24 V. S. BUREAU OF FISHERIES 



A preliminary report dealing with the fishery industry of the 

 Great Lakes, which is supported largely by the coregonines, has 

 been submitted for publication. The first draft of the accounts of 

 the systematic relationships and natural history of 7 of the 11 spe- 

 cies, and illustrations of the various forms, have been prepared, and 

 it is hoped that the final report may soon be ready for the press. 



The investigation of the life histories of the coregonine fishes of 

 Lake Huron has been continued and extended during the past year. 

 Two investigations have been conducted in the field with the financial 

 support of the department of conservation of the State of Michigan. 

 The first was carried on in the region of Alpena, Mich., with the 

 principal object of obtaining additional material and data on the 

 Slackfin, a species gradually undergoing extermination. More than 

 2,500 coregonine scales were secured, of which 1,250 were taken from 

 blackfins. Many of the bays of Lake Huron were seined for juvenile 

 coregonines, but none were obtained. The second expedition in- 

 volved a survey of the waters of Grand Traverse Bay, Lake Michi- 

 gan, and four inland lakes — Elk, Torch, Pine, and Walloon. These 

 waters were studied primarily for the purpose of collecting data on 

 the distribution and ecology of the coregonines, and on the habitat 

 of the juvenile fish. A report of this survey has been prepared. 



During the past year the final report covering most of the work 

 of the last two years was completed and is now being prepared for 

 publication. In it the scientific status of scale study, as applied to 

 the lake herring {Leucicthys artedi)^ is critically discussed. By this 

 method a rather detailed and complete life history has been worked 

 out for the herring and a less complete one for the whitefish, black- 

 fin, and pilot. 



With regard to the herring it was found, among other things, that 

 from 87 to 97 per cent of the commercial catches of herring con- 

 sisted of individuals in their third, fourth, and fifth year of life, 

 and that no one year class predominated for more than one year. 

 Another thing of interest is the fact that the herring of Saginaw 

 Bay suddenly increased their rate of growth during and since the 

 year 1919. This sudden acceleration in growth in Saginaw Bay is 

 correlated with improvements in the environmental conditions in the 

 bay. Many historical data on the pollution of Saginaw Bay were 

 obtained, and they showed that the increased growth rate is cor- 

 related with decreased pollution. The growth of the Bay Citj 

 herring was compared with that of herring taken at 11 other locali- 

 ties on Lake Huron. 



"A Study of the Scales of Whitefishes of Known Ages." by Mr. 

 Van Oosten. has been published by the New York Zoological vSociety. 

 It is believed that the results of this scale study will give an added 

 value to future investigations of this kind, for never before has 

 such material been available for study. Scales from whitefish 

 hatched in January. 1913, from eggs from Put in Bay hatchery 

 and reared in the New York aquarium were examined. The scales 

 studied were removed from fish that Avere in their eighth and ninth 

 year of life. It was found that the annuli in the scales of the 

 aquarium whitefish corresponded in number with the winters of 

 the fishes' lives, not including the first one, in which the fish were 

 hatched. The ages of whitefish may therefore be determined from 

 their scales. These annuli were winter marks, formed on the re- 



