Nature Life
By Obiabin Onukwugha
Salmon is the common name for several commercially important species of euryhaline ray-finned fish, native to tributaries of the North Atlantic (Salmo) and North Pacific (Oncorhynchus) basins.
Salmon are typically anadromous, which means they hatch in the shallow gravel beds of freshwater head streams and spend their juvenile years in rivers, lakes and freshwater wetlands, then migrate to the ocean as adults and live like sea fish, then return to their freshwater birthplace to reproduce. However, populations of several species are restricted to fresh waters (i.e. landlocked) throughout their lives.
A portion of a returning salmon run, may stray and spawn in different freshwater systems; the percent of straying depends on the species of salmon.
Salmon are important food fish and are intensively farmed in many parts of the world, with Norway being the world’s largest producer of farmed salmon, followed by Chile. Salmon are a good source for Vitamin A.
They are also highly prized game fish for recreational fishing, by both freshwater and saltwater anglers. Many species of salmon have since been introduced and naturalized into non-native environments such as the Great Lakes of North America, Patagonia in South America and South Island of New Zealand.
It is reported that salmon can make amazing journeys, sometimes moving hundreds of miles upstream against strong currents and rapids to reproduce. Chinook and sockeye salmon from central Idaho, for example, travel over 1,400 km (900 mi) and climb nearly 2,100 m (7,000 ft) from the Pacific Ocean as they return to spawn. Condition tends to deteriorate the longer the fish remain in fresh water, and they then deteriorate further after they spawn, when they are known as kelts.
Salmon are mid-level carnivores whose diet change according to their life stage. Salmon fry predominantly feed upon zooplanktons until they reach fingerling sizes, when they start to consume more aquatic invertebrates such as insect larvae, microcrustaceans and worms. As juveniles (parrs), they become more predatory and actively prey upon aquatic insects, small crustaceans, tadpoles and small bait fishes. They are also known to breach the water to attack terrestrial insects such as grasshoppers and dragonflies, as well as consuming fish eggs (even those of other salmon).
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As adults, salmon behave like other mid-sized pelagic fish, eating a variety of sea creatures including smaller forage fish such as lanternfish, herrings, sand lances, mackerels and barracudina. They also eat krill, squid and polychaete worms.
Scientists say prior to spawning, salmon depending on the species, undergo changes. They may grow a hump, develop canine-like teeth, or develop a kype (a pronounced curvature of the jaws in male salmon). All change from the silvery blue of a fresh-run fish from the sea to a darker colour.
To lay her roe, the female salmon uses her tail (caudal fin), to create a low-pressure zone, lifting gravel to be swept downstream, excavating a shallow depression, called a redd. The redd may sometimes contain 5,000 eggs covering 2.8 m2 (30 sq ft). The eggs usually range from orange to red. One or more males approach the female in her redd, depositing sperm, or milt, over the roe. The female then covers the eggs by disturbing the gravel at the upstream edge of the depression before moving on to make another redd. The female may make as many as seven redds before her supply of eggs is exhausted.
According to scientists, depending on the specie, mature individuals die within a few days or weeks of spawning, a trait known as semelparity. Between 2 and 4% of Atlantic salmon kelts survive to spawn again. However, even in those species of salmon that may survive to spawn more than once (iteroparity), post-spawning mortality is quite high (perhaps as high as 40 to 50%).
They are called “eja salumoni” in Yoruba, “kifi”, in Hausa while Igbo describe it with the general name for fish, “azu”.
The salmon is an important creature in several strands of Celtic mythology and poetry, which often associated them with wisdom and venerability.
In Irish folklore, fishermen associated salmon with fairies and thought it was unlucky to refer to them by name. In Irish mythology, a creature called the Salmon of Knowledge plays key role in the tale ‘The Boyhood Deeds of Fionn’. In the tale, the Salmon will grant powers of knowledge to whoever eats it, and is sought by poet Finn Eces for seven years. Finally Finn Eces catches the fish and gives it to his young pupil, Fionn mac Cumhaill, to prepare it for him. However, Fionn burns his thumb on the salmon’s juices, and he instinctively puts it in his mouth. In so doing, he inadvertently gains the Salmon’s wisdom.
Salmon also featured in Welsh mythology. In the prose tale Culhwch and Olwen, the Salmon of Llyn Llyw is the oldest animal in Britain, and the only creature who knows the location of Mabon ap Modron. After speaking to a string of other ancient animals who do not know his whereabouts, King Arthur’s men Cai and Bedwyr are led to the Salmon of Llyn Llyw, who lets them ride its back to the walls of Mabon’s prison in Gloucester.
In Norse mythology, after Loki tricked the blind god Höðr into killing his brother Baldr, Loki jumped into a river and transformed himself into a salmon to escape punishment from the other gods. When they held out a net to trap him he attempted to leap over it but was caught by Thor who grabbed him by the tail with his hand, and this is why the salmon’s tail is tapered.
