Does the value of newly accessible spawning habitat for walleye (Stizostedion vitreum) depend on its location relative to nursery habitats?

Abstract

The benefit accrued from habitat restoration actions may depend not only on the quality and quantity of habitat restored, but also on its location relative to other critical habitats. For example, walleye (Stizostedion vitreum) larvae need to be transported by river currents from spawning to nursery habitats soon after emergence. We developed a model of river transport survival for larval walleye to evaluate potential recruitment from riverine spawning habitats to lacustrine nursery areas. Published relationships were used to model transport survival as a function of temperature and velocity. At greater distances from nursery areas, mortality risk increases, particularly as a result of starvation at relatively high river temperatures. We applied the model to the Sandusky River, a tributary to western Lake Erie, and found potential larval production from spawning habitat above an existing dam to exceed the potential of presently accessible spawning areas by a factor of 8. We used a generalized version of the model to show that for transport distances of less than 100 km, transport survival is much more sensitive to variations in river flows, whereas at greater distances, temperature becomes increasingly important.