Migratory salmon smolts exhibit consistent interannual depensatory predator swamping: Effects on telemetry-based survival estimates

Academic Article


  • AbstractMigrations of juvenile salmon smolts are generally high‐risk, with predation often implicated in reduced survival. In theory, smolts can maximise survival via depensation, or synchronising movements to swamp predators. Depensation, however, is difficult to assess in the wild. Accounting for depensation could also generate more realistic telemetry‐based survival estimates for management. Here, we assess six years (2010–2014, 2016) of acoustic telemetry and outmigration density data for sockeye salmon (Oncorhynchus nerka) from Chilko Lake, British Columbia, Canada. Prevoiusly, depensation for this population wasassessed for a single year, but interannual consistency is not known. We found evidence of depensation in each year, although its strength varied. In addition, by integrating depensation with outmigration densities, annual population‐level survival estimates in this initial (14‐km) migratory segment increased by 0.02–0.24 relative to previously published estimates. However, when extending these survival rates from the first 14 km through the entire tracked migration (1,044 km), increases in estimates were small (~0.01). Potential conservation and management applications of depensation include implications for recovering imperiled populations and informing hatchery release strategies.
  • Authors

  • Furey, Nathaniel
  • Martins, Eduardo G
  • Hinch, Scott G
  • Status

    Publication Date

  • January 2021
  • Has Subject Area

    Published In


  • Oncorhynchus nerka
  • acoustic telemetry
  • density dependence
  • depensation
  • mark-recapture models
  • sockeye salmon
  • Digital Object Identifier (doi)

    Start Page

  • 18
  • End Page

  • 30
  • Volume

  • 30
  • Issue

  • 1