Abundance, distribution, production, and consumption of mysis diluviana in Lake Huron

Mysis diluviana is an important part of the food web in all of the Laurentian Great Lakes except Lake Erie.  While it has historically been an important food item for fish, recent declines in Diporeia spp. may have resulted in greater predation pressure on M. diluviana.  The literature on recent abundance and production of M. diluviana in Lake Huron is lacking, so it is unclear how food web changes have affected this species and whether or not additional predation would lead to declines in M. diluviana abundance.  In this study, we examined lake-wide late-summer abundance and distribution over several years (1971, 2005, 2007, 2008, and 2009) to determine whether long-term changes have occurred.  We then provide more detailed analysis in 2007, when we had seasonal estimates of M. diluviana abundance and production.  Finally, in 2007 we compared M. diluviana production from size-frequency data to bioenergetic estimates of consumption of M. diluviana by pelagic fish based on seasonal fish diet information, both field and literature estimates of fish growth rates, and acoustic and bottom trawl estimates of fish density.  Our analyses will provide considerable insight into how the changing Lake Huron food web has affected M. diluviana.