4 
bulletin of The bureau of fisheries 
This may be accepted as an adequate statement of our belief respecting these 
species up to the present time. It has lacked in definiteness and in detail. No con- 
clusive evidence has been presented concerning the age of the markedly undersized 
fish or “grilse,” which are conspicuous parts of the king salmon and sockeye runs. 
We have no knowledge concerning the extreme age which any species may attain, nor 
concerning the proportions in which different ages are represented in the spawning run. 
Furthermore, the question of size with relation to age has been wholly undetermined, 
the belief being yet widely entertained that no such relation exists, size being solely 
dependent on richness of feeding in the sea. 
There remains to be noticed a recent attempt by Prof. J. P. McMurrich “ to solve 
these problems by a consideration of scale and otolith markings. The figures of scales 
and otoliths presented in this paper show sufficiently that these structures present 
seasonal markings which when correctly interpreted will afford reliable indication of age. 
It is to be sincerely regretted that Prof. McMurrich’s interpretations have been based 
on inadequate data, and these have misled him into announcing a series of conclusions so 
largely erroneous as to confuse rather than clarify the questions at issue. A further 
discussion of these matters will appear under each of the species considered below. 
The present paper contains a purely preliminary statement of certain facts in the 
history of our salmon which can be substantiated through a study of scale structure. 
This method offers certain obvious advantages over that of determining the age by 
marking the young, although the latter method should be employed and rigidly super- 
vised in corroboration of the former. But the scale method is of unlimited application. 
Any desired number of individuals can be investigated in connection with size and sex and 
other modifying factors. It thus becomes possible to analyze an entire salmon run into 
its age components, and each of these can then be the subject of further investigation and 
analysis. We can thus determine the range in size of each group and of the males and 
females separately for each age, and when definite events in the life history of the fish 
record themselves upon the scales — as we believe to be the case — corresponding cate- 
gories can be formed and the possible effects of these events on growth and period of 
maturity can be determined. A very wide usefulness, therefore, attaches to this method, 
and for its proper elaboration discriminating study of many thousand specimens must 
be made. 
While the method is new as regards Pacific salmon, it has been experimentally 
tested and fully approved by the Fisheries Board for Scotland in the case of the Atlantic 
salmon, and is now universally accepted as furnishing reliable data as to the age and 
many other facts in the life history of that fish. It has been shown to be applicable also 
to various species of trout, and its value has been demonstrated in fishes as widely 
divergent as the carp, the eel, the bass, the flounder, and the cod. Descriptions of this 
scale structure and its significance have appeared in a large number of papers, both 
scientific and popular. It will suffice here to repeat that the scale in general persists 
throughout life, and grows in proportion with the rest of the fish, principally by addi- 
o The life cycles of Pacific coast salmon belonging to the genus Oncorhynchus, as revealed by their otolith and scale 
markings. Transactions Royal Society of Canada, 1912. 
