42 



THE MIGRATION AND CONSERVATION OF SALMON 



as active fish in the summer, they do not 

 scatter widely and far as do salmon in 

 ocean water entering the Gulf on the New- 

 foundland side of Cabot Strait (Fig. 8) but 

 fail to leave the steady zone of influence of 

 the St. Lawrence and associated rivers that 

 fills the southern part of the Gulf and 

 passes out through Cabot Strait along the 

 Cape Breton coast. In this zone they move 

 rather far and widely to the west and 

 south, where there is no Margaree influ- 

 ence, but not quite so far to the north and 

 east, whither the influence extends. In 

 these movements to other districts, there is 

 to be observed the phenomenon that Men- 

 zies (1937 and 1938) has described for sal- 

 mon of the Scottish coast. Those showing 



Fig. 8. Fastest rates of travel of salmon to 



VARIOUS points AS LIBERATED IN 1937: (1) 



OFF Port-aux-Basques, Newfoundland, and (2) 



NEAR THE MOUTH OF THE MARGAREE EIVER, CaPE 



Breton Island. The comparative rates are 



SHOVPN BY the LENGTHS OF THE ARROWS. 



the fastest rate of travel to a distant dis- 

 trict have a more rapid rate than those with 

 the fastest rate to a nearby district. It 

 might be thought that those going to dis- 

 tant districts travel more rapidly or do not 

 linger on the way. But if caught at the 

 beginning and again at the end of this 

 course why should not some be caught on 

 the way and upset the order? It may be as 

 well to avoid unfounded assumptions and 

 consider whether known things will not ex- 

 plain the phenomenon. Going out from 



shore, the circulation of the water, that is 

 the long-term movement in one direction, 

 becomes more rapid, e.g., from two miles to 

 four miles, to six miles, and even to eight 

 miles per day as shown by drift bottles 

 (Huntsman, 1924). Also, the salmon when 

 near shore or bottom in turbulent tidal cur- 

 rents will orient itself and, where the 

 strength of the current matches its activity, 

 will come to rest in relation to the bottom. 

 Therefore, those salmon that happen to 

 wander farthest out from the coast will be 

 carried most rapidly in the direction in 

 which the water is circulating, and will 

 have least opportunity to come to rest in 

 relation to the bottom. I doubt that any- 

 thing more is required to explain the more 

 rapid rates shown by the salmon that reach 

 distant districts. 



Movements in the River 



It is well established and well recognized 

 that the young salmon (as smolts) and the 

 spawned salmon (as kelts) descend rivers 

 to the sea and that the sexually maturing 

 salmon ascend rivers from the sea. It is 

 not, however, generally appreciated that 

 such directions of movement are far from 

 being invariable. Depending upon the con- 

 ditions with which they are faced, smolts 

 and kelts will ascend as well as descend 

 rivers, and sexually maturing salmon will 

 descend as well as ascend. Nor is it that 

 any physical difficulty prevents the usual 

 behavior. It is clearly a matter of how the 

 individual fish reacts to the conditions to 

 which it is exposed. To understand the sal- 

 mon's movements, it is necessary to under- 

 stand both the way in which the fish reacts 

 and what the conditions are. 



As observed in the Margaree River the 

 salmon parr when at least 4|-inches long 

 in the spring transform into smolts as the 

 temperature rises. This change in nature 

 results in their tending to leave the bottom, 

 coming nearer the surface under the same 

 conditions of light and wandering rather 

 than staying in rapid water. This results 

 in their going downstream to the river 

 estuary, where they collect. With spring- 

 ing tides which empty the estuary very 



