Geology topics
D.A. Venditti
Publications and source records attributed to D.A. Venditti.
Gas bubble disease in resident fish below Grand Coulee Dam. Annual report 1999
Abstract not available
Migratory behavior and forebay delay of radio-tagged juvenile fall chinook salmon in a lower snake river impoundment
During July and August 1995-1997, we used radiotelemetry to estimate the migration rate of 405 juvenile fall chinook salmon Oncorhynchus tshawytscha (mean fork length, 138-144 mm) through Little Goose Reservoir. Migration rates decreased significantly as fish approached the dam. Median migration rates in 1995 were 26.0 km/d through the 45.9-km reach immediately below Lower Granite Dam, 14.9 km/d through the next 14.4 km, and 0.8 km/d in the Little Goose Dam forebay (0.6 km). Median migration rates through the same reaches were consistent among years: 24.8, 13.4, and 0.8 km/d in 1996 and 20.2, 10.2, and 1.0 km/d in 1997. Most fish migrated through the upper 45.9 km within 5 d and through the lower two reaches (15.0 km) within an additional 5 d. However, 10% to 20% of the fish spent a week or more in the forebay and lower reservoir. Radio-tagged smolts displayed two behaviors after entering the forebay: crossing the forebay and upstream excursions. Study fish crossed the forebay an average of 0.6-1.0 time/h, and 157 upstream excursions were identified, 15 of which were at least 14.4 km in length. Fish behavior in the forebay was associated with declining water velocities near the dam. Detections of passive integrated transponder tags suggest that similar delays occur in other lower Snake River reservoirs. Based on studies from the Columbia River, delays for 20% of the juvenile fall chinook salmon outmigrants in each of these forebays may have contributed to high predation losses and pose a serious challenge to efforts aimed at restoring this threatened salmon stock.
Thermal exposure of wild juvenile fall Chinook salmon in Little Goose Reservoir, Snake River
No abstract available
Thermal exposure of juvenile fall Chinook salmon migrating through Little Goose Reservoir. Annual report 1998
Abstract not available
Nearshore movements of juvenile fall Chinook salmon in the Columbia River. Annual report 1995
No abstract available
A non-lethal measure of smolt status of juvenile steelhead based on body morphology
A nonlethal morphometric method to assess smolt status of juvenile steelhead Oncorhynchus mykiss was validated. Fish were collected from hatcheries before release and during their seaward migration in a large river system. Fifteen anatomical landmarks were digitized from photographs of each fish, resulting in 34 morphometric characters based on a truss network. Principal component and canonical discriminant function analyses were used to assess smolt status. A single canonical variate was significantly correlated with gill Na + ,K + ‐ATPase activity, a commonly used measure of smolt status. This nonlethal method may be a useful measure of smolt status when sacrificing fish is not desirable or possible; it requires little training to perform, but it does require a larger sample size than some other methods.
Assessment of smolt condition for travel time analysis. Annual report 1990
No abstract available