The University of Washington and Battelle Marine Sciences Laboratory are jointly conducting a multiyear, three-phased research program to determine whether ferry terminals affect migrating juvenile salmon, and if so, how future design of ferry terminals and modifications to both terminals and operations can mitigate those impacts. Phase I resulted in a report synthesizing the technical knowledge regarding the potential effects of shoreline structures on migrating juvenile salmon. This report summarizes results from Phase II pilot field studies at the Port Townsend ferry terminal in spring 1999 and provides recommendations for proposed on-site tests of the effects of a range of different Washington State Department of Transportation ferry terminals and vessel activity patterns in Phase III (spring-winter 2000). The overall goal of Phase II was to perform pilot field experiments with releases of hatchery chum and chinook fry to test whether the Port Townsend terminal stops or delays the natural migration of juvenile salmon. Monitoring methods included diving surveys, beach seining surveys, single-beam and split-beam hydroacoustics, remote underwater video, and in situ light sensors.
River otters directly and indirectly resulted in mortalities to approximately 29,000 of the 30,000 chinook fry and 39,700 of the 40,000 chum fry that we were holding in net pens for experiments. We released the remaining fish 30 m from the southern edge of the Port Townsend ferry terminal on June 11, 1999. On the basis of this one-time experiment, we found no evidence that the Port Townsend ferry terminal was a barrier to the migration of the 1000 chinook that we released. We have no data or observations for the 300 chum fry after their release. The released chinook fry stayed in a school and did not disperse upon encountering the Port Townsend ferry terminal. The chinook fry did not divert their migratory route into deeper water or around the offshore perimeter of the terminal. Surface observations, underwater video, and the single-beam and split-beam hydroacoustics confirmed that the chinook migrated from the release point directly to the shadow line underneath the terminal. The chinook fry stopped at the shadow line and then displayed a consistent behavior of swimming from the darkness of the shadow line and near the bottom into the light to feed at the surface. As the sun set and the shadow line progressed further underneath the terminal, the chinook school appeared to follow the shadow line under the terminal and, we assume, out the other side. However, we caution that it is neither prudent nor valid to conclude that ferry terminals either do or do not have an effect on juvenile salmon migration, on the basis of these preliminary findings. The loss of the majority of our fish for experiments, the hard-drive crash on the navigation computer, and the malfunctioning of some of the single-beam transducers compromised this study. The fundamental question of whether ferry terminals are a "barrier" to juvenile salmon migration remains unanswered.
May 21, 2007
David K. Shreffler, Russell A. Moursund.
Battelle Marine Sciences Laboratory, The University of Washington.
- # of Pages: 92 p., 2,680 KB (PDF)
- Subject: Environmental impacts, Ferries, Ferry terminals, Field studies, Fishes, Habitat (Ecology), Marine terminals, Salmon, Sunlight.
- Keywords: Salmon migration, over-water structure, hydroacoustics, underwater video, light sensors, predation, chum salmon, Chinook salmon, Port Townsend, Puget Sound Region.
- Related Publications: Impacts of Ferry Terminals on Juvenile Salmon Migrating Along Puget Sound Shorelines. Phase I, Synthesis of State of Knowledge, (WA-RD 472.1).
This abstract was last modified April 29, 2008