Salmonid Fish Habitat

Applications of habitat data to fishery management

Distribution and abundance of habitat for different life stages• Barriers to migration; Waterfalls / dams• Adult habitat; Deep pools / cover • Spawning habitat; Glides / smaller substrates• Fry habitat; Shallow / smaller substrates• Parr habitat; Deeper / larger substrates

Assessing habitat quality & condition• Cover for fish; in-stream and bank structure• Climate control; shading • Pressures; impacts of Land and water use

In-stream coverShelter & territories; physical cover from floods & predators

• Size of substrates – Roughness layer• Interstitial spaces – subsurface layer• Flow type• Vegetation• Large woody debris

Flow cover

• Riffle / Run – Broken water• Glide / Pool – depth or canopy

Bank-side cover

• Undercut• Draped vegetation• Tree roots• Rock• Marginal vegetation• Other

Typical habitat requirementsLife Stage Salmon Brown Trout

Spawning Eggs Alevins

3+ m channel widthGlide or riffle flow (35-80 cm/s ¹)ˉWater depth 17-76 cmSubstrate Golf–tennis ball (20-100mm)Low fines (< 1 mm) 2.3 – 8 %Depth of substrate >15 – 25 cm

< 3 m channel width Glide or riffle flow (15-75 cm/s ¹)ˉPea-tennis ball substrate sizeLow fines (< 1 mm) 8 – 12 %Depth of substrate >14 cm

Fry (< 1 yr)< 20 cm depth

Golf – tennis ball substrate size Shallow / broken water / Fast flow

Golf ball – tennis ball substrateShallow /medium flow / marginal cover

Parr (=> 1 yr)20 – 40 cm depth

Tennis – football substrateDeeper / broken water / fast flow

Variety of substrateDeeper / slower waterUndercut banks / tree roots

Smolt Habitat connectivity Habitat connectivity

Adult Deep pools > 80 cm depth Deep water > 0.4 m depthSlow sustained flow Bank / bed / canopy cover

Habitat / River Sequence

JuvenileAdult

Spawn

Habitat / River Sequence

SpawnAdult Juvenile

Typical salmon habitat – low gradient

Adult pool habitat

Spawning habitat

Fry habitat

Mixed juvenile habitat (0 – 1++)

Typical salmon habitat – moderate gradient

Adult pool habitat

Spawning habitat

Fry habitat

Mixed parr habitat (1 – 2+)

Typical trout habitat - tributaries

Fry habitat

Spawn Habitat

Parr / adult habitat

Typical trout habitat – larger streams

Adult pool habitat

fry habitat

Spawn Habitat

Parr habitat

SFCC walkover Field surveys– Main components

General observations• Channel dimensions; Area of habitat• Channel type; gradient / character• In-stream cover; Flow & substrate types / LWD• Bank cover; bank type / riparian vegetation / shade

Point location observations• O.S Grid refs; Survey start / end points• Spawning; Area / type / condition• Adult pools; Area / depth / cover• Obstacles; type / height / fish passage• Modifications; revetment / embankment / pollution