lo Introduction 



The appearance of the sea lamprey, Petromyzon marinus , in 

 the upper Great Lakes and its spread and multiplication in these 

 waters d-aring the past t-vvo decades has become a matter of in- 

 creasing concern to those engaged in the fishing industry and to 

 conservation agencies in those states bordering on the laJceSo 

 As early as 1937, Hubbs and Pope (1937) suggested that this preda- 

 tory parasite night become an increasingly damaging factor in an 

 already depleted fishery. Tlie gravity of the problem today is all 

 too apparent in the large spa'ivning runs of this species observed 

 in Michigan streams and in the reports of lamprey-scarred fish 

 submitted by commercial fishermen. 



In June of 1914.6, the IiILchigan Conservation Commission ordered 

 a comprehensive investigation and study on the sea lamprey in 

 Great Lakes Tra.ters, vdth the object of attempting to discover and 

 develop effective control methods. Immediately follomng this 

 directive, irJ'ormation •was solicited from commercial fishermen by 

 the conservation officers concerning knoim spaivning streams, per- 

 centage of total fish taken that were scarred, and the effect of 

 scars on the marketability of the fish. These data ■were summar- 

 ized by Shetter (19U9) and are discussed, in part, elsev.iiere in 

 this report. 



The problem received further consideration in September and 

 November, I9I46, at conferences called by Dr, John Van Oosten, In 

 Charge, Great Lakes Fishery Investigations, U. S, Fish and 7/ild- 

 life Service, with representatives from the states bordering on 

 the Great Lakes and from the Province of Ontario attendingo A 

 Great Lakes Sea Lamprey Coinmittee was formed and a coordinated 

 program of investigation and study was evolved, A surama.iy of the 

 activities of this Committee and the implementing legislation has 

 been presented by Applegate (19U7)o 



The present I'eport mil discuss the results of various phases 

 of an intensive study of "the distribution and life history of the 

 sea lamprey in Michigan waters, begun early in 1914-7 by the Michigan 

 Institute for Fisheries Research. These investigations repi-esent 

 this State's part of the cooperative program of research outlined 

 at the previously cited conferences. The initial step in the in- 

 vestigations ■vvas an inventory of the size and distribution of sea 

 lamprey spaimir.g runs entering Michigan streams in the spring. 

 This information is vitally important for it provides a measure of 

 the population to be considered for reduction and a basis for cost 

 estimation for certain proposed controls. Tlie results of this in- 

 ventor^'- conducted in 19U7 and I9I48 follow, preceded by a summary 

 of the records which illustrate the spread and increase of the sea 

 lamprey in the i.ipper Great Lakes. 



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