The threadfin shad, Dorosoma petenense, is a small pelagic fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate 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...

 common in rivers, large streams, and reservoirs of the Southeastern United States

Southeastern United States

The Southeastern United States, colloquially referred to as the Southeast, is the eastern portion of the Southern United States. It is one of the most populous regions in the United States of America....

. Like the American gizzard shad

American gizzard shad

The American gizzard shad, Dorosoma cepedianum, is a fish of the herring family Clupeidae native to fresh and salt waters of eastern North America....

, the threadfin shad has an elongated dorsal ray, but unlike the gizzard shad its mouth is more terminal without 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. They occur 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 7 inches, but only rarely. This fish is very sensitive to changes in temperature and dissolved oxygen, and die offs are frequent in fall and late summer especially when water temperature reaches 42 °F. The threadfin shad is a favorite food for many game fishes including striped bass

Striped bass

The striped bass is the state fish of Maryland, Rhode Island, South Carolina, and the state saltwater fish of New York, Virginia, and New Hampshire...

, largemouth bass

Largemouth bass

The largemouth bass is a species of black bass in the sunfish family native to North America . It is also known as widemouth bass, bigmouth, black bass, bucketmouth, Potter's fish, Florida bass, Florida largemouth, green bass, green trout, linesides, Oswego bass, southern largemouth...

, smallmouth bass

Smallmouth bass

The smallmouth bass is a species of freshwater fish in the sunfish family of the order Perciformes. It is the type species of its genus...

, and catfishes. This fish is widely introduced throughout the United States as a forage fish for game fish.

Geographic distribution

The threadfin shad is native to the U.S. west of the Eastern Appalachian mountains. This species tends to do best in large lakes and rivers. Due to the demand for power, dams have been a source for many states to create energy and thus creating more large reservoirs for the Threadfin Shad. This species home range has been growing from small rivers becoming reservoirs and warmer water temperatures in northern lakes.

Ecology

Adults may reach up to 8 inches in length but most are one inch long. These shad tend to have problems in the winter when water temperature is around 45 degrees Fahrenheit. Threadfin shad feed on plankton near the surface of the water late in days. Threadfin Shad are very important food source for many game fish such as large mouth bass Micropters salmoides. It has little known competition but one species that is know to have a similar life style is the gizzard shad Dorosoma cepedianum. The Threadfin lives a pelagic life in reservoirs and for the most part in large streams. If humans were to effect the water temperature of this species it could effect this species spawning pattern because they spawn when water is around 60 degrees Fahrenheit in the spring.

Life history

They spawn in the spring when water temperature is in the upper 60’s. 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.

Current management

Many populations of Threadfin shad have been introduced by humans to far north causing large die-offs in the winter when water temperatures reach below 42 degrees Fahrenheit. This die-off effects both humans and wildlife, Once the die-off occurs the dead fish tend to float ashore creating a strong odor unpleasing to humans. The die-off also gives some birds species a unnatural feeding habit as well. To best manage this species its best to have a body of water that does not get below 42 degrees Fahrenheit. This species is not endangered and has relatively healthy populations. The Threadfin Shad is mainly stocked and maintained due to its importance for game fish forage. Since this species plays a valuable role in a economic outdoors sport stocking of this species occurs more often. If this shad was not a forage source for game fish it would be considered much less important.

Management recommendations

Threadfin shad sometimes grow larger than their prey when this happens they tend to take up a large number of the biomass and a method of reduction is required. Threadfin Shad have a healthy population across their native range when compared to most fish species. They have done very well in new and restored reservoirs that are greater than 10 ha in their native range. This shad should monitored so that the population does not overwhelm the body of water and take up a good deal of its biomass. To avoid this have a healthy population of game fish species (Large and small mouth bass are good) also if population is to large chemical treatments my be needed. Do not put Threadfin Shad in body’s of water that do not have any predators or that have temperatures lower than 42 degrees Fahrenheit. Electroshocking in open water in the summer is a good time to get a population density. It is also important to check for loss in the winter. Shock in the summer and then shock in late winter to check population loss within the body of water.