Lecture 7 - Fish Migration

Question 1

Diadromous (2)

Answer 1

Fish travel between salt and fresh water to breed

Eg. Pacific salmon and pacific lamprey

Question 2

Anadromous (2)

Answer 2

Fish live mostly in the ocean and travel to freshwater to breed

Eg. Pacific salmon and pacific lamprey

Question 3

Catadromous (2)

Answer 3

Fish live in fresh water and breed in the ocean

Eg. American eel and European eel

Question 4

Potadromous (2)

Answer 4

Fish migrate within fresh water only

Eg. Bull trout and arctic greying

Question 5

Oceanodromous (2)

Answer 5

Fish migrate within salt water only

Eg. Bluefin tuna and flathead catfish

Question 6

Amphidromous (2)

Answer 6

Migratory fish that travel between fresh and salt water but not to breed

Eg. Dolly Varden and river goby

Question 7

What percentage of species migrate between freshwater and saltwater?

Answer 7

Only 1% - the majority of species migrated totally within either freshwater or saltwater

Question 8

Why do fish migrate? (4)

Answer 8

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)

Question 9

What are the 2 types of reproduction in anadromous fish?

Answer 9

Semelparous - they die after spawning (eg. Pacific salmon)

Iteroparous - they can spawn multiple times (eg. Steelhead/white sturgeon)

Question 10

How do salmon migrate? (3)

Answer 10

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

Question 11

What aids salmon in detecting magnetic fields?

Answer 11

Magnetite (Fe3O4) crystals found in their lateral lines

Question 12

What are the 3 parameters that salmon can obtain from magnetic fields?

Answer 12

1. Field polarity (North and south)
2. Field intensity (position due to change from poles to the equator)
3. Inclination angle (slope of field lines in relation to earth surface)

Question 13

Which direction do most salmon swim?

Answer 13

Counterclockwise

Question 14

How do salmonids detect their natal streams?

Answer 14

As juveniles, they can smell the unique odour of their natal streams - called olfactory imprinting

Question 15

How do salmonids avoid predators during migration?

Answer 15

They can detect L-serine (an amino acid found in all mammals) at exceptionally low concentrations

Question 16

Why is it important to know fish migration information for ecological restoration? (5)

Answer 16

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

Question 17

What is the “anadromous nutrient pump” (2)

Answer 17

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

Question 18

When/how is an assessment of migration barriers conducted? (3)

Answer 18

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

Question 19

What are the 3 types of swimming speeds for fish?

Answer 19

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)

Question 20

What pool depth provides ideal conditions for a fish to leap over an obstacle?

Answer 20

1.25X the height of the obstacle

Question 21

What are the 4 common types of naturally occurring obstructions to fish movement?

Answer 21

Log jam debris

Blockages resulting from mass movements (eg. Landslides)

Poorly designed culverts (create perching)

Beaver dams

Question 22

How can you remove natural blockages to fish passage? (5)

Answer 22

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

Question 23

What is the non-explosive demolition agent that can be used for removing large debris?

Answer 23

Dexpan

Question 24

What are the main issues that poorly designed culverts create for migration? (6)

Answer 24

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

Question 25

What is the hydraulic criteria that should be adhered to in culvert design construction? (4)

Answer 25

For adult migration, average water velocity should not exceed:

1. 2 m/sec for culverts shorter than 25 m
2. 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

Question 26

How deep below the natural grade line of the stream should culverts be placed?

Answer 26

20-40% of the culvert diameter below the grade line because then natural substrates can line the culvert bottom and control natural erosion downstream

Question 27

What size of flood should a culvert be designed to accommodate?

Answer 27

1 in 100 year flood flows minimum

Question 28

What should be installed in addition to a well-designed culvert?

Answer 28

Trash racks at the upstream end to prevent clogging of the culvert by large woody debris

Question 29

What swimming speeds are culverts usually designed for and how can we make them easier to pass through (3)

Answer 29

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

Question 30

What are some examples of hydraulic control structures/functions that can be constructed outside of a culvert? (5)

Answer 30

Backwatering of the culvert barrel to maintain adequate depths

Weirs to control grade and the water surface profile

Resting pools

Newbury riffles

Step pools

Question 31

What are 3 reasons to consider a fish ladder and 2 kinds of fish ladders?

Answer 31

1. Lack of attraction flow
2. High velocities
3. Injury, mortality, predation
4. Fish elevator
5. Pool and weir structure