Research Needs and Knowledge Gaps in Habitat Hydraulic Modeling for Salmonid Species in Atlantic Can

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Research Needs and Knowledge Gaps in Habitat
Hydraulic Modeling for Salmonid Species in
Atlantic Canada

• David A. Scruton
• Fisheries and Oceans Canada
• St. Johns, Newfoundland CANADA

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Outline

• Background
• Institutional Setting in Canada
• Biotic Considerations
• Biological Criteria
• Abiotic Considerations
• Hydrologic/Hydraulic Aspects
• Habitat Limiting Considerations
• Migration Considerations
• Scaling
• Temporal Aspects
• Integration
• Monitoring and Adaptive Management
• New Approaches/New Metrics

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Background

• Hydraulic modeling has achieved a high degree of
  acceptance and sophistication e.g. 1-D, 2-D, and
  3-D capabilities
• Biological models within habitat-hydraulic
  modeling are less well developed, largely as a
  result of the assumption that biological
  communities are limited and controlled by
  physical habitat (D, V, S)
• Many other biotic and abiotic influences are not
  considered
• This is an area that requires much research and
  development and is the focus of this talk

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Institutional Setting

• Water resource management is a joint regulatory
  responsibility of federal and provincial (n10)
  or territorial (n3) governments
• Federal responsibility fish habitat
  management/conservation and river navigation
• Provincial responsibility water management and
  utilization

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Institutional Setting Federal

• Fisheries Act
• Prevents harmful alteration, disruption or
  destruction of fish habitat (HADD)
• Requires adequate water for habitat maintenance
  and migration/fish passage
• Policy for the Management of Fish Habitat
• Provisions for habitat conservation (NNL),
  habitat restoration and habitat development (net
  gain)
• Strong Sustainable Development and Conservation
  Focus

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Institutional SettingProvincial (NF)

• Water Resources Management Act
• Responsibility for the control, development,
  improvement and proper utilization of water
• Allocates water use based on competing users
• Controls pollution
• Strong Development Focus

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Biotic Considerations

• There are a large number of biotic processes
  that, in addition to physical habitat, determine
  fish populations and fish production and these
  are rarely included in habitat hydraulic models.
• Food
• Competition (intra-, inter-specific)
• Predation
• Disease
• Growth
• Survival/mortality
• Fertility (fecundity)
• Density dependence
• Exploitation

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Biotic Considerations (2)

• Need to consider all aspects of the biological
  community, not just fish
• Benthos, primary productivity, macrophytes,
  algae, and trophic linkages with fish
• Aspects of alteration of energy dynamics
  controlling production (photosynthetic process,
  allocthonous sources detritis, etc.)

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Biotic Considerations (3)

• For salmonids in northern climates, basic
  knowledge of winter biology of species (habitat
  selection and use, activity and behaviour,
  feeding) is lacking
• Winter is a major regulator of salmonid life
  histories and salmonids have developed strategies
  for over-wintering very different from open
  water period
• For some salmonids, considerations of
  territoriality is critical as available habitat
  may be strongly influenced by this trait

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Biological Criteria Development

• Need to develop improved habitat suitability/use
  criteria
• Need to develop criteria for all aspects of life
  histories (life stage, seasons)
• Criteria for all abiotic conditions
• Large river, deep water conditions
• River specific versus generalized/regional
  habitat criteria
• Methods of developing criteria
• Weighting by availability
• Equal area sampling
• Curve fitting techniques

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Biological Criteria Development (2)

• Methods of combining and integrating criteria
• multivariate relationships
• 3-D response surfaces
• Logistic regression approaches
• use of dimensionless metrics (e.g. Froude number)
• Transferability of criteria and models and true
  predictability
• Basic need for testing, field validation,
  transferability assessment

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Abiotic Considerations

• Macro-Habitat Considerations
• Macro-habitat variables poorly integrated into
  current modeling approaches
• Currently only temperature and some water quality
  aspects considered
• Slope and gradient, channel stability, sinuosity
  are important in defining river character ata
  larger scale
• Relative scope of flow alterations (i.e. flow
  changes affect small rivers proportionally more
  than large rivers)

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Abiotic Considerations

• Flow regimens to maintain channel dynamics and
  substrate conditions (e.g. flushing flows) need
  to be considered
• Source of spawning substrates, woody debris, and
  other habitat features (riparian conditions)
• Relationships between surface water flows and
  groundwaters (critical for egg incubation, early
  survival, thermal refugia)
• Spawning fish may seek down-welling or upwelling
  conditions and not the surface water velocities
• Consideration and inclusion of of cover variables
  in modeling process

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Hydrology/Hydraulic Aspects

• Relative benefits of higher resolution, more
  sophisticated hydraulic models (1-D, 2-D, and
  3-D) needs to be rigorously evaluated
• Are 3-D models better for understanding
  conditions for benthic fishes and benthos (is the
  resolution sufficient), incorporation of other
  abiotic variables (e.g. shear stress)?
• Appropriate data collection needs for the various
  hydraulic models (spatial density of transects or
  measurement points, in 3 dimensions), model
  calibration and validation
• Tradeoffs versus data collection requirements and
  resolution versus data quality objectives

