Transcript Coldwater Streams Chapter 18

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 - 100150 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



Densityindependent
factors
Spring floods
High summer
temperatures
Salmonid Characteristics


Densityindependent
factors
Predation
Birds
 Mammals
 Fish

Salmonid Characteristics


Densityindependent
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