1. Cowichan Chinook Workshop March 2013
Critical Habitats and Key Limiting Factors

2. The Next 20 Minutes… Critical Habitat & possible Limiting factors
Life History Phases
Adult migration and Spawning
Egg to Smolt
Follow Chinook Freshwater Life History

3. Adult Migration - Holding
Critical Habitat
Safe adult holding habitats in Lower River
Possible Limiting Factors
Excessive predation by pinnipeds in lower river

4. Adult Migration – Upstream Passage
Habitat Requirement
Adequate flows to facilitate upstream passage
Possible Limiting Factors
Low flows in lower Cowichan

5. Adult Migration – Upstream Passage
Habitat Requirement
Unlimited passage through/around physical barriers
Possible Limiting factor
delays in migration due to counting fence, Skutz fishway, Cowichan Lake fishway, LWD jams or other barriers

6. Adult Migration and Spawning – Water Quality
Habitat Requirement
suitable water quality for adult salmon
Possible limiting factors
Low D.O., High temperatures, High bacterial counts, other water quality issues resulting in reduced fitness or mortality

7. Adult Migration and Spawning – Suitable in-river Habitat
Habitat Requirement
Deep holding pools, complex habitat to provide cover
Possible limiting factors
Lack of complex pool habitat; adequate channel depth

8. Adult Migration – Stable River Morphology
Habitat Requirements
stable channel and banks with natural level of bedload movement
Possible Limiting Factors
high bedload deposition in lower river limits channel capacity and fish passage, reduces of channel complexity and increases risk of channel evulsion and instability

9. Spawning – Suitable Habitat
Habitat Requirements
Sufficient quantity and quality of spawning habitat
Possible Limiting Factors
Lack of sufficient gravel recruitment in upper river and at lake outlet. Impacts of invasive exotics (didymo)

10. Incubation – Suitable Flow Regime & Stable Conditions
Habitat Requirements
Stable river flows throughout
incubation period
Possible Limiting Factors
Freshet flows (egg scour), Low
flows (dewatering of Redds), over-spawn
or other substrate disturbance; predation by fish or birds

11. Incubation – Substrate Condition
Habitat Requirements
Good subsurface water quality and unrestricted passage for alevins and emergent fry through substrate
Possible Limiting Factors
water quality issues, high sediment loads, compacted gravel

12. Rearing/Outmigration – Unrestricted Passage
Habitat Requirements
Unlimited access down mainstem and into and out of off channel habitats
Possible limiting factors
High spring flows (displacement of juveniles prematurely), low spring flows (restrict access to preferred rearing habitat, dewatering of habitat, stranding in off channel habitats), physical barriers to outmigration.

13. Rearing/Outmigration – Adequate Habitat
Habitat Requirements
Complexity and cover
in mainstem and off
channel
Possible Limiting Factors
Channelization, limited
access to historic off
channel habitats, loss of
complexity throughout lower floodplain, loss of complex riparian habitat, increased
predation as a result of limited cover availability

14. Rearing/Outmigration – Adequate Food Supply
Habitat Requirements
Natural sources of food for rearing fry and pre-smolts
Possible Limiting Factors
Lack of ecosystem health and resultant prey availability

15. Rearing/Outmigration – Suitable Water Quality
Habitat Requirements
suitable water quality and temperature
Possible Limiting Factors
high suspended solids, high temperatures, toxic conditions

16. Summary…
Complex relationship between an organism and the habitats that support it
Health of the Cowichan watershed and river is directly linked to the health of Cowichan Chinook stocks
Hopefully this brief overview has provided you with a starting place and a foundation for this workshop’s discussion of what freshwater habitat features may be limiting to the health of Cowichan Chinook and possible interventions that could address some of these limiting factors.