Effects of land use and land cover on alosine spawning habitat in non-tidal tributaries to the Bush River, Maryland: Implications for Ecosystem Based Fisheries Management

Abstract

There is extensive literature on the effects of land use and land cover on aquatic biodiversity and integrity of habitat. Aquatic health in lotic systems has been found to decline with increasing development and construction of impervious surfaces. Other research has also demonstrated that certain types of land use and land cover affects anadromous fish habitat in tidal waters, raising concerns on the effects of increased development on the long-term viability of valuable commercial fisheries. To assess the importance of land use and landcover in making ecosystem based fisheries management decisions for anadromous species, I conducted an analysis of alosine (shad and herring) spawning survey data collected by the Maryland Department of Natural Resources (MD DNR) from 2005-2008 in the Bush River watershed, a subestuary of the northern Chesapeake Bay. This data was coupled with geomorphic, hydrological, and physical habitat data collected by Chesapeake Environmental Management, Inc. (under contract to MD DNR) in 2008 in several of the non-tidal tributaries to the Bush River. I attempted to relate changes in land use to changes in spawning habitat integrity by incorporating 22 years of landuse and land cover data collected by the U.S. Geological Survey. Using CART analysis, I showed that alosine eggs and larvae reacted negatively to increases in stream current velocity. In addition, while development increased over time in the watershed, percent coverage of agriculture in subwatersheds greater than 25% appeared to be correlated with absence of spawning activity. These results may prove insightful when it comes to developing ecosystem reference points for desired levels of land use types for fishery management plans.