Modeling largemouth bass growth following reductions in phosphorous loading in a recovering urban lake

Onondaga Lake, NY has experienced a drastic reduction in phosphorous loading and increasing water clarity since 2000.  Decreasing productivity has likely affected fish growth.  While the lake supports a diverse fish community, black bass are the most important sportfish and tournaments are held regularly.  With a massive remediation effort planned, understanding the changes in sportfish growth rates will help guide management decisions.  We modeled largemouth bass growth using the Weisberg method.  This method fits models to hard-part increments and allows explicit statistical tests to determine changes in growth caused by management actions or other environmental factors.  Otoliths were removed from 76 largemouth bass captured by electrofishing in November, 2009.  Cross sections were prepared and increments between annuli were measured using Image Pro software.  These data will be fitted to a two-way analysis of variance model to detect changes in growth between years and identify trends.