Calibrating acoustic acceleration transmitters for estimating energy use by wild adult Pacific salmon

This study is the first to calibrate acceleration transmitters with energy expenditure using a vertebrate model species. We quantified the relationship between acoustic accelerometer output and oxygen consumption across a range of swim speeds and water temperatures for Harrison River adult sockeye salmon (Oncorhynchus nerka). First, we verified that acceleration transmitters with a sampling frequency of 10 Hz could be used as a proxy for movement in sockeye salmon. Using a mixed effects model, we determined that tailbeat frequency and acceleration were positively correlated (p < 0.0001), independent of tag ID. Acceleration (p < 0.0001) was positively related to swim speed while fork length (p = 0.051) was negatively related to swim speed. Oxygen consumption and accelerometer output (p < 0.0001) had a positive linear relationship and were temperature dependent (p < 0.0001). There were no differences in swim performance (F_2,12 = 1.023, p = 0.820) or oxygen consumption (F_1,12 = 0.054, p = 0.332) between tagged and untagged individuals. Five tagged fish were released into the Fraser River estuary and manually tracked. Of the five fish, three were successfully tracked for 1 h. The above relationships were used to determine that the average swim speed was 1.25 ± 0.03 body lengths s^? 1 and cost of transport was 3.39 ± 0.17 mg O₂ kg^? 1 min^? 1, averaged across the three detected fish. Acceleration transmitters can be effectively used to remotely evaluate fine-scale behavior and estimate energy consumption of adult Pacific salmon throughout their homeward spawning migration.