Spatial variability in energetic condition of Lake Michigan preyfishes

Session: 57. - Advances in Understanding Nearshore Ecosystems in Great Lakes and Connecting Channels

David Bunnell, USGS Great Lakes Science Center, [email protected]
Steve Pothoven, NOAA-GLERL, [email protected]
Patricia Armenio, USGS Great Lakes Science Center, [email protected]
Lauren Eaton, USGS, [email protected]
David Warner, USGS, [email protected]

Abstract

Prey fish populations in Lake Michigan have been declining over the past several decades, likely owing to increasing predation and declining prey resources.  The nearshore of Lake Michigan has spatial heterogeneity driven by pulses of nutrient inputs from tributaries.  Many prey fishes occupy both nearshore and offshore regions, and the 2015 CSMI sampling effort targeted transects that varied in their proximity to tributaries with varying nutrient inputs.  We hypothesized that transects near high loading tributaries would produce alewife and round goby in higher energetic condition than other transects.  Alewife and round goby energetic condition varied among transects.  For large alewife, the St. Joseph transect (high nutrient input) yielded the highest energetic condition, but the opposite pattern was detected for small alewife.  At the lakewide scale, alewife energetic condition was relatively unchanged from the 1990s despite declining lake productivity. For round goby, no consistent spatial patterns were detected. Because the nearshore is a temporally dynamic region and fish likely move between the nearshore and offshore, using fish as sentinels of nearshore productivity would take a more comprehensive effort than we undertook in 2015. 

1. Keyword
fisheries

2. Keyword
alewife

3. Keyword
bioenergetics