Status and trends of pelagic prey fish in Lake Huron, 2013

Abstract

The USGS Great Lakes Science Center (GLSC) conducted acoustic and midwater trawl surveys of Lake Huron during 1997 and annually during 2004-2013. The 2013 survey was conducted during September and October and included transects in Lake Huron’s main basin, Georgian Bay, and North Channel. Pelagic fish density was 1,033 fish/ha in 2013 and increased 62% over the 2012 estimate. Total biomass in 2013 (6.07 kg/ha) was similar to the 2012 estimate (6.97 kg/ha). Mean numeric density of alewife Alosa pseudoharengus was substantially greater in 2013 than in 2012, but the 2013 estimate has low precision. Age-0 rainbow smelt Osmerus mordax abundance increased from 2012, whereas age-1+ rainbow smelt decreased. Age-0 bloater Coregonus hoyi abundance increased over 2012 estimates. Density and biomass of large bloater in 2013 was similar to 2012 levels. Emerald shiner Notropis atherinoides density and biomass increased during 2013. Two adult cisco Coregonus artedi were captured in Georgian Bay. Based on comparable biomass estimates during 2012 and 2013, prey fish availability during 2014 will likely be similar to 2013. Lake Huron has pelagic fish biomass similar to that observed in recent lake-wide acoustic surveys of Lake Michigan and Lake Superior, but species composition differs in the three lakes. There is an increasing gradient of diversity and native species occurrence from Lake Michigan to Lake Superior, with Lake Huron being intermediate in the prevalence of native fish species like coregonines and emerald shiner.