A new microcontrolled fish tag for accurately estimating life span and survey life of spawning salmon

Abstract

A microcontrolled fish tag which records post-tagging life span, was developed and tested as a prototype. The method of making thetag and the results of tank test trials on chinook salmon (Oncorhynchus tshawytscha) andfield trials on chum salmon (Oncorhynchus keta) are presented. This tag was specifically designed to measure survey life (SL) but may have other applications. Survey life is an essential component for area-under-the-curve (AUC) estimation of Pacific salmon (Oncorhynchus spp.) spawning escapements. Accurate escapement estimates are critically important for salmon fisheries management and science. However, AUC spawner estimates must often employ average SL values from historic rather than year-specific studies because direct estimates of SL can require extensive and costly tag- recapture programs. Using assumed SL values can introduce serious bias in population estimates, therefore alternative methods of determining annual SL are important. In this study, the new tag estimated SL by measuring the elapsed time from tagging until the fish came to rest permanently on its lateral or dorsal surface. Details on how to construct the tag are provided so that researchers will be able to make their own.