Chilkat Taku Stikine Unuk 15 Years of Troll Contribution and Escapement History
Troll Contributions for Four Wild Chinook Systems in Southeast Alaska Purpose: This document reviews the past 15 years of Chinook Troll contributions for four Southeast Alaska rivers with long histories of coded wiretag (CWT) smolt tagging: Chilkat River (115 32), Taku River (111 32), Stikine River (108 40), and Unuk River (110 75) to look at trends in light of the low returns in recent years. Method: Fifteen years of coded wire tag (CWT) data for the years 2003 2017 was downloaded from the ADF&G Tag Lab database, with the criteria species = Chinook, Rearing Code = Wild. The data contains both Alaska and non Alaska sites where wild fish are tagged. Eight Alaska systems showed some level of tag recoveries. I limited this analysis to the four with a full time series, and which account for 99.6% of the total contribution for the 15 year period. I summarized the data in various ways to show: Annual contributions for all sites. Monthly contribution across all return years to give an estimate of return timing. Weekly contribution by site with general fishery designation (Winter Troll, Spring Troll, Summer Troll. I split the Summer Troll by initial opening and later openings. Annual Troll contributions by Site. Annual Troll contribution and Escapement estimates. Annual contributions by District to give an idea of where fish are caught. Medvejie Troll contribution and wild river comparison.
Chilkat Taku Stikine Unuk
Annual Troll Contribution 4 Wild Rivers 2004 12 average = 9,335 Chinook 2013 17 average = 2,643 (28.3% of 2004 12) 2017 to date = 1,462 (15.7% of 2004 12)
Monthly Troll contribution across all return years to give an estimate of return timing. Data shows the majority of Chinook are harvested in April June. Collectively, these three months account for about 82% of the annual total. The Chilkat and Unuk Rivers seems to have a later return timing.
Weekly Troll by Site Fishery designations are approximate. Summer is split into July opening and later openings (usually August) by shading.
Weekly Troll by Site (Chart of data on previous slide) One idea being discussed for the 2018 Summer Troll is to delay opening until mid July (approx. week 29). By this point, about 92% of the annual harvest has happened.
Individual River data: Chilkat River Escapement & Troll Estimates Chilkat Preliminary 2017 Chilkat Escapement is 1,173. This is the lowest on record and 53% of the 10 year average. Biological Escapement Goal Range = 1,750 3,500.
Individual River data: Chilkat River
Individual River data: Taku River Escapement & Troll Estimates Taku Preliminary 2017 Taku Escapement is 7,500. This is the lowest on record and 34% of the 10 year average. Biological Escapement Goal Range = 19,000 36,000
Individual River data: Taku River
Individual River data: Stikine River Escapement & Troll Estimates Stikine Preliminary 2017 Stikine Escapement is 10,000. This is the 5 th lowest on record and 59% of the 10 year average. Biological Escapement Goal Range = 14,000 28,000.
Individual River data: Stikine River
Individual River data: Unuk River Escapement & Troll Estimates Unuk Preliminary 2017 Unuk Escapement is 1,203. This is the 3 rd lowest on record and 45% of the 10 year average. Biological Escapement Goal Range = 1,800 3,800.
Individual River data: Unuk River
Medvejie Troll Contributions
Data files Excel files: SEAK WILD CHINOOK in TROLL fisheries 2003 17 1.9.17.xlsx SEAK Escs Runs_111017 from Ed Jones ADFG.xlsx