C'AXADIAN FIS^HERIES EXPEDITION, 191 'rl5 159 



the fish had not yet commenced their growth, while the remaining samples revealed a 

 distinct new summer helt on the scales. 



An interesting feature in connection with these fish is the fact that tlic summer 

 growth commences so late. Off the coast of Norway, the new summer growth com- 

 mences in April ; but far up in the Baltic, near the coast of Finland, similar conditions 

 are observed. Hellevaara (IV) who has investigated the herring of these waters, 

 observes in this connection; " Not imtil the 27th of June did I observe that the scales 

 had begun to grow on the young fish 1 or 2 years old; but not on those which had 

 reached maturity.'' 



XIV. EESULTS OF AGE AND GROWTH STUDIES, VIEWED IN THE LIGHT 

 OF OBSERVATIONS AS TO RACIAL CHARACTERS. 



In the foregoing I have endoavinired, by analysis of the age determinations and 

 growth measurements made, to arrive at a satisfactory solution of some of those 

 problems which group themselves about the two more comprehensive questions, as to 

 the numerical proportions of the different year-classes, and the growth of the fish in 

 different waters. It became very soon apparent, during these studies, that the area, 

 within which the samples analysed were collected, presented contrasts often most 

 pronounced, and it would therefore be natural to consider both age and growth obser- 

 vations against the background, so to speak, of the third problem, viz., whether several 

 more or less distinctly different races of herring could be shown to e.xist within 

 the area investigated. 



We may therefore, in conclusion, glance at this question, while considering the 

 observations as to racial characters, and discussing the possibility of employing growth 

 observations as a means of distinguishing races. 



The results of the age and growth studies bearing on this problem may be briefly 

 summed up as follows: The different waters exhibit different conditions with regard 

 to the age-composition in the samples and the growth of the fish. 



In seeking foij the cause of the differences observed between samples from 

 different waters, and of the resemblance between those from the same locality, we are 

 naturally led to the supposition that several local tribes or races of herring must 

 exist, each having its own particular area of distribution. Without such hypothesis, 

 it would appear difficult to understand how the different waters could differ so 

 remarkably with regard to age and growth of the fish, as seen, for instance, in the 

 marked dissimilarity between the 'herring of the ^Magdalen islands and those taken off 

 the coast of Newfoundland, despite the short distance — but a few days' swim — between 

 the two localities. By presupposing the existence of such local races, we are at least 

 able to accept without surprise the fact that such differences do exist, albeit we can, 

 from our present slight knowledge of the subject, form but vague and uncertain ideas 

 as to how the differences in question may have arisen. 



It would therefore be must useful, if other methods of investigation could be 

 brought to bear upon the problem as to existence of local races in these waters. One 

 in particular immediately suggests itself, to wit, that formulated by Heincke for the 

 very purpose of studying the racial distribution of the herring, by arithmetical descrip- 

 tion of the morphological features. 



As mentioned in the introduction, countings of vertebrae, fin-rays, and keel- 

 scales were carried out with a number of herring from different waters, at the time 

 the material was collected. These observations should, however, as Dr. Hjort has 

 pointed out in his preliminary report, only be regarded as of a tentative character, 

 the samples in question being few and small. Hence, I can, as a matter of fact, add 

 but little to what Dr. Hjort lias already stated with regard to these observations; 

 nevertheless, it may yet be of interest to consider them here in connection with what 

 has been set forth in the foregoing pages respecting age and growth. 



