Spawning Substrate Condition Influences Walleye Egg Adhesion

Deposition of fine sediments on walleye spawning habitat is known to affect reproductive success by decreasing the availability of interstitial space and impeding delivery of sufficient oxygen to incubating embryos.  However, the affect that fine sediment deposition has on the ability of fertilized eggs to adhere to spawning substrates has not been investigated.  The ability of fertilized eggs to adhere to spawning substrates during the water hardening process may be an important ecological adaptation to prevent eggs from being entrained in the water column, where they are subject to numerous sources of mortality.  To investigate how substrate siltation influences the adhesive capacity of walleye eggs we compared egg adhesion on mud-covered and clean rocks in a hydraulic flume.  Rock condition significantly influenced egg adhesion.  Clean rocks had a mean (± S.E.) egg retention of 35.9% (6.47%) and mud-covered rocks did not retain any eggs throughout the course of the experiment.  This study demonstrated an additional negative impact of fine sediment deposition on walleye spawning substrates.  Maintaining clean spawning substrates (through scouring effects and reducing siltation via watershed improvement) are essential for the reproductive success of walleye.