dory or dore
are piscivorous fish common to the Great Lakes and inland waters.
They spawn in either lakes or streams, depending on local water conditions.
Also, there is evidence of a heritable component of spawning site selection
(i.e. there are genetically driven river spawning stocks and lake spawning
stocks.) In impounded systems, (such as the Au Sable) the tail waters
of dams may be used as spawning grounds.
walleye feed on some invertebrates (such as mayflies, chironomids, and
crayfish), but the primary component of their diet is fish. They
will forage on shiners and other minnows, alewife, yellow perch, white
sucker fry, and other available prey fish. Their diets
may vary seasonally according to prey availability. There is little
evidence of cannibalism in walleye populations.
Walleye were stocked
into the Au Sable system above Alcona dam until 1990. The original
stock came from the Muskegon River, although the population is presently
naturally reproducing. DePhilip (1997) found that most walleye activity
occurred near sunset and continued into the night. The most overall
movement occurred in April and May as walleye moved from the Alcona Dam
Pond to the tailwaters of Mio Dam to spawn. Some walleye stayed in
the river all summer, others moved back to the reservoir in the fall.
All walleye that DePhilip tracked overwintered in Alcona Dam Pond.