1950's 



Lake trout production reached zero in Lake Michigan and began to 

 decline in Lake Superior in 1950. Walleye production started to decline in 

 1950 in Lake Michigan. Cisco (chub) production dropped below 100,000 

 pounds in Lake Ontario, the first of the lakes to lose its chub population. 



In 1952 production of lake herring in Lake Michigan and blue pike in 

 Lake Ontario began their "terminal" decline. Lake whitefish, blue pike, 

 and walleye production began declining in Lake Erie by 1956. By 1959 pro- 

 duction had fallen below 100,000 pounds for lake herring in Lake Ontario, 

 Huron, and Erie; sauger in Lake Erie; and blue pike in Lakes Ontario and 

 Erie. Within a few years the blue pike had become virtually extinct in 

 Lakes Ontario and Erie. The emerald shiner, once exceedingly abundant, 

 became extremely scarce in Lakes Michigan and Huron. 



Increases also occurred in the 1950's. Smelt production exceeded 

 200,000 pounds in Lakes Ontario and Huron; 800,000 pounds in Lake Superior; 

 6 million pounds in Lake Erie; and 9 million pounds in Lake Michigan. The 

 rainbow smelt had become a significant species in the commercial catch of 

 all the lakes in less than 30 years after its introduction in Lake Michigan. 



The first alewife was reported in Lake Michigan in 1949, and the 

 species was first reported in the commercial catch in Lake Michigan in 1956. 

 By 1957 production exceeded 100,000 pounds, and by 1958 (9 years after it 

 was first reported) over 1 million pounds of alewives were produced in Lake 

 Michigan. Similar rapid colonization of the white perch occurred in Lake 

 Ontario; only 5 years elapsed between the first record of its presence 

 (1950) and the first report of it in the commercial catch (1955). 



1960's 



During this decade species of the whitefish family continued to decline 

 in the Great Lakes. Lake whitefish production fell below 100,000 pounds in 

 Lakes Ontario and Erie; lake herring began declining in Lake Superior and 

 fell below 100,000 pounds in Lake Michigan; deepwater Cisco (chub) produc- 

 tion began declining in Lakes Huron and Superior. Shallow water species 

 also declined: walleyes in Lakes Michigan and Ontario; yellow perch in 

 Lake Michigan; and northern pike in Lake Huron. The fourhorn sculpin, once 

 abundant in Lake Ontario, was extremely rare in the 1960's. A major decline 

 of the fourhorn sculpin during this period was also noted in Lake Michigan 

 (Wells and McLain, 1972). 



Rehabilitation of the Fish Stocks 



Biologists recognized that rehabilitation of fish stocks, principally 

 lake trout, could not begin until the sea lamprey was brought under con- 

 trol. A special agency, the Great Lakes Fishery Commission, was created 

 19b6 by a treaty between Canada and the United States to fund and coordi- 

 nate existing efforts to control the sea lamprey. Initial control methods 

 attempted to block spawning migrations into streams by means of mechanical 

 and electrical barriers. This method proved ineffective. In 1957, after 



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