Salmon fry just 3 weeks after hatching are dependent on a plum-shaped external food sack as they grow old enough to feed. Temperature has a major effect on their growth, and these infant fishes have their age measured in "temperature-days", the product of their age in days since hatching multiplied by temperature in °C. These fry are 620 degree days, and by 900 degree-days they will be old enough to eat a mixture of fish meal and fish oil.
All the fish come from parents that were captured in the Vosso River (near Bergen) in 1960. The eggs are placed in hatching trays where freshwater temps are raised from 4°C up to 8°C. After leaving the egg, the fish subsist on food that they hatched with for 900 "degree days" and when the water temperature is raised to 14°C they are given a diet of granulated fish meal and fish oil. After they get mature they are introduced to saltwater and put into pens in the fjord to go from 200 grams to 5 kg, and gain approximately 1 kg of body weight for every 1 kg of food.
This hatchery is owned and managed by MOWI, formerly Marine Harvest, the biggest grower of farmed salmon in the world, with approx. 25% of market share.
- ©2016 George Steinmetz
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