Life Cycle of Salmon
The life cycle of a salmon in a hatchery is managed to mimic, as closely as possible, the natural life stages of the fish, albeit in a controlled environment to improve survival rates. Here’s an overview of the typical life cycle stages of salmon at a hatchery:
Egg Collection
Broodstock Capture
Mature salmon are caught as they return to freshwater to spawn. These adult fish are known as broodstock
Spawning
The eggs and milt (sperm) are manually extracted from the female and male broodstock, respectively
Fertilization
The eggs and milt are mixed together to facilitate fertilization.
Incubation
Egg Sorting
After fertilization, the eggs are sorted to remove any that are unfertilized or dead.
Incubation Trays
The fertilized eggs are placed in incubation trays with flowing water to simulate river conditions.
Water Quality
Throughout incubation, water quality parameters like temperature, oxygen levels, and pH are closely monitored.
Hatching
After a period of incubation, the eggs hatch into alevins, the first larval stage of salmon, which have a yolk sac attached for nourishment.
Rearing
Transfer to Rearing Tanks
Once the yolk sac is absorbed, the alevins become fry and are moved to rearing tanks.
Feeding
Fry are initially fed a diet of high-protein food pellets that provide the nutrients they need to grow.
Monitoring
Water quality is continually checked, and the health of the fish is regularly monitored.
Grading and Sorting
As the fish grow, they are graded and sorted based on size to ensure even growth rates and to reduce competition for food.
Smoltification
Eventually, the fry undergo a physiological change known as smoltification, preparing them for life in saltwater.
Release
Tagging
Prior to release, some fish may be tagged for research and tracking purposes.
Acclimatization
In some cases, smolts are moved to net pens in the river or estuary for a short period to acclimatize to natural conditions
Release
Finally, the smolts are released into rivers or streams, where they will make their way to the ocean to mature
Adult Life and Return
Ocean Phase
After release, the salmon live in the ocean, where they continue to mature. This phase can last from one to several years, depending on the species.
Migration
Mature salmon navigate back to freshwater to spawn, completing their life cycle. Some of these fish may be caught again as broodstock, and the cycle begins anew.