Bocking and Peacock, 2004

Bocking, R. C., and D. Peacock. 2004. Habitat-based production goals for coho salmon in Fisheries and Oceans Statistical Area 3. Fisheries and Oceans Science Canada, Research Document 2004/129, British Columbia.

Smolt productive capacity and the number of spawners that are required in order to fully seed the available habitat and produce the maximum number coho smolts (Smax) were estimated for 102 coho streams in Statistical Area 3 using a habitat-based model. Stream length accessible to coho salmon was determined from terrain resource inventory maps (TRIM) using GIS. Stream order, gradient and known barriers were used to define the accessible length of stream. The number of smolts per kilometre was derived using two models. The first used a log-linear predictive regresssion of smolt yield and stream length for Alaskan and British Columbia streams. The second used recent decadal smolt yield and stream length for three northern British Columbia coho indicator streams (Lachmach, Zolzap, and Toboggan). Estimates of smolt productive capacity and required spawner numbers were stratified into four geographic regions of Statistical Area 3: Outer Coastal Area, Outer Nass Area, and Nass River Area. The predicted smolt yield from both models for Zolzap Creek was comparable to maximum smolt yield from Ricker and Hockey Stock smolt recruitment relations. However, the estimated required number of spawners to seed the available habitat in Zolzap, and for all streams in general, was highly variable and depended on the assumed values of egg-to-smolt survival and the number of smolts produced per spawner.