Survival of walleye eggs in Upper Red Lake and the Tamarac River

Walleyes experience spawning runs each spring in the Tamarac River, a tributary of the Red Lakes. However, data about walleye egg survival in the lake and river is lacking. Mesh cages were placed in both the Tamarac River and Upper Red Lake to compare survival rates. A total of twenty cages were set, ten in the river and ten in the lake. Each cage contained one hundred fertilized eggs which were checked every third day to measure survival. Temperature (°C), dissolved oxygen (mg/L), and pH were measured at each cage location. The river had an average survival rate of 22% and the lake 8%. There was a significant difference in survival rates between the lake and river (p = 0.007), meaning that the river in the spring of 2015 was more suitable for walleye egg survival. Temperature did not differ significantly between the lake and river (p = 0.12) and therefore was not a likely cause of differences in egg survival. Dissolved oxygen significantly differed between the lake and river, (p = 0.004) however, it likely had little influence on survival because dissolved oxygen levels were in the optimal range for egg survival throughout the study in both systems. The lake had a lower survival rate than the river likely resulting from a higher average pH (p < 0.001). High average wind speeds may have also caused low egg survival in the lake.