Larval fish community dynamics during 2017 Lake Huron CSMI

Session: 29. - Preliminary Results from the 2017 CSMI Intensive Field Year on Lake Huron

Lauren Eaton, USGS, [email protected]
David Bunnell, USGS Great Lakes Science Center, [email protected]
Patricia Armenio, USGS Great Lakes Science Center, [email protected]
David Warner, USGS, [email protected]
Paris Collingsworth, Purdue University, US EPA, [email protected]

Abstract

In Lake Huron, changing ecosystem dynamics from declines in prey fish to primary production have led to an interest in understanding more about growth and survival of larval fish.  For the intensive 2017 CSMI year, multiple components of the food web were sampled at nine nearshore to offshore transects near tributaries with varying phosphorus loads.  Monthly sampling occurred from April to August using a 1-meter diameter, 500-micron mesh net towed at the surface and obliquely through the water.  We compared larval fish densities spatially and temporally, and how that relates to primary production, Mysis densities, as well as zooplankton densities for a subset of the data.  We hypothesized that transects closest to tributaries with high phosphorus loads would have higher larval fish densities and faster growth rates, due to greater prey resources.  Otoliths were removed from a subset of larval rainbow smelt, the most abundant species collected, to determine age and growth rates.  Preliminary results show highest larval fish densities occurred in June near Thessalon, Ontario which has historically had lower tributary phosphorus loads.

1. Keyword
fish

2. Keyword
nutrients

3. Keyword
food chains