The threadfin shad (''Dorosoma petenense'') is a small

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

common in rivers, large streams, and reservoirs of the

Southeastern United States The Southeastern United States, also referred to as the American Southeast or simply the Southeast, is a geographical region of the United States. It is located broadly on the eastern portion of the southern United States and the southern por ...

. Like the

American gizzard shad The American gizzard shad (''Dorosoma cepedianum''), also known as the mud shad, is a member of the herring family of fish, and is native to large swaths of fresh and brackish waters of the United States of America. The adult has a deep body, wi ...

, the threadfin shad has an elongated dorsal ray, but unlike the gizzard shad, its mouth is more terminal without a projecting upper jaw. The fins of threadfin shad often have a yellowish color, especially the caudal fin. The back is grey to blue with a dark spot on the shoulder. ''D. petenense'' is more often found in moving water, and is rarely found deep in the water column. It occurs in large schools, sometimes with gizzard shad, and can be seen on the surface at dawn and dusk. The threadfin shad may reach lengths of , but only rarely. This fish is very sensitive to changes in temperature and dissolved oxygen, and die-offs are frequent in late summer and fall, especially when water temperature drops to 42°F. The threadfin shad is a favorite food for many game fishes, including

striped bass The striped bass (''Morone saxatilis''), also called the Atlantic striped bass, striper, linesider, rock, or rockfish, is an anadromous perciform fish of the family Moronidae found primarily along the Atlantic coast of North America. It has al ...

largemouth bass The largemouth bass (''Micropterus salmoides'') is a carnivorous freshwater gamefish in the Centrarchidae ( sunfish) family, a species of black bass native to the eastern and central United States, southeastern Canada and northern Mexico, but ...

, smallmouth bass, and

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

. This fish is widely introduced throughout the United States as a

forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used m ...

for game fish.

Geographic distribution

The threadfin shad is native to the U.S., west of the eastern

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...

. This species tends to do best in large lakes and rivers. The construction of

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, a ...

s has created more reservoirs, providing more water bodies for the shad to inhabit. This has expanded the home range of the fish, as has the rise in temperatures in northern lakes.Green, B. W., et al. (2010)
Threadfin shad impacts phytoplankton and zooplankton community structures in channel catfish ponds.
''Aquaculture Research'' 41:e524-e536.

Ecology

The adult may reach up to 8 in long, but most shad are about 1 in long. It feeds on

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

near the surface of the water late in the day.Mettee, M. F., et al. ''Fishes of Alabama and the Mobile Basin.'' Birmingham, Alabama. Oxmoor House, Inc. 1996. It is a very important food source for many game fish such as the largemouth bass. It has little known competition, but one species known to have a similar lifestyle is the

gizzard shad ''Dorosoma'' is a genus that contains five species of shads, within the herring family Clupeidae. The five species are native to the North and/or Central America, and are known from both fresh water and the waters of estuaries and bays. The Ame ...

(''Dorosoma cepedianum''). The threadfin lives a

life in reservoirs and for the most part in large streams.

Life history

The shad spawns in the spring when the water temperature is in the upper 60s (°F). A pelagic (open water) schooling species often introduced as a supplemental forage, threadfin shad spawn in the spring and early summer with a secondary spawn often occurring in the early fall. Spawning usually occurs early in the morning on available vegetation. The eggs adhere to submerged and floating objects. Females lay from 2,000 to 24,000 eggs. The young and adults feed on a variety of planktonic organisms and organic debris. Many researchers believe that threadfin shad often compete for plankton with young-of-the-year predator species, especially largemouth bass. Life expectancy seldom exceeds 2 to 3 years.Higginbotham, B
Forage Species: Range, Description, and Life History.
Oklahoma State University. Oklahoma Cooperative Extension Service.

Current management

Many populations of threadfin shad have been introduced by humans to the far north, resulting in large die-offs in the winter when water temperatures fall below 42°F. This die-off affects both humans and wildlife. A tide of dead fish floats ashore, creating a strong odor unpleasant to humans. The die-off also gives some bird species an unnatural feeding habit, as well. The species should not be transplanted into water bodies that drop below 42°F. This species is not endangered and has relatively healthy populations.

References

External links

{{Commons category, Dorosoma petenense Clupeidae Fish of North America Fish described in 1867 Taxa named by Albert Günther Freshwater fish of North America