The Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry compiled brook trout presence and absence data for rivers and streams within the Mixedwood Plains Ecozone of Ontario. Data from hundreds of electrofished sites were grouped into two time periods, past (1970-1980) and recent (2000-2010), to quantify the change in brook trout occupancy in streams of the Mixedwood Plains Ecozone in Ontario at different spatial scales. The data include information for five spatial scales: 1) tertiary watersheds; 2) quaternary watersheds; 3) the well-sampled Credit River-Sixteen Mile Creek tertiary watershed; and, 4) sites within 50 m of each other were sampled in both the past (1970-1980) and recent (2000-2010) periods, and 5) at each spatial scale brook trout occupancy along the longitudinal axes of the rivers was assessed using Strahler stream order. This data set will be cited in a manuscript that quantifies the declines in brook trout occupancy in rivers and streams of southern Ontario.

Brook trout presence or absence data were extracted from a compilation of electrofishing sampling data collected by the Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry, 22 Conservation Authorities, Fisheries and Oceans Canada, and the Royal Ontario Museum. Additional site data include tertiary or quaternary watershed codes, the number of sites where brook trout were present, the number of sites where brook trout were absent, the Strahler stream order of the sites, and the mean number of times the sites were sampled during the past (1970-1980) and recent (2000-2010) time periods.

tertiary_model_input_data.csv: tertiary watershed level data

Watershed_ID: tertiary watershed code

Time_period: past (1970-1980) or recent (2000-2010) period

Stream_order: Strahler stream order

Sites_with_BT_present: number of sites with brook trout present

Sites_with_BT_absent: number of sites with no brook trout

Sample_number: mean number of times site was sampled during each period

quaternary_model_input_data.csv: quaternary watershed level data

Watershed_ID: quaternary watershed code

Time_period: past (1970-1980) or recent (2000-2010) period

Stream_order: Strahler stream order

Sites_with_BT_present: number of sites with brook trout present

Sites_with_BT_absent: number of sites with no brook trout

Sample_number: mean number of times site was sampled during each period

credit_16mile_model_input_data.csv: credit-sixteen mile tertiary watershed data for within watershed analysis

Time_period: past (1970-1980) or recent (2000-2010) period

Stream_order: Strahler stream order

Sites_with_BT_present: number of sites with brook trout present

Sites_with_BT_absent: number of sites with no brook trout

Sample_number: mean number of times site was sampled during each period

overlapping_model_input_data.csv: site data for sites with 50 m of each other that were sampled during the past and recent periods.

SITE_CODE: unique identifier for each site

Time_period: past (1970-1980) or recent (2000-2010) period

BT_present: 0 or 1 for brook trout absence (0) or presence (1)

Stream_order: Strahler stream order of site

Sample_number: number of times site was sampled during each time period