Applying Impervious Surface Thresholds in a Fisheries Management Context

Applying Impervious Surface Thresholds in a Fisheries Management Context

Margaret McGinty and James Uphoff

Maryland Department of Natural Resources¹, Fisheries Service, Annapolis, MD, USA

            We have evaluated habitat impacts on tidal fisheries related to urbanization. Results show a decline in spawning habitat occupation, larval feeding success and juvenile habitat occupation, attendant to increased impervious surface in a watershed. From this work, we have developed thresholds of impervious cover, that we have related to Fisheries management options. Watersheds with less than 5% impervious cover show few habitat impacts, allowing management of fish populations with traditional stock assessment tools. Watersheds with 5-10% impervious begin to show habitat impacts and fisheries managers should account for habitat losses in developing stock assessments. Habitats in watersheds with greater than 10% impervious cover, are greatly compromised, and reproduction and presence is highly variable. Fisheries management options are limited in these watersheds, because recruitment and mortality are limited by degraded habitat.

            Because Fisheries Managers do not have authority in land management decisions, we are exploring ways to communicate habitat management needs and collaborate with land managers to develop policies to protect key Fisheries habitats. We are developing a mapping tool that will communicate key fisheries management priorities. These maps will be useful in permit review and landscape planning exercises.