Fin Clipping

They are marking the spring Chinook salmon at the Gnat Creek Hatchery this week. As I mentioned a few days ago, the adipose fin on the fish’s back is clipped so anglers know that the fish they catch is a hatchery fish, not a wild salmon. We were told that clipping the fin is like cutting our fingernail, so it doesn’t hurt the fish. But they fish are anesthetized because otherwise it is nearly impossible to pick them up to do the clipping. Many years ago large chunks of ice were added to the water in the tanks where the fish were kept to slow them down enough to allow the fin to be clipped.

Last week a trailer was delivered to the hatchery to use by the fin clippers. The whole job is very labor-intensive. It took at least two days to set up the trailer for the work. Then pipes need to be set up to run water through the trailer and from the trailer to whichever pond the clipped fish will be sent.

Net pens (which John and I helped set up last week) are filled with fish, which makes it easier to dip the fish out and run them into the trailer. After the pens are in place and the pump is set up, a small chute is connected so the fish can be sent to the net pen. Then one of the technicians Dave, uses a large screen to crowd the fish at one end of the pond.

Next, he dips the fish out, hands the net to Mike, who carries the net to the chute, where the small fish are sent sailing into the net pen.

Twenty or so dips of the net moves maybe 40,000 fingerling salmon. They fish remain in the pens until they are again dipped out and sent into the trailer.

Now workers standing at small tables put some fish in the anesthetic, then move them into a second small net, pick them up one at a time and cut off the fin, drop the fish down a drain, and hit the counter to account for how many they clip. They work from 7:30 am to 4 pm. (I’m glad I don’t have to do that.)


The fish slide through the drain and into this clear pipe, down into a longer hose or pipe and arrive in a fish tank where they will live for the next few months.

This will go on for two to three weeks. The first day, with a short crew, 46,000 fish were clipped. They have nearly 900,000 to do before they finish.