Fish of the Connecticut River The Anadromous Fish of the Connecticut River The Obstacles the Travelers Encounter How the Ascents Are Made The "Elevators" at Holyoke The Ladders at Turners Falls Fishways on the Connecticut River The Progress of Our Fishways Fish Passageways

The Anadromous Fish of the Connecticut River
Every spring, usually in late April, anadromous fish, including the American shad, sea lamprey and Atlantic salmon, migrate upstream in the Connecticut River from their ocean homes to spawn. Anadromous (ah-‘nad-rah-mus) means the fish are born in fresh water, mature in the ocean and return to the fresh water rivers of their birth to spawn. On their way, they overcome dams, falls and fishways to reach their destination.

During this migration, which ends in about mid-June, the fish-viewing facilities at Turners Falls and Holyoke, Massachusetts are open to the public.

In 1999, 251,620 fish passed through the Robert E. Barrett Fishway at Holyoke dam, including 192,604 American shad; 91 Atlantic salmon; 2,669 blueback herring; 34,514 gizzard shad; 21,084 sea lamprey; and 658 striped bass. A total of 7,939 fish migrated through the Turners Falls fish ladders in 1999, including 6,737 American shad, 8 Atlantic salmon, 3 blueback herring, 273 gizzard shad and 918 sea lamprey.

Information follows on three of these anadromous fish. Information about the others is available on the U.S. Fish and Wildlife Service Web site.

The American Shad
After four to six years at sea, adult shad travel upstream to their native, fresh-water spawning areas. They return when river temperatures reach 50 to 54 degrees Fahrenheit and spawn when the water reaches 56 to 61 degrees. A shad can lay about 130,000 eggs; each egg is about 1/16 inch in diameter. After spawning, the adults return to the ocean and spend the summer and fall in the Gulf of Maine.

The fertilized eggs hatch in about six days. Hatching at 3/8 inch long, the larva develops backfins and grows to about 5/8 inch long within 17 days. Once able to feed itself, the immature shad is called a fry. A fry spends four to six months in the river, until the cooling waters of autumn signal it to swim to the ocean. By the time the fry reaches the ocean, it is three to six inches long.

Young shad join adult shad in the ocean and migrate south during the winter, feeding on plankton until they mature and are ready to continue the cycle.

Most adult shad are from 16 to 20 inches long and weigh three to five pounds, although females can weigh as much as six pounds. Shad can live for four to six years; however, disease, fatigue or injuries caused by the journey upstream cause as many as 90 percent to die after spawning.

The Sea Lamprey
Sea Lampreys, fish that resemble eels, travel as many as 200 miles upriver to spawning areas. Considering they only travel two to three miles per day, this takes them a long time.

Lampreys live in the ocean during the winter and can be found from Greenland to Florida. They undergo great physiological changes when they enter fresh water, including going blind. They orient to the current as they move upstream and attach themselves to rocks and dams to rest. Lampreys do not always return to the place where they were born. They spawn when the river temperature reaches 77 degrees Fahrenheit.

Lampreys, which weigh from two to three pounds and can be up to three feet long, spend their first four to six years in fresh water, burrowed into the mud. After migrating downstream, they spend two to four years in the ocean before returning to fresh water to breed.

The female lamprey creates a gravel nest for the 200,000 eggs it lays when spawning. Lampreys use their disk-shaped mouths to carry stones up to four inches in diameter to form a semicircle to catch the floating eggs below the spawning site. Mating occurs during a 48-hour period; both adults die shortly after spawning is completed.

The Atlantic Salmon
Although some migrate in the fall, most Atlantic salmon begin their spawning migration in the spring. Spawning takes place in October or November with the female’s seeking out a gravel stream bottom to build her redd (nest). Eggs fertilized by the male’s milt develop over the winter and hatch in the early spring. After spawning, the kelts (adults) either swim back to the ocean or stay in the river until spring.

