Facts on a Salmon
posted on 16 January 2014 | posted in Hints and Tips
Common name: Atlantic salmon
Latin name: Salmo salar
Record weight: One of the oldest records on the books, and one that is veryunlikely
to be beaten in the future. The Atlantic salmon is thesecond largest fish (behind the
wels catfish) found in British freshwaters with arecord weight of 64lb caught By Miss
G.W. Ballantine in 1922.
Distribution: Salmon are an anadromous species that lay their eggs infreshwaters, then migrate as juveniles to the sea where they grow and maturebefore returning to freshwaters to spawn. Although salmon tend to return totheir stream of birth to lay their eggs some do get lost and so they spreadquite quickly. The main limit to their spread in present times is warm water.Salmon are most at home in the cool streams of Northern Europe and Canada andso are found as far South as the mountain streams of the Massif Centrale inFrance. Once common throughout the rivers of the UK, salmon are now mostlylimited to the rivers of the West and North of the country, where pollution andweirs have not impacted so severely on the young fish.
Features: A silvery fish with steely blue spots on fresh fish. Quite similar tofresh run sea trout (Salmo trutta) one simple means of identifying salmon is totry to pick the fish up by the root of the tail. The salmon has a distinctnarrowing here which allows it to be handled easily.
Diet: In the sea, adult salmon feed upon small fish and crustaceans,particularly sandeels and juvenile herring. In freshwaters, adult salmon do notfeed and must spend several weeks or months travelling to the spawning streamswithout nourishment. Young salmon feed upon small invertebrates, particularlyfreshwater shrimps and caddis larvae. Juvenile salmon tend to be highly nocturnal,particularly in the Winter months when the risk of predation by herons is highduring daylight.
Spawning: Adult salmon tend to enter the river in two distinct waves. Thelargest fish tend to enter the river during the Spring and make their way quitequickly upstream to spawn. The second run of salmon occurs in the Autumn justprior to spawning in November and December. When conditions are right, thefemale excavates a large area of gravel in shallow fast flowing water. Thegravel, known as a redd, can be several feet in diameter and more than twelveinches deep. The female lays her eggs in the redd where they are fertilised bythe male fish. The female then moves upstream and covers the eggs with moregravel so that they are buried deep within the bed of the river. The eggs takeseveral months to hatch in the cool water of Winter streams. Once hatched, thelarval salmon have a large yolk sack that sustains them for several more weeksbefore they need to start hunting small invertebrates, still deep within thegravel. When the salmon finally emerge from the gravel after approximately amonth they are known as parr and are fully formed fish that grow rapidly duringthe warmer Summer months.
Growth: The growth of salmon is highly variable both within a stream andbetween streams. Young salmon spend up to three years in their natal streamsbefore migrating to the sea. In some environments a small percentage of themale salmon do not migrate to sea. These males remain no more than twelveinches in length and are called sneaker males as they will sneak in and spawnwith the much larger females. Generally though, the salmon spend between oneand four years at sea before returning to spawn. Most fish will die as a resultof the rigours of making their way upstream and spawning, but around tenpercent will survive and return to the sea for another period of growth beforereturning again. Very large salmon are now very rare as a result ofover-fishing of the small number of returning fish.