|Family overview: The herrings are primitive, bony fish. The family Clupeidae dates back 120 million years. Worldwide the family includes about 200 species, including sardines, anchovies, menhaden, shad and herrings. Most herring family species are ocean-dwelling or anadromous, living in salt water as adults, but returning to fresh water to spawn, and spending the early part of their lives in fresh water. Other herring family members are strictly freshwater fish.
Pennsylvania is known to have, or have had, seven species of herrings. Skipjack herring have been reported by creel checks in angler catches. This species occurs in the Ohio River, near Pittsburgh. The skipjack looks much like the uncommon hickory shad, which has been reported in the lower Delaware River. Other herrings in Pennsylvania are the blueback, alewife, American shad and gizzard shad. The herrings can be found in the Delaware River and its estuary, especially during the spawning migration. Some (especially the American shad) are appearing in the Susquehanna River watershed because of fish lifts on dams and stocking. Other herring family members live in western Pennsylvania, in the Lake Erie and Ohio River watersheds (gizzard shad). The alewife has been introduced into larger reservoirs in the state as a forage species for large game fish.
Identification: Very young herring are long and slender, much different from the adults. Adults of the herring family are deep-bodied when viewed from the side. They are extremely compressed and flattened when viewed head-on. They have large, brilliant-silver scales, which are cycloid, smooth to the touch, and easily shed when touched. There is one soft-rayed dorsal fin in the center of the back, and the tail is deeply forked. The eye is large. There are no scales on the head, and no lateral line on the sides. The scales on the midline of the belly are modified and have sharp points. These “scutes” give the belly a rough, saw-toothed edge. They account for several herring species’ common name of “sawbelly.”
Life history: Most herrings are pelagic–they are midwater forms not associating with bottom structure. Herrings are school fish and can occur in very large concentrations. All spawn in the spring, some migrating great distances from the adult’s marine home, swimming upstream many miles into freshwater rivers. Other herrings spawn in tidal, brackish bays, or in the shallows in freshwater lakes. Herrings produce a large number of eggs for their size. A 12-inch, one-pound gizzard shad, for example, can hold 250,000 eggs at maturity. Schools of herring, the males and females pairing, scatter adhesive, fertilized eggs over various bottom types, including the rocky riffles of rivers and the pebbled shoals of reservoirs. There is no nest-building or parental care. Herrings eat mostly zooplankton, tiny aquatic animal life. The larger species may also eat shrimp, fish eggs and fry. Herrings grow rapidly and are not long-lived.
Species overview: Blueback herring look much like a closely related species, the alewife. Their marine range is along the Atlantic Coast from Nova Scotia to Florida. They migrate for spawning into the lower reaches of freshwater streams and rivers. In Pennsylvania, the blueback herring is found only in the lower Delaware River and the Delaware estuary, where it returns to spawn. Throughout its range, dams have blocked the blueblack from entering streams, and reduced its abundance and distribution in freshwater. South of Pennsylvania, blueback herring can be very common in river mouths in the spring, giving it the common name “glut herring.”
Identification: Blueback herring look like alewives, with which they associate. The main difference between the alewife and blueback herring is internal: The alewife has a silver-gray lining (peritoneum) to its body cavity. The blueback’s peritoneum is black. The eye of the blueback is smaller, comparatively, than the alewife’s eye. Bluebacks have a single blueblack spot behind the upper part of the gill cover on the side of the body. The back is blue-green and the body sides are bright-silver. The cheek is longer than it is deep. The lower jaw projects slightly beyond the upper jaw, giving them a “stick out your chin” look. Bluebacks are generally more slender than alewives and are darker in color than other members of the herring family. The maximum size is about 15 inches and less than one pound. As in the other herrings, there is a row of saw-toothed scales along the belly line. There is also one dorsal fin, and the tail is deeply forked.
Habitat: Adult blueback herring are marine, inhabiting a narrow band of water off the coast. Fish enter the coastal rivers to spawn. Bluebacks spawn in fresh water several miles upstream of the tidal line in the Delaware River. While in streams, the blueback lives in the current over a rocky bottom, although its time there, during spawning, is brief.
Life history: As anadromous fish, blueback herring begin their lives in the flowing sections of ocean tributaries, not far from the stream’s outlet. Adult bluebacks are mature and spawn in their fourth year, migrating from the sea into the mouths of freshwater rivers in late spring, after the alewife has spawned. These schooling fish spawn in brackish water and in fresh water over a firm, not silted bottom. Their sticky eggs sink and adhere there. After spawning, the parents head for the sea again, taking no care of the eggs or young. The tiny one-millimeter-long eggs hatch in two or three days, at a little over 70 degrees. When young bluebacks are about one month old and about two inches long, they head for salt water. Bluebacks feed on zooplankton, as well as shrimp, small fish and fish eggs.
