Coldwater Streams Chapter 18

1
Coldwater StreamsChapter 18
2
Coldwater Streams

• Game fish - predominantly salmonids
• Salmon, trout

3
Coldwater Streams

• Anadromous type 1 - use streams only for
  spawning, move out immediately after emergence
• Chum, pink, sockeye

4
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)

5
Coldwater Streams

• Residents - spend entire life in stream
• Bull, rainbow, cutthroat, brown, brook
• Brown is only species not native to North America

6
Coldwater Streams - sustain spawning and rearing

• Physical conditions
• Water temperature lt22C
• Dissolved oxygen gt8 ppm
• Stream size - greatest abundance, diversity in
  4th-5th order streams
• Stream gradient - best 0.6-6.0
• Hydrograph -variable

7
Other Fish Species

• Low diversity in west, higher diversity in east
• Cyprinids - minnows - Notropis

8
Other Fish Species

• Cyprinids - dace
• Rhinichthys, Phoxinus

9
Other Fish Species

• Cyprinids - chubs - Semotilus

10
Other Fish Species

• Catostomids - suckers - Catostomus

11
Other Fish Species

• Cottids - sculpins - Cottus

12
Other Fish Species

• Darters - Etheostoma

13
Salmonid Characteristics

• Territoriality
• Agonistic behavior
• Dominance hierarchy
• Focal points
• Probability of use curves

14
(No Transcript)
15
(No Transcript)
16
Salmonid Characteristics

• Growth
• Suboptimal temperature
• Limited food and space
• Initial year - 100-150 mm, decline in following
  years to 20-40 mm/year

17
Salmonid Characteristics

• Mortality - 50 or more annually
• Density-dependent factors
• Intraspecific competition - starvation

18
Salmonid Characteristics

• Density-independent factors
• Spring floods
• High summer temperatures

19
Salmonid Characteristics

• Density-independent factors
• Predation
• Birds
• Mammals
• Fish

20
Salmonid Characteristics

• Density-independent factors
• Overwinter mortality
• Starvation
• Predation - low
• Physical injury - ice

21
Salmonid Characteristics

• Higher mortality among males
• Longevity - 4-5 years

22
Angling Mortality
23
Salmonid Characteristics

• Reproduction
• Sexual maturity
• Age or size
• Fall spawners
• Brown, brook
• Spring spawners
• Rainbow, cutthroat

24
Salmonid Characteristics

• Redd - spawning bed
• Water velocity
• Depth
• Substrate

25
Salmonid Characteristics

• Eggs develop in gravel until hatching
• Emergence - early or late spring

26
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

27
Annual Production

• Similar in single- or mixed-species streams
• Softwater streams - 15-50 kg/hectare
• Hardwater streams - 100 kg/hectare

28
Management

• Historical
• Introductions followed by maintenance stocking
• Current
• Habitat restoration, management
• Restoring species
• Special regulations