August 1966 



COMMERCIAL FISHERIES REVIEW 



31 



A total of 44 drags was completed with a 

 52-food (headrope) fish trawl in southern and 

 central Lake Michigan. All drags were of 30 

 minutes duration except 16 which were short- 

 ened due to large catches and one which 

 snagged on a bottom obstruction. Bottom top- 

 ography and fish concentrations were contin- 

 uously monitored and recorded with a high 

 resolution echo-sounder. 



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Fig. 3 - Lake Michigan explorations by R/V Kaho Cruise 32 (May 

 2-20, 1966). 



Very good catches of alewife were taken in 

 4 of the 6 areas checked as follows: 8,000 

 pounds in 1 minute in the entrance piers at 

 Port Washington; 1,800 pounds in 15 minutes 

 at 20 fathoms off Waukegan; 6,350 pounds in 

 15 minutes inside Chicago Harbor; and 3,100 

 pounds at 5 fathoms off Benton Harbor. None 

 of those areas are being fished by commercial 

 fishermen. Best catches of alewife off White 

 Lake and Ludington were only 150 and 650 

 pounds, respectively. Chubs were taken in 

 significant quantities between 25 and 40 fath- 

 oms off Waukegan and Ludington only. 



Fishing (bottom) temperatures during the 

 cruise ranged from 37° to 4 4° F. 



NotS See Commercial Fi sheries Review , July 1965 p. 27. 



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Great Lakes Fishery Investigations 



BIOLOGICAL RESEARCH AND 



SEA LAMPREY CONTROL MAY 1966: 



Some of the highlights of Great Lakes bio- 

 logical research during May 19 66 by the Bio- 

 logical Laboratory at Ann Arbor, Mich., op- 

 erated by the Bureau of Commercial Fisheries : 



Sea Lamprey Control : The mid -seas on 

 returns of spawning-run sea lampreys at the 

 assessment barriers on Lake Superior were 

 most encouraging in May 1966 since a 50-per- 

 cent reduction from the previous 4 -year low 

 level was becoming evident. The total catch 

 of sea lampreys at the end of May was 2,301, 

 compared with 5,275 lampreys a year earlier. 

 Optimism was running high because a signifi- 

 cant decline occurred in the Brule River where 

 81 sea lampreys hadbeentaken as of that time, 

 compared with 2,838 a year earlier. The catch 

 from the 3 index barriers on tributaries of 

 northern Green Bay also showed a decrease. 

 A total of 786 sea lampreys was taken com- 

 pared with 2,158 at the same time in 1965. 

 The Ocqueoc River barrier located in north- 

 ern Lake Huron captured 673 lampreys, com- 

 pared with 871 a year earlier. 



Chemical treatment of lamprey-producing 

 streams progressed rapidly during May. Ini- 

 tial treatments were completed on the 5 re- 

 maining sea lamprey streams in Lake Michi- 

 gan. They were the Galien River, Donns Creek, 

 State Creek, Trail Creek, and Burns Ditch, all 

 tributaries along the south shore of the lake. 



Completion of the scheduled treatment of 

 Lake Superior streams during fall 1965 has 

 allowed the laboratory's Marquette chemical 

 unit to gain ground on next fiscal year's 

 schedule in Lake Huron. With the approval of 

 the Great Lakes Fishery Commission, 9 lam- 

 prey-producing tributaries of northern Lake 

 Huron were treated for the first time. 



Lake Michigan Research : The Laboratory's 

 research vessel Cisco completed a biological 

 cruise on May 31 in southeastern Lake Mich- 

 igan. One of the principal objectives of the 

 cruise was to fish for alewife and yellow perch 

 larvae and to collect alewives from perch 

 spawning grounds. Collections of other spe- 

 cies and crustaceans also were made to pro- 

 vide material for laboratory studies. 



Yellow perch began spawning in May off 

 Saugatuck, Mich., at the termination of the 

 cruise. However, about half of the mature 

 females had spawned in the vicinity of Mich- 

 igan City, Ind. Examination of stomachs from 

 alewives taken from the perch spawning grounds 

 revealed no perch eggs. 



Preliminary information from laboratory 

 feeding experiments designed to determine 

 food preferences of lake trout indicated an ap- 

 parent dislike for alewives. Lake trout from 



