Tests of Efficiency of Hydraulic Sampler for Collecting Salmon Eggs
eggs, Fisheries Research, hydraulic sampler, hydraulics, salmon, salmon eggs, spawning, University of Washington
Since the hydraulic sampler was first developed by the Fisheries Research Institute of the University of Washington in 1956 to estimate abundance of young salmon in spawning beds, there has been a tendency to reduce the area of streambed sampled at each point. During early studies about 1 m2 was sampled; but more recently the area sampled has been reduced to about 0.2 m2. In 1963, the Bureau of Commercial Fisheries used a 0.1 m2 sampling unit in its studies at Olsen Bay and Little Port Walter. The small 0.1 m2 sampling unit offered an evident advantage in that more points could be sampled in a given amount of time. With larger sampling units of 0.4 and 0.2 m2, there is evidence that 90 percent or more of eggs and alevins enclosed within the boundaries are collected with the hydraulic sampler. However, there was concern that this high percentage of collection might be altered by reducing the area of sampling unit to 0.1 m2. Accordingly, direct comparisons were made between 0.1 and 0.2 m2 sampling units by Bureau scientists working in Olsen Bay and Sashin Creek. The results of these comparisons are reported here.