Horizontal and Vertical Distribution of Juvenile Salmoids in Howard Hanson Reservoir

摘要

Horizontal and vertical density distributions of juvenile anadromous salmoids were monitored at the intake end of Howard Hwanson reservoir during expected normal emigration period (April through July). Our objectives were to 1) characterize the horizontal and vertical distribution of juvenile anadromous salmoids, by day and by night, during the spring migration at the intake end of the reservoir, 2) sample for trends in species and age class composition, by day and night, during the spring migration, and 3) analyze results for implications in the design of a new intake structure. Horizontal and vertical density distributions were obtained from biweekly day and night dual-beam hydroacoustic surveys of six transects. Vertical gill nets were used during this same time period, biomonthly sampling, to obtain specific information on individual species, year class, and day and night behavior. Horizontal density distributions for shore areas. Both daytime and nightime vertical density distributions showed a strong preference for the upper 15 m, ranging from 80% to 97% of the total fish observed.