The precipitous decline in abundance of walleyes (Stizostedion vitreum vitreum) in western Lake Erie during the 1960s caused major concerns for the future of this resource. Mercury contamination in walleyes in 1970 resulted in a moratorium on commercial fishing in United States and Canadian waters. The opportunity arose for resource agencies to develop a plan for rehabilitation of the walleye stocks, and quota management for walleyes was begun in 1976. After 8 years, the resource had recovered dramatically and the estimated standing stock in 1983 was more than three times that in 1976. In the mid‐1970s, however, certain detrimental changes suggested that self‐regulatory mechanisms were occurring. The growth rate declined gradually but rather consistently. Growth changes were most evident for young‐of‐the‐year (YOY), yearlings, and 2‐year‐old fish, which usually constituted more than 80% of the standing stock in 1976‐1983. Average lengths of YOY fish in the fall decreased by nearly 50 mm (from about 240 mm in 1961 to 190 mm in 1983). Average lengths and weights of yearling and older fish began to decline after 1975 and decreased markedly after 1980. Historically, growth of walleyes in western Lake Erie exceeded that reported for many walleye populations in other waters. Another sign of self‐regulation was an increasing delay in the onset of maturity. Most (usually more than 90%) of the yearling males were sexually mature each fall before 1979, but this percentage decreased to only 32 by fall 1983. Usually 80% or more of the age‐II females were mature each fall during the 1960s and early 1970s, but this percentage decreased rapidly to only 7 by fall 1983. Prey fish populations declined somewhat in the early 1980s, and their ability to sustain the high abundance of walleyes is a great concern to resource managers.

Of 2427 walleyes (Stizostedion vitreum vitreum (Mitchill)) examined from Lake Erie in 1964–66, no females were mature at ages below III and all were mature at age V. All male walleyes from the eastern basin were mature at age II, and those from the western basin at age III. Females from the western basin matured at a shorter length and a younger age than those from the eastern basin. Males from the western basin, on the other hand, matured at a longer length and greater age than those from the eastern basin.Egg production, which was estimated for 60 walleyes from the eastern basin and 78 from the western basin, ranged from 48,000 to 614,000. The number of eggs increased rapidly with increase in total length, but the relation between fecundity and weight was almost linear. Walleyes from the western basin were much more fecund for any given length, weight, or age than those from the eastern basin. Weight was the most accurate indicator of fecundity. The mean diameter of eggs from 32 ripe walleyes was 1.72 mm. Little relation existed between egg diameter and length or age of fish.

A total of 3,998 yearling walleyes, Stizostedion vitreum vitreum (Mitchill), were captured, tagged, and released along the south shore of western Lake Erie to determine their movements and their dispersal from a known nursery area. Four hundred ninety‐nine recoveries were made over a period of 3 years. Tagged walleyes traveled primarily north toward the islands in the Western Basin during their first year of liberation, and in succeeding years moved progressively toward the extreme western end of the lake. Some walleyes were recaptured within 6 months in the Detroit River, Lake St. Clair, the St. Clair River, and southern Lake Huron, and the percentage of fish recaptured in these waters north of Lake Erie increased annually. Movement eastward into the Central and Eastern Basins of the lake appeared negligible. The greatest distance traveled by a marked walleye was 236 miles. The average distance traveled by all tagged fish was 25 miles.

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-ram advantage in the 2nd yr and a 30-ram advantage in the 3rd yr. In later years, the increments of growth of males and females were similar. All males were mature after 2 yr and females after 3 yr. The stomachs of northern pike contained only fish; the alewife (Alosa pseudoharengus) was the principal forage species consumed. Electivity indexes for alewives, white perch (Morone americana), and yellow perch (Perca fiavescens), the three most common species in the diet, indicated a positive selection for alewives that increased from June to October during a period when the relative abundance of alewives steadily decreased. The northern pike (Esox lucius) is a major component of the predator population in the shallow inshore waters of the eastern outlet basin of Lake Ontario. Species inhabiting these waters include smallmouth bass (Micropterus dolomieui), muskellunge (Esox masquinongy), American eel (Anguilla rostrata), white perch (Morone americana), yellow perch (Perca fiavescens), brown bullhead (Ictalurus nebulosus), alewife (Alosa pseudoharengus), and rock bass (Ambloplites rupestris). Rainbow smelt (Osmerus mordax) are abundant in the nearshore waters during the spring only. Northern pike are prominent in the sport fishery (no detailed catch data are available) and are taken in the Ontario commercial fishery (annual average catch in 1950-1974, 12,250 kg). During 1972, the International Field Year on the Great Lakes, extensive surveys of the various fish stocks in Lake Ontario were conducted. This paper describes the age composition, growth, and food of northern pike in the eastern outlet basin. Previously published information on northern pike in Lake Ontario is limited to a listing of men-• Contribution 533, Great East Lansing, Michigan 48823. sural data taken from a small collection of

A limited commercial gill‐net fishery for walleyes (Stizostedion vitreum vitreum) in New York waters of Lake Erie was established in the 1950's. Since then year class strengths have varied considerably; four have been outstanding—those of 1959, 1962, 1964, and 1971. A rapid rate of rise in water temperature during spawning and incubation was positively correlated with the strength of these year classes. Each time a strong year class appeared, small‐mesh gill‐net effort was markedly increased, and an average of 46% of the fish of each year class was harvested at age I before they were sexually mature. If the small‐mesh gill‐net fishery had not been operating, the total annual production by the large‐mesh gill‐net fishery could have been increased by an average of 35%.