Fraser River, Port Mann Bridge-Douglas Island Eulachon Study, 2009

Resource: Fraser River, Port Mann Bridge-Douglas Island Eulachon Study, 2009

Authors / Publisher: Elmar M. Plate, LGL Consulting and Terra Remote Sensing for Kwikwetlem First Nation and Watershed Watch Salmon Society

Date: July 2009

PDF: Fraser River, Port Mann Bridge-Douglas Island Eulachon Study, 2009

Summary:

Little is known about the specific eulachon migration and spawning corridors adjacent to the Port Mann Bridge and within Kwikwetlem territory. As part of the Gateway Program and construction of the new Port Mann Bridge, the Kwikwetlem First Nation and Watershed Watch Salmon Society contracted LGL Consulting and Terra Remote Sensing to investigate eulachon densities, migration and spawning patterns in the area near the new bridge. The 2009 Port Mann bridge eulachon study presents the following findings:

In general, eulachon spawn directly beneath the Port Mann bridge pillars and in the close upstream vicinity of the bridge and as expected eulachon use all channels under the bridge for migration to upstream areas.

In more detail, eulachon caught in this study spawned in areas with sandy and gravelly bottom, medium depth (<6m) and lower maximum current speeds (>0.6m/sec) on plateaus and edges. Areas with a mobile sand layer were not used for spawning. The fork length of eulachon in this study ranged from 14-22cm and their weight ranged from 20-100g. Age classes could not be positively indentified from weight or length frequency plots and otoliths have not yet been analyzed. The plots suggest potentially three age classes which have been described as two, three and four year old spawners in the Fraser before. The sex ratio of eulachon in the lower Fraser appeared unbiased early in the season and skewed towards female fish later in the season.

Far more work is needed to describe eulachon general behaviour and specifically spawning behaviour in vicinity of the Port Mann Bridge and the whole lower Fraser.