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Migratory Fish, Coastal Tributaries & Salt Marshes

Long Island's tributaries and salt marshes - and the migratory fish populations they help support - are a vital part of our coastal ecosystem, as well as our local well being, identity, and economy. Seatuck plays a leadership role in a number of research and policy initiatives focused on the protection and restoration of these aquatic resources, including, in particular, river herring and other migratory fish. 

Areas of focus:

Tributaries & Migratory Fish

The coast of Long Island is punctuated by numerous small creeks and rivers draining to three major outlets; the Long Island Sound to the north, Peconic Bay to the east, and the group of bays comprising the South Shore Estuary.  In all, there are over 150 creeks and rivers in Nassau and Suffolk Counties.  The combined physical, chemical and biological contributions of these small tributaries help drive the ecology of the important, larger estuarine systems.

Coastal tributaries provide important sources of freshwater and nutrients to Long Island's estuaries.  Additionally, they provide crucial habitat for a variety of fishes and other wildlife, including diadromous fish species that utilize tributary habitat for distinct portions of their life cycles.

Unfortunately, many of these important tributaries are seriously impaired as a result of human-induced development and land use pressures.  Once clean, cool and free flowing, our tributaries now too often carry too many nutrients and chemical toxins in a smaller, warmer volume of water than they once did.  Structures such as dams, culverts and dikes redirect flows, change water chemistry and block fish migrations greatly altering the capacity of many of these streams to support native ecosystems.

The populations of native species, including river herring and American eel, are substantially reduced compared to historic levels, but populations remain in many systems, increasing restoration potential. Similarly, while water quality is degraded, our tributaries are not past the point of no return so long as we employ proactive, sustainable watershed management strategies.

Seatuck is a leading partner in an island-wide effort to restore Long Island's tributaries. The organization chairs and hosts the Long Island Diadromous Fish Workgroup, organizes the annual Long Island Volunteer Alewife Survey, conducts video-based and electronic surveys of alewife runs across Long Island, educates the public and government officials about the benefits of healthy coastal tributaries, and advocates for restoration projects.

Salt Marshes

Salt marshes are an ecologically and economically important feature of the coastal landscape. The expansive emergent flats, dominated by the salt-tolerant grasses including cord grass (Spartina alterniflora) and salt hay (Spartina patens) are important habitat for many resident and migratory birds. The shallow tidal channels and pools provide habitat for prey fish, nursery habitat for sport and commercial species (e.g. Atlantic croaker and blue claw crab), and help to promote a predator balance that favors clam and oyster populations. Marshes can act as biological filters, sequestering excess nutrients from upland runoff before it reaches the ocean and can also help protect coastal property by absorbing wave energy during storm surges.

Many of Long Island's salt marshes have been lost due to development and dredging as the island has become more heavily populated. Most of the remaining salt marshes have been physically altered through ditching or other approaches in an effort to control mosquito populations. Additionally, there are less obvious and less easily managed threats to the long-term integrity and existence of Long Island salt marshes including hydrologic alterations, invasive species and sea-level rise. It will take a comprehensive and innovative approach by environmental managers to ensure that these valuable ecosystems persist.  Hurricane Sandy and other recent storms have raised awareness about the importance of salt marshes and generating new interest and funding for their protection and restoration. Seatuck is partnering with agencies and environmental organizations to help ensure salt marshes continue to serve their valuable ecological role on Long Island.


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