Results of the 2004 Fall Walleye Index Netting (FWIN) Surveys

Walleye (Sander vitreus) have become one of the most popular sport fish in Washington and continue to grow steadily in popularity. Although they inhabit only about twelve lakes in eastern Washington they also occupy the entire mainstem of the Columbia River from the Canadian border to near the mouth at the Pacific Ocean.

In general, due to favorable conditions, Washington’s walleye populations grow faster and establish higher relative abundances than the average conditions in other areas of North America that walleye inhabit. Because of the walleye’s importance as a renewable recreational resource, WDFW began the FWIN surveys in 2001 in order to manage them more efficiently and
effectively. Six waters were sampled in 2004.

All the data collected during the fall walleye surveys was obtained by using the standardized Ontario FWIN protocol. This standardized sampling method allows valid comparisons of results from water to water and year to year. During the fall, walleye are more evenly distributed throughout the lake and the water column providing the most consistently good time to obtain a representative sample of the population. Sampling begins when surface water temperature lowers to 15oC and must stop when it reaches 10oC. The walleye were collected with gillnets only. The nets are 60m in length by 1.8m in depth. Each net contains eight panels of increasing mesh size from 25mm to 152mm (stretched mesh). Each net was set in a randomly selected site for approximately 24 hours. In order to make effort comparable, the number of net sets was determined by the surface area of the water being sampled. Each walleye captured was sampled for total length, round weight, visceral fat weight, and gonad weight. Sex and sexual maturity were determined by examination of the gonads. Otoliths were taken from each fish for age analysis.

The results from our 2004 surveys are shown in this report in the form of graphs followed by a brief explanation of each. The information displayed herein includes relative abundance (the average number of fish per net), size distribution (the percentage of walleye in each size category), age distribution (the percentage of each age group), and species composition (the percentage of each different species in the fish community for each lake). A more detailed report of our FWIN results from 2002-2004 will be forthcoming.