Results of the 2007 Fall Walleye Index Netting (FWIN) Surveys


Published: 2008

Pages: 20

Author(s): Warmwater Program Personnel


This report documents the results of the 2007 fall walleye index netting (FWIN) surveys in five eastern Washington waters (Figure 1). For more information on Washington walleye biology and distribution and the FWIN sampling protocol, please see the 2005 report on this website.

Similar to the previous web reports for our FWIN surveys, the results from our 2007 surveys are shown in the form of graphs followed by a brief explanation of each. The relative abundance graph compares the average number of walleye captured per net from all lakes for all years combined, on a single graph (we use the geometric mean for these values). After that, there are four individual graphs for each lake: size distribution (the percentage of walleye in each size group), age distribution (the percentage of walleye in each age group), species composition pie chart (the percentage of each different species captured in our survey, for each lake) and species composition bar graph over time, which shows the general species composition from 2002 â€" 2007 for each lake. The size and age distribution graphs compare the 2007 values with the average values from 2003 â€" 2007 so you can see how 2007 compared with an â€�"average” year on that water for size and age distribution. At the end of the report is a length-at-age graph, which shows the average length at each year of age for walleye from all six FWIN waters on one graph. Please bear in mind that since we sample exclusively with gill nets for the FWIN surveys, the species composition graphs may or may not accurately represent the fish communities from each lake. These graphs will only provide a general picture of the fish community make-up. Like any single capture technique, gill nets have particular biases for and against certain species and sizes of fish. They are however, the best single technique for capturing a representative sample of the walleye populations and fall is the best time to do it.