The Life Cycle of the Atlantic Salmon
Eggs
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From June until October the principal runs of salmon enter the Saint John River to seek out the shallow, rapid areas of the main river and its tributaries where spawning gravel is available. During the latter part of October, the female selects her spawning site, digs a shallow depression or redd with her tail and deposits her eggs.
The eggs are immediately fertilized by the male and covered with a layer of gravel.
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With spawning completed, the parent fish, now referred to as kelts or black salmon, prepare to return to the sea, which some may not reach until the following spring.
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Alevins
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The eggs, lying protected in the gravel, hatch and become alevins in the spring.
After the yolk sack is absorbed, in late May or early June, the young salmon emerge from the gravel and begin to feed on the small insects in the stream. At this time they are about 2 cm - 3 cm long and are known as underyearling parr or fingerlings.
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Parr
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After this first year in fresh water, the young salmon are called postyearling parr. The majority of juvenile salmon spend a total of three years in the stream before going to sea.
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Those reared in the hatchery migrate to sea after one year in fresh water.
Smolt
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Migration to the sea takes place in May and June after the parr has acheived a length of about 15 cm. At this time, the parr takes on the silvery appearance of its parents and is called a smolt.
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Tagging experiments have shown that smolts travel considerable distances from their fresh-water homes, reaching the coastal waters of Nova Scotia, Newfoundland and Greenland.
Adult - Grilse and Large Salmon
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Salmon may spend one or more years at sea before returning to their home river to spawn, and during this time they grow rapidly. Salmon which have spent one winter at sea before returning to spawn are called grilse, and weigh up to 2.5 kg when they enter the river.
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Salmon which have spent two winters at sea range between 3.5 kg and 6.0 kg in weight, and additional increases in size occur with subsequent migration cycles. Salmon weighing between 9 kg and 12 kg are occasionally observed among the salmon returning to Mactaquac. Salmon which spend two or more winters at sea and fish that have spawned previously are collectively referred to as large salmon. Generally less than 10 out of every 100 spawners return to spawn again.
Male fish returning to the Saint John River are generally a year younger than females; about 19 out of 20 grilse are males and 17 out of 20 large salmon are females. Each large slamon female deposits about 7,600 eggs in the gravel of the stream bed. On average, 100 of these eggs survive to enter the sea as smolts. Only 12 survive through the first year at sea. Three of these are caught in the sea fisheries, mainly during the second summer after entering the sea, and the remaining 9 return to the Saint John River, 4 as grilse and 5 as large salmon. On average, a pair of spawners produce a return of 9 salmon to the river. By comparison, the eggs from a single female large salmon placed in the Mactaquac Fish Culture Facilities and reared for release as one year smolts, produce a return to the river of more than 100 grilse and older salmon.
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