Newly hatched alevins remain in the gravel redd until May or June. As they feed and grow, they develop from fry to fingerlings (three to four inches long) to parr (four to five inches long). The parr, known for their vertical striped bars, spend one to two years feeding and growing in fresh water while their bodies change to prepare them for life at sea.

When the parr lose their vertical bars and turn silver, they are called smolts and are ready to head downstream to the ocean. Once there, they swim to feeding grounds off the coasts of Canada and Greenland. After one to two years in the ocean, they return to the rivers of their birth to spawn. Unlike sea lampreys, Atlantic salmon do not die when spawning is completed.

The Obstacles the Travelers Encounter
The historic upstream migration of American shad, Atlantic salmon, sea lamprey, striped bass, blueback herring and gizzard shad was thwarted at the end of the 18th century by the construction of shore-to-shore dams, which blocked the path to traditional spawning grounds.

How the Ascents Are Made
In 1955, a system was devised at Holyoke dam that paved the way for a series of successful fishways along the Connecticut River.

A fishway provides passage over a dam for migrating fish. The fishways enable shad, salmon, sea lamprey and other anadromous and resident fish to bypass dams. At Holyoke, elevators actually lift the fish over the dam. At Turners Falls, the fish are assisted by special ladders.

The "Elevators" at Holyoke
On their upstream journey, fish seek out the main stem of the river. When they get to Holyoke, they find themselves at the base of the dam or below the powerhouse, whichever has the stronger current. A fish elevator awaits them at both locations.

Attracted by the current, the fish instinctively swim into the elevators. They pass by steel gates into a "crowding area" near the elevator’s base. When enough fish are in the area, the gates close behind them and nudge the fish toward the lift. A rack is then lowered to enclose the fish in the elevator.

The elevators hoist as many as 500 fish 52 feet up before releasing them into a 300-foot-long flume, which carries a gentle current of water from the river. The fish swim into this current and past the fish-viewing area, counting station and holding pool before they enter the Connecticut River above the Holyoke dam. The Holyoke elevators lift about 2,000 fish per hour.

In 1955, the first fish elevator lifted 4,899 shad. That achievement earned the Holyoke Water Power Company the U.S. Department of the Interior Conservation Service Award of the year. Over time, major improvements were made and today, the number of shad lifted over the dam each year usually exceeds 500,000. Holyoke dam has the most successful fish passageway on the East Coast.

The Ladders at Turners Falls
After the fish pass Holyoke, they come to the fishway at Turners Falls. Unlike Holyoke’s elevators, the Turners Falls fishway relies on the ability of migrating fish to make the climb using their own power. Here, they swim over a series of rising pools in much the same way they would have overcome the natural rises in the river before dams were built.

The fishway at Turners Falls is located at Cabot Station, which is the gatehouse, and at the spillway.

Water flowing through an entrance gallery attracts the fish to the ladder. Once inside, they ascend 66 pools to the power canal and then swim two miles to the gatehouse.

Fish that bypass the Cabot Station fishway find themselves at the base of the Turners Falls dam. There, at the spillway ladder, the fish climb 42 pools, joining the fish from the power canal in passing through the gatehouse fishway. The fish then swim past a viewing area and a counting area and exit the fishway above the Turners Falls dam.

Fishways on the Connecticut River
With fish now successfully migrating past Turners Falls, other fishways have been locate on the Connecticut River at Vernon, Bellows Falls and Wilder dams in Vermont.

The Progress of Our Fishways
The first fishway at Holyoke underwent many refinements. Hand netting was replaced by sluicing, a second elevator was added and finally, a closed flume, rather than wheeled tubs, carried the fish into the river. Many experiments were done with flow regulation, flow openings and crowding.

At Turners Falls, the pools in the fishway were modified for greater effectiveness. Model studies have been helpful. Fishways require fine-tuning to accommodate their users’ behavior.

Several government organizations have contributed to the success and design of the fishways. They include the Massachusetts Division of Fisheries & Wildlife, the U.S. Fish and Wildlife Service, the Silvio O. Conte Fish and Wildlife Refuge and the National Marine Fisheries Service.