McLean, Jonathan2017-10-022017-10-022016http://hdl.handle.net/1773/40365Like many marine ecosystems, the San Juan Archipelago has several critical species of forage fish in the middle trophic level. These species play a critical role in energy transfer. This study examines variations in diet across different species, locations, and seasons. I studied the Pacific sand lance, Pacific herring, and Surf smelt. In contrast to past studies that indicated PSL were preferential to calanoid copepods, in my analyses PSL appeared to feed on a combination of amphipods and copepods, while herring and smelt fed primarily on copepods. In comparing sand lance across multiple sampling locations, both in an established nearshore population at Jackson Beach and a newly discovered nearshore population at South Beach, we noted feeding activity and foraging behavior. PSL at South Beach eat primarily copepods whereas PSL in Jackson Beach are eating both amphipods and copepods. In contrast, no observable feeding activity was measured in the larger, older fish in the offshore location that we measured on multiple occasions (San Juan Channel Wave Field). Upon examining San Juan Channel data from spring 2015, fish appeared to be leaving their winter dormancy period. Based on this new data, the winter dormancy period was estimated to be between late February and early October.en-USPacific sand lancePacific herringSurf smeltSouth BeachJackson Beach