Escapement monitoring of the Lillooet River Coho Salmon CU via Digital Imaging

Inconsistent, and sometimes absent, annual funding and a lack of resources to develop a Coho centric assessment program have resulted in DFO being unable to generate an estimate of Coho salmon escapement to the Lower Fraser River Management Unit (LFR MU) from observed data. The absence of reliable escapement estimates for Coho in the LFR MU and its three component Conservation Units (Lillooet, Boundary Bay and Lower Fraser) represents a critical information gap for Southern Boundary Coho salmon Management.
Coho returning to the Lillooet CU must transit through the Lower Lillooet River, thus providing the unique potential for a census-style assessment for much of the CU. Funding from the PSC enabled LGL Limited and the Lil’wat Nation to identify and establish an imaging sonar monitoring site on the Lillooet River at the mouth of Rogers Creek to assess escapement of Coho salmon to the Lillooet CU. Operations in 2019 found that Coho migrate earlier than expected as indicated by the distribution profile of observed fish, which was similar to the right hand tail of a normal distribution. To better capture the full migration, we have moved the start date a full month forward to mid-September. This project will improve management of Southern Boundary Coho salmon, and better enable the implementation of both the Wild Salmon Policy and the Pacific Salmon Treaty through improved stock assessment.

S19-SP23 Escapement of wild coho salmon to the Lillooet River 2019 Report

S18-SP30 Site Assessment of Lillooet River for Use of Imaging Sonar to Estimate Coho Salmon Escapement