Variability and reliability of counts of fish made by divers in sections of two British Columbia rivers are examined. Repeated counts of several species of fish by a team of divers in a stream section are reasonably homogeneous, and not markedly different from total numbers subsequently recovered by poisoning. Diver counts of large spawning rainbow trout also agree closely with those made in areas with good visibility from the river bank or from helicopter. Under suitable conditions a diver team can rapidly census the fish population of long stretches of stream and obtain estimates of species composition and abundance in types of habitat difficult or impossible to sample by usual methods.

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