Blue sunfish
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Blue sunfish ( Lepomis macrochirus ) |
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| Lepomis macrochirus | ||||||||||||
| Rafinesque , 1810 |
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The blue sunfish ( Lepomis macrochirus ), English bluegill, is a species of perch from the sunfish family (Centrarchidae) and belongs to the perch relatives (Percomorphaceae). The blue sunfish has been the state fish of the US state of Illinois since 1986 .
Occurrence
Lepomis macrochirus is native to North America and lives in slow-flowing streams, rivers, lakes (including the Saint Lawrence River , Great Lakes, and Mississippi River System), and ponds. It is mainly found east of the Rocky Mountains . Its range extends from Virginia to Florida , western Texas and northern Mexico , from western Minnesota to western New York . Well-known bodies of water are found in the Santee Cooper River system in South Carolina , Tennessee Valley, Kentucky, and Texas. The blue sunfish, which tolerates a salinity of up to 1.8%, was also found in the brackish water of the Chesapeake Bay .
Blue sunfish have been introduced to Europe , South Africa , Zimbabwe , Asia , South America, and parts of Oceania . In some countries such as Germany or Japan , Lepomis macrochirus has been classified as an invasive species. In Japan, specimens of this species of fish were given as a gift to Crown Prince Akihito by the Mayor of Chicago, Richard J. Daley , in 1960 . From there they were taken to national fisheries research facilities and escaped to freedom. In Lake Biwa in particular , they caused great damage by displacing native species.
description
The blue sunfish is high-backed, laterally flattened and has toothed ctenoid scales . The fish has an upper mouth and fleshy lips. It can be between 30 to 40 centimeters long and weigh up to two kilograms. In 1950, an exceptional fish weighing 2.15 kilograms was caught in Ketona Lake near Birmingham (Alabama) . Typical of the blue sunfish is its colorful drawing with an intense blue, violet, crimson over a black spot on the gill cover and an olive-dark band along the side line. The abdominal area is often yellow to orange in color. The color drawing is controlled by chromatophores on a neuronal basis (physiological color change) . The blue sunfish thus resembles its close relatives, the orange-spotted sunfish ( Lepomis humilis ) and the red-eared sunfish ( Lepomis microlophus ).
Way of life
Lepomis macrochirus is an omnivore and eats a variety of food, the size of which just fits in its mouth. These include small aquatic insects and small fish, often juvenile fish. They play an important key role in the food chain of North American waters and in turn serve as prey for other larger perch species ( black bass , largemouth bass, etc.), pike , muscle lung , pikeperch and trout . They are also hunted by herons , kingfishers , snapping turtles and otters . However, their high-backed body shape and spiky dorsal fin can cause problems with swallowing.
The diurnal blue sunfish often lives close to the ground and looks for underwater structures such as sunken tree trunks, dead wood or fields of aquatic plants as cover and hiding places. In the course of the day and the season it stays in different water depths. It prefers shallow waters with temperatures between 16 and 27 ° C. They don't mind high water temperatures; however, they usually avoid direct sunlight. Adult animals often hover just below the surface of the water in search of plankton and other aquatic life. In schools of ten to 20 animals, they often mix with other sunfish species such as common sunfish / pumpkin seed bass ( Lepomis gibbosus ), orange- spotted sunfish ( Lepomis humilis ), black-spotted sunfish ( Pomoxis nigromaculatus ) and others.
Young fish feed on microorganisms such as water fleas , caddis flies , dragonfly larvae , crustaceans , leeches , water snails and fry. When there is a shortage of food, blue sunfish also eat vegetable food or their own offspring. As with many other fish species, the main feeding phases take place predominantly in the morning and evening hours when visibility is good. Blue sunfish actively suck in their food by using the pharynx with the water suction, so that the prey only has to be 1.75 centimeters from the mouth. Blue sunfish can reach high speeds with their fin movements, swim backwards and are able to maneuver well. These escapes help them to escape their predators in many situations.
The spawning season for bluegills begins at the end of May and extends into August with a peak in June with water temperatures of 19 to 27 ° C. The spawning process takes place in shallow water over a spawning bed, which is defended by the males. Their territorial behavior is so pronounced that they try to drive away divers with threatening gestures. Sport fishermen take advantage of this behavior by offering the fish artificial bait during this time, which are violently attacked by the males. Female animals are lured into the spawning bed with circular movements and grunting noises. The male also shows a dominant-aggressive behavior towards the female. Smaller females can produce around 1,000 eggs, while larger, healthy females can produce up to 100,000 eggs. The growth of the juvenile fish is rapid in the first three years, then gradually slows down again. The fish can live between five and eight, in extreme cases up to eleven years.
Economical meaning
Blue sunfish are popular "panfish" in the USA, which are very popular with sport fishermen because of their widespread distribution and their relatively easy catch. They can be caught with live natural bait such as worms, crickets, grasshoppers, maggots, small frogs, shrimp pieces, but also bread, corn and other foods. In the morning and evening light, they react to artificial bait with bright colors such as red, orange, yellow or green. In some waters, such as Lake Scugog in Canada , they have become accustomed to human presence, are trusting and can be easily attracted. Since the blue sunfish can eat up to six times its own body weight in the summer months, it plays a role in the management of ponds by killing unwanted crustaceans and insects. Lepomis macrochirus can also be kept in larger aquariums.
Web links
- Lepomis macrochirus . Rafinesque, 1819 Bluegill on Fishbase
- Lepomis macrochirus . (bluegill) CABI
- Bluegill. Fish and Aquatic Conservation. US Fish & Wildlife Service
- Invasive Species of the Pacific Northwest: Bluegill, Lepomis macrochirus . Kaili Park
- Biology of Bluegills
Individual evidence
- ↑ Fish lexicon: Blue sunfish ( Lepomis macrochirus )
- ^ Illinois State Symbols. Department of Natural Resources
- ↑ Bluegill ( Lepomis macrochirus ). Fish of the Mississippi River
- ↑ Emperor regrets introducing invasive US bluegill 50 years ago. The Japan Times. November 16, 2007
- ↑ Japan in culinary offensive to stop spread of US fish. The Guardian. November 26, 2007
- ↑ Bruce Drager and David Chiszar: Growth rate of bluegill sunfish ( Lepomis macrochirus ) maintained in groups and in isolation . Bulletin of the Psychonomic Society volume 20. 1982
- ↑ Fact check: Bluegill are not dangerous to humans but are a popular sport fish. Social media users have been sharing an image of a bluegill fish with text that warns readers about the species being one of the most dangerous in North America. This claim is false. Reuters
- ↑ Easy to find and fun to catch, bluegill are America's fish. Special to USA Today. 29 May 2018