The Beaded Channel: A Low-Cost Technique for Enhancing Winter Habitat of Coho Salmon.

Tributaries of the Clearwater River, Washington, support substantial populations of overwintering juvenile coho salmon Oncorhynchus kisutch . In 1986, a 2-year study was initiated to further explore opportunities for enhancing the survival and growth of overwintering juvenile coho salmon in wall-base channel streams. In this study, six 7-m-long by 4-m-wide by 1-2.5-m-deep ponds were blasted into the mud substrate of an ephemeral wall-base channel, which came to be known as Swamp Creek. The series arrangement of the small ponds that were created along the stream channel, termed a beaded channel, resulted in a significant increase in overwinter survival and growth of juvenile coho salmon. Survival increased from zero before construction to 43% the first winter (1986-1987) and 70% the second winter (1987-1988) after construction. Mean overwinter increases in length and weight of immigrants changed from nothing (due to zero survival) before construction to 20 mm and 5.6 g after construction. The total cost of the Swamp Creek beaded channel was $3,340 (personnel plus materials)