I was up at my normal time today, but instead of heading into the office in Woodland, I headed out to the Nimbus Fish Hatchery in Rancho Cordova to watch the first salmon egg-gathering session of the season. It was about 47° outside when I got there.
I wasn’t expecting a lot of fish to be in the ladder, because it’s so early in the season and this was the first time this year the eggs were being taken, so I was surprised to see part of the fish ladder full of huge thrashing fish. I could also see the salmon moving along the shores of the river and jumping out of the water here and there. It was neat! Before the egg-gathering starts, the hatchery personnel close off the gate to the fish ladder (so they’re not inundated with fish) – and you can see the salmon coming up to the gate and banging on it because they’re so anxious to get up the ladder to spawn. They can spawn in the river, but because the majority of them were raised in the hatchery, the majority of them try to come up the ladder.
Then they corral the salmon at the top of the ladder into a pool and push them toward the hatchery building with a moving wall. When the fish come into the building, they’re given an electrical shock to get them quiet. Then they’re lifted up into the spawning room where a group of scientists handle all the aspects of egg-gathering. Personnel at the head of the line separate the males from the females, and separate the “ripe” females (those whose eggs are ready to harvest) from the “unripe” ones. They can tell which is white by palpating the salmon’s stomach. Sometimes, they’ll also squeeze the belly to see if some eggs squirt out. The ripe ones go on to the egg-gathering table, and the unripe ones are shunted down a tube into raceways where they can stay until their eggs are ready.
Because the salmon will die immediately after spawning anyway – (unlike Steelhead which can be returned to the river after their eggs are taken) – the males and ripe females are then killed with a hammer. There was a good deal of blood that went along with that, and some of the people who were watching the process – especially the small children – were upset by that. All of the dead fish are put into bins, however, and their bodies are harvested for meat for the regional food closets, and leftovers that will go to make pet food and fertilizer. So, all parts of the dead fish are used.
The ripe females are slit open and their eggs are hand-shoveled into white square spawning trays where their fertilized with sperm squeezed out of a male fish. Then an iodine wash is added to kill and errant bacteria and the eggs are sent to the tanks in the back of the building to hatch and grow into fry. There was also a team of female scientists there who, before all the eggs were taken from the females, would take a small sample of the eggs and test them for diseases, check them for DNA to see where they came from (if they were wild or if they came from a hatchery), and check for viability. It’s all soooo fascinating to watch.