||Field Evaluation of Barriers to Walleye Egg and Larva Survival in the Lower Fox River, Wisconsin.
Auer, N. A. ;
Auer, M. T. ;
||Michigan Technological Univ., Houghton.;Environmental Research Lab.-Duluth, MN.
Fox River(Wisconsin) ;
Field tests ;
Water quality ;
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||A substantial population of walleye Stizostedion vitreum inhabits the lower Fox River between DePere and Green Bay, Wisconsin. Once an indigenous species, walleyes are now maintained through stocking; natural recruitment has not been observed over the 7-year stocking period. In the manuscript an examination is conducted of the potential importance of water quality as a barrier to walleye egg hatching success in the river. A novel technique involving dialysis membranes was employed to study the effect of river water quality on egg development uninfluenced by factors such as fungal infestation, predation, or siltation. Gametes were stripped from several ripe walleyes collected from the lower Fox River in April 1985. Fertilized eggs and filtered river water were placed in dialysis tubes and rotated on a rack in a large tank receiving a continuous flow of river water. Hatch success averaged 61% (range, 34-82%) and varied with the size of the female used as an egg source. The observed hatching success is similar to the best egg survivals measured in many field and laboratory studies. Measurements of pH, dissolved oxygen, hydrogen sulfide, and ammonia- and nitrite-nitrogen offered additional support for the conclusion that water quality was not a barrier to walleye egg development in the Fox River. Spawning substrate, sediment chemistry, water temperature fluctuations, predation, and fungal infestation may be important barriers to natural recruitment of walleyes in the lower Fox River. (Copyright (c) American Fisheries Society, 1987.)
||Pub. in American Fisheries Society Symposium 2, p93-101 1987. Sponsored by Environmental Research Lab.-Duluth, MN.
|NTIS Title Notes
||Reprint: Field Evaluation of Barriers to Walleye Egg and Larva Survival in the Lower Fox River, Wisconsin.
||PC A03/MF A01