Fish utilization of restored, created, and reference salt-marsh habitat inthe Gulf of Maine

In the Gulf of Maine region, projects to restore or create salt-marsh habit at to replace saltmarsh functions and values reduced or lost to tidal restr iction are increasing. We assess fish utilization of marsh restoration and creation projects along the central Gulf of Maine coastline by addressing t hree questions: (1) how do fish assemblages in manipulated and reference ma rshes compare, (2) how do differences between manipulated and reference mar shes change over time, and (3) how do fishes respond to different types of restoration? Fish utilization of restored and created marshes in New Hampsh ire and Maine (two created and four tidally restored marshes) is compared t o adjacent reference marshes. The comparison of manipulated marshes with lo cal reference marshes provides an internal standard for the monitoring of e ach restoration project, making it possible (1) to follow changes over time while accounting for natural variation and (2) to make valid comparisons a bout the magnitude and direction of changes between independent restoration projects. Our study provides the first density estimates for fish utilizat ion of vegetated salt-marsh habitat in the Gulf of Maine. The highest fish densities from this study just overlap with the lowest fish densities repor ted from more southerly marshes. Overall, fish were distributed similarly a mong manipulated and reference marshes, and fish distribution did not chang e with time. Trends in the data suggest that fish utilize elevated marshes restored by dug channels to a lesser degree than impounded marshes restored by culverts. It appears that fish will readily visit restored and created marshes in assemblages similar to those found in reference marshes over the short term (one to five years post-restoration) but are subject to the inf luence of differences in tidal regime, access to marsh habitat, and vegetat ion density. In the large majority of cases, hydrologic restoration of tida lly restricted marshes will improve a much larger area of fish habitat per unit cost than creation of new marsh and will not be subject to many of the constraints that limit the function of created marshes. The primary consid eration in tidal restoration projects is not necessarily the cost of constr uction but the social, economic, and political issues that must be addresse d. Often, tidally restricted marshes are in highly developed coastal areas where many individual property owners may perceive the increased tidal flow as a threat, even when flood hazard studies show that no such threat exist s. In spite of this caution, thousands of hectares of coastal fish habitat can be improved through a concerted program to restore the hydrology of tid ally restricted marshes in the Gulf of Maine.