|Shorthead redhorse (Moxostoma macrolepidotum)|
The shorthead redhorse (Moxostoma macrolepidotum) is a wide-ranging species in North America. The shorthead redhorse is native to central and eastern North America. However, its range has expanded to include areas like the Hudson estuary and Grayson County, Texas. It inhabits small to large rivers and lakes, and lives in the benthic zone. Shorthead redhorse feed on benthic invertebrates and can consume plant material from the benthic environment that it inhabits. When it spawns, shorthead redhorse move into more shallow streams and spawn over gravel or rocky shoals. They will also spawn in springs with swift moving water. The shorthead redhorse is important to humans because it is a game fish. It is also important to anglers because of its role in the ecosystem; it is prey for larger game fish such as northern pike and muskellunge.
Historically, the shorthead redhorse is native to North America. Its native range includes the Great Lakes, Hudson Bay, Mississippi River, and Saint Lawrence River basins. They ranged across from Quebec to Alberta and as far south as northern Alabama and Oklahoma. Shorthead redhorse also originally occupied the Atlantic Slope drainages, ranging from the Hudson River in New York to the Santee River in South Carolina. When the Tennessee Valley Authority started building dams in the 1930s in an attempt to create power, the dams blocked different fish such as striped bass, from moving upstream to their spawning ranges. While some fish ranges have decreased since the construction of the dams, the shorthead redhorse's range has expanded. The shorthead redhorse is a “habitat generalist near the core of its range,” so it can tolerate disturbance better than other related redhorse species such as the river redhorse, M. carinatum. Shorthead redhorse can now be found in the tidal zones of the Hudson River. They are believed to have invaded the Hudson by way of the Mohawk River and have established themselves in the Hudson estuary. Other areas they have been found in include the Embarras River system in Illinois and the Red River below Lake Texoma dam in Grayson County, Texas.
Shorthead redhorse have a wide habitat range. They live in fresh water and are found in streams, lakes and rivers. Shorthead redhorse can tolerate clear to cloudy water and likes loose substrate like gravel and sand. These fish are benthic feeders that like to feed in riffles and rifle margins. During a study done in Illinois by Sule et al., they found that “shorthead redhorse consumed items from approximately 60 food categories, primarily invertebrate taxa”. Twenty-four to sixty-eight percent of their diet was unidentified when stomach contents were analyzed. Also found, 21-50% of the unidentified matter, or 13% of their total diet, was organic matter. Shorthead redhorse eat the most insects out of all the fish in the sucker family. They can also eat microcrustacea and plant matter. Predators of shorthead redhorse vary depending on size. Juveniles can be eaten by northern pike, walleyes, and smallmouth bass. Adult or larger shorthead redhorse are eaten by northern pike and muskellunge. The shorthead redhorse does not actively compete for food. Because of their wide range of prey and eating the most vertebrates of all the suckers, they do not have a competitor. Humans impact shorthead redhorse habitat. The construction of dams blocked free flowing rivers like the Mississippi in which they live, disrupting their spawning migration routes. Shorthead redhorse are killed easily by pollutants in the water. “The upstream migratory range of shorthead redhorse in a Maryland river decreased due to an increase in chlorinated sewage outfalls”. Factory pollutants are dumped into streams or rivers and will settle onto the bottom. Because such a large portion of the shorthead redhorse's diet is sediment, it ingests high concentrations of the chemicals and can die.
The shorthead redhorse spawning season ranges from March to June, depending on location. In order to spawn, the water temperature has to be between 7 and 16 degrees Celsius. Shorthead redhorse spawn once a year and will travel either upstream or downstream to reach their spawning ground. Spawning areas are usually smaller rivers or steams. They are locally migrant so they do not travel long distances to get their spawning area. Shorthead redhorse spawn in shallows at the edges of sand bars or in rifles over gravel substrate. During spawning, females can produce anywhere from 18,000 to 44,000 eggs. It can take anywhere from 2-5, even 6 years for a shorthead redhorse to become sexually mature. In northern areas of cooler water, growth rates tend to be lower than more southern, warmer areas. The average life span of the shorthead redhorse varies depending on location. More northern locations with cooler water tend to have shorthead redhorse that can live to be older than 17 years of age. Typical adult size is 12-18 inches in length, and 2-3 pounds, although some individuals can reach up to 25 inches in length and 6 pounds in weight. However, in more southern, warmer water areas, such as the Kankakee River, the average max age is only six to seven. As mentioned previously, the construction of dams has not had a large effect on the population of shorthead redhorse, but it has had some effect. The dams affect the shorthead redhorse just as they do other fish by blocking migration pathways to spawning areas. Because of the wide range and great abundance of the shorthead redhorse, no negative effects of dams have been accounted for in their population.
The shorthead redhorse is abundant across its range and has one of the largest ranges of any sucker. This species is not endangered or threatened and is not currently at risk. As of 2002 there was no management plan for the shorthead redhorse.
Relationship with humans
Its small size limits the appeal of shorthead redhorse as a game fish. The shorthead redhorse is said to be one of the better tasting fish, however there are lots of little bones throughout the meat that make it unappealing to many American consumers. The meat also spoils rapidly in warm temperatures making it hard to transport. Shorthead redhorse play a key role in their ecosystems as prey for larger game fish. They are often used for bait if caught small enough. Humans impact the population the most through chemical contamination of their habitat. Bioaccumulation of chemicals is common in fish that feed near the benthic zone, like the shorthead redhorse. The current IGFA all tackle world record for the species stands at 5lbs 6oz caught from the Prairie River in Minnesota, USA.
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