Science Response 2015/034

Review of the applicability of Habitat Suitability Index (HSI) Model and Habitat Assessment Tool (HAT) for assessment of Westslope Cutthroat Trout habitat characteristics and associated productivity

Context

Teck Coal Limited (hereafter the Proponent) has proposed the development of three new coal mining areas, which would expand the existing operating areas of Line Creek, Coal Mountain, and Fording River, all located near Sparwood, BC.  The Provincial Environmental Assessment (EA) for the Line Creek Phase II Expansion is complete, with construction underway.  The Fording River and Coal Mountain Phase II Expansions are currently under Federal and/or Provincial EA review.  The majority of the proposed developments occur within the Dry Creek, Lake Mountain Creek, and Wheeler Creek drainages, respectively. The Proponent currently has two existing Fisheries Act Authorizations associated with the Line Creek Operations, which require "offsetting" to be identified to counterbalance serious harm to fish that are considered a part of a commercial, recreational or Aboriginal (CRA) fishery.  One of the key species considered a part of a CRA fishery in the Fording River area is the Westslope Cutthroat Trout, Oncorhynchus clarkii lewisi.  Westslope Cutthroat Trout (WCT) is a popular freshwater sport fish in western Canada and is a Province of British Columbia managed fish resource. The British Columbia population of Westslope Cutthroat Trout is listed as Species of Special Concern by the Committee of the Status of Endangered Wildlife in Canada (COSEWIC). Westslope Cutthroat Trout is also identified as an indicator species of general ecosystem health, due to their restrictive habitat requirements (COSEWIC 2006).

Proposed offsets for these developments will require assessment of the Fording River and tributaries to develop a greater understanding of Westslope Cutthroat Trout populations and limiting habitats affecting productivity.  As a component of this assessment, the Proponent has developed and submitted a Habitat Suitability Index (HSI) model and a Habitat Assessment Tool (HAT) model which is being reviewed by the Fisheries Protection Program (FPP).  As part of the Fisheries Act Authorization process, FPP will review the proposed models to determine whether they are appropriate as tools to evaluate project effects, and potential benefits of offsetting measures.  

In general, Habitat Suitability Indices are curves used to quantify and evaluate habitat quality for a specific species, based on the known selection of particular habitat conditions during specific periods of the species’ life history (Bovee 1986). The HSI curves are therefore applicable only to the life stages and areas that are specified in the model, and for which field data has been obtained.  In the absence of such field data, HSI curves from other regions have been adapted and applied in some cases; but adapted HSI information may not be appropriate for other areas, habitats or species (Larocque et al. 2014).  Additionally, the statistical approach used to incorporate individual curves into composite indices for a complete HSI model will produce different estimates of habitat suitability.

The Habitat Assessment Tool is a population model that links changes in abundance of WCT to changes in habitat conditions or management actions. Such models can be used to evaluate the potential impacts of habitat changes on growth, survival rate, fecundity, migration or carrying capacity.  Population trends can be projected over time. The model can potentially incorporate HSI models as a means to link habitat characteristics to population processes.

The Province of British Columbia has provided incremental reviews and advice to the Proponent regarding the development and application of both HSI and the HAT models, and the subsequent validations both in informal technical reviews and as participants in the Fording River Operations Swift Project Fish and Fish Habitat Working Group. The HSI and HAT models and an assessment of the models by the BC Ministry of Environment were presented to the Elk Valley Fish and Fish Habitat Committee, which is comprised of the Proponent, Provincial and Federal regulators, and the Ktunaxa First Nations.

FPP is requesting Science Branch assistance to further assess the HSI for its suitability as a tool to quantify habitat quality and the HAT as a tool to predict the response of CRA fisheries species to various potential management strategies, in the context of Fisheries and Oceans Canada’s (DFO’s) regulatory obligation to consider impacts to fish and fish habitat of a CRA fishery. The purpose of this Science Response is to review information provided with respect to the above mentioned modelling in “Westslope Cutthroat Trout Suitability Model Validation” (Golder Associates), and “Habitat Assessment Tool for the Upper Fording Westslope Cutthroat Trout Population” (Ecofish Research Ltd.) to meet the following objectives:

1. Review the inputs, parameters and assumptions of the Habitat Suitability Index (HSI) and provide advice regarding the adequacy of the HSI Version 5 Models as surrogates of fisheries productivity when considering project related impacts to Westslope Cutthroat Trout and their habitats and corresponding offsets. Include a discussion of uncertainties and data gaps.
2. Review the inputs, parameters and assumptions of the Habitat Assessment Tool (HAT) and provide advice regarding the adequacy of the HAT to determine limiting habitats and to assess the population response of the Upper Fording Westslope Cutthroat Trout population from potential management and strategies and offset actions.  Include a discussion of uncertainties and data gaps.
3. Provide a summary of recommendations and advice consistent with recent National guidance regarding the use of these tools as a suitable proxy for future projects to determine fisheries productivity when considering impacts to fish and fish habitat of a CRA fishery and corresponding offsetting proposals.

This Science Response Report results from the Science Response Process of August 2015 on the Review of the applicability of Habitat Suitability Index (HSI) Model and Habitat Assessment Tool (HAT) for assessment of Westslope Cutthroat Trout habitat characteristics and associated productivity.

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