Stauffer sought to explain the continued down- 

 stream runs of recently transformed individuals on 

 the basis of either a longer larval lifespan (as 

 much as 8 or 9 years) or, the sporadic addition of 

 further generations of larvae to the population fol- 

 lowing escapement of adults to the spawning 

 grounds. The possibility of a longer larval life 

 than originally postulated cannot be dismissed. On 

 the other hand, there is little doubt now that some 

 adults have escaped to the spawning grounds and 

 that their spawning is largely responsible for the 

 continued runs of recently transformed sea lampreys. 



In view of these circumstances, the records 

 in this report can in no way be utilized to deter- 

 mine accurately the maximum duration of the lar- 

 val life of the sea lamprey. 



LITERATURE CITED 



Apple gate, Vernon C. 



1950. Natural history of the sea lamprey 

 (Pettomyzon marinus ) in Michigan. 

 U. S. Fish and Wildlife Service, 

 Special Scientific Report: Fisheries 

 No. 55, 237 p. 



Applegate, Vernon C. , and Clifford L. BrynUdson 

 1952. Downstream movement of recently 



transformed sea lampreys, Petromyzon 

 marinus , in the Carp Lake River, Mich- 

 igan. Transactions American Fisheries 

 Society, vol. 81 (1951), p. 275-290. 



DOWNSTREAM MOVEMENT OF FISHES 



Nearly all fish captured in the downstream 

 trap during the 10 years of operation were identi- 

 fied as to species. The numbers and kinds of these 

 fishes, other than lampreys, that were taken are 

 summari/zed by semimonthly periods in tables 14 

 through 23. Total lengths of fish in occasional 

 samples of most species were measured to the near- 

 est 0. 1 inch. Where these data are available, they 

 are included as footnotes to the tables. A list of 

 the common and scientific names of all species 

 taken in the trap catches is given in table 24. 



ACKNOWLEDGMENTS 



The Carp Lake River dam and inclined -screen 

 trapwereconstructed by the Michigan Department 

 of Conservation. The structure was operated by 

 Mr. Albert N. Gabrielson, an employee of that 

 Department. The cooperation of the Department 

 of Conservation in permitting me to supervise the 

 operation of the trap is gratefully acknowledged. 

 I also wish to thank Mr. John H. Howell, Mr. 

 Alan Rick, Mn. Rose L. Hoffman, and Mrs. Janet 

 K. Webster for assistance in measuring and weigh- 

 ing specimens and in tabulating the data. 



