Gas bubble trauma monitoring in the Clearwater River drainage, Idaho 1998: report211 to National Marine Fisheries Service and Pacific Marine Fisheries Commission, 211 Portland, OR

摘要

Select portions of the Clearwater and North Fork of the Clearwater rivers were211u001eelectroshocked to estimate the incidence of gas bubble trauma (GBT) occurring in 211u001eresident fish populations for the spring and summer months of 1998. The study 211u001earea was divided into four sections and sampled weekly during periods of spill 211u001eand non-spill from Dworshak Dam. Five thousand five hundred and forty one fish, 211u001erespesenting 22 different species, were captured and examined for GBT. Two fish 211u001ewere detected with signs of GBT; exhibiting the lowest incidence of GBT in the 211u001elast four years (0.04%). Reduced discharge and lower levels of total dissolved 211u001egases may have resulted in lower incidence of GBT in the 1998 monitoring period.