in Massachusetts as the Pioneer Valley), depositing rich silt and loam soils known internationally for their agricultural merit. Abundant riparian hardwood species include sycamores, cottonwood, basswood, willows, sassafras, box elder, black elder, osier dogwood and more. The river itself and its many tributaries are home to many typical New England freshwater species. These include dace, crawfish, hellgramites, freshwater mussels, typical frog species, snapping turtles, brook trout, freshwater sturgeon, catfish, walleye, chain pickerel and carp. Introduced species include stocked rainbow trout. The river is an important conduit of many anadromous fish, such as American shad, lamprey, and Atlantic salmon. American eels are also present, as are predators of these migratory fish including striped bass. Shad run as far north as Holyoke, Massachusetts where they are lifted over the Holyoke Dam by a fish elevator. This station publishes annual statistics of the run, and has recorded an occasional salmon. They pass an additional elevator in Turners Falls, Massachusetts, and make it at least as far as Bellows Falls, Vermont. Harbor seals have been recorded traveling upriver as far north as Holyoke in pursuit of migratory fish; it is possible that they ranged farther upstream before the dam was built. There are 12 species of freshwater mussels. Eleven of them occur in the mainstem of the Connecticut; the brook floater is found only in small streams and rivers. Species diversity is higher in the southern part of the watershed (Connecticut and Massachusetts) than in the northern part (Vermont and New Hampshire), largely due to differences in stream gradient and substrate. Eight of the 12 species in the watershed are listed as endangered, threatened, or of special concern in one or more of the states in the watershed. A number of colonial animal species make their home in the waters of the Connecticut. Deeper areas are habitat for a diversity of colonial organisms including bryozoa. Freshwater sponges the size of dinner plates have been found by scuba divers at depths of more than , thought to be the deepest location of the river, around the French King Bridge in Orange, Massachusetts. Mussels, eels, and northern pike were also observed there. Fish There are several species of anadromous and catadromous fish, including brook trout, winter flounder, blueback herring, alewife, rainbow trout, large brown trout, American shad (Alosa sapidissima), hickory shad, smallmouth bass, Atlantic sturgeon, striped bass (Morone saxatilis), American eel, sea lamprey, and endangered shortnose