Great Lakes Fishery Investigations 

 Ann Arbor, Michigan, U. S. A. 



NOTICE TO FINDER Drift Card No 



This card is being used to study currents of the Great Lakes. Please fill in blank 

 spaces. Mail every card you find. Canadian postage will be replaced. You will be 

 told the time and place this card was released. Thank you. 



a. ni. 

 -. p. in. 



Time of recovery: Date Hour . 



Was a metal fin attached to the bottle? Cj Yes; LJ No 

 Exact location card was found -_ 



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Remarks: 



(City) 



(County) 



(State) 



Please print : 



(Name) (Address) 



U. S GOVERNMENT PRINTING OFFICE 16 — 71459-1 



Jigure 3. — Reply card similar to that placed in each bottle. 



Reply cards (fig. 3) were placed in 

 4-ounce Boston-round bottles after which 

 the bottles were stoppered with corks and 

 the stoppered ends dipped into beeswax. 

 Several drops of beeswax were then placed 

 in the bottle caps and the caps screwed on 

 the bottle. Drags were squares of 28-gage 

 galvanized metal (4" X 4") so cut arid 

 bent that water movement from any 

 direction struck areas of the three 

 planes of the drag. During periods 

 of high winds cind heavy seas the 

 horizontal fin of the dreig would in- 

 hibit vertical movement so the bottle 

 would be under the surface much of 

 the time. 



Studies on Ljike Michigan in 1955 

 disclosed that many bottles lost 

 their drags before they were washed 

 eishore. The comments of finders 

 indicated that the drags were lost 

 because the soft iron suspension wire 

 was broken at the neck of the bottle. 

 The break was caused, most likely, 

 by the bending of the wire as the 

 bottle was moved by the waves. In 

 the Saginaw Bay-Lake Huron project, 

 loss of drags was reduced by placing 

 a brass ring in the suspension wire 

 at the neck of the bottle (fig. 2). 

 The bottle could then move freely 

 without bending the wire. As satis- 

 factory as this arrangement proved 



to be, it did not end loss of drags. Of 

 1,076 bottles recovered within 29 days 

 after release, only 18 (1.7 percent) had 

 lost their drags. Of 523 bottles recovered 

 after more than 29 days, 168 (33.3 percent) 

 had lost their drags (table 1). Undoubtedly 

 some of the 523 bottles recovered after 



Table 1. — Loss of drags from drift bottles released in 1956 

 in relation to number of days between release ajid recovery 



