Depth and Velocity as a Factor in Stream Rearing and Production of Juvenile Coho Salmon


C P. Ruggles

Publication Date



behavior, channel, coho, downstream fish passage, downstream migration, flow velocities, food, instream flow, juvenile, migration, pool, production, riffle, salmon, smolt, streams, upstream

Journal or Book Title

The Canadian Fish Culturist


Coho salmon smolt production was measured in four artificial stream channels 50 (?) feet long by 20 feet wide. Two years' data are presented on the effect of depth and velocity on fish food production, smolt production and fish behaviour. A known number of wild coho fry were introduced to each channel and allowed to take up residence in the channel on a volitional basis. The amount of downstream migration was influenced by the availability of low velocity water. Over twice as many fry remained in a pool-like environment as in a riffle-like condition; an intermediate number remained when the depth-velocity situation was somewhere between pool and riffle. Whereas fish preferred the pool-like environment, fish food production was much higher in the riffle-like environment. The most coho smolt production occurred in a channel composed of one-half riffle and one-half pool. Differences in behaviour were noted between coho fry which had migrated upstream of their place of emergence and fry which had moved downstream from their place of emergence.





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