ASL Environmental Services Selected for Hydroacoustic Study

ASL Environmental Sciences was chosen by Hemmera Envirochem and the Vancouver Fraser Port Authority to perform a hydroacoustic study of eulachon fish distribution in the vicinity of Deltaport Terminals off the mouth of the Fraser River, BC.  To support the development of the Dredging and Sediment Discharge Plan that will form part of the Construction Environmental Management Plan of the Roberts Bank Terminal 2 Project, the port authority has committed to developing eulachon-specific mitigation that will be used during dredging activities. A pilot study was developed to examine the efficacy of hydroacoustic techniques in detecting adult eulachon.

ASL proposed using the Acoustic Zooplankton Fish Profiler (AZFP), a calibrated multi-frequency echosounder, to measure distribution of the eulachon, particularly during the spring period when they are believed to migrate past Roberts Bank and up the Fraser River to spawn.  The AZFP is a four-frequency acoustic profiler that can be deployed for months, continuously measuring day and night, or can be used in real-time transect mode. In the spring of 2020, three AZFPs were moored off Deltaport for six weeks, covering the peak April migration period. The acoustic profile data covered the water column down to 150 meter depth at one shallow site and one deep site.  The eulachon are known to occur near-bottom but during migration may be present at shallower depths.