Lecture 8 - Biostandards Flashcards
What is the hierarchical stream restoration strategy? (10)
- Complete hill slope and riparian stabilization first
- Examine the need for off-channel restoration (refuge during construction)
- Examine all feasible restorative and rehabilitative options
- Prioritize sub-watersheds that are less highly impacted first
- Emulate nature by use of natural templates within undisturbed reaches of streams
- Assess and quantify if the resource (stream channel and fish habitat) is impaired and to what extent
- Estimate the time to recovery without management (passive restoration)
- If too long, assess if restoration is feasible (cost, logistics etc.)
- Be sure that the restoration plan you are considering will be resilient to climate change
- Do all feasible restoration, rehabilitation, or mitigation options (first at the impact site or if necessary in an adjacent watershed)
Why should we use biostandards? (7)
- Permits quantitative assessment of expected restoration efforts
- Allows estimation of costs vs benefits
- Can be used to prioritize project implementation
- May be required for legal purposes
- Facilitates effectiveness monitoring of projects
- Encouraged learning from experience
- Provided personal protection from the bean counters and naysayers
Why focus on salmonids? (5)
Salmon require high quality water and intact habitat
Habitat restored to “salmon quality” is usually adequate for most species (except in some specific cases)
Salmonids are a key component of BC, Canadian, and Pacific Northwest cultural heritage
Salmonids are critical to social and spiritual well-being of many of BC’s First Nations communities
Keystone species
What are the first 2 questions you ask before starting any stream restoration project?
What species are involved?
Do they have an anadromous or resident life history?
Why is life history important? (5)
Some anadromous salmonids have an extended freshwater period (eg. Steelhead)
Whereas some fry leave for the ocean shortly after hatching (eg. Pink Salmon)
Some anadromous species even have different life history characteristics within the same species (eg. Chinook)
Salmonids particularly have a wide range of life history characteristics
This influences the restoration options that will be effective
What are the 7 main categories important for salmonids rearing habitat, and which 4 are the most important?
Depth
Velocity
Substrate
Cover
Temperature
Nutrients
Dissolved Oxygen
What is the scale for classifying the diameters of sediments?
Wentworth Scale
What fish characteristic is very important in dictating rearing habitat and how does it relate to the 3 most important rearing habitat variables?
Fish body size, as larger fish require deeper (depth) and faster (velocity) water with larger cobbles (substrate)
How do salmon select foraging areas? (3)
Based on the trade-off between obtaining a sufficient supply of invertebrate drift and the energy costs of maintaining their position in the river current
Because energy increases as a function of body weight, larger fish expend less energy swimming in higher currents
Microhabitat and fish size must be taken into account in restoration
Why is cover important for rearing habitat? (3)
Salmon require cover, especially if the water is shallow
Amount and type of cover varies with species and life history stage
Juveniles require cover to avoid predation while adults use cover to avoid larger predators and to prey in smaller organisms
Why is temperature an important aspect of rearing habitat? (4)
Salmonids are cold-blooded animals so their body is controlled by the environment in which they live
Salmonids have an optimal range as well as lower and upper lethal limits for various activities
High temperatures can increase metabolic rate which increases oxygen uptake and food demand
It can also increase incidence of disease and invasive species like largemouth bass
What happens when canopy cover is removed? (5)
Increased light and temperature increases primary production because of higher algae production and increased decomposition of OM
This may lead to an increase in invertebrate production or a change in species composition
Which may lead to an increase of drift (fish food) within the stream ecosystem
This increased food supply will increase fish growth and production up to a certain optimum temperature
The metabolic rate of fish will also increase, however, which can cancel the beneficial effect on increased food supply when exceeding optimum temperatures
What is the optimum and lethal temperatures for sockeye salmon? (2)
Optimum = 12-14 degrees C
Upper lethal = 25 degrees C
What benefit might the hypoheic zone have on temperature?
Although it is the same temperature as the flow in the stream, there is a potential buffering effect that might be a temporary refuge for overheated salmonids
When is dissolved oxygen at maximum concentration and what factors determine the saturation concentration? (2)
Saturation concentration of oxygen is determined by water temperature, salinity, and atmospheric pressure (elevation)
The max amount of DO that water can hold is 14.7 parts per million (or mg/L)
What is an adequate amount of dissolved oxygen for salmonids? (2)
Over 5 ppm - anything below 6-7 ppm creates a decrease in performance
Anything below 3 does not support fish
What’s the relationship between fish size and territory? (2)
Territory size limits the density and production of stream dwelling salmonids because it is dependent on food abundance - if food is high, fish would require smaller areas to sustain themselves
It is also dependent on fish size - thus fish size can be used to predict the space requirements and hence maximum densities or salmonids in streams (bigger fish need bigger territories)
Why is off-channel and overwintering habitat important? (2)
Salmonids often seek over-wintering areas until water temperatures increase sufficiently to make active feeding a net positive energy gain
Depending on the species, salmonids often make short migrations into over-wintering habitat (coho) or stay in the stream and hide under large substrate (steelhead)
What are the 5 most important aspects of spawning habitat?
Depth Velocity Substrate Temperature Dissolved oxygen
Where do salmonids often build their redds? (2)
At the top crest of a riffle to increase oxygenated water
Some build their reds in areas of groundwater seepage
Why does fry emergency occur in the spring?
Salmonids have evolved to take advantage of increased lake and stream productivity during the summer months
What is the general water velocity and water depth good for salmonids spawning? (2)
Average velocity = 49 cm/sec
Average water depth = 35 cm
What is an important characteristic of fish that affects their spawning habitat? (2)
Their size - the bigger the fish, the deeper and faster the stream and larger the substrate needed for spawning
Larger fish also generally build larger redds and defend larger territories (4X the size of the redd)
Why is marine survival of salmonids decreasing? (3)
PDO and El Niño causing a reduction in nutrient upwelling causing less production and less zooplankton that can be eaten by juvenile salmonids
Net pen diseases are also an issue = open net pen aquaculture and sea lice
Predation = can especially be a problem during El Niño and warm PDO years when mackerel appear off the BC coast
