Friday, March 18, 2011

Hoh River Project - Field Work 3

Seining in the Hoh River
 We continued field work for the Hoh River Engineered Logjam (ELJ) study in March 2011. Fish abundance, density, and diversity were assessed using seining and mark-recapture methods.  
At each of the two sites, we captured and marked fish with Bismarck Brown on one night, then recaptured fish the following night. We caught a total of 419 fish during the surveys. Recapture rates for coho and Chinook salmon at Hoh I and Hoh II sites were 11% and 13%, respectively. From these numbers, we will be able to make rough population estimates. Additionally, we recaptured 1 fish that we had PIT-tagged at the Hoh I (ELJ) site last year.
It was a fun-filled but hectic couple of days as we scrambled to get everything done before forecasted rain increased river discharge to a point where we couldn’t work, which would have washed away all of our sampling efforts. We compressed all of our work into two nights; one night for marking at both sites and one night for recapture at both sites. The work was completed just in time, with river discharge increasing to 5,000 cfs the day after we finished.
Data entry, checking, and analysis will be completed from April through May.  A final report will be completed by June 30, 2011.