Comparing Alewife (Alosa pseudoharengus) Diets to Zooplankton Community Composition in Lake Ontario

Session: 54. - Food Web Ecology and Dynamics of Lake Ontario: Nearshore ? Pelagic Linkages

Mary Hanley, Ontario Ministry of Natural Resources and Forestry, [email protected]
Julie Munro, ON Ministry of Natural Resources, [email protected]
Ana Carolina Taraborelli, MNRF, [email protected]
Brent Metcalfe, ON Ministry of Natural Resources, [email protected]
Timothy Johnson, Ontario MNRF, Glenora Fisheries Station, [email protected]

Abstract

Zooplankton samples and alewife (Alosa pseudoharengus) diets were collected from a number of paired locations across Lake Ontario during spring, summer, and fall 2013. Diets were examined for composition with respect to both species and size of zooplankton, as well as preference based on relative abundance in the lake-based samples. Diets of sub-adult alewife differed from adults, with adult alewife consuming higher proportions of predatory cladocerans. Dreissenid veligers were an important prey to sub-adult alewives in the summer, especially in the central portion of the lake. Seasonally, both sub-adult and adult alewives consumed predominantly cyclopoids in the spring with the relative importance of cladocerans increasing through summer and fall. Predatory cladocerans dominated the diets of adult alewives in the fall, favouring Cercopagis in the west and Bythotrephes in the east. Alewife are the dominant planktivore and prey fish in Lake Ontario, and serve as a key link between the lower trophic levels and piscivorous fish community.

1. Keyword
alewife

2. Keyword
zooplankton

3. Keyword
diets