AMERICAN SHAD

Alosa sapidissima


For inquiries contact Jill Leonard or Joseph Zydlewski of the Conte Anadromous Fish Research Ctr., Turners Falls, MA 01376

The American shad, the largest of the herrings, is the most abundant anadromous fish on the east coast of the United States. These sleek, silver, schooling fish are unique inhabitants of our local rivers. Large populations support growing commercial and sport fisheries. American shad have even been successfully introduced to the west coast where they are also fished by commercial and recreational fishermen. Anglers can finds themselves in the midst of vast rafts of these silver fish providing an experience unequalled in freshwater fishing. Historically, the American shad has been an important food fish earning the title of "poor man's salmon", while the eggs, or 'roe', are considered to be a delicacy.

American shad enter rivers in the early spring and can travel hundreds of miles upstream to spawn. This energetically taxing migration allows juveniles to hatch and be reared in an advantageous freshwater environment since larval development cannot occur in salt water. American shad spawn in open waters and do not often move up into the tributaries of the large rivers that they ascend. During the evening, spring boaters can find themselves surrounded by schools of splashing, spawning shad. A large female is usually chased by a group of several eager males. The female releases her eggs into the water column and they are then fertilized by her accompanying males. A single female may spawn several times during her migration and produce as many as 200-250,000 eggs during a single year. The eggs hatch after 4-9 days in early summer and metamorphose into juveniles approximately a month later. These young are important ecologically since they provide food for a number of piscivorous sport fish including large- and smallmouth bass, walleye and pike.

Juveniles remain in the river until fall when they migrate downstream to the ocean when they are approximately 2-3 inches long (less than 0.5 oz.). These migrating juveniles are preyed upon by numerous ocean fish, including striped bass and bluefish. After entering the ocean, these planktivores take advantage of the abundant food resources available and quickly grow to adult size in 2-3 years. During this period of ocean growth, American shad migrate south during the winter to areas off North Carolina and north during the spring to summer feeding grounds in the Bay of Fundy . It is during this spring migration that reproductively mature fish will make their way back to their natal river to spawn and thus complete their life cycle. Unlike Pacific salmonids, a freshwater spawning migration does not necessarily end the life of an American shad. A proportion of the Connecticut River population survives spawning and returns to the ocean to enjoy the productivity of the sea; 30-50% of spawning adults will successfully return to spawn in another year. Interestingly, southern populations (Florida, Carolinas, etc.) do not have this "iteroparous" life style and are, in fact, "semelparous" like the Pacific salmon and do not survive spawning. In rivers north of the Carolinas, post-spawning survival increases so that in the Delaware River 10-20% survive to spawn a second time while 80% spawn more than once in the St. Johns River in Canada. Small adults are approximately 2 pounds while large females commonly attain 6-7 pounds and historically have reached 13 pounds.

In the Connecticut River, American shad were important to the indigenous peoples of the area and likewise comprised a large proportion of settlers' diets. Some of the best fishing areas were deemed neutral territories for local tribes and during the spawning run hundreds of people would congregate in these areas to spear and net migrating fish. However, the industrial revolution, and the building of river dams, drastically reduced the number of shad, and other migratory fish, in the river. A large dam was built in 1798 at Turners Falls and this dam eliminated all spawning habitat for shad beyond 120 miles upriver. The dam at South Hadley Falls in Holyoke, constructed in 1849, severely restricted the shad's spawning habitat to the lower 87 miles of the river. Finally, in 1880 the habitat was further restricted by the construction of a low-head dam at Enfield Falls in Enfield, CT. Following this construction, shad were limited to the lower 68 miles of the river during periods of low water. While spawning habitat was not completely eradicated by these manmade obstacles, the population was drastically reduced by these intrusions. Subsequently, however, changes in legislation and in public opinion focussed attention on the problem and placed the responsibility for fish passage on the owners of the dams.

