World Aquaculture 35 Fig. 4. Air-lift system to recirculate water in stream channels. Compressed air injected through smaller grey pipe lifts water up larger white pipe. cms). With two exceptions, all water flow through the OHRC is by gravity through a network of approximately 10 km of (mostly) underground plastic (HDPE) pipes and valves. The two exceptions to gravity water flow are a water re-use system for the stream channels, and a water treatment facility inside the research building. The water re-use system for the stream channels injects compressed air from turbines (Figure 4) into the water outlet from each stream. This operates as an airlift to recirculate water back to the head of the stream channel, and to increase water flow in each channel by up to 50 percent to a design maximum flow of 1.4 cms. The water treatment facility is located inside the main research building (Figure 5). We take intake water from Fall Creek, Carnes Creek or a combination of the two, put it through a micron filter, sterilize it with ultraviolet light and then adjust the temperature (cold, ambient, or warm) with counter-current heat exchangers. This water is then available for controlled experiments in the wet lab. Water is put through an abatement pond it is returned to Fall Creek. Water is taken from Fall Creek through an automated intake (Figure 6). The intake meets current NOAA standards, including screens. An innovative system was designed and installed to clean these intake screens. When activated by an automated programming system, the series of electrically driven brushes rotate against the intake screens to loosen debris that is moved away by the sweeping water flow. Water can be directed to a number of locations and functions, depending on research needs. The stream channels are a key feature of the OHRC (Figure 7). Water from the intake flows through a settling pond, to allow large silt and sand particles to drop out before it Fig. 5. Dr. Dan Edge, Head of Fisheries and Wildlife Department at Oregon State University, inspects the water treatment facility at the OHRC. Fig. 6. Water intake from Fall Creek at the OHRC. passes through the four replicate channels, each 65 m long, 6.5 m wide and 2 m deep. River gravel, large wood, root wads and stones can be arranged within each channel as required in each experiment. Automated PIT tag detectors in the channels can be used to record positions and movements of fish in the channel. A series of television cameras, mounted about 3 m above the channels, can be remotely controlled from the dry lab, and used to record the behavior of fish in the channels. We have had steelhead, coho and Chinook salmon spawn successfully in the channels, and we have subsequently reared hundreds of juveniles resulting from those spawning events. The juveniles feed solely on natural benthic invertebrate production in the channels Fig. 7. Experimental stream channels at the Oregon Hatchery Research Center.
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