Toggle ContentThe SMHM has been addressed in two separate USFWS federal recovery plans, the Salt Marsh Harvest Mouse and California Clapper Rail Recovery Plan (USFWS 1984) and the Recovery Plan for Tidal Marsh Ecosystems of Northern and Central California (USFWS 2013). These plans outline threats to the species, actions that should be taken to help the species rebound, and criteria that must be met for the species to be down-listed from Endangered to Threatened, or de-listed completely.
The original recovery plan, which addressed only the SMHM and California Ridgway’s rail (formerly California clapper rail) recommended protecting large existing marshes, restoring diked marshes to tidal action, restoring upland transition zones, performing research on human activities that could impact habitat, performing research on marsh accretion and erosion dynamics, and to perform habitat management (USFWS 1984). The updated recovery plan, which addresses the entire ecosystem, recommended protecting, restoring, managing and monitoring existing tidal wetlands, conducting range-wide SMHM monitoring, conduct research as necessary such as demographic analyses and habitat restoration and management techniques, and to improve coordination and participation by researchers and managers, and increased public outreach efforts. For down-listing to threatened, the 1984 recovery plan required acquisition and management of 3,900 hectares of occupied, public agency-owned essential habitat, and either 3,200 hectares of occupied, privately owned essential habitat, or 7,000 hectares of tidal and diked baylands. Full delisting required an additional 3,000 hectares of essential habitat and restoration on wildlife refuges within the species range.
For down-listing the updated recovery plan, finalized in 2013, broke down the required acreage of protected habitat (totaling 6,100 hectares) by bay, with ~2,500 in the Central and South San Francisco Bay, ~1,800 in San Pablo Bay, and ~1,800 in Suisun Bay. It also required 3-5% catch per unit effort during annual SMHM population surveys in designated areas, and reduction and control of invasive plants. For full delisting, this plan also required implementation of the Suisun Marsh Habitat Management, Preservation, and Restoration Plan, the South Bay Salt Pond Restoration Plan, and the development of an oil spill response plan, in addition to the creation and preservation of high marsh and upland habitat to accommodate sea level rise.
Currently, management for SMHM differs among land-owners and agencies. Especially in the South San Francisco Bay, acquisition of non-tidal lands—especially old salt production ponds—for restoration to tidal action is a priority, and has results in the conversion of thousands of hectares of previously unsuitable land to potential SMHM habitat within the past several decades. In the northern SMHM range, substantial amounts of non-tidal, diked wetlands, which already support SMHM exist. In one such area, the Suisun Marsh, populations of SMHM in diked and managed wetlands equal those in tidal wetlands, and conversion of these areas to tidal action may have little to no value for local SMHM populations (Smith et al. 2019), so protection and enhancement of diked wetlands is a priority, in addition to tidal restoration. In some cases, restoration of diked wetlands to tidal action will result in a reduction in acreage of SMHM habitat, as some areas become permanently subtidal. Therefore, habitat restoration and enhancement actions must take into account both local conditions, as well as existing populations of SMHM at potential sites.