Takshanuk Watershed Council

Run timing and population estimates for eulachon
Thaleichthys pacificus in the Chilkat and Chilkoot rivers
in S.E. Alaska 2010-2011

Prepared for the Chilkoot Indian Association
by
The Takshanuk Watershed Council

Abstract

The Chilkoot Indian Association (CIA) and Takshanuk Watershed Council (TWC) initiated a study with funding from the U.S. Fish and Wildlife Service to identify the upper extent of spawning and quantify Eulachon Thaleichthys pacificus populations in the Chilkoot and Chilkat rivers.  Population estimates of eulachon returning to the Chilkoot River were 2.2 million (95% CI 1.7 to 2.7 million) and 12.6 million (95% CI 11.5 to 12.6 million) in 2010 and 2011 respectively. The upper reach of spawning on the Chilkoot River was identified to be 1.3 km upstream of the Lutak Road Bridge in 2010 and all of the Lower Chilkoot River ( 2.6 Km) before entering Chilkoot Lake in 2011.  In addition, eulachon crossed Chilkoot Lake in 2011 and entered the lower 150 meters of the Chilkoot River as it entered the Lake.  However, spawning could not be documented and a subsample of the population resulted in 100% males.  In addition, gender distribution was collected for eulachon returning to the Chilkoot River with 34% and 26% being female in 2010 and 2011 respectively. 

Due to the braided nature of the Chilkat River the CIA and TWC crew were unable to capture sufficient numbers of Eulachon to provide a population estimate in 2010 or 2011.  However, CIA examined 784 individual eulachon in 2010 and 990 in 2011 finding 23% to be female in 2010 and 10% to be female in 2011.  The upper extent of spawning on the Chilkat River was 11.2 km upstream from the mouth of the river in 2010 and 20.6 km in 2011.

Report

Note:  This is a fairly large file (7.7MB) so it may take some time to download.

http://takshanuk.org/sites/default/files/EulachonReportFinal14Nov2011small.doc