Abstract
Fish surveys have been periodically conducted on Onondaga Lake since 1927; more intensive surveys began in 1989 by the State University of New York, College of Environmental Science and Forestry, and have continued annually. Recent efforts (2000-2012) by the Onondaga County Department of Water Environment Protection documented the fish community prior to and following (post-2005) major reductions in nutrient loading to Onondaga Lake from the wastewater treatment facility in Syracuse, New York. These upgrades have had dramatic effects on the lake fish community; adult species richness has increased from 13 species recorded in 1946 to more than 40 species documented annually since 2008 and more than 50 species documented since 2000. Adult species diversity has varied since 2000, with increasing dominance by largemouth bass, yellow perch, and brown bullhead. Adult fish diversity was significantly higher following wastewater treatment plant upgrades in 2004 and 2005 (F-1,F-18 = 5.26, P = 0.03). Dramatic increases in macrophyte coverage and dreissenid mussel densities also have been documented. Rarefaction analysis was conducted to standardize survey results by computing expected species richness values from 2000 to 2012 as well as relative to 1946. Expected species richness was not statistically significant following upgrades compared to prior (F-1,F-23 = 3.81; P = 0.075). Linear regression of expected species richness showed a significant increasing trend for the 2002-2012 gillnet data (ES52 = 0.391* YEAR + 67.66, r(2) = 0.59, P < 0.006) and the 1946-2012 trap net data (ES164 = 0.203* YEAR + 4.44, r(2) = 0.81, P < 0.005). The Onondaga Lake fish community is still adapting to the various water quality changes, and continued monitoring is necessary to understand the trophic structure of the lake and how this may affect sportfishing opportunities in the future.