Considerations around effort and power for an occupancy-based Redside Dace (Clinostomus elongatus) monitoring program across spatial and temporal scales

Abstract

Redside Dace (Clinostomus elongatus) is a small minnow with a limited distribution in southern Ontario and is listed as Endangered under the Species at Risk Act. The draft federal recovery strategy for Redside Dace outlines the need to develop a monitoring program to quantify the abundance and distribution of the species in Canada. A repeat-survey design, whereby surveys are replicated spatially and temporally, could be used to inform models for assessing the abundance and distribution of Redside Dace and subsequent management decisions that may impact the species. An introduction to Redside Dace monitoring is presented, including a summary of previous and current monitoring efforts. Potential objectives of a Redside Dace monitoring program are described as well as an introduction to the use of a repeat-survey design for estimating species detection and occupancy. Considerations around the allocation of effort for a Redside Dace monitoring program are presented, including: (i) the effect of scale on site definition and subsequent implications for total monitoring effort and statistical power; (ii) targeted versus random sampling; and, (iii) how stratified random sampling across different gradients (e.g., space, time, threats) can inform the conservation status of the species. Occupancy is emphasized over an abundance-based approach as it provides relatively greater power per sampling effort for generating conclusions. Nevertheless, sampling Redside Dace using repeated surveys within and between sampling seasons can be used to inform abundance estimates. Overall, stratification of sampling effort for Redside Dace spatially (i.e., across populations) and over time will allow statistically powerful conclusions about changes in occupancy and (or) abundance at the local, population, and Canadian scale. Implementation of such a monitoring approach would inform management activities such as the review of development and instream work proposals, population status assessments, and future restoration projects.