532 Memoir Sears Foundation for Marine Research 



growing seasons. Wilder's data show that the survival rate declines abruptly for both 

 Salters and nonmigratory fish of the Moser after they pass their fourth season and that 

 very few of either survive for as long as six years (jS), though it is known that an 

 occasional /o«/z«a/« may survive into its eighth year elsewhere (9: 14). 



Spawning and Reproduction. The migratory populations of S.fontinalis, like the 

 nonmigratory fish, spawn exclusively in fresh water in autumn at temperatures ranging 

 from about 49°F (9.4° C) down to about 40° F (4.4°C). In general, spawning hj fon- 

 tinalis takes place earlier in the season to the north than to the south, but the precise 

 spawning period at any particular locality is governed by the rapidity with which the 

 water cools with the onset of autumn rather than by the latitude. Brook Trout 

 spawn from mid-October until early December on Cape Cod (probably), from mid- 

 October on into December to the north in New Hampshire {26: 499), from mid- 

 October into November in the Rangeley region of Maine {45: 84), from late Oc- 

 tober through December into January (exceptionally into February) on Prince Ed- 

 ward Island (7^: 356, 357), during October in the Moser River, Nova Scotia {y^: 

 185), and from mid-October to middle or late November on the coast of eastern 

 Newfoundland {24: 8). In shallow, rocky streams, however, in the Maritime Provinces 

 of Canada, where the water chills very rapidly, they may commence to spawn as soon 

 as late September (7^: 356, 357). Hence the spawning dates given by Vladykov for 

 the high-lying Laurentide Park lakes, north of Quebec City (68: 800), probably are not 

 applicable to the coastal streams along the north shore of the Gulf, where it is more 

 likely thzt fontinalis spawn from mid-October to mid-December, as they do in southern 

 Ontario (^^y. 99). No information is available in this regard for the outer coast of 

 Labrador. Along the southern shoreline of Ungava Bay, however, "it is probable 

 that spawning takes place in September or October," to judge from the state of the 

 gonads (Dunbar and Hildebrand, 16: 96). 



S.fontinalis, like Salmo salar, spawn on bottoms of sand or gravel in shallow water, 

 in streams, ponds, or lakes, where either the current or the inflow from some spring 

 keeps the eggs clear of detritus. Here the females smooth out a shallow depression 

 (the so-called redd) into which the eggs settle with the milt from the attendant male, 

 and immediately after the spawning act, the eggs are covered with gravel. The eggs, aver- 

 aging about ^/,e of an inch (about 5 mm) in diameter, do not hatch until the following 

 April or May, the precise date depending on the temperature of the water; 53° F 

 (i i.7°C) is about the upper limit for their development (xp: 281-289); ^"d the eggs 

 develop normally in water as cold as 35° F (i.7°C). The fry, about 0.5 inch (14 or 

 1 5 mm) long at hatching, carry a large yolk sac at first, as do species of all the Sal- 

 monidae; and they tend to remain close to the redd until they have grown to a length 

 of 1.5-2.0 inches (about 38— 50 mm). 



Some of the sez-going fontinalis of the Moser — probably this is true of the majority 

 — spawn in the autumn of the same year in which they make their first migration to the 

 sea. Others, like young Atlantic salmon (grilse), do not spawn until the second autumn 

 following their original descent to salt water. 