Species overview: Hickory shad live in coastal marine waters and move into fresh water to spawn. Hickory shad range from the Bay of Fundy in Maine to the St. Johns River in Florida. The hickory shad is common from Chesapeake Bay to North Carolina and in coastal waters of the northeast states. Between these areas, it is scarce. In Latin, the name “mediocris” means “not important,” or “ordinary.”
Like American shad, hickory shad are anadromous. They live in coastal ocean waters as adults and enter brackish estuaries, like the Delaware, and swim far upstream to spawn in freshwater rivers and creeks. Hickory shad are returning to the Susquehanna River watershed because of fish lifts on dams. Currently, they are on the list of endangered, threatened, and candidate fishes because of their extremely limited distribution and abundance. In states where their numbers are sufficient to allow sport fishing, they are pursued by light-tackle specialists for their fighting and leaping abilities.
Identification: The hickory shad is silver-sided with a dark spot on the shoulder followed in some individuals by several less distinct dark spots. The fish are grayish green on top fading to silvery on the sides. The sides of the head are bronze. The tip of the lower jaw, and the dorsal and caudal fins, are darker. The tail is deeply forked with pointed lobes. The lower jaw projects beyond the upper jaw.
The hickory shad’s shape is unique. The back curves only slightly. The body is long but compressed. In cross section it is wedge-shaped.
The hickory shad ranges in size between the bigger American shad and the smaller blueback herring and alewife. The most common size of a hickory shad is about 12 to 15 inches. A very large specimen would measure 24 inches long, but hickory shad rarely reach two pounds.
Habitat: In its coastal ocean enviroment, the hickory shad feeds on squid, small fish, fish eggs and some invertebrates such as crabs and crustaceans. It is unknown whether or not hickory shad feed when they enter fresh water to spawn.
Life history: Very little is actually known about the hickory shad’s life history, except that the species is anadromous. It is believed that hickory shad enter the Delaware estuary and Delaware River, and Chesapeake Bay and the Susquehanna River, in the spring, from April to June, to spawn. Spawning is believed to take place at night, between dusk and around midnight, when water temperatures reach 61 degrees. The eggs, which are buoyant and somewhat adhesive, are easily carried downstream by swift water and current. The eggs hatch in 48 to 70 hours.
Species overview: The alewife is an anadromous herring in its natural range, living its adult life in salt water and swimming into freshwater tributaries to spawn. Its original distribution was along the Atlantic Coast, from South Carolina northward into Canada. Alewives enter Pennsylvania’s Delaware River on spawning migrations.
The alewife can also live entirely in fresh water. It has become established in all the Great Lakes, including the Pennsylvania portion of Lake Erie. It was first reported in Lake Ontario in the 1870s, there either by accidental introduction or by making its way through water routes from New York’s Finger Lakes, the St. Lawrence River or the Erie Canal. By 1931, the alewife was reported in Lake Erie, having bypassed Niagara Falls via the Welland Canal. As a food fish for larger game fish, alewives have also been stocked in impoundments across the state. They have also been accidentally spread as escapees from fishermen’s bait buckets.
Its small size, large schools and availability to openwater game fish have made the alewife suited for stocking in some inland reservoirs as a forage fish. It has been introduced in Pennsylvania for that purpose in some of our larger impoundments. The species name “pseudoharengus” means “false herring.”
Identification: On the exterior, the alewife is nearly identical to the closely related blueback herring. The surest difference is inside the fish. The alewife has a silver-gray lining (peritoneum) to its body cavity. The blueback’s peritoneum is black. Alewives are bluish green or bluish gray on the back, silvery on the sides, with faint, dark stripes. They have a large eye that is wider than the distance between the front of the snout to the front of the eye. Like the blueback herring, alewives have a single dark spot behind the upper gill cover, and the rear edge of the upper jaw extends to the middle of the eye. The alewife’s lower jaw does not project noticeably beyond the upper jaw. Like the American shad, the alewife has a deep notch in its upper jaw. Saltwater alewives seldom weigh over one pound. Their maximum length is 12 to 15 inches. Landlocked freshwater alewives rarely go more than nine inches. The usual size is three to six inches.
Habitat: Alewives can live in both fresh and salt water. Coastal marine fish, they enter freshwater tributary rivers seasonally to spawn, negotiating rapids and fishways to gain access upstream on their migration. Alewives can also spend their lives entirely in cool, freshwater lakes, reproducing successfully and becoming extremely abundant. Alewives are pelagic, schooling and feeding in midwater or at the surface, over any bottom type.
Life history: Alewives spawn about two or three weeks earlier in the spring than the American shad. They migrate upstream in April and May from the mouths of rivers and creeks that open to the ocean into the freshwater flows. They spawn in quiet areas with slow current or in still pools, randomly releasing their minute, sticky eggs over the rocks, pebbles or other bottom material. After spawning, the adults return to the stream mouth and may live in the shallow estuary until fall, before going back to the ocean for the winter.
