Naugatuck River and roadways, through the time of development of Connecticut Route 8. The river enters a forested, hilly area between Connecticut Route 118 and Thomaston. The largely industrialized cities of the Naugatuck River Valley were developed on each side of the river, with periodic sections of forested areas, before it enters the Housatonic River at Derby, at about above sea level. As part of the Housatonic River watershed, the Naugatuck River historically hosted the southernmost Atlantic salmon ("Salmo salar") migrations. Historical runs of anadromous fish also included native American shad ("Alosa sapidissima", Connecticut's state fish), alewife ("Alosa pseudoharengus") and blueback herring
Coastal fish but ascend rivers to spawn; eels are catadromous, living in rivers and streams, but returning to the sea to breed. Besides the species that migrate through estuaries, there are many other fish that use them as "nursery grounds" for spawning or as places young fish can feed and grow before moving elsewhere. For example, herring and plaice are two commercially important species that use the Thames Estuary for this purpose. Mangrove swamps are associated brackish water habitats. Many, though not all, mangrove swamps fringe estuaries and lagoons where the salinity changes with each tide. Among the most specialised residents of