Bioenergetic Modelling

Software is now available to apply a salmonid bioenergetic drift-foraging model to generate values of net energy intake (NEI) over a range of water depths and velocities. The predictions can be used to build univariate “habitat” suitability curves or multivariate “habitat” selection models for use in instream habitat modelling programs. Capture success and swimming cost sub-models are basic components of the bioenergetic model and there is a need to understand their influence of NEI predictions.
The use of bioenergetic drift-foraging models to predict the effects of flow changes on drift foraging fish is increasing (Piccolo et al. 2014). If fish are occupying energetically advantageous locations, NEI integrated over a river reach becomes an index of potential fish abundance (e.g., Hayes et al. 2007, 2016, 2018a) analogous to habitat suitability. This has led to the development of habitat suitability curves based on bioenergetic models (Baker and Coon 1997; Rosenfeld et al. 2016). Habitat suitability curves allow the results of bioenergetic foraging models to be applied in widely available instream habitat modelling software. Analyses in SEFA can also allow for depth-velocity interaction and the variation in drift concentration with flow.
Recently developed software (BioenergeticHSC) can be used to predict values of NEI over a range of water depths and velocities (Naman et al. 2020; Hayes et al. 2020). Software inputs include fish length and weight, water temperature, fish focal height, and prey size distribution and energy content. The software is largely based on Hayes et al. (2016) salmonid bioenergetic drift-foraging model. The download includes reports and papers describing the model.

The steps in applying a bioenergetic model are:

1. Use BioenergeticsHSC.exe to predict NEI for a range of water depths and velocities for a selected swimming loss sub-model and a drift concentration (concentrations of 0.3 to 5 /m³ are suggested)
2. Save as generalised additive model (GAM). Do not change the filename
3. Repeat this process for another drift concentration if you want to vary drift concentration with flow
4. This process can be repeated for other fish sizes, loss curves, water temperatures or roughness values
5. Combine all the saved GAMs (*.MOD) into a zip file
6. In SEFA, Hydraulic Habitat>>Bioenergetic predictions for Reach select the zip file. A dialogue will then allow you to select water temperature, fish size, substrate roughness, swimming loss model, drift concentration and whether or not it varies with flow.