Biologging in combination with biotelemetry reveals behavior of Atlantic salmon following exposure to capture and handling stressors

Abstract

We investigated the response of Atlantic salmon (Salmo salar) to capture and handling stressors by analyzing fine-scale locomotor activity using accelerometer data loggers and broader-scale movements by tracking migration with radiotelemetry. Half the sample population was exposed to experimental exercise and air exposure and released with a control group to simulate fisheries handling. All but two of the surviving fish (both in the treatment group) returned to the counting fence to resume the 2016 spawning migration (survival = 86%–91%). There were no differences in postrelease locomotor activity, measured by an index of total body action (jerk), between control and treatment salmon (p = 0.81). Comparison of mean time to return to the counting fence against a null model revealed that treatment salmon were significantly delayed in returning to the counting fence (p < 0.01), whereas control fish were not (p = 0.24). Both the abiotic environment and human interactions influenced locomotor activity of the migratory fish and synchrony of the migration with untreated conspecifics.