In April, the landlocked alewife in large freshwater lakes moves from its deepwater habitat toward shore to spawn in the shallow water along beaches and on shoals. Spawning occurs day or night from June through August, but normally peaks in mid-July. After spawning, the school of adult alewives retreats to deep water. The eggs sink to the bottom, and develop and hatch on their own. Landlocked alewife females can spawn 10,000 to 22,000 eggs, while the larger oceangoing alewives can produce up to 100,000 minute eggs.
Young alewives reach two or three inches long their first year. The males spawn at two years old, the females at three. They eat zooplankton and other tiny water organisms, some crustaceans, shrimp, small fishes and fish eggs. Even as adults, alewives are able to feed extensively on zooplankton, because the gill rakers that filter the microscopic food from the water increase in number as the fish grow. They are not always a welcome addition to a lake because they compete with the young of other fishes for food and they eat larval fish. Along the Great Lakes, summer die-offs of immense numbers of alewives have occurred, the dead fish washing onto shorelines. This summer kill is probably the result of water temperature change, spawning stress and other causes.
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.
Species overview: The gizzard shad is a herring with a difference. It is set apart from its herring relatives (that are in the genus Alosa), by its gizzardlike stomach. The gizzard shad is found mainly in the Ohio River watershed and Lake Erie in appropriate habitat. However, as a result of both intentional and unintentional stocking, it is found statewide. The gizzard shad’s original home range was the southeastern United States, except for the Appalachian Mountains, but the fish seems to be spreading northward. Biologists question whether or not the gizzard shad was native to Lake Erie. They believe it probably invaded the Great Lakes from the upper Mississippi River. Today, gizzard shad can be found in the St. Lawrence River, the Great Lakes, the Mississippi River and its tributaries, and the Atlantic and Gulf Coast watersheds.
The gizzard shad gets its common name from its muscular, gizzardlike stomach, which helps process the plankton and plant food this fish strains from the water. The genus name “Dorosoma” refers to a lancelike body. The species name “cepedianum” recognizes a French ichthyologist named Lacepede.
Identification: The gizzard shad has the typical herring family shape, but with a distinctive dorsal fin. Its short, soft-rayed dorsal fin is located at the center of its back. It has a long, trailing filament as the rear ray, longer than any of the other rays. The gizzard shad’s back is silvery blue-green to gray. The sides are silvery or reflect blue, green, brassy or reddish tints. There is no lateral line. The tail is deeply forked, and the lower jaw is slightly shorter than the upper jaw. The snout is blunt. The mouth is small, and there is a deep notch in the center of the upper jaw. The gizzard shad’s eye is large. There is a big, purplish-blue spot near the edge of the upper gill in young gizzard shad and small adults. This spot is faint or disappears completely in larger, older fish. The fins are dusky and there are the usual herring sawtooth-edged belly scales. Gizzard shad grow rapidly and can reach a maximum size of about 20 inches.
Habitat: The gizzard shad is a school fish of lakes and impoundments. It also lives in the backwaters of sluggish rivers and the deep, slow pools of smaller streams. Gizzard shad become more abundant as a lake eutrophies– that is, as it gains fertility through natural aging or added pollutants. Generally found in fresh water, gizzard shad can also live in the brackish water of tidal zones and estuaries. Unlike many other herrings, gizzard shad are nonmigratory and stay near their home areas. They are often found over a mucky bottom, which they filter when feeding.
Life history: The gizzard shad spawns in spring, May to June, when water temperatures reach the mid-60s to mid-70s. Spawning gizzard shad gather in large schools to broadcast their eggs in water several feet deep, near the shore. The actual spawning is done near the surface. The females participate with several males. An average female gizzard shad produces about 300,000 eggs, but some may expel a half-million, with maximum production by two-year-old fish. After releasing their eggs and milt, the adults return to the water depths. The sticky eggs fall to underwater roots, plant fibers and other debris. There they adhere and hatch in two or three days. Young gizzard shad are a food source for game fish, but grow rapidly, to as much as seven inches their first year. Their use as a forage fish is limited because they quickly grow past the prey size preferences of all but the largest predatory fish. In some fertile waters, gizzard shad become numerous, and extensive winter die-offs are not uncommon. Winter die-offs are associated with temperature stress. Massive mortality of gizzard shad may also follow spawning.
Gizzard shad are filter-feeders, straining small animal organisms and plants from bottom mud and organic deposits. The adults have very many, often more than 400, fine gill rakers that can catch even minute plankton. Gizzard shad have an unusual digestion process for fish. The vegetable material they eat is ground in a gizzardlike stomach.