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Hydrology/Hydraulic Aspects (2)

• Models to address all aspects of flow alteration
  regulation and reductions, diversions and
  augmentations, peaking power production
• Models abilities to predict substrate conditions
  needs to be as reliable as for depth and velocity
  conditions
• Solutions for difficult conditions to model -
  braided complex channels, chutes and cascades,
  areas of constriction, flow accretions from
  numerous tributaries and/or groundwater sources,
  transverse flows and/or large lateral variation
  in WSE

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Habitat Limiting Considerations

• Generally considered that fish populations may be
  more influenced by habitat limiting events than
  by constancy of habitat quality
• Habitat limiting events can be acute or chronic
• Salmonids may compensate for poor survival at one
  life stage with improved growth or survival at
  another
• Winter conditions (ice cover, frazil ice, anchor
  ice), importance of substrate (voids or
  interstices are important habitat) and less
  importance of depth or velocity
• Spate conditions (velocity refugia, displacement,
  etc.), models do not include important velocity
  shelters (boulder clusters, woody debris, under
  cut banks, etc.)

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Habitat Limiting Considerations (2)

• Need to identify the true habitat limiting
  variable which may not be the classic depth,
  velocity, substrate
• Timing of flow events winter peak flows (thaws)
  can be related to poor egg to fry survival
• Species survival indices (curves) for areas
  exposed to droughts and harsh over-wintering
  conditions
• Flow increases need to find velocity shelters
  stress index
• In peaking production there may be an energetic
  cost of frequently changing flow conditions (i.e.
  constantly seeking refugia and food)

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Migration Considerations

• Criteria needs to be developed for migratory
  needs (upstream adult migration, downstream smolt
  and kelt movements)
• Some habitats may be only valuable as migratory
  corridors
• Depth/velocity, channel width, flow stimulus
  thresholds
• May require site specific analyses (difficult
  points of passage, falls, chutes)

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Scaling

• It is widely recognized that viable habitat
  hydraulic models need to integrate across a
  variety of spatial scales
• Micro-habitat
• Meso-habitats (riffles, pools, etc.)
• Stream reach
• Tributary
• Catchment/watershed
• Variation within and across spatial scales
• Need to match resolution of criteria development
  and hydraulic simulation with appropriate scale

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Temporal Aspects

• Research is lacking in temporal aspects of
  habitat requirements (hourly, daily, monthly
  seasonally)
• Issues of timing, magnitude and duration of
  habitat quantity and quality and relationships to
  individuals, populations and communities
• In peaking production, need to consider both the
  magnitude and rate of change (ramping rate)
• Current time series approaches are too simplistic
  (apply a static function HSI to discharge
  variability)
• Some consideration of exceedance criteria or
  thresholds (e.g. CUT curves) to link to limiting
  factors

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Integration

• A major shortcoming of habitat hydraulic modeling
  is the need to integrate within a species at the
  population level and for multiple species at the
  community level
• Consideration of habitat bottlenecks, critical
  life history phases, and compensating mechanisms
  within species
• Equating flow related mechanisms to fish
  populations and production (productive capacity)
• Considerations of connectivity and adjacency
  (e.g. fry rearing habitats near spawning
  habitats, over-wintering habitats near rearing
  habitats)
• Trophic inter-connectivity

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Monitoring and Adaptive Management

• Follow up monitoring and refinement for
  validation of instream flow studies has been
  lacking
• Adaptive Management (AM) process
• What metrics should be measured as the
  appropriate biological response (habitat
  conditions, fish populations, production)?
• What time scale (life cycles of important biota)?
• For AM to work, response variables must point the
  appropriate management action (i.e. cause-effect)

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New Approaches/New Metrics

• Alternative Sampling Strategies/Tools
• Hydrodynamic potential (drag coefficient, relate
  to ability to find shelter and resist velocity)
• Dimensionless habitat attributes (e.g. Froude
  number, Reynolds number)
• Statistical hydraulic models coupled with
  multivariate habitat use models
• Mechanistic or bioenergetic modeling
• Spatial niche approach
• Landscape ecology concepts

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New Approaches/New Metrics

• Mechanistic or bioenergetic modeling
  Incorporates
• biological parameters fish size, swimming
  ability, reaction distance
• Habitat parameters Water velocity, depth,
  temperature, and turbidity
• Food Density and size distribution of prey
• Use bioenergetics concepts to estimate NEG to
  predict stream position
• attractive alternative to index curve approaches

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New Approaches/New Metrics

• Spatial Niche Approach
• Flow dependent characteristics of spatial niches
  used to consider generalized community based
  criteria
• A fish community may be partitioned by species
  and life stages into a simple spatial matrix
  representing habitat use along a gradient of
  depth and velocity
• linkages of meso and macro-scale process driven
  biological models

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New Approaches/New Metrics

• Landscape Ecology
• Landscape ecology metrics may integrate across
  habitat interfaces and implicitly integrate
  biotic functions (e.g. territoriality, predation)
• adjacency or edge effect
• spatial heterogeneity, patch size
• fractal dimension or contagion
• diversity or evenness indices