Development of a Carcass Analog for Nutrient Restoration in Streams

Abstract

Abstract Resource managers are becoming more interested in restoring nutrients to food-limited salmonid bearing streams, but all of the current approaches have some shortcomings. The objective of our work was to develop a nutrient restoration product that reduced these shortcomings. The product we developed, a carcass analog, was made from fall Chinook salmon (Oncorhynchits tshawytscha) from Spring Creek Hatchery, Underwood, Washington. These fish were pasteurized during the process that dried the ground salmon carcasses into a fishmeal. No known fish pathogens were detected in the pasteurized product. The analogs were easy to transport and distribute throughout the stream channel, generally sank to the bottom, and were retained within the channel. Approximately half of the analog had dissolved or been eaten after being in streams two weeks, and the analog was almost gone after four weeks. We discuss other studies that have demonstrated that carcass analogs reproduce the main food pathways historically pr...