LAKE AND RIVER FISHERIES 81 



Decline of the Traditional Great Lakes Fishery 



In the early 1940's, the lake trout, long the backbone of the Great 

 Lakes industry, suddenly began to decline^. The annual trout catch in 

 Lake Huron, for example, dropped from over 5 million pounds before 

 1940 to about 300,000 pounds in 1953. The same fate began to overtake 

 Lake Michigan's trout in 1946, and the catch there fell from over 6 

 million pounds to a mere 402 pounds in 1953. Lake Superior, which has 

 provided the last remaining U.S. lake trout fishery, normally producing 

 about 4>^ million pounds of lake trout annually, started dechning in 

 1947 and by 1959, the take was only 870,000 pounds. 



The rapid disappearance of these highly-prized lake trout stocks has 

 been attributed solely to the invasion of the Great Lakes by the sea 

 lamprey^, a parasitic eel-like fish which is equipped with a sucker-like 

 mouth, sharp teeth, and a file-like tongue. By attaching itself to an 

 unwary victim by its mouth, it quickly rasps a hole in the body of the 

 fish and feeds on the blood and tissue fluids. The sea lamprey almost 

 certainly entered the Great Lakes above Niagara Falls through the 

 Welland navigation canal; the first specimen was identified from Lake 

 Erie in 1921. Once it had made its way across the unfavorable environ- 

 ment of Lake Erie into Huron, it spread rapidly and developed tremendous 

 stocks. 



Species of fish that were not originally major targets of lamprey preda- 

 tion are in serious peril following depletion of trout stocks^ Two species 

 of large chub are almost extinct; other large chub have been reduced 

 markedly. Whitefish have been reduced until the stocks are very low. 

 There is evidence of rather serious predation on walleyes and suckers in 

 several locahties. Selective fishing against the higher-priced species, 

 progressive changes in environmental conditions in Lake Erie, and pollu- 

 tion in shallow bays of the other Lakes near industrial centers have also 

 taken their toll of the once-valued fish stocks of the Great Lakes. In 

 an attempt to control the lamprey, the new primary predator of the 

 Lakes, the U.S. Fish and Wildlife Service, the states bordering the Great 

 Lakes, and the Province of Ontario in 1950 initiated an intensive research 

 program^ Successful control of the sea lamprey and re-establishment of 

 lake trout in the Great Lakes will prove a tremendous undertaking. Only 

 time will reveal the relative success of this program. 



To make problems of the Lakes fishery even more complex, the inva- 

 sion of the sea lamprey was preceded or followed by the introduction 

 of other marine species — the smelt and the alewife — much smaller, lower- 

 valued, and frequently unmarketable fish. Furthermore, the disappear- 



