Predicted Effects of Historic Habitat Loss and Novel Habitat Creation on Blueback Herring in the Hudson River Watershed.

Stich, Dan¹, Wes Eakin², Gregg Kenney³, ¹SUNY Oneonta, NY, ²Cornell University and NYSDEC, Poughkeepsie, NY, ³NYSDEC, Poughkeepsie, NY

We used life-history simulation models to understand potential influences of historic habitat loss and novel habitat creation on blueback herring abundance in the Hudson River watershed, in concert with additive mortality sources such as mortality during passage of navigational locks and marine bycatch. Access to historical habitat in the upper Hudson River increased population abundance with sufficiently high upstream passage and downstream survival, but abundance was reduced relative to a “no passage” scenario when either juvenile or adult downstream survival through dams was less than about 0.50. Threshold passage efficiencies in the upper Hudson River required to maintain or increase abundance of blueback herring were lower than those for American shad owing to differences in life-history. Access to novel spawning habitat in the Mohawk River canal system resulted in increased abundance of Blueback Herring when downstream survival of adults and juveniles was at least 0.80 per dam and both upstream passage and probability of using the Mohawk River were greater than about 0.25. Mortality during upstream passage of locks in the Mohawk River and marine bycatch had the potential to reduce Blueback Herring abundance below historic population abundance dependent upon upstream and downstream passage and additive mortality sources.