2000 Pine Lake Survey: The Warmwater Fish Community of a Lake Traditionally Managed for Rainbow Trout

Pine Lake, six miles north of Issaquah, was surveyed by the Warmwater Enhancement Program from September 5 through 7, 2000. Largemouth bass dominated the species composition which included smallmouth bass, yellow perch, pumkinseed, and brown bullhead. However, catch rates for stock-size warmwater species were low compared to western Washington averages, suggesting low population densities. Although growth rates were relatively high, suggesting little competition for available food resources, size structures were skewed toward smaller fish. Few quality-size largemouth bass were sampled. However, sampling effectiveness for capturing larger fish may have been limited by such things as low conductivity, high transparency, and numerous docks. Low numbers of large fish may also be the result of overfishing in this popular urban lake. Large numbers of young-of-year largemouth bass were found as well as moderate numbers of young-of-year smallmouth bass. Aquatic vegetation coverage appeared sparse and offered little refuge for small fish. The large size of age 1 yellow perch and absence of young-of-year yellow perch and low numbers of pumpkinseed may suggest these fish were particularly vulnerable to predation because of lack of cover. A few rainbow trout and brown trout, stocked by WDFW, and cutthroat trout were captured during the survey. Historically, growth rates for Pine Lake trout generally exceeded those of other lakes in the region managed for trout. Since the mid-1980s, Pine Lake has been managed as a mixed species sport fishery with stocked catchable-size rainbow trout, fry plants of other species of trout, and self-reproducing populations of largemouth bass and other warmwater species. Management options for Pine Lake include but are not limited to the following: implementing a slot limit (12 - 17") for largemouth and smallmouth bass, augmenting aquatic macrophyte coverage to enhance refugia for smaller fish, enhancing littoral zone with artificial structures, conducting creel survey to determine angler effort for warmwater species, and conducting follow-up dive surveys to examine dock use by bass.