Publications

The stock of lake herring (Coregonus artedii) in the Apostle Islands (Wisconsin) region of western Lake Superior has diminished severely during the past 30 yr, and predation by rainbow smelt (Osmerus mordax) on herring larvae has been considered a possible cause of this decline. In contrast, the herring stock in Black Bay, 160 km to the northeast, has remained nearly stable despite the...

In May, October and November of 1968, 2,456 walleyes of various ages were captured, tagged and released in eastern Lake Erie to determine seasonal movement of walleyes in that basin and the degree to which they intermingled with fish of the central and western basins. From 1968 to 1971, 275 of the tagged fish were recovered. Walleyes tagged in the spring on spawning grounds near...

Using ovaries sampled seasonally from Lake Michigan bloaters in 1968-1969, we determined that one complement or modal group of eggs is produced each year and spawned mainly during January, February, and March. Fecundities estimated for 65 fish taken in October ranged from 3,230 eggs in one medium-size bloater (241 mm long) to 18,768 in the longest (305 mm). We regressed these estimates...

Northern pike (Esox lucius) from eastern Lake Ontario were sampled with gill nets and trap nets in 1972-1973. Fish of age-groups IV, V, and VI were predominant in the catch. Although males were slightly longer after the 1st yr of life, females gained a 25-mm advantage in the 2nd yr and a 30-mm advantage in the 3rd yr. In later years, the increments of growth of males and females were...

In the early and mid-1960s the abundance of yellow perch (Perca flavescens) in Lake Michigan declined abruptly. The decline began in the northern part of the lake and spread progressively southward. Circumstantial evidence suggests that the nonnative alewife (Alosa pseudoharengus), by interfering with perch reproduction, was the primary cause of the decline. The alewife was first...

White perch, Morone americana, was first reported in Lake Erie in 1953. No further reports of capture were recorded until 1973, when one fish was taken. Three other captures were confirmed in 1974, and 34 in 1975. All but 3 of the 38 specimens were taken in the warm, shallow western basin and the extreme eastern end of the central basin. The widespread distribution and the sizable...

No abstract available.

Age and length distributions are given for 6,764 walleyes, Stizostedion v. vitreum (Mitchill), sampled during 1963-1968 from commercial landings of walleyes representing discrete populations in the eastern and western basins of Lake Erie. In the eastern basin, where all catches were made with gill nets, age-groups III and IV predominated in samples from large-mesh nets and age-group I in...

Eggs stripped from lake whitefish (Coregonus clupeaformis) spawning in Lake Michigan were incubated in the laboratory at temperatures similar to those on whitefish spawning grounds in Lake Michigan during December-April. Observed times from fertilization to attainment of each of 21 developmental stages were used to test a model that predicts the rate of development at daily fluctuating

Sea lampreys en route to their spawning grounds have been captured at mechanical or electrical structures that have been in operation for 1 to 27 spawning seasons (1949-75) on some 167 tributaries of the upper Great Lakes; more than 750,000 were taken in 1949-70 (Smith 1971). Among these lampreys (all of which were routinely examined at the time of capture) was one female (length, 434 mm...

Samples of crustacean zooplankton were collected monthly in west-central Lake Erie in April and June to October 1968, and in July and August 1970, before and during periods of hypolimnetic dissolved oxygen (DO) depletion. The water column at offshore stations was thermally stratified from June through September 1968, and the hypolimnion contained no DO in mid-August of 1968 or 1970...

Mercury‐contaminated yellow perch (Perca flavescens) and rock bass (Ambloplites rupestris) were collected from Lake St. Clair and stocked in two earthern ponds in September 1970. Twenty‐six months later, concentrations of total mercury in the fillets had declined 53% in the yellow perch and 59% in the rock bass; however, the mean weight of the fish increased 88 and 183%, respectively...