David A. Scruton Fisheries and Oceans Canada St. John’s, Newfoundland CANADA

1. Research Needs and Knowledge Gaps in Habitat Hydraulic Modeling for Salmonid Species in Atlantic Canada David A. Scruton Fisheries and Oceans Canada St. John’s, Newfoundland CANADA

2. 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

3. 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

4. Institutional Setting • Water resource management is a joint regulatory responsibility of federal and provincial (n=10) or territorial (n=3) governments • Federal responsibility – fish habitat management/conservation and river navigation • Provincial responsibility – water management and utilization

5. 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

6. Institutional Setting–Provincial (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

7. 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’

8. 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.)

9. 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

10. 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

11. 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

12. 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)

13. 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

14. 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

15. 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

16. 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.)

17. 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)

18. 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)

19. 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

20. 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

21. 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

22. 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)

23. 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

24. 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

25. 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

26. 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