Behind the Scenes of Survive the Sound
A lot of effort goes into tracking juvenile steelhead.
People often ask us how we’re able to pull off tracking 48 juvenile steelhead, and they’re are always impressed to find out what goes into it. So, we’ve outlined the process in the steps below!
1. Over the course of about 2 months during spring, scientists from Washington Department of Fish and Wildlife and NOAA’s Northwest Fisheries Science Center work together to trap 300-350 wild steelhead migrating from their natal streams to the saltwater.
2. Scientists surgically implant a small acoustic tag inside the body cavity of each juvenile steelhead. The tags are the size of a large pill and cost hundreds of dollars each. Each tiny tag is programmed to transmit, or “ping”, a unique code every few seconds. The fish are anesthetized for surgery and placed in a special recovery tank afterwards. They are back up and swimming strong in a matter of minutes!
3. When scientists release the tagged fish back into the river and they continue migrating towards the Pacific Ocean, acoustic receivers placed underwater all around Puget Sound log every acoustic ping they ‘hear’ from nearby (200m or less) tagged steelhead. The batteries in the tag die soon after the fish reach the Pacific Ocean, therefore we are unable to track their return as adults.
4. In late summer, scientists travel to the location of each receiver and download its data. The data goes through a preliminary stage of processing and then 48 fish, who are representative of the larger group of tagged fish, are selected for Survive the Sound. Scientists interpret the data for all 48 fish to create a smooth migration path over a 12 day period.
5. The tracking data from each of the fish is assigned to a Survive the Sound character and 24 hours of the fish’s movements are shown on the map each day of the migration.