Salmon are Anadromous: for the first year of their lives young salmon live in rivers and streams before moving to the sea to feed, grow and return to lay their eggs.
By instinct, salmon return to the fresh water they were born in to spawn their eggs. They will leave the ocean they usually call home and swim up freshwater streams to do so.
Their fierce determination to return to their birth place is spectacularly symbolised by images of salmon shooting out of the water to fly over small rapids just to reach the next level of their journey home.
This unique instinct to ascend and swim upstream made salmon vulnerable to prey. Of those who manage to make it upstream and spawn, as many as half of them die naturally within weeks or days of doing so, a trait known as ‘semelparity’. In the wild, Atlantic salmon may average only two or three spawnings a lifetime.
But modern aquaculture practices select and protect the broodstock and its pregeny from prey and provide the optimum conditions for healthy growth.
Huon’s hatcheries mimic the natural lifecycle of the salmon
In the wild, a depression (redd) is made in the river bed into which the female releases as many as 5000 roe (eggs) at a time. Male salmon approach the female in her redd and fertilise the roe within with a milky white sperm known as milt. Only around 10% of eggs will survive in the wild to reach smolt stage.
When the eggs hatch the Fry emerge and start absorbing nutrients from a large yolk-sac attached to their bodies until ready to eat externally sourced food and they grow into a stage known as Parr, recognizable by their distinctive patch markings to help camouflage them from predators.
Unlike most other types of salmon, the Atlantic variety like to stay and feed in fresh water for the first year of their life. Once they have reached around 100 grams they are known as Smolts and they are ready to acclimatise to the ocean by spending time in brackish waters like those found near where rivers meet the sea. Triggered by lengthening day light, smolts migrate to sea every spring.
Once fully acclimatised to both fresh and salt water, salmon will migrate to the ocean where they continue to grow and mature until they are ready to return to their freshwater home and reproduce.
|Atlantic Salmon Ova
As in nature, we too lay the eggs down in our hatchery every May. We incubate them for almost 3 months, during which time they hatch and become alevins.
|Yolk Sac Fry & Parr
When ready to take food after incubation, fry are transferred from the hatchery into small tanks where they are nurtured and protected from predators as they grow into Parr.
|First Year Smolts
As our parr grow, so too the size of their tanks. After 8-12 months, they are transferred to brackish waters in large open water pens. Now known as smolts, they adapt to living in both fresh and salt water as they grow into salmon. By providing the best growing conditions and mimicking the day length changes salmon experience in the wild as winter turns into spring, Huon progeny become big enough to smolt and be put to sea from March to October, thus ensuring a regular supply of salmon.
As time passes our salmon adjust to the salt water and so we move the open pens we store them in further away from the brackish end of the river and out into the open ocean where they can fully benefit from life at sea. Still well protected, nurtured and fed, they thrive and grow to anywhere between 2 to 10 kilos before being selected for harvest.
Young maturing salmon with a silvery blue skin and plump flesh like this example from Huon are ready to be harvested.
|Sexually Mature Salmon
Unlike farmed salmon that are harvested young, as salmon in the wild reach full maturity they divert nutrient intake towards their sexual organs, becoming leaner and less palatable in the process. Externally, their skin typically becomes darker or more colourful.