American Shad Alosa sapidissima
Download 22.78 Kb.
|
| American Shad Alosa sapidissima
Species overview: The American shad is the largest member of the herring family that lives in or visits Pennsylvania waters. The annual migration of shad up rivers that feed the Atlantic Coast was used as food by American Indians as well as early European settlers. The spring shad run is credited with helping to save General Washington’s starving troops at Valley Forge during the Revolutionary War, arriving just in time. Shad also supported a commercial fishery on the Susquehanna River as well as the Delaware River. The Susquehanna’s runs stopped when hydroelectric power dams were built across the river in the early 1900s. Since that blockage, efforts led by the Pennsylvania Fish & Boat Commission have been aimed at restoring shad to the Susquehanna watershed. The result is that now there are fish passage devices to enable fish passage at nearly all the dams. Full access to the river system should be possible soon. Shad are once again returning to the Susquehanna through the fishways, and the shad are providing evidence of natural spawning. The Pennsylvania Fish & Boat Commission has also stocked shad in the Juniata River system, above the Susquehanna River dams, to help restore the run. There are also fishways that allow shad migration over dam obstacles on the Schuylkill River and Lehigh River, but the only major waterway completely accessible to the natural shad migration in Pennsylvania is the Delaware River. Adult shad travel at least as far up as the confluence of the West Branch and East Branch of the Delaware, in extreme northeastern Pennsylvania. Along the Atlantic Coast, shad range from Labrador to Florida, ascending coastal rivers all along the way during spawning runs, but they are most abundant from Connecticut to North Carolina. American shad were introduced into the Sacramento and Columbia rivers in California in 1871, and today there is a shad fishery on the Pacific Coast. In fact, shad eggs collected from the introduced population in the Columbia River have been used in the Susquehanna River restoration efforts. Past attempts failed to establish shad in Lake Ontario, the Mississippi River watershed and the Great Salt Lake. The American shad’s genus name “Alosa” is from “allis,” an old Saxon name for the European shad. The species name “sapidissima” means “most savory.” Even though shad are bony, the meat is tasty, and the roe, or eggs, are a delicacy.  Identification: Female shad, carrying their eggs during the spawning run, average four to five pounds, with a six- or seven-pounder fairly common. The males are smaller for their age. Shad can grow to 30 inches, with a maximum weight of about 12 pounds. Shad are brilliantly silver on the sides, with a greenish or bluish-metallic sheen on the back. The scales are large and readily detach when the fish is handled. Shad have one to two, rarely three, rows of dark spots extending along the side from the back edge of the gill cover. The first spot is the largest. The body is deep from the side and narrow seen head-on. Shad have sharp-edged modified scales along the belly line, as do other herrings. The dorsal fin is at the center of the back, and the tail is deeply notched. The dorsal and caudal fins are dusky. The caudal fin has a black edge, and the other fins are clear to light-green. The upper and lower jaws are about equal in length, neither jutting past the other. The rear corner of the upper jaw extends to the rear edge of the large eye. The head has a short, triangular look. The shad is notorious for its thin, easily torn mouth tissue. Habitat: American shad are anadromous. They live in the open-water ocean as adults, entering brackish estuaries and swimming far upstream to spawn in freshwater rivers. They do not normally enter small streams and creeks, as does their cousin the hickory shad. American shad stay in the mainstem, bigger rivers. As marine adults, shad travel in schools extensively along the coast. Life history: Shad run upriver from salt water into fresh water on their spring spawning migration when the water temperature is in the mid-50s to 60 degrees, with peak spawning activity occurring at about 65 degrees. The males travel upriver in schools ahead of the females. Shad spawn over sandbars or rocky riffles at night. Females, which are larger than the males, produce 100,000 eggs as an average, with 300,000 a documented high. Shad eggs are not adhesive and are just slightly heavier than water, so they do not readily sink. Instead, they drift along with the current. They develop and hatch in eight to 12 days, depending on water temperature. Adult shad feed little on their upstream spawning run, although they strike anglers’ offerings. The spawned-out, or spent, fish do eat on their way downriver to the sea again. Hatched shad live several months in fresh water, reaching the ocean by their first autumn. Shad stay in salt water for four or five years and until they are about 18 inches long, when they become sexually mature. Then they make their first freshwater spawning run. Some return to their home streams, but others show no migratory pattern. Shad feed mostly on microcrustaceans, or zooplankton, as well as some worms and small fish. While in fresh water, the young feed on insect larvae. Directory: wordpress -> wp-content -> uploads -> 2010 uploads -> Bury st edmunds hockey club uploads -> Professor rona s beattie and dr david bamaung glasgow caledonian university email for corresponding author uploads -> Best Offensive Players: qb #19 keenan reynolds, N, ’16. Lg #57 E. K. Binns, N, ’16 uploads -> Smart Supervision Research Partner Orientation Course fy13 and fy14 Grantees September 29- october 1, 2015/San Antonio, tx uploads -> Autonomous Control for a Reliable Internet of Services (across) 2010 -> Ainsley Bourque Jan. 28, 2008 2010 -> Are There Any Who Are Wise? September 12, 2010 2010 -> Century to date. This is a very rough sketch without dragging in too much detail just to provide background Download 22.78 Kb. Share with your friends:
|