Coldwater Streams Chapter 18
Coldwater Streams Game fish - predominantly salmonids Salmon, trout
Coldwater Streams Anadromous type 1 - use streams only for spawning, move out immediately after emergence Chum, pink, sockeye
Coldwater Streams Anadromous type 2 - spend 1 or more years in stream before leaving Chinook, coho, Atlantic salmon Anadromous trout (some races of rainbow, cutthroat, brown, brook)
Coldwater Streams Residents - spend entire life in stream Bull, rainbow, cutthroat, brown, brook Brown is only species not native to North America
Coldwater Streams - sustain spawning and rearing Physical conditions Water temperature <22°C Dissolved oxygen >8 ppm Stream size - greatest abundance, diversity in 4th-5th order streams Stream gradient - best 0.6-6.0% Hydrograph -variable
Other Fish Species Low diversity in west, higher diversity in east Cyprinids - minnows - Notropis
Other Fish Species Cyprinids - dace Rhinichthys, Phoxinus
Other Fish Species Cyprinids - chubs - Semotilus
Other Fish Species Catostomids - suckers - Catostomus
Other Fish Species Cottids - sculpins - Cottus
Other Fish Species Darters - Etheostoma
Salmonid Characteristics Territoriality Agonistic behavior Dominance hierarchy Focal points Probability of use curves
Salmonid Characteristics Growth Suboptimal temperature Limited food and space Initial year - 100-150 mm, decline in following years to 20-40 mm/year
Salmonid Characteristics Mortality - 50% or more annually Density-dependent factors Intraspecific competition - starvation
Salmonid Characteristics Density-independent factors Spring floods High summer temperatures
Salmonid Characteristics Density-independent factors Predation Birds Mammals Fish
Salmonid Characteristics Density-independent factors Overwinter mortality Starvation Predation - low Physical injury - ice
Salmonid Characteristics Higher mortality among males Longevity - 4-5 years
Angling Mortality
Salmonid Characteristics Reproduction Sexual maturity Age or size Fall spawners Brown, brook Spring spawners Rainbow, cutthroat
Salmonid Characteristics Redd - spawning bed Water velocity Depth Substrate
Salmonid Characteristics Eggs develop in gravel until hatching Emergence - early or late spring
Stream Species Composition Most streams influenced by past introductions Brook, brown, rainbow Competition for resources Brook trout replace cutthroat trout Brown, rainbow replace brook trout
Annual Production Similar in single- or mixed-species streams Softwater streams - 15-50 kg/hectare Hardwater streams - 100 kg/hectare
Management Historical Introductions followed by maintenance stocking Current Habitat restoration, management Restoring species Special regulations