Introduc tion 



As the result of a special Congressional appropriation (Public 

 law 2u9-8lst Congress) the Service's sea lamprey investigations were 

 greatly expanded at the beginning of the 1950 calendar year. A per- 

 manent staff of seventeen individuals with an equal number of seasonal 

 employees was assigned specifically to these investigations. Permission 

 to occupy the former Hammond Bay Coast Guard Station on northern Lake 

 Huron was obtained from that agency and the nine buildings and other 

 properties involved are now known as the Hammond Bay Fishery Laboratory. 

 Alterations and additions to provide office and laboratory space, run- 

 ning-water aquaria and tank rooms, work shop, net-shop, boathouse, and 

 raceway facilities have been completed or are in progress. Considerable 

 time and energy have been expended to equip this field station and in 

 training the permanent staff. 



A number of investigations of both the biology of the sea lamprey 

 and of methods of controlling that parasite are currently underway. 

 This report is the first of a series describing the results of one 

 group of studies and activities brought to a conclusion during the 1950 

 season. Subsequent reports will treat other phases of the work. 



Installation and operation of sea lamprey control structures in 19 $0 



Lake Huron . — In northern Lake Huron 11 weirs and traps were operated 

 in an area which was termed Control Zone H-l. This zone extends a dis- 

 tance of about 90 miles from Waugochance Point at the west end of the 

 Straits of Mackinaw to the southern boundary of Presque Isle County, 

 Michigan (Figs. 1 and 2). Weirs were placed in every stream in this zone 

 in which sea lampreys were known to run. Among these structures were the 

 Ocqueoc River and Carp Creek weirs which were operated in former years. 

 During the 1950 season these two traps were run cooperatively with the 

 Michigan Department of Conservation by crews made up of employees of 

 both agencies. With the exception of the permanent- type Ocqueoc weir 

 all others installed were standard, portable-type sea lamprey weirs 

 (Figures 3, 4, and 5). Complete runs were captured in all but two 

 streams and in these, only a minor escapement occurred. 



The objectives in establishing this "control zone" were manifold 

 and may be briefly outlined as follows: 



(1) To institute immediately a measure of sea lamprey control on an 

 organized basis. Experience gained from such an operation would be, 

 and was, invaluable in revealing administrative and operational problems 

 which would present themselves in a large-scale control program; 



(2) To determine whether destroying the potential to produce sea 

 lampreys in the streams tributary to a limited area of shoreline would 



