Habitat and Fish: correlation approaches, limitations, scale, and uncertainty

Correlation

• Two things occur simultaneously in space or time (both) • Consistent pattern (predictions) • Does not imply causation (suggests hypotheses) • Biggest sources of uncertainty – difficulties determining causation

Salmonid Watershed Assessment Model (SWAM)

Estimates relative distribution of fish based on broad-scale habitat features

ln(redds/km + 0.5) = 6.89 - 0.3625t + 0.4216ln(w + 0.0001) + 0.0003546p

Salmonid Watershed Assessment Model (SWAM)

Estimates relative distribution of fish based on broad scale habitat features    map occur of where the highest densities of fish are likely to ecological hypotheses about factors driving salmon abundances in a particular basin factors to control when setting up monitoring projects or management experiments

Landscape Data

Human Impacts Forest cover classes Land Surface Ownership Hydrology Geology Climate

SWAM CAN NOT

Habitat Characterization and Capacity Historic production capacity Current production capacity Preliminary Identification of Recovery Actions Where to protect and how to protect Restoration actions Improvement per action Prioritization of actions

Model Uses

     Identify areas likely to support high abundances Prioritize areas for watershed assessments Predict relative salmonid abundances behind barriers Generate hypotheses about causal relationships Identify important strata for monitoring programs

Example 2: Broad-Scale Habitat Inventory

Predict fish occupancy Predict habitat conditions Estimate habitat quantities Prioritize information needs Develop hypotheses

Broad-Scale Habitat Inventory

I. Inventory Approach   Generate stream network Segment network and calculate channel characteristics  Classify segments  Link segments with geospatial data II. Applications  Predicting in-stream conditions  Estimating population characteristics (extinction thresholds)  Predicting relative occupancy behind impassible barriers

Deep Creek, Clackamas Does not meet fish passage standards Deep Creek, Clackamas Passage Unknown Foster Creek, Clackamas Meets fish passage standards

reach/segment length 384m 98m 420m 238m 105m 120m 111m 174m 123m gradient 1.2% 6.0% 0.4% 2.1% 3.0% 5.2% 5.3% 0.3% 0.5% 102m 411m

“ “

“ “ 7.4% 0.3% “ “ “ “ land-use rural res new forest ag/shrub rural resid urban forest forest ag urban forest ag/urban … … … … … … … … … … … … “ “

Available Analysis Variables

Stream Generation Model: stream gradient, stream order, valley floor width, side slope gradient Existing: precipitation, geology, land use, road density, wetlands, soil type, barriers, habitat survey data (partial coverage) Plan to Predict: channel width, pool density, bank stabilization, lateral habitat

Channel Width

Potential predictors: basin area, channel gradient, precipitation 13 watersheds in WLC .15 < mR 2 Overall mR 2 < 0.76

= 0.41

Area > precip > gradient

Pool density (distribution) channel gradient, channel width, geology, constrained/unconstrained, land-use Probability of bank stabilization proximity to road, stream gradient, channel width, constrained/unconstrained, side slope gradient KM lateral habitat / KM main channel channel gradient, channel width, floodplain width E. Beamer

• Natural Variability • Measurement error • Parameter Uncertainty • Model Uncertainty • Prediction Uncertainty

Uncertainty

• Predictions across space, time, scale (correlation) • Mechanisms – survival as a function of habitat quality • Use of uncertain predictors • Range of conditions