Matanuska-Susitna Borough

Salmon Research: Alexander Creek Pike Suppression

Scope

This project will continue the ongoing effort to increase salmon productivity in the Alexander Creek drainage by removing invasive northern pike from side-channel sloughs of Alexander Creek.  ADF&G’s northern pike suppression efforts in Alexander Creek include monitoring and evaluation to study the correlative relationship of northern pike removal and salmonid abundance.  Catch rates of invasive northern pike, sizes of pike and their diets, and distribution patterns of juvenile salmonids will also be monitored to investigate changes over time as the pike are removed.  Program has been in place since 2011.  Funding from the Alaska Sustainable Salmon Fund will expire in 2016 and state budget reductions have resulted in loss of funds.

Timeline: March 2017-June 2018

Project Benefits

Project Status

In 2017, field crews gillnetted 53 hydrologically-connected side-channel sloughs of Alexander Creek until they reduced pike catches by approx. 85% from the first day's catch in each slough.  In total, 994 pike were removed which is a reduction from previous years' pike catch which may indicate pike population is in decline, however low water levels likely influenced catch rates as well.    In spring 2018, field crews repeated the 2017 gillnetting for 60 hydrologically-connected side-channel sloughs, removing 1,110 pike. This is an increase from 2017's catch likely due to higher water levels allowing netting on several sloughs that were previously inaccessible. Monitoring of 180 minnow traps continued to show juvenile salmonids present, starkly contrasting situation prior to gillnetting efforts beginning in 2011. Stomach content analysis corroborated results of minnow trap survey: juvenile salmonids were found in pike stomachs throughout the river, showing positive trends that indicate the pike suppression efforts are having a positive effect on salmonid survival in Alexander Creek.  Spring gillnetting for pike in Alexander Creek will continue into the foreseeable future, pending funding.