Juvenile Abundance Surveys of ESA-listed Salmonids in Tributaries of the Upper North Fork Toutle

FY2008 Actual: Habitat surveys and eletro-fishing methods were completed during the low flow season of the year (August-September). Of the 12 major upper NF Toulte Tributaries 9 were surveyed upstream to fish passage barriers. Three tributaries were inaccessible or dry. Habitat Types (pool, glide, riffle, cascade or tail-out) were measured and mapped. Canopy Cover was recorded. Channel substrate type (mud, sand gravel, cobble, and boulder) was recorded. Channel width and depth was measured for each Habitat Type. Large Woody Material counts were recorded.
Lower, middle and then a selected upper reach of each tributary was electro-fished. Seven fish species were observed: coho salmon, steelhead, rainbow and cutthroat trout, sculpin, dace and shiners. While all tributaries had good pool habitat for coho juvenile rearing, only one tributary had a few coho (Cow).
High rearing densities of trout were found in some glide and pool reaches in all creeks. The creeks either had good numbers of rainbow (Castle Creek) or cutthroat trout (Deer, Pullen and other creeks), but no coho.
Our preliminary hypothesis from this survey work is that the limiting factor on juvenile salmonid production Upper NF Toutle is fish passage for juveniles between tributaries during low flow times, and coho adult spawner distribution during high flow times of the year.
High value summer rearing habitat is abundant. Only about 1% of existing coho summer rearing habitat is utilized by coho. Glide and riffle habitat, preferred by trout for summer rearing is widely under-utilized. This may be due to low flow fish passage conditions between tributaries. All salmonids observed displayed excellent body condition and vigor. The body condition of rearing rainbow trout in Castle Creek was exceptionally good.

Proposed Project Outcomes:
a. Juvenile abundance surveys will collect data revealing the abundance of juvenile steelhead and coho in tributaries of the North Fork Toutle River. The deliverable will be a single years data set.

b. A single year of habitat assessment surveys, which will characterize habitat quality in tributaries of the North Fork Toutle River. Habitat data is expected to change less rapidly than juvenile abundance, therefore only one year of data collection effort is required. The deliverable will be the single years dataset.

c. A final project report will present and analyze all the juvenile abundance data. The final report will also spatially correlate the juvenile abundance with the habitat quality assessment data. For PCSRF, the deliverable will be the final project report.

d. Another final report will re-assess the habitat data in context with any spatial correlation with juvenile fish abundance. This process will identify a prioritized list of high-value habitat restoration projects available in the North Fork Toutle River watershed.

e. Both the two final reports (including the prioritized list of habitat restoration projects) will be distributed to watershed stakeholders, including landowners, federal and state resource management agencies, private industry, fisheries consultants and the Tribal community.

f. If appropriate, the final juvenile abundance report may be prepared in the format of a fisheries science or management journal and submitted for review and potential publication.

g. One goal of this project is to inform, influence and modify as necessary the future direction of both the fisheries and habitat resources management agencies tasked with managing for ESA-listed steelhead and coho in the North Fork Toutle River watershed. This outcome completes the adaptive management circle.

h. The ultimate goal of this project is to directly increase overall steelhead and coho abundance, increase population stability and resiliency across the region, and diminish the risk of extinction for the two species.