LIFE HISTORY OF LAKE HERRING OF LAKE HURON 267 



INTRODUCTION 



The most extensive inland fisheries of this country, those of the Great Lakes, 

 had an output in 1922 of more than 102,000,000 pounds, and the gross return to the 

 fishermen was some $6,500,000.' Statistics of the Great Lakes fisheries have been 

 collected for United States waters nine times, at intervals varying from three to 

 nine years. In 1893, 1899, and 1903 the whitefish and herring statistics were variously 

 combined in the several lakes with those of other species of fish. The statistics 

 collected in the other years show that on the average 49 per cent of the product has 

 consisted of species of whitefishes and herrings, fishes constituting the family Core- 

 gonidse. Attention has been called often to the depletion of the coregonid fisheries. 

 (See P. Reighard, 1910, and citations for the whitefish.) As the result of an exhaus- 

 tive study of the history of the coregonid fisheries of the Great Lakes recently com- 

 pleted for the United States Bureau of Fisheries, Dr. Walter Koelz (1926) concludes 

 that, on the whole, these species are dmiuiishing in varying degrees in all the Great 

 Lakes. 



Proper measures of conservation or rehabilitation can be formulated only after 

 thorough study of all phases of the biology of the individual species and of the eft'ect 

 of the fishing industry on them. Doctor Koelz has laid the foundation by describing 

 the species and by collecting data on their occurrence and life history and on the 

 fisheries. The present study aims to contribute by other methods to our further 

 knowledge of the biology of the coregonids. 



Many investigators in many countries have found it possible to determine the 

 age and rate of growth of fishes by a statistical study of the structure of the scales. 

 The same characters often have permitted the discrimination of local races not other- 

 wise distinguishable. The method is referred to currently as the scale method. 

 The results, embodied in a voluminous literature, have been used in formulating 

 fisheries regulations. The method has been used for determining the age of core- 

 gonids by Seligo (1908), Heide (1912), Jarvi (1920, 1924), Clemens (1922), Couch 

 (1922), Van Oosten (1923), Prawdin (192,5), and Riakhovsky (1925), and divergent 

 views have developed as to its validity. Before applying the method extensively to 

 the coregonids of the Great Lakes, therefore, it has seemed best to test its basic 

 assumptions and its applicability to a coregonid species. 



THE PROBLEM 



This paper, based on the structure of the scales and on the weights and measure- 

 ments of a single coregonid species, attempts (1) to determine whether the structural 

 characters of these scales are so clearly recognizable as to permit their use by the scale 

 method; (2) to determine from the same material, if usable, how far the fundamental 

 assumptions underlying the method are warranted (this involves a critical study of 



' For detailed statistics see Sette (1925 and 1928) and U. S. Tariff Commission, Taritf Information .Series No. 36, 1927. For 

 statistics of the Canadian waters see the annual reports of the game and fisheries department of Ontario, Canada. The manu- 

 script for this paper was submitted to the bureau in June, 1927, and has not been revised to include data and reviews of 

 publications that have appeared since January, 1927. 



