even if later released, are required to be counted as part of a fishermen’s harvest.  Illegal culling adds to the angling mortality of fish populations and is detrimental to the long term quality of fishing.

Although it will take some time for the new regulation to prove it’s value, it will be reviewed annually and adjusted if crappie population dynamics change significantly.  The regulation is expected to quickly improve angling satisfaction and quality.  Improved fishing quality and satisfaction should benefit local fishermen, attract additional fishermen, and will provide a benefit to the local economy as well.

For further information or to comment contact Illinois Department Natural Resources Fisheries Biologist  Michael J. Mounce at (217) 345-2420.