Many Canadian Coho Management Units (MUs) have been “data limited” since the reduction in assessment priority for coho which started about the same time as the Southern Coho Plan was finalized in 2002. The implementation plan for the 2020 Pacific Salmon Treaty (PST) brings an opportunity to improve coho assessment and management. The PST Chapter 5 Southern Coho management framework is based on assessment of Canadian and US management units into one of 3 status zones (Low, Moderate, and Abundant), which have commensurate total exploitation rate (ER) caps and sharing of this ER between the US and Canada. This proposed approach could address the current inability to assess status in several Canadian MUs.
Tools such as DNA can accurately identify wild coho to the Conservation Unit (CU), MU, or even river of origin and can accurately identify hatchery of origin through a combination of parental based tagging (PBT) and regular genetic stock identification (GSI) (see Beacham et al. 2019). We propose that these assessment tools can be the basis for estimating wild coho escapement.
The proposed approach uses September fishery information, combined with representative DNA information from the fishery and escapement results from key hatchery indicators, to form the basis for estimating aggregate escapement of wild coho, especially in the GST management unit, but also Lower Fraser, Southwest Vancouver Island (SWVI), and other stock aggregates. The objective is to track catch of wild coho catch and escapement by management unit. These tools will also be used to estimate exploitation rate.
