University of Washington

Smolt-to-Adult Ratio (SAR) estimates for CWT Methods

Go to Query: CWT SAR

The method for calculating Smolt-to-Adult Ratio (SAR) estimates for CWT is based on:

Skalski J.R., and R.L. Townsend. 2005. Pacific Northwest Hatcheries Smolt-to-Adult Ratio (SAR) Estimation using Coded Wire Tags (CWT) Data [PDF]. Technical Report to Bonneville Power Administration, Project No. 1991-051-00, Contract No. 00013690.

Definitions

  • Excluded from returns: SAMPLE_TYPE 5 = Voluntary or select recoveries from a sampled fishery with known catch and no awareness estimates available; use of these recoveries leads to double counting.
  • Brood Year: Calendar year when majority of parents of the fish in the release group spawned.
  • Tag Code: Unique identifier for a release group.
  • End Release Date: Last date of release for the release group.
  • Number Released: Total number tagged with CWT corrected for tag loss and tagging mortality.
  • Estimated Returns (Total N) : Estimate of the total CWTs recovered for a release group, taking into account the subsampling process of examining fish for tags.
  • SAR: Estimate of smolt-to-adult ratio. In a generalized form, SAR is proportional to N / R (number released). Release size weighted SAR presented for Brood Year; Equation 10 from Skalski and Townsend, 2005. Standard error calculated from SAR varianced weighted by release size, Equation 11.
  • Singles: 'Y' indicates that the SAR includes returns with no sample size and the SAR value is a minimum estimate.
  • * Incomplete Data.