Timing of the spawning run is believed to be influenced primarily by water
temperature and water velocity. Although there can be considerable variation in water
temperatures, spawning activity generally coincides with temperatures which enhance
egg viability. For example, the optimal temperature for fertilization is between 6-12°C,
while the optimal incubation temperature is from 9-15°C (Hokanson 1977; Alberta
Department of Forestry, Lands and Wildlife 1986; Newbury and Gaboury 1993). A
review of information on water temperatures associated with walleye spawning activity
(Appendix 1) reveals that the first movements of male fish generally commence at
temperatures in the 2-5°C range. Although spawning activity can occur over a wide
range of water temperatures, it usually occurs from 5-10°C with peak activity in the 7-
8°C range. Spawning activity has usually ceased (females left the spawning grounds)
by the time water temperatures reach 10-11°C.
The info is a little old...lol, but I would imagine it is still much the same...Here is the link if you want to read more.....
http://www.mnr.gov.on.ca/stdprodconsume ... 226887.pdf