Long-Term Field Test of Habitat Change Predicted by PHABSIM in Relation to Brook Trout Population Dynamics during Controlled Flow Reduction Experiments;Research rept

摘要

We assessed the utility of the Physical Habitat Simulation system (PHABSIM) in a Michigan trout stream by testing the assumption of a positive linear relation between modeled habitat (weighted usable area, WUA) and brook trout Salvelinus fontinalis population levels. We also determined the effects of water withdrawal on brook trout survival, growth, and movement. We simulated irrigation withdrawals by diverting water from a 0.6-km reach of Hunt Creek from 1 June through 31 August each year during 1991-98. We withdrew about 50% of normal summer discharge in 1991-94, 75% in 1995-96, and 90% in 1997-98. We compared abundance, survival, and growth of brook trout between each dewatering period and to pretreatment levels during 1984-90. Ratios of brook trout population parameters in the treatment zone to those in upstream and downstream reference zones were used to help identify temporal influences unrelated to dewatering treatments.