Yakoun River, Haida Gwaii, Annual Chinook & Coho Escapement Monitoring Using ARIS Imaging Sonar

The Yakoun River supports several Pacific salmon stocks including the only indigenous Chinook salmon stock on Haida Gwaii. Intensive logging activities and consequent habitat degradation coupled with increased fishing harvest pressures resulted in severe declines of Pacific salmon stocks, particularly Chinook. By the mid-1980s the number of adult Chinook, which typically begin to enter the river in mid-June and spawn in late August and September, returning yearly to the Yakoun River to spawn was estimated to be as low as 300. In partnership with Fisheries and Oceans Canada (DFO) the Old Massett Village Council (OMVC) established the Yakoun River Hatchery on Marie Lake to rebuild the declining Chinook stock.  Over the past 30 years efforts to rebuild the Chinook stock, through hatchery-rearing and protective management measures designed to minimize commercial and recreational harvests, appear to have been effective. A rough yearly index of escapement based on anecdotal opportunistic visual observations made during broodstock collection suggest the stock is recovering. Hatchery production and restraints on harvest have yielded increased numbers of Chinook spawners in the Yakoun River, with estimated escapement shown to approach management targets in recent years. However, DFO North Coast Stock Assessment does not acknowledge current estimates of salmon escapements to the Yakoun River as biologically defendable enough to base management decisions on. As a result, there is little opportunity to improve stock size and/or change current regulations affecting harvest and management until a more reliable method to determine salmon escapement is established.

Escapement estimates for Coho specific to the Yakoun River are not available so general abundance patterns are unknown for historical and current Coho stocks in the Yakoun. The Yakoun River management target for Coho is 45,000 spawners (DFO 2012). Coho have been reported to enter the river in mid-August and continue through at least late September (Spilsted et al. 2010), however Coho run-timing in the Yakoun is typically through the period mid-September to late October (Haida Fisheries unpublished data).  Methods for estimating escapement of Pacific salmon stocks in the Yakoun River have been insufficient (other than during even years in the 1980’s and early 1990’s when a counting fence was in operation for the assessment of pink salmon). Opportunistic surveys, anecdotal observations, and the inability of fence count programs to operate during high water conditions have all contributed to incomplete escapement data and uncertainty around escapement estimates. Improved accuracy and consistency of escapement estimates will allow for improved management of the Yakoun River salmon stocks. To that end the Council of the Haida Nation (CHN) has taken the initiative to establish an Adaptive Resolution Imaging Sonar (ARIS) for assessing salmon escapements on the Yakoun River.