Linking Landscapes and Habitat Suitability Scores for Diadromous Fish Restoration in the Susquehanna River Basin

Abstract

Dams within the Susquehanna River drainage, Pennsylvania, are potential barriers to migration of diadromous fishes, and many are under consideration for removal to facilitate fish passage. To provide useful input for prioritizing dam removal, we examined relations between landscape‐scale factors and habitat suitability indices (HSIs) for native diadromous species of the Susquehanna River. We used two different methods (U.S. Fish and Wildlife Service method: Stier and Crance (1985), Ross et al. (1993a, 1993b, 1997), and Pardue (1983); Pennsylvania State University method: Carline et al. (1994)) to calculate HSIs for several life stages of American shad Alosa sapidissima, alewives Alosa pseudoharengus, and blueback herring Alosa aestivalis and a single HSI for American eels Anguilla rostrata based on habitat variables measured at transects spaced every 5 km on six major Susquehanna River tributaries. Using geographical information systems, we calculated land use and geologic variables upstream from each transect and associated those data with HSIs calculated at each transect. We then performed canonical correlation analysis to determine how HSIs were linked to geologic and land use factors. Canonical correlation analysis identified the proportion of watershed underlain by carbonate rock as a positive correlate of HSIs for all species and life stages except American eels and juvenile blueback herring. We hypothesize that potential mechanisms linking carbonate rock to habitat suitability include increased productivity and buffering capacity. No other consistent patterns of positive or negative correlation between landscape‐scale factors and HSIs were evident. This analysis will be useful for prioritizing removal of dams in the Susquehanna River drainage, because it provides a broad perspective on relationships between habitat suitability for diadromous fishes and easily measured landscape factors. This approach can be applied elsewhere to elucidate relationships between fine‐ and coarse‐scale variables and suitability of habitat for fishes.

Assessing Freshwater Habitat of Adult Anadromous Alewives Using Multiple Approaches

“…Our larger-scale survey of habitat units mirrored some elements of basinwide assessments and multistage approaches employed by others (Dolloff and Jennings 1997;Toepfer et al 2000). In other systems, GIS provides a useful summary of habitat when the metrics being mapped are relevant to fish (Kocovsky et al 2008). Our transect data reinforced the results of the habitat unit survey while providing useful high-resolution ecological data for restoration efforts.…”

ESA Protection for the American Eel: Implications for US Hydropower

“…Physiological condition was also poorer among eels in reaches in urban watersheds (Machut et al 2007). A habitat suitability model developed for eels in the Susquehanna River based on geology found weak positive associations of mudsiltstone and negative associations of carbonate geology with eel abundance (Kocovsky et al 2008). Thus far, no studies have considered all of these predictors-including those related to connectivity and dams, substrate, fish and smaller eel densities, land use, and microhabitat-in one analysis.…”

Spatial analysis of American Eel (Anguilla rostrata), fish passage and land use in Chesapeake Bay tributaries

“…For example on the Susquehanna River, improving passage at upstream dams without changing the initial dam did not significantly improve upstream eel densities [52]. For migrating salmon, the Washington State Fish & Wildlife Department uses criteria such as habitat suitability, production potential for adults, potential habitat gain, species mobility, species stock condition (whether or not the stock is "of concern" or "depressed") and potential costs [53,54]. But since eels have the opposite migration patterns as salmon, this framework may not be completely applicable for conservation measures.…”