MIGRATION AND CONSERVATION OF ATLANTIC 



SALMON FOR CANADA'S MARITIME 



PROVINCES 



By A. G. HUNTSMAN 



FISHERIES RESEARCH BOARD OF CANADA AND DEPARTMENT OF BIOLOGY, UNIVERSITY OF TORONTO, 



TORONTO, ONTARIO 



The view that the salmon migrates from 

 its river far out into the ocean to specific 

 grounds in order to find abundant food, 

 and that at the appointed season it mi- 

 grates back by instinct to its river in order 

 to spawn is simple, clear-cut and in ac- 

 cordance with certain well-established 

 facts. Salmon do leave the rivers, do grow 

 rapidly and become fat in the sea, do re- 

 turn to the rivers at rather definite seasons 

 and do spawn in the rivers after return. 

 The history of knowledge shows us, how- 

 ever, that the simple and obvious interpre- 

 tation of the facts may, with fuller knowl- 

 edge, have to be modified or abandoned, 

 and that things are much more complex 

 than they at first appear to be. That the 

 earth is flat and that the sun rises in the 

 east and sets in the west seem so simple 

 and in accordance with fact that not a few 

 people still refuse to accept the more com- 

 plicated conception of a spherical, rotating 

 earth, one of quite a number of planets in 

 a system, of which the sun is the center. 

 Scientists, however, insist that with all the 

 facts the conception of the solar system is 

 necessary. 



The facts that have been accumulating 

 in relation to the Atlantic salmon of the 

 Canadian Maritime provinces have forced 

 me to abandon or modify the simple view of 

 salmon migration and to realize that the 

 salmon's movements form a very compli- 

 cated picture. Some salmon do not leave 

 the river system, most of them seem not to 

 go far out in the ocean, there seem to be no 

 specific feeding grounds, the time of re- 

 turn to fresh water varies greatly with 

 conditions and quite a considerable number 

 of the salmon from some rivers scatter 

 widely and may enter very distant rivers. 



It has been customary to refer such di- 

 versity in behavior to differences in the 

 nature of the salmon, that is, to differences 

 in racial inheritance. However, the struc- 

 tural peculiarities that have been relied 

 upon to distinguish races are being shown 

 one after the other to be produced by dif- 

 ferences in environment during the devel- 

 opment of the individual, and, therefore, 

 not to be heritable. Like the structural 

 peculiarities, the differences in behavior 

 are themselves proving to be related to en- 

 vironmental differences. In a recent ex- 

 periment (White and Huntsman, 1938) the 

 fry from Restigouche River salmon, which 

 return to the river principally after two or 

 three years in the sea, many of them early 

 in the season, were planted in the east 

 branch of the Apple River at the head of 

 the Bay of Fundy. Their behavior was in- 

 distinguishable from that of the local sal- 

 mon, for they returned to the river almost 

 wholly as grilse, that is after one year in 

 the sea, and only late in the season. That 

 the environment alters behavior is un- 

 doubted. It has yet to be proved that there 

 are differences in behavior of the Atlantic 

 salmon that are heritable. 



This recently developed view of the im- 

 portance of the environment in determin- 

 ing the behavior of the salmon has now 

 made it necessary to study the physical 

 conditions to which the salmon of any par- 

 ticular river are exposed, if one is to expect 

 to be able to understand their behavior. 

 The burden of work for the investigator is 

 a heavy one, since the difficulty of follow- 

 ing the salmon's movements is great 

 enough without having to procure data on 

 the various factors that may affect those 

 movements. Progress must inevitably be 



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