All About This Favorite Fish

The Growth Rate Chart: Comparison of average mean back-calculated length at each age for walleyes in South Dakota and Minnesota. Age Determination: Scale reading has been the traditional method for determining the age of fish and the average growth rate of populations. The assumption is that scales grow proportionately with fish length. And this relationship usually holds true. During periods of slow or no growth, as in winter, rings, called circuli, are narrowly spaced. Fast growth brings widely spaced circuli. Year marks or annuli show rather clearly under magnification, and measurements from the central focus to succeeding annuli provide the fish’s growth history. Scales of slow-growing fish or fish from consistently warm climates may not reveal true age. For these fish, otoliths (ear bones) are more accurate. But they must be removed from the skull and usually sectioned, a more difficult process than scale reading.

In many lakes in the northcentral and northeastern portions of the walleye range, yellow perch are the dominant prey once walleyes in their first year switch from invertebrates to a fish diet. Studies on Oneida Lake in New York indicate that perch are such important prey that they affect the strength of walleye year classes by buffering cannibalism. When young perch are abundant, walleyes selectively feed on them; when perch year classes are weak, walleyes cannibalize on each other, reducing year classes.

Various members of the minnow family, commonly called shiners, form huge schools; lack spines, speed, or other defenses; and inhabit almost every lake, river, and reservoir containing walleyes. The two most important shiner species are spottail shiners, which range from Georgia northwest into Saskatchewan, and emerald shiners, whose range overlaps that of the spottail but is absent from the Atlantic coast.

Walleyes key on shiners, particularly in May and June when these species spawn on gravel shoals and near the mouths of feeder creeks. At this time of year, other prey aren’t so abundant in shallow hard-bottom areas.

In northern lakes of moderate or low fertility, walleyes prey heavily on ciscoes, a small member of the whitefish family. Ciscoes, also called lake herring and tullibees, range from the upper Mississippi drainage and the Great Lakes basins north to Labrador and northwest to the MacKenzie River drainage. Ciscoes are coolwater fish, preferring temperatures below 60°F.

Ciscoes school in open water, rising toward the surface at dusk to eat zooplankton and invertebrates. Walleyes near main-lake structure or suspended in the main basin approach these schools and feed heavily during the night. Anglers keying on this pattern make great catches from tough lakes by trolling after dark. In late fall when ciscoes spawn on reefs, walleyes again focus on them, producing great fishing for trophy-size walleyes for anglers who venture out in frigid conditions.

Since smelt entered the Great Lakes, walleyes as well as salmon and trout have preyed on them. The success of this coldwater preyfish led to its stocking in other important walleye waters like lakes Oahe and Sakakawea. In these waters, spots where deep structure intercepts the preferred coolwater habitat of smelt, the best walleye fishing is in late spring and early summer.

In Lake Erie and many reservoirs in the southern portion of the walleye range, gizzard shad are the principal walleye prey from early summer until fall. In most waters, schools of shad suspend in open water or graze along shallow flats, eating plankton and detritus from the bottom. Shad schools move with their food source, along with wind and current, and walleyes follow.

Successful fishing in shad-laden waters depends on using sonar to locate prey and predators, and then longline trolling to place baits at the correct depth. Key on points, wind-blown flats, and other spots where walleyes may try to intercept shad schools.

Water Quality

Walleyes tolerate a wide range of environmental conditions, as indicated by their broad distribution and variety of habitat. They’re generally most abundant in medium to large lakes and river systems with cool temperatures, shallow to intermediate depths, extensive shorelines, slight turbidity, large expanses of clean rocky bottom, and medium fertility.

Walleyes survive and grow in water from crystal clear to murky, but become most abundant in moderately turbid conditions. Peak feeding conditions occur in water with surface visibility (Secchi disc) between 3 and 6 feet. Activity decreases when visibility is less than 3 feet or more than 16.