Previously, I described the overall goal of our experiment – to quantify the effects of two common hatchery marking practices, coded-wire tagging and removing the adipose fin as an external mark, on the marine survival of Chinook salmon (see Post 2). But how do we actually mark the fish? Well, the suspense is over!
Marking fish requires three things – a great crew of people, fun music, and some specialized equipment. To process 215,000 fish, we work in a small shed for 8 hours a day for 2.5 to 3 weeks, so things can get fairly monotonous. Additionally, our hands are in very cold water (3 to 6 degrees Celsius) all day. It REALLY helps to have a motivated crew and everyone’s favorite tunes to maintain a positive, fun atmosphere. This year at Little Port Walter, the tagging crew comprises myself, the station manager John Eiler, the resident culturist Gerard Foley, and contractors Mattea Berglund, Katlyn Fuentes, Alexa Marinelli, and Debra Rose. We also need a few specialized items: surgical scissors to clip the adipose fin, spools of coded-wire tags, a machine to cut individual tags and insert them into the fish, and a detector to verify that each fish has a tag.