DV-07-005 Stable Isotope Signatures of Marine Fish Predators and their Prey

Theodore Willis
University of Southern Maine


Willis and his colleagues analyzed the diets of anadromous fish to assess their role in nearshore food webs. Yet diet analysis only presents a snapshot view of what fish are eating at any given time. Stable isotope analysis, which measures the amount of marine- versus freshwater-derived nutrients, will provide an integrated perspective on the food web position occupied by different species. Together, diets and stable isotopes are much more effective in describing how an organism interacts with closely associated predators and prey. Willis sampled shorthorn sculpin (Myoxocephalus scorpius), as well as their predators and prey, from Boyden Stream, St. Croix River, Damariscotta River, and St. George River estuaries. These analyses began the process of building a stable isotope library, as well as inform development of a full study of nearshore marine food webs. Sea Grant funds supplemented this Northeast Consortium-funded project.

1-year project: $2,000

Associated publications:

Schmitt, C. 2008. Alewives: Feast of the Season. Maine Boats, Homes & Harbors 99:78-84.
Schmitt, C. 2008. Founding fish: alewife harvesters organize. Fishermen’s Voice 13(6).