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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



are lost permanently from the breeding popula- 

 tion. But the much greater numbers that remain 

 localized not very far from their parent streams 

 are believed to follow about the same routes on 

 their return journeys that they followed when 

 they went to sea. Thus, only a few are caught 

 on the Nova Scotia shore between the entrance to 

 St. Mary's Bay and Digby Gut, but fish en route 

 to the Shubenacadie River system are taken in 

 some numbers as they follow the shore of An- 

 napolis and Kings Counties (the Annapolis River 

 also yields a few salmon in its lower course, and 

 some are taken in the Annapolis Basin). Simi- 

 larly, salmon approaching the St. John River 

 strike the coast about Point Lepreau (about 23 

 miles to the west) and support an important 

 fishery from there to the mouth of the river. 



A question closely bound to the movements of 

 salmon to the sea is: what proportion of them 

 return to spawn in the very rivers in which they 

 were hatched? It seems demonstrated by a 

 variety of evidence, especially by the recapture 

 of tagged fish, that the majority do return. 

 Huntsman, for example, reports 83 an extraordinary 

 instance, of a kelt taken from the Sackville River 

 on the outer coast of Nova Scotia that was tagged 

 and released in the Shubenacadie River system at 

 the head of the Bay of Fundy, and then found its 

 way out of the Bay, around the Nova Scotia 

 coast, and back again to the Sackville, where it 

 was recaptured. We can only speculate how it 

 directed its course, and why it did not turn in to 

 the mouth of any of the other salmon rivers it 

 passed en route. On the other hand, marked 

 fish are sometimes caught in strange rivers. 

 Fish, for instance, that were tagged in Minas 

 Channel have been caught later in the St. John 

 River. 84 And odd fish appear from time to time 

 in rivers where no salmon have been hatched for 

 many years (in the Merrimac for instance) . 



In short, the parent-stream theory does not 

 always hold. Probably the truth is that while 

 most of the fish never stray far away and do 

 return to the home stream, wanderers that chance, 

 in the spring, to be in the physical state leading 

 to maturity may enter any unpolluted stream 

 they encounter, no matter how far from home. 



Dr. Huntsman's studies, carried on through 

 many years, make it increasingly probable that 



•» Ann. Rept. Fish. Res. Bd. Canada (1947) 1948, p. 33. 



" Huntsman, Ann. Rept. Fish. Res. Bd. Canada (1948) 1949, p. 40. 



the journeyings of our salmon in salt water are 

 not the result of purposeful swimming in a definite 

 direction, but that they tend to drift with the 

 current as herring do (p. 97), so that the direction 

 in which they travel depends chiefly on the depth 

 at which they happen to be, in relation to the dif- 

 ferential circulation of the water at different 

 levels. If so, the St. John River fish tend to drift 

 out with the river water as they scatter. And 

 most of them do appear to remain more or less 

 concentrated in the mid-depths where the princi- 

 pal mixing takes place between the river dis- 

 charge and the water of the open Bay of Fundy, 

 some 20 to 30 miles from St. John Harbor, living 

 where they find an abundance of herring of various 

 sizes as food. Here Dr. Huntsman 85 calculates 

 the space for them is so great that no two of the 

 approximately 50,000 fish that comprise the total 

 yearly catch need be closer to each other than 

 three-quarters of a mile in a layer of water 5 feet 

 thick; so there is no crowding. But the tagging 

 experiments have shown that the fish that go to 

 sea from Minas Channel, where the outflow is not 

 so definitely localized, scatter more widely, some of 

 them drifting right around the Bay of Fundy 

 with the anti-clockwise circulation. 88 



The situation is not so clear for the coast of 

 Maine, partly because of the paucity of present- 

 day information, partly because the several 

 rivers there that once had runs of salmon are so 

 closely spaced along the coast that it is not pos- 

 sible to evaluate their individual contributions to 

 the yearly catches. 



With the relationship between salmon journeys 

 and water movements so extremely complex, all 

 we dare say in this regard is that the inshore drift 

 of the deeper layers (characteristic of circulation 

 of the estuarine type) and the slackening of the 

 offshore drift of the fresher surface water that is 

 to be expected as the spring freshets diminish, 

 may be the cause, at least in part, for bringing 

 the salmon into the estuaries, and close inshore 

 elsewhere, in spring. But the nature of the stim- 

 ulus that impels a salmon to enter fresh water, 

 and then fight his or her way upstream, remains 

 a mystery. 



It is not known whether all the salmon move 

 inshore in spring, or only those that are destined 



" Bulletin 21, Biol. Bd. Canada, 1931, p. 96. 



M This was shown by Huntsman, Ann. Rep. Fish. Res. Bd. Canada (1947) 

 1948, p. 37. 



