DIDSON Chum Enumeration East Coast Vancouver Island

Dual Frequency Identification Sonar (DIDSON) technology has been the primary method of Chum Salmon enumeration on the Cowichan River since 2007. This enumeration method has also been implemented on the Nanaimo and Chemainus Rivers in more recent years. DIDSON counts provide in-season escapement estimates which are used to manage Chum Salmon stocks in these rivers.
DIDSON software produces video-like imagery which allows viewers to count individual fish as they move up or downstream. However, review of DIDSON data is time-consuming (i.e., costly) and highly subjective, causing counts to vary substantially depending on such factors as viewer experience, attentiveness, and the volume of migrating fish. As a result of such factors, significant inconsistencies in Chum escapement estimates occur.
Software to automate review of DIDSON data now exists (Echoview Version 9.0). Echoview software has the potential to increase the processing time period for DIDSON files, significantly reduce human error from review of DIDSON data and greatly improve Chum escapement estimates. We propose to implement Echoview during fall 2019 and conduct a comparative analysis between Echoview software and the manual counting procedure used to review DIDSON data. The first step will be to gain experience with the program by re-analyzing 2018 DIDSON files and comparing results. Echoview software has the potential to greatly increase the accuracy of DIDSON based salmon escapement estimates, which can be used to improve management of Chum Salmon on the East Coast of Vancouver Island.

S19-SP21 DIDSON Chum Enumeration, East Coast Vancouver Island 2019 Report