Use of Electromyogram Telemetry to Assess Difficult Passage Areas for River-Migrating Adult Sockeye Salmon

Abstract

Abstract We conducted laboratory respirometry trials using adult sockeye salmon Oncorhynchus nerka implanted with electromyogram (EMG) radio transmitters to investigate the relationship between oxygen consumption and EMG pulse interval. The strong association that was observed suggested that EMG telemetry could be used to assess activity and, thus, relative energy expenditure in freely migrating sockeye salmon. Using EMG telemetry, we then assessed the relative energy costs of upstream migration by adult sockeye salmon through specific reaches of the Fraser River, British Columbia. Greatest energy costs were incurred during migration through Hell's Gate fishways, a known point of difficult passage. Another energetically demanding area was a gravel bar that had not been previously identified as difficult for passage. Three other areas that historically had been identified as difficult for passage were energetically less expensive to migrate through during our study. Our results demonstrate that EMG telemet...