7 GEORGE V SESSIONAL PAPER No. 38a A. 1917 
ON THE SCALES OF THE SPRING SALMON. 
By C. McLean Fraser, Ph.D., Curator Pacific Coast Biological Station, Departure 
Bay, British Columbia. 
A paper on “ Growth of the spring salmon ” was read at the San Francisco meeting 
of the Pacific Fisheries Society, August 9-11, 1915, and appears in the proceedings 
of that meeting. A more detailed analysis of the data on which it was based and of 
data obtained from new material, is here presented. 
» The spring salmon (Oncorhynchus tschawytscha), otherwise known as the king, 
tyee, chinook, or quinnat, has been the most highly favoured for investigation of all 
the Pacific Coast species, and much good work has been done by Rutter, Gilbert,. 
Chamberlain, and others, largely in connection with the United States Bureau of 
Fisheries. By means of long-continued observations, these men and their associates 
have been able to put on record many facts concerning the life-history of this valuable 
species. In this instance, some additions, obtained by the methods recently made use 
of in the North Sea investigations by Hjort, Dahl, and others, are offered. MceMurrich 
and Gilbert have included the spring salmon in the species of which the age at 
maturity was discussed. Incidentally, that phase of the study of scales will be con- 
sidered in connection with an investigation into the rate of growth, and its bearing 
on the life-history of the species. 
The validity of the conclusions drawn from scale study depends largely on the 
Interpretation of the “annual rings” or “ winter checks.” The propriety of intro- 
ducing these terms has been seriously questioned by many whe have failed to see such 
a significance in the portions of the scale under discussion. It seemed useless to go 
on with scale investigation unless some definite assurance could be obtained on this 
point. Two species, the Pacific herring and the spring salmon, may be obtained 
throughout the year in the strait of Georgia, and hence these offered a basis for 
information. For reasons given later, the spring salmon was chosen and an investiga- 
tion that began with the idea of personally settling the “ winter check” question was 
enlarged to include other points in connection with the life-history. 
THE “WINTER CHECK.” 
There is no disputing the fact that in the scales of some species of fish there are 
areas arranged concentrically, having a different appearance to the remainder of the 
scale. As they are concentric they may be appropriately called “rings.” Under 
normal conditions of growth is there one of these rings formed on each scale during 
each year? 
Einar Lea has investigated the matter in the case of the North Sea herring, and 
the argument he advances is a convincing one. By examining herring of the same 
year class, caught at short intervals over a considerable period, and from these getting 
measurements, he concluded that the somewhat transparent ring on the scale was 
formed during the period from December to March, the main growth of the scale or 
almost the entire growth, taking place during the other months. Though this ring is 
annual and is produced during the winter months, his evidence shows that the rate 
of growth is not primarily dependent on temperature. 
1A study of the growth of herrings, Publ. de Circonstance, No. 61, Conseil Perm. Inter. pour 
VExplor. de la Mer, 1911. 
38a—24 21 
