SALMONID HABITAT–GEOMORPHOLOGY RELATIONSHIPS IN LOW-GRADIENT STREAMS

A link between stream geomorphology and lotic ecosystems was demonstrated by quantitatively examining the precise locations of salmonid redds with respect to the planform geometry of streams using a differential global positioning system. A total stream distance of 59 km was surveyed in 17 streams, in which a total of 309 redds of Sakhalin taimen (Hucho perryi) were recorded. The average size (±sd) of these redds was 227 ± 60 cm in length and 122 ± 42 cm in width. A meta-analysis of these data showed that channel sinuosity was significantly greater at sites where Sakhalin taimen redds were constructed than the average stream sinuosity. This salmonid preference for highly sinuous reaches was detected when the sinuosity index was calculated at 50-m increments and became insignificant at greater distance increments. This habitat–sinuosity relationship will be more pronounced in streams with only moderately sinuous channels, less abundant large woody debris, and higher spawner densities.