shad run far upstream. The apparent longest distance is in the St. Johns River of Florida, an extremely slow (drops 1 in per mile, 1.5 cm per km) river that widens into large lakes; shad have been found upriver. The spawning fish select sandy or pebbly shallows and deposit their eggs primarily between sundown and midnight. Females release eggs in batches of about 30,000 eggs, though an estimated as many as 156,000 eggs are deposited by very large fish. Total annual egg production is 200,000–600,000 eggs per female with larger fish producing more. In rivers north of Cape Fear, the spent fish, now very emaciated, return to the sea immediately after spawning. In southern rivers, most shad die after spawning. The eggs are transparent, pale pink, or amber, and being semibuoyant and not sticky like those of other herrings, they roll about on the bottom with the current. The eggs hatch in 12 to 15 days at , in six to eight days at , which covers the range characteristic of Maine and Bay of Fundy rivers during the season of incubation. The fry are about long. Juvenile shad remain in the rivers until fall, when they move down to salt water; they are now long, resembling their parents in appearance. Ecology and diet As adults, shad filter feed at sea and during their return journey to spawn. They are pursued and hunted primarily by striped bass, and at times, harbor seals. They may not actively feed on their return, and are caught with special 'dart' lures instead of typical bait. Nutritional information Like most herring species, American shad are very high in omega 3 fatty acids, and in particular contain nearly twice as much per unit weight as wild salmon. They are also very low in toxins such as PCBs, dioxins, and mercury by EPA estimates. The American or Atlantic shad (A. sapidissima) is a valued food fish. Shad populations Declines in the Atlantic coast shad population were documented as early as the turn of the 20th century. Traditionally, shad were caught along with salmon in set nets, which were suspended from poles driven into the river bed reasonably close to shore in tidal water. Many of the rivers where shad were once common now suffer from pollution; however, the short time spent by shad in fresh water may minimize contamination. For example, fisheries scientists have found that shad