Each fall, hatchery crews begin their egg pick, a salmon egg sorting process.
During egg picks, crews divide fertilized, good eggs from the eggs that may have missed fertilization or otherwise didn’t make it to this stage. Egg picks remove decomposing material that could cause excess bacteria in incubators as alevin begin to hatch from their eggs.
Not every egg collected will hatch, but the juvenile salmon from these eggs have a better chance of success at hatcheries than in the wild.
Here are the different steps we follow during egg pick:
Step 1: Shock
The first step in a well-executed egg pick is something called “shock,” which has nothing to do with electricity.
Instead, eggs are dropped from a certain height and allowed to bounce off of a hard surface. The reason this is done is because not every unviable egg looks like an unviable egg. When shocking, fertilized viable eggs will bounce off this surface unharmed. An unviable egg that hits the same surface will not bounce, instead its yolk sack will burst.
After shock, viable eggs remain a nice bright orange color while unviable eggs turn white. Eggs are set aside to allow this color transformation to occur for at least a day before the next step.
Step 2: Pick
“Pick” is used as the general term for this whole process, but is really only one step along the way. When we say pick, what is really meant is “picking” the bad eggs out of the good eggs.
Sorting millions of eggs would be impossible without the help of technology along the way. CIAA uses jensorters, special equipment that uses light reflection to recognize if an egg is good or bad.
A good egg will allow light to pass through instead of reflecting light back into a sensor. Bad eggs are typically white and will reflect all the light. After determining whether an egg is good or bad the egg sorter uses compressed air to sort eggs into two buckets.
Eggs are continuously fed into the machine by the hopper, an oversized funnel, and a controlled flow of water. The flow of water feeds eggs into a spinning wheel that carries the egg to the light sensor and then to where the compressed air will distribute it into its respective bucket.
CIAA uses two different models of jensorters. One is used at Trail Lakes Hatchery for sockeye and coho eggs. These models are rated to sort approximately 190,000 eggs per hour. The other model is used for pink eggs at Port Graham and Tutka Bay Lagoon hatcheries. These models are rated for much quicker sorting at 600,000 eggs per hour.
Step 3: Sample
Following the separation of eggs, it’s crucial to know how many bad and good eggs you’re left with. This is done by measuring the weight of a small number of eggs, maybe about 100, and calculating the total number of eggs by weight. This number is used to track the number of fish throughout the rest of the rearing process until they are released.
Sanitation is a major concern throughout this process. Personnel take extra measures to ensure we aren’t spreading potential disease between incubators. Between picking incubators, all equipment and clothing will be disinfected in iodophor disinfectant.
Egg pick in action
If you’d like to see our jensorter machines in action, please check out this video from a crew member at Trail Lakes Hatchery.