Fishes of the JVestern North Atlantic 475 



There is a good deal of evidence that these fish in some way, probably through 

 their olfactory sense, are able to recognize the water of the river in which they spent 

 the early part of their life. Hasler has reviewed the results of observations and experi- 

 ments on the perception of pathways by fishes in migration (5^). He concluded that 

 there is in river and creek water some characteristic odor to which the young become 

 conditioned while they are in the stream and which they recognize and to which they 

 orient upon coming in contact with it. Hasler, et al. (^^^ have carried out experiments 

 that support the theory that fish, when out of touch with the shore or of the water 

 of their natal stream, have a sun-compass mechanism for direction-finding similar to 

 that found in birds (gy) and in bees (4g). 



Coastal and River Spawning Runs. A spawning run usually occurs in two stages, 

 the first being the coastal run, the second the river run. During the coastal run, the fish 

 enter the river mouth or estuary and remain there for varying lengths of time before 

 they actually enter the fresh water on their river run. The river run may take place 

 shortly after the coastal run, or the two stages may be so widely separated that "early 

 running" and "late running" have little meaning as applied to a particular lot of fish. 

 If the fish appear early off the river mouth they may be referred to as "early running" 

 by the commercial fishermen who catch them there, and if their actual entrance into 

 the river is long delayed, they may be "late running" to the anglers who take them in 

 the river. 



With reference to the coastal run, no Atlantic Salmon move in from the sea oft" 

 Canadian rivers when the water is coldest, from January to April, with the probable 

 exception of the southern outer coast of Nova Scotia. Most of the fish that are 

 heading for the rivers of the Maritime Provinces (New Brunswick, Nova Scotia, and 

 Prince Edward Island) appear in coastal waters sometime between late May and July. 

 In Newfoundland, where there is a major and minor coastal run each year (gs), the 

 fish of the major run appear in the latter half of May off St. John's (in the southeast) 

 and progressively later northward, with the fish appearing at Cartwright (Labrador) 

 late in June; this coastal run in the spring is short, and profitable fishing can be pursued 

 for only about three weeks in any one locality; the minor run in the winter is much 

 more restricted, and evidence of it is confined almost entirely to the Avalon Peninsula 

 in the southeast, where some fish are taken in November and December. To the 

 south, in the St. John River, N.B., it has also been observed that some fish, mostly 

 large female grilse, enter the estuary in November and December, where they remain 

 until the following May before ascending the river; however, they do not spawn until 

 October {^g). 



Two of the conditions that determine how long Atlantic Salmon remain in or 

 near the river mouth before beginning their ascent of the river appear to be water 

 temperature and volume of river discharge, with high temperatures and the absence 

 of freshets being nonconducivc to their movement {8g). The Margaree River in 

 northern Nova Scotia presents a striking case of the action of these two factors {63). 

 The Northeast Margaree, which has cool spring water that travels from high land 



