From 2013-16 we deployed 3 motion-sensing cameras paired with hair (DNA)-snaring devices within each of 263 24-square kilometer primary sampling units distributed systematically across the Olympic Peninsula in northwestern Washington. The data set contains detection histories of fishers during each of 3 14-day sampling intervals at each hexagon. The data set also includes detectability and environmental covariates measured at the detection stations and within a 1,262-m buffer inscribed around the detection stations in each hexagon. Reported covariates include the sampling year, Julian date of sampling visit, proportion of 14-day sampling intervals that bait was functional, landscape composition within buffer regions, average 30-year precipitation, mean elevation, and distance to federal wilderness boundaries. Landscape composition variables measured within the buffer zones included: proportion of buffers within each of three land management categories (federal wilderness, federal non-wilderness, and other [State, private, and Tribal]), 3 stand structural condition classes (tree layer dominated by small, medium, and large trees, respectively), and canopy closure classes (tree layer dominated by open, medium, and dense overstory crown closure, respectively). Additionally we report the Simpson's diversity index of structural classes present within each buffer.