Fishes of the Western North Atlantic 477 



fish often spawn only a short distance above the head of tide. It has also been observed 

 that most of the rivers having only fall runs are small, with their spawning grounds 

 relatively short distances from the river mouth. The Miramichi is the only large 

 Canadian river that has a fall run. 



As they gradually work their way upstream, from one resting place to another, 

 they assemble in the deeper and stiller parts; these are known as salmon pools to 

 anglers. In some rivers they must ascend through long stretches of turbulent rapids, 

 some of which culminate in falls. Whether or not the fish can surmount falls depends 

 on the configuration and height of the falls and on the amount of water at the base; 

 the deeper the water the higher they can leap, but 10—12 feet seems to be the maximum. 

 Salmon leap" not only in attempting to surmount falls but in the quieter stretches of 

 the river, and at sea. 



Differences and Changes in Composition of River Runs. Salmon entering each river 

 system have certain characteristics, such as smolt age, size, length of sea-life, and time 

 of running (early or late), that distinguish them from those of other rivers; and 

 these characteristics, with minor variations from year to year (9 : 304), tend to persist 

 over long periods of time. For Newfoundland waters it has been demonstrated {g^) 

 that there are no fewer than 25 classes of fish with different life histories, and ^Z 

 types are listed as likely to be found in these waters. According to the laws of permu- 

 tations and combinations, a very large number of types could and possibly do occur, 

 some of them rarely. 



Spawning runs consist of both grilse and older Atlantic Salmon of all sizes and 

 ages with two to four or more years of sea-life behind them ; and, whether grilse or older 

 fish, those returning early in the season are generally smaller than those returning 

 later because their growth period at sea has been shorter. Grilse, ready to spawn, return 

 to fresh water during their second summer at sea, and these are mostly males; for 

 example, in the Little Codroy River, Newfoundland, only 1 5 "/„ of the spawning grilse 

 taken were females, and in Norway only 19 "/q. But in certain localities of Scotland, 

 females may constitute more than 50 "/o of the grilse {lOO: 79). 



In some rivers grilse are the more numerous in a run and in other rivers the 

 older fish predominate.^^ Rivers reported as having a high proportion of grilse in- 

 clude: The Minas system, northern Bay of Fundy, 89^/0 {5g)\ the Little Codroy, 

 southeastern Newfoundland, 64 "/o in 1954, 74% in 1955 {106). For grilse in other 

 rivers, the following percentages have been reported: six western Newfoundland 

 rivers, 34.3 "/o (J-T); an unidentified Greenland river, 33.4 "/o (5j). In the Moisie and 

 Grand Cascapedia (north shore of the Gulf of St. Lawrence and Chaleur Bay, respec- 



11. It is from its habit of leaping that the Salmon gets its Latin name. Both Salmo and salar are apparently from the 

 same root, salire, to leap. 



12. Estimates of the composition of a catch or population of fish may be subject to large error, as in the case of esti- 

 mating the proportions of grilse and older Salmon. In commercial fishing, the gear used may take a selective rather 

 than a representative sample of the run, being designed to take only the larger individuals. Often the fishing effort 

 is concentrated on the main run and is not carried on throughout the year. Even in experimental fishing, a good 

 representative sample can be obtained only if the fishing is continuous and is done with gear designed to sample 

 accurately the various sizes. 