Fish passage devices, such as ladders and fish elevators, were constructed on the five main stem dams. The first attempts at building fish ladders occurred in 1893 at Holyoke Dam; however, few fish successfully ascended this structure. During the late 1800s there was also a growing movement artificially to rear shad and other anadromous species, but these attempts met with varied success. In the early 1900s further modifications of the main stream dams were made; however, passage was still limited. In the early 1950s the primary construction of a fish elevator at Holyoke Dam was completed by the power company and federal personnel. This fish elevator became operational in 1955 and allowed some access above the facility. More improvements in the 1970s finally allowed substantial passage past Holyoke dam. During this same period, fish ladders were constructed at the Turners Falls dam complex. The current structures were built in the late 1970s and early 1980s. The Enfield Dam was also breached by the river prior to this period, so that by the 1980s there was functional fish passage for American shad in the lower 144 miles of the river. Currently, American shad migrate as far as Bellows Falls, VT (174 miles upriver), which is thought to be close to the historical upriver range of the population. Although much attention has focussed on upstream migration, it has only been in recent years that the welfare of downstream migrants has been addressed seriously. Downstream migrants approaching hydropower facilities are small enough to pass easily through turbine gates and mortality due to turbines can be considerable. Currently, there are modified log sluices that direct juveniles away from the turbines and around the dam; however, the turbulent environment may also lead to mortality. Additionally, the delay of downstream migration caused by dams results in a pooling of downstream migrants which attracts predators both above and below the dams: the effect of predation at the dams on these migrants is unknown.

Currently, the Connecticut River American shad population is estimated at 1-2 million returning adults each year with between 2-600,000 passing through the Holyoke Dam fish passage elevator. While in many rivers along the eastern coast populations of American shad were extirpated and restoration efforts have proved problematic, the outlook for the Connecticut River American shad is bright. There have been slow, but consistent, improvements to water quality, fish passage and management practices all contributing to the return of the Poor Man's Salmon. The cooperation of state and federal agencies, utility companies and the public is leading to the restoration of this native, New England fish.

You might enjoy this old fish tale or learning about the great shad war.

References:

Atkinson, C.E. Feeding habits of adult shad (Alosa

sapidissima) in fresh water. Ecology 32(3):556-557.
1951.

Chittenden, M.E.J. Weight loss, mortality, feeding and

duration of residence of adult American shad, Alosa
sapidissima, in freshwater. Fisheries Bulletin 74(1):
151-157. 1976.

Dadswell, M.J., Melvin, G.D., Williams, P.J. and Themelis, D.E.

Influences of origin, life history and chance on the Atlantic
coast migration of American shad. American Fisheries
Society Symposium 1:313-330. 1987.

Dodson, J.J. and Leggett, W.C. Role of olfaction and vision in

the behavior of American shad (Alosa sapidissima
homing to the Connecticut River from Long Island Sound.
Journal of the Fisheries Research Board of Canada 31:1607-
1619. 1974.

Leggett, W.C. The American shad (Alosa sapidissima), with

special reference to its migration and population dynamics in
the Connecticut River. In: The Connecticut River
Ecological Study: The Impact of a Nuclear Power Plant.
(eds. Merriman, D. and Thorpe, L.M.) American Fisheries
Society, 1976.

O'Leary, J.A. and Kynard, B. Behavior, length and sex ratio of

seaward-migrating juvenile American shad and blueback herring
in the Connecticut River. Transactions of the American
Fisheries Society 115:529-536. 1986.

Neves, R.J. and Depres, L. The oceanic migration of American

shad, Alosa sapidissima, along the Atlantic coast.
Fishery Bulletin 77(1):199-212. 1979.

Melvin, G.D., Dadswell, M.J. and Martin, J.D. Fidelity of

American shad, Alosa sapidissima (Clupeidae), to its
river or previous spawning. Canadian Journal of Fisheries
and Aquatic Science 43:640-646. 1986.