At Goldstream Hatchery, the process of raising salmon is carefully managed through several distinct stages to ensure the healthy development of fish from eggs to smolts. They are then released into the wild to fend for themselves, and hopefully come back to the Goldstream River in a few years to repeat the cycle. Here’s an overview of each step:
Broodstock Collection
During October and November, mature salmon are collected from our fish fence installed on the Goldstream River. They are selected based on species, condition, maturity and sex. These fish are transported to tanks at the hatchery to become parents of the following year’s fish.
Egg Collection from Females
Female salmon are assessed for ripeness by gently palpating their abdomens to determine if the eggs have detached from the ovarian sacs. Once identified as ripe, the eggs are carefully extracted for fertilization.
Milt Collection from Males
Milt, or sperm, is collected from the mature males. This process involves gently massaging the males to release milt, which is then used to fertilize the extracted eggs.
Fertilization
The collected eggs and milt are combined in a controlled environment to facilitate fertilization. Water is added to activate the sperm and harden the eggs. Excess sperm, ovarian fluid, and blood are then rinsed away before the eggs are transferred to incubation trays. The remains of the parent fish are saved to later return to the environment where they provide nutrients to the surrounding waters and forest.
Incubation
Fertilized eggs are placed in banks of Heath trays in the hatchery’s incubation room, where they remain until they hatch as alevins. This period typically lasts 4-5 months, depending on water temperature. About half way through this process, the eggs reach the ‘eyed’ stage, where eyes can be seen within the egg wall. Physical agitation is then used to damage non-viable eggs, making them easy to identify and remove. This is called ‘shocking’ the eggs. Non-viable eggs turn milky white after shocking, allowing them to be separated from the viable, translucent eggs. This process prevents fungal growth and maximizes survival rates.
School Programs
While in the ‘eyed’ stage, eggs are counted and carefully transferred to each school participating in the raising of salmon in classrooms. Fish tanks are provided to schools and volunteers from the hatchery deliver the eggs, providing instruction about how to raise the fish and their importance in the ecosystem. When the fish reach the smolt stage, they are released by the students into local streams.
Alevin Stage
Upon hatching, the young salmon, known as alevins, possess conspicuous yolk sacs. They remain in the incubation trays, absorbing nutrients from their yolk sacs until they are ready to begin feeding externally. This stage is crucial for their initial development and lasts until the yolk sacs are nearly absorbed.
Ponding
Once the alevins have absorbed most of their yolk sacs and developed into fry, they are released into large tanks within a roofed ponding area. Volunteers slowly introduce the small fry to external food. Automatic feeders can be used to extend feeding times while the young fish gradually learn to fend for themselves.
Rearing to Smolt Stage
As the fry grow, they are transferred to larger outdoor tanks where they continue to develop into smolts. Feeding during this stage is typically done by hand to monitor their health and growth closely.
Clipping
Rules for recreational fisherman are different for wild and hatchery salmon. To allow hatchery fish to be identified once they are in the wild, coho salmon raised at Goldstream Hatchery are clipped in preparation for release. This involves removing their adipose fin with small scissors. It’s a labour intensive job, so the hatchery often invites local groups who want to help with the clipping.
Release
Once the smolts have reached the appropriate size and developmental stage, they are prepared for release into the wild. This process is carefully timed to coincide with natural migration patterns, enhancing their chances of survival and successful integration into the ecosystem.
Each of these steps is carried out with careful attention to detail by the dedicated volunteers and staff at the Goldstream Hatchery, ensuring the continued health and sustainability of the salmon populations in the region.