I got up about 6:16 this morning, so I could get out the door a little after 7:00… and headed out to the Nimbus Fish Hatchery. I wanted to see them gather the eggs from the Steelhead Trout. I got there about 10 minutes before the process started, so one of the docent guys in the visitors’ center walked me through it and showed me all the key things I should look for when the fish were let in. When the process started, it was just me and a woman with her two kids, and a couple of staffers watching it, so I was able to see everything really easily. I got photos and some video… but I was shooting through a dirty glass wall most of the time, so the camera was having trouble focusing on what I wanted it to.
I’m glad I went to see the Steelhead eggs gathering rather than the Chinook Salmon egg gathering process. When the salmon go through, they’re killed: smacked on the head with a hammer and gutted. They’re going to die right after they spawn anyway, but the process sounded really bloody and brutal. Steelhead, on the other hand, can spawn year after year, so the hatchery doesn’t kill them and instead puts them through a process that allows them to go back into the river after the eggs are gathered and fertilized.
The process starts outside of the hatchery building. Fish come up the 260-foot ladder from the river and then go into a “crowding tank” which is about 12 feet wide and 60 feet long. Once in the tank is closed off, a mechanical arm pushes the fish forward to a lifting tank on the outside of the hatchery building. A gate on the side of the hatchery’s wall opens up, and the fish in the crowding tank swim into a “lift-tank” inside the building. From this point, you watch the egg-gathering through a glass wall.
There’s a curling cable that goes down into the lift-tank, and it “anesthetizes” the fish with a low electrical charge. Once the fish are calm, the tank rises and the handlers check each fish. Rainbow trout (trout that haven’t gone to sea yet) were mixed in with some of the Steelheads, so they were put into a chute that sent them right back to the river. The Steelheads are all checked to see who’s “ripe” and who isn’t. The “unripe” fish are put into a run (outside) to hold them for a day or two to see if they can “ripen” before being returned to the river. They don’t keep the Steelhead in the run for very long, because the fish don’t handle being confined well and can die of shock.
Ripe males and females are “tagged’ by cutting a notch in their tail, and separated into large pans by sex. Inside the large pans is a mixture of mineral salts that also helps to keep the fish calm. (When the fish are released back into the river, they sometimes turn around and come back up the ladder again. The handlers can tell if they’ve already seen and counted the fish by whether or not there’s a notch cut into its tail.) Even with the electrical zap and the chemical bath, some of the fish were still really spry. The docent said that the fish are really strong, and if they’re not handled properly, they can injure themselves or the handlers. The salmon, especially, he said, are so tough that they’ve actually smacked the handlers hard enough to knock them out, split their lips open and and break their noses.
Then the females are taken out of the “girl pan”, one at a time, and one guy holds her while another guy uses a syringe to pump a little air into her belly. The air pushes against the mass of eggs inside the mama fish and helps to push them out. The handler squeezes out all of the remaining eggs, and then “burps” the female to get all the air bubbles out of her. (If all of the air isn’t removed, then the fish can’t swim properly because she’d be too buoyant.) She’s then turned over to a team of biologists who measure her, and take scale, blood, tissue and ovarian fluid samples for research purposes before she’s released down the chute into the river. Her eggs are put into in a plastic pot, and then a male Steelhead is pulled out of the “boy pan”. The handler squeezes the male’s belly to push out the milky sperm (“milt”) over the eggs, and the guy holding the pot stirs the eggs and milt together with his hand. The male Steelhead goes to the biologists and then down the chute, while the guy holding the pan of now fertilized eggs carries the pan over to another guy who then moves the eggs to a tank with betadine-like stuff in the water to kill any microbes or diseases that might have been in the ovarian fluid. After their betadine bath, they’re put in cylindrical clear-walled hatching tanks where the Steelhead eggs hatch into fry.
It was really neat to watch the process; they have it down so well that no one got in anyone’s way, and the fish were all processed quickly. Here are a couple of short videos:
The docent said that last year at this same time they would get about 26-30 pairs of Steelhead each time they did an egg-gathering round, and the rounds could continue on back-to-back for the whole day. Today, because the river is so low, there were only 4 pairs of Steelhead in the first round (of fish that came up the ladder) and about 6 pair in the second round (that came out of the holding run)… and then the crowding tank was empty. So egg-gathering this morning only took an hour. Yikes! He also noted that the hatchery releases about 4 million Chinook fry and 1 million Steelhead fry into the adjoining rivers each year… but their numbers will probably be lower this year because of the drought conditions.
When I was done watching the egg-gathering process, I walked on the path along the American River and took some photos of the water birds out there. Lots of cormorants, seagulls, and ducks… and one little Phoebe. Awwww… It was a fun morning!