September 1966 



COMMERCIAL FISHERIES REVIEW 



15 



about 15.7 million fish since rehabilitation of 

 the lake trout fishery began in 1958. 



The remiarkable comeback of the lake 

 trout attests to the success of the control 

 efforts and replanting with hatchery-raised 

 stock. Natural reproduction now is return- 

 ing, the Bureau of Commercial Fisheries 

 said, pointing out that in fall 196 3, one of its 

 research vessels made the first catch of 

 natural (not produced in a hatchery) lake 

 trout in Lake Superior since 1959. Also, 

 the whitefish and rainbow trout fisheries 

 have improved in Lake Michigan as an extra 

 bonus of the war on sea lampreys. 



The stocking program was initiated in 

 Lake Michigan in 1965. For Lake Huron, 

 plantings with selected hybrid splake (a 

 combination of lake trout and speckled or 

 brook trout) are being scheduled to coincide 

 with the sea lamprey control program and 

 are expected to get under way in 1969. This 

 new species, developed by Canadian fishery 

 scientists as a result of a decade of selective 

 breeding research, is expected to offer a 

 special advantage over the lake trout since 

 it will mature and reproduce at an age of 

 three years or earlier, before reaching the 

 size at which it becomes vulnerable to sea 

 lamprey predation. Lake trout become vul- 

 nerable at about four years of age, but do not 

 mature and reproduce until seven years of 

 age. 



Efforts to find commercial uses for sea 

 lampreys to compensate for the destruction 

 they cause have been unsuccessful. They 

 are unacceptable to Americans as a food, 

 although they are eaten in many European 

 countries. Analyses indicate that oil yield 

 and Vitamin-A potential are much too low 

 for commercial exploi tation. 



Note: See Commercial Fisheries Review « October 1965 p. 31, 



Great Lakes Fisheries Explorations 

 and Gear Development 



SEASONAL DISTRIBUTION AND ABUNDANCE 

 STUDIES OF ALEWIFE AND CHUB 



IN LAKE MICHIGAN CONTINUED: 



M/V "Kaho" Cruise 33 (June 7-23, 1966): 

 To further knowledge regarding the seasonal 

 abundance, distribution, and availability of 

 alewife and chub stocks, upon which the com- 

 mercial fishing industry in Lake Michigan 



has become more dependent since the de- 

 terioration of other prime fish stocks, was 

 one of the objectives of this cruise by the 

 exploratory fishing vessel Kaho . The vessel 

 is operated by the Bureau of Commercial 

 Fisheries, U. S. Department of the Interior. 



- TRAVn MAC 

 -SKAG ENOXJMTEREO. 

 FATHOM COHTQUH. 



Lake Michigan explorations by M/V K»ho Cruise 33 (June 7-23, 

 1966). 



The Bureau, through various research and 



development studies, is striving to improve 

 the economic utilization of alewife and chubs. 

 The low -co St, high -volume production of 

 those species by trawling makes it possible 

 to use them for pet food, mink food, or fish 

 meal. Such use is still increasing. In 1965, 

 a total of 14.1 million pounds of alewife and 

 0.9 million pounds of chubs from Lake Mich- 

 igan were used for that purpose. 



The major objective of this cruise was 

 monitoring the availability of the alewife 

 population to bottom trawls at a time of the 

 year when they become difficult to catch-- 

 especially on the west side of southern Lake 

 Michigan. Special emphasis was placed on 

 exploration of shoal water areas. Secondary 

 functions of the cruise were to provide fish 

 samples for studies in relation to pesticides 

 and botulism, collect information on lake trout 

 populations, obtain length and fin-clip records 

 for each trout taken during the cruise, and 

 preserve specimens for lake trout food studies 

 conducted by the State of Michigan Conser- 

 vation Department. 



A total of 33 exploratory drags was com- 

 pleted in southern Lake Michigan during the 



