A Model of Steelhead Movement in Relation to Water Temperature in Two Lake Michigan Tributaries

Abstract

Abstract We used movement data from two Lake Michigan tributaries to develop a new approach for analyzing upstream adult steelhead migration. Our data included 28 radio-tagged steelhead Oncorhynchus mykiss in the Pere Marquette River and a larger (5,876-10,083-steelhead), multiyear (1993-1999) data set of camera-recorded steelhead passages through a fishway on the St. Joseph River. To quantitatively predict the probability of upstream movement, our model used a rule for temperature-based movements developed from the data. Exponential, logistic, and power functions were evaluated as possible ways to express the probability of movement. Of these, the power function resulted in the closest fit between observed and predicted movements. The probability of movement increased with increasing water temperatures above a movement-threshold water temperature. Stream flow was incorporated into the temperature-based movement (TBM) model but did not add substantially to the model's ability to describe the migratory beh...