Lecture 7 - Fish Migration Flashcards
Diadromous (2)
Fish travel between salt and fresh water to breed
Eg. Pacific salmon and pacific lamprey
Anadromous (2)
Fish live mostly in the ocean and travel to freshwater to breed
Eg. Pacific salmon and pacific lamprey
Catadromous (2)
Fish live in fresh water and breed in the ocean
Eg. American eel and European eel
Potadromous (2)
Fish migrate within fresh water only
Eg. Bull trout and arctic greying
Oceanodromous (2)
Fish migrate within salt water only
Eg. Bluefin tuna and flathead catfish
Amphidromous (2)
Migratory fish that travel between fresh and salt water but not to breed
Eg. Dolly Varden and river goby
What percentage of species migrate between freshwater and saltwater?
Only 1% - the majority of species migrated totally within either freshwater or saltwater
Why do fish migrate? (4)
Reproduction - spawning grounds may be safer and it’s easier to locate a mate if all in same place
Feeding - food resources my be more abundant/favourable somewhere else at a certain time of year
Avoiding predators - fish might migrate into different areas during active times for predators (eg. Kokanee migrate to the bottom of a lake in the day to avoid predation)
Different habitat requirements for different life stages - as fish grow, they require different habitat types (eg. Estuaries for salmon fry)
What are the 2 types of reproduction in anadromous fish?
Semelparous - they die after spawning (eg. Pacific salmon)
Iteroparous - they can spawn multiple times (eg. Steelhead/white sturgeon)
How do salmon migrate? (3)
Smolts use passive drift at night and migrate tail first down rivers to the ocean
In the open ocean, salmon use magnetoreception (they can detect magnetic fields) And the sun (as a general compass) to migrate
What aids salmon in detecting magnetic fields?
Magnetite (Fe3O4) crystals found in their lateral lines
What are the 3 parameters that salmon can obtain from magnetic fields?
- Field polarity (North and south)
- Field intensity (position due to change from poles to the equator)
- Inclination angle (slope of field lines in relation to earth surface)
Which direction do most salmon swim?
Counterclockwise
How do salmonids detect their natal streams?
As juveniles, they can smell the unique odour of their natal streams - called olfactory imprinting
How do salmonids avoid predators during migration?
They can detect L-serine (an amino acid found in all mammals) at exceptionally low concentrations
Why is it important to know fish migration information for ecological restoration? (5)
Site fidelity (the fact that salmon return to their natal streams) had resulted in reproductive isolation which had resulted in specialized adaptations
This creates genetically unique, discrete stocks (eg. Early Stewart sockeye have much higher oil and fat content than late run Harrison Lake sockeye because they migrate farther)
Site fidelity has resulted in Evolutionarily Significant Units (ESU)
This will dictate restoration in that practitioners will need to maintain diversity of stocks and manage populations at risk given their unique needs
The SARA applies to stocks of salmon rather than species
What is the “anadromous nutrient pump” (2)
Describes salmon as they can “pump” nutrients uphill against the force of gravity when they migrate upstream - salmon are 0.3% P and 3.0% N
They are the critical link between aquatic and terrestrial ecosystems
When/how is an assessment of migration barriers conducted? (3)
During adult upstream migration, as then you can see if a culvert etc. is a barrier to their passage
You determine this visually by sampling upstream and downstream of the passage
You can also look at species life history and jump height/swim velocity tables to make decisions
What are the 3 types of swimming speeds for fish?
Sustained - for regular swimming that can be maintained for extended periods of time
Prolonged - for passing through higher than normal velocities
Burst - for short duration (escape/feeding)
What pool depth provides ideal conditions for a fish to leap over an obstacle?
1.25X the height of the obstacle
What are the 4 common types of naturally occurring obstructions to fish movement?
Log jam debris
Blockages resulting from mass movements (eg. Landslides)
Poorly designed culverts (create perching)
Beaver dams
How can you remove natural blockages to fish passage? (5)
Small log jams - open manually with chain saws etc.
Large log jams - commercial log yarder, skidder, excavator etc.
Blasting - requires fish salvage beforehand
Debris removal - small rocks can be removed manually but large rocks might need explosive or non-explosive fracturing
Removal/replacement of culverts
What is the non-explosive demolition agent that can be used for removing large debris?
Dexpan
What are the main issues that poorly designed culverts create for migration? (6)
Direct loss of riparian and in-stream habitat
Poor hydraulic conditions that worsen the problem
Velocity barriers
Insufficient flow depths
Debris accumulation
Erosion and sedimentation
What is the hydraulic criteria that should be adhered to in culvert design construction? (4)
For adult migration, average water velocity should not exceed:
- 2 m/sec for culverts shorter than 25 m
- 9 m/s for culverts longer than 25 m
Water depth should not be less than 0.23 m at any point within the culvert
Any sudden drops in the water surface profile should not exceed 0.3 m
How deep below the natural grade line of the stream should culverts be placed?
20-40% of the culvert diameter below the grade line because then natural substrates can line the culvert bottom and control natural erosion downstream
What size of flood should a culvert be designed to accommodate?
1 in 100 year flood flows minimum
What should be installed in addition to a well-designed culvert?
Trash racks at the upstream end to prevent clogging of the culvert by large woody debris
What swimming speeds are culverts usually designed for and how can we make them easier to pass through (3)
Sustained swimming speeds
Baffling or weirs in the culvert can be used however, to reduce velocities and increase depth of flow
Smaller fish (eg. Juveniles) also need slower water to pass so it is important to look at velocities of culverts leading into overwintering off-channel habitat so you need to take this into account in the design
What are some examples of hydraulic control structures/functions that can be constructed outside of a culvert? (5)
Backwatering of the culvert barrel to maintain adequate depths
Weirs to control grade and the water surface profile
Resting pools
Newbury riffles
Step pools
What are 3 reasons to consider a fish ladder and 2 kinds of fish ladders?
- Lack of attraction flow
- High velocities
- Injury, mortality, predation
- Fish elevator
- Pool and weir structure
