Walleye Spawning Habitat Restoration and the Influence of Substrate Size, Shape, and Condition on Egg Retention

Walleye spawning habitat restoration in streams and the influence of substrate size, shape, and condition on egg retention

Walleye spawning habitat degradation has been recognized as an important limitation to natural reproduction throughout the Great Lakes Basin and the desire to increase natural production of this valuable sport fish has led to numerous restoration projects.  However, despite the growing interest in habitat remediation, few studies have focused on developing or evaluating these techniques.  The lack of empirical feedback into the restoration process has resulted in significant information gaps and managers have little scientific guidance during restoration efforts, which may limit the success of projects. 

To address information gaps in walleye spawning habitat restoration and strengthen the knowledge of walleye reproductive ecology we investigated; 1) how substrate size and composition influence walleye egg retention under different flow regimes in a laboratory setting; 2) how substrate siltation influences the adhesive capabilities of walleye eggs.  We found crushed small gravel to have the highest egg retention rate under all water velocities tested.  Additionally, eggs placed on clean substrates had a 36% higher retention rate than those placed on rocks covered with a fine layer of silt and clay.  Maintaining clean spawning substrates (through scouring effects and reducing siltation via watershed improvement) may be important for the reproductive success of walleye.  Information on the optimal substrate particle size to promote egg retention will aid managers with stream bed restoration approaches.