Our assessment strategy was consistent with the guidelines established by the National Marine Fisheries Service for fish habitat evaluation on Essential Fish Habitat (EFH) (Schreiber and Gill, 1995; Minello, 1999). EFH defines four levels of evaluation, ranging from the most basic, initial fish presence-absence characterization (Level 1) to the most sophisticated, estimates of fish production (Level 4) (Able, 1999). We used this multilevel approach to assess the impacts of piers on fishes in the Hudson River. First, we employed Level 1 and 2 approaches, and estimated distribution (Level 1) and abundance (Level 2) of fishes around piers and in other adjacent habitats to rank their habitat value relative to one another. Next we used estimates of feeding and growth (Level 3) to quantify the habitat value of each of those areas. We have not attempted to employ a Level 4 approach, estimating fish production, as this method requires additional estimates of population size, rates of natural mortality, and fish immigration and emigration that are currently unavailable. Nonetheless, by using the first three levels of assessment we have provided a layered, multidimensional, and independent assessment of the habitat value of piers for fishes.
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