American shad migrate into the Connecticut River during late March or April, reaching the upstream fish passage facility at the Project during late April or early May. During the run, water temperatures at Holyoke Dam range between 12° and 20° C; and river flow is generally declining from the spring peak, though spates occasionally occur.
Most shad are lifted over the Holyoke Dam and allowed to continue upstream migration, where fishways at the Turners Falls, Vernon, and Bellows Falls hydroelectric projects also provide a means to enhance upstream passage for migrating species. Some shad are trapped at the Holyoke Project and transported in trucks by state and federal agencies to upstream reaches of the Connecticut River, or to other river basins. After spawning, adult shad swim back downstream, primarily during daylight hours in June and July, and may survive to spawn more than once.
Young-of-the-Year (YOY) shad are abundant in many locations upstream of Holyoke Dam throughout the summer. They provide a forage base for predatory fish in the impoundment of the Project and upstream to Turners Falls Dam. Although some YOY shad may move downstream through the Project at other times, the seaward migration out of the Connecticut River occurs from September through November, peaking when water temperature is 9° to 14° C. The young migrate to areas in the North Atlantic from the Maritimes to Florida and remain at sea for four to six years before returning to their native river to spawn.
- Every river has its own mineral and chemical ‘scent.’ Scientists think that shad find their way home by using their sense of smell.
- The largest American shad on record, 11 lbs. 4 oz., was caught