TWhite suckers, as a rule, migrated concurrently r.-ith the sea 

 lampreys (Appendix D). Like the lamprey, their greatest migratory 

 activity came at temperatures of $0 degrees F. or higher. Golden 

 redhorse suckers moved during verj^ short periods between late April 

 and mid-l!ay and usually before the peak of the sea lamprey rxin. 

 Lalce chubs attained the peak of their migration during and shortly 

 after the major upstream movement of sea lampreys and wliite suckers. 

 The maximum ingress of Great Lakes longnose dace vras generally prior 

 to that of the aforementioned two species. Smelt runs took place, 

 and ended, as the scattered early migrants among the sea lampreys 

 penetrated the stream. 



Other species entered the traps in small numbers throughout 

 the periods of weir operations. Numbers taken, hoivever, were 

 insufficient to reveal periodicity in migratory activity (Appendix D). 



(3) Species and numbers bearing lamprey scars 



All suckers, trouts, northern pike, rock bass, and bullheads 

 talcen in the traps were examined for evidence of lamprey attacks. 

 Of those individuals which were lamprey scarred, few bore wounds 

 so fresh that they could have been inflicted while the fish was 

 traversing the short distance from the stream mouth to the trap. 

 For the same reason they could not have been inflicted in the trap 

 itself, Com.parison of these fish irith a series of scarred "vdiitefish 

 and "chubs" (deepwater ciscoes) taJcen in Lalce Huron, on some of 

 which the lampreys vrere still attached when the nets vrere lifted, 

 supports this view. On the latter, the scars had a bright red, 

 raw appearance which was seldom approached in freshness of appear- 

 ance in the specimens talcen in the trap. Furthermore, only one 

 instance of recent feeding was found among the captured sea lampreys 

 (the digestive tracts of nearly all trapped lampreys tai:en in 19h7 

 and 19h8 were opened and found to be empty) , Tlie exception vras a 

 17c 3-inch, female sea lamprey talcen on May 1, 19^75 i'ts intestine 

 ivas partially distended T.vith blood. This specimen was in a retarded 

 state of sexual maturity as evidenced by the condition of its liver 

 and the underdevelopment of the gonad. This evidence that trapped, 

 scarred fish were attacked sometime prior to their entrance into 

 the stream is emphasised since the concentration of so many fish 

 and lanpreys moving in the narrow confines of a stream might lead 

 the casual observer to believe that the incidence of attacks noted 

 was directly related to coincident spawning runs of predator and 

 prey. 



In order to relate extent of scarring to possible trends of 

 population, a summary of the pertinent data follows: 



Carp Creek , 191^7 ; — Of the 3,700 white and redhorse suckers 

 transferred upstream, 2^7 or 7,0 percent of the run bore one or 

 more relatively fresh or recent scars. Occasional fish had tv;o 

 lesions and two instances were noted of three on a single fish. 



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