Cowichan Chinook Workshop March 2013 Critical Habitats and Key Limiting Factors

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

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

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

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

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

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

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

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)

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

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

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.

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

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

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

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.