"Regarding older walleye vs. younger walleye----the older, larger 'hog size walleye' may produce more eggs than younger fish. However, it's a well known fisheries science fact that as females grow older and bigger, the 'viability' of those eggs (ability to become fertilized, incubated and hatched) decreases significantly. The younger females, ages 4-7 and lengths of 18-24 inches (these are averages, and can vary), will produce the most 'viable' eggs.
In comparison, walleyes in far northern Ontario lakes are known to reach sexual maturity at age 7, and may only be 13-14 inches at that time, compared to age 4 and 17-18+ inches in Lake Erie.
Northern Ontario walleyes exhibiting the highest 'viability' of eggs range from 13-22 inches---with walleye over 22 inches significantly less viable than the younger, shorter females.
Why is this? In Lake Erie, due to our warmer waters and abundant food supply, our walleyes grow fast and die young. Colder waters and less abundance of food result in northern Ontario walleyes growing slow and dying old.
Regulations a few years ago for specific regions in Northern Ontario for walleye allowed a bag limit of 4. All 4 must be 16 inches and under, or 3 can be under 16 inches, with one being over 22 inches (this provides a big trophy walleye to be taken by outfitter/guide clientele). This protects their most viable spawners and helps improve recruitment when a walleye stock is low. Mixed emotions were raised among anglers when first imposed, yet the realization for a better fishery in the near future has now been accepted.
This may be a great management program for cold, northern Ontario lakes where food abundance is low, grow rates are slow, and both angling pressure and native Indian netting has impacts on the fishery.
However, you must remember that these northern cold water lakes are NOT comparable to the size and productivity we experience on Lake Erie