Salmon (Malcolm et al., 2019a) and trout benchmark densities (Malcolm et al., in prep) were obtained from models relating fish densities to habitat proxies derived from spatial data. The benchmark densities represent the average densities that would be expected for a particular habitat if populations were “healthy”. Benchmarks can thus be considered similar in concept to “intrinsic habitat potential” (Burnett et al., 2007). Benchmark densities for both salmon and trout, fry (0+) and parr (>0+) were predicted across the river network.
Regional benchmarks (for each strata) were calculated by estimating the mean benchmark density across the sample frame within each strata (See Jackson et al., 2025 for details). These strata benchmarks can be compared to mean density estimates for individual strata (from the GRTS survey) to assess regional performance.