2008 Warmwater Fisheries Survey of Newman Lake, Spokane County, Washington

Washington Department of Fish and Wildlife biologists surveyed Newman Lake (Spokane County) on June 8-10, 2008 as a follow-up to a similar survey conducted in September 2000. Fish were sampled using boat electrofishing, gill netting, and fyke netting. A total of 942 fish from twelve species were collected during the survey. Bluegill sunfish Lepomis macrochirus was the most abundant species (43%), followed by yellow perch Perca flavescens (16%) and largemouth bass Micropterus salmoides (13%). The majority of the biomass was comprised of carp Cyprinus carpio (37%), largemouth bass (17%), and tiger muskellunge Esox lucius x E. masquinongy (10%). Pumpkinseed sunfish L. gibbosus, black crappie Pomoxis nigromaculatus, brown bullhead Ameiurus nebulosus, smallmouth bass M. dolomieu, yellow bullhead A. natalis, rainbow trout Oncorhynchus mykiss, and tench Tinca tinca, were also sampled in lower numbers.

The results of this survey suggest that little has changed with the Newman Lake fish communities since 2000. Newman Lake continues to be prey-crowded; however, the structure of the fish community has shifted from one being dominated by yellow perch (in 2000) to one dominated by bluegill sunfish (in 2008). Fewer largemouth bass were sampled in 2008 (n=124) compared to 2000 (n=208). Despite the apparent decrease in relative abundance, condition of largemouth bass remains below the national 75th percentile, particularly for fish <300 mm total length. This suggests that largemouth bass larger than quality size continue to have adequate forage, whereas smaller bass are having to compete with the abundant bluegill and yellow perch, as well as themselves, for available resources. Stock density indices for bluegill sunfish, yellow perch, and pumpkinseed sunfish were similar between 2000 and 2008, suggesting that predation rates by largemouth bass, smallmouth bass, and tiger muskellunge continue to be insufficient to control the overpopulation of those prey species. Although relatively low in density, the black crappie population continues to be above average in terms of its quality and the angling opportunity it provides.

Carp have, thus far, been overlooked as a potential obstruction to water quality restoration goals for Newman Lake, and even though the operation of the hypolimnetic aerator and alum injection system have improved water quality conditions over the last two decades, hypolimnetic hypoxia remains a lake management issue. We recommend monitoring the carp population to determine whether, or to what extent, this species is impeding water quality restoration measures. If carp are found to be an obstruction, the regulation of carp density should be integrated into the comprehensive water quality management scheme for Newman Lake.

Other future management considerations include the continued stocking of tiger muskellunge, the introduction of channel catfish, and determining the factor(s) that are limiting the condition of larger black crappie in the lake. We also recommend that future surveys be conducted during spring to allow for statistical comparability with this survey.