The connection between the marine and riverine systems of the Bronx River has been severed since the 1600s when the first dam was erected at what is now the 182nd Street Dam. The first of three fish passages on the Bronx River, The “Fish Ladder” is intended to permit fish migration for alewife for the first time in 330 years, and improve migration of American eels. Both of these species are on the decline worldwide and this project is part of larger efforts to support biodiversity in the world's oceans.