The bigmouth buffalo (Ictiobus cyprinellus) also known as the gourd head, redmouth buffalo, buffalo fish, bernard buffalo, roundhead, or brown buffalo, is a large species of the Catostomidae or "sucker" carp family.
The bigmouth buffalo is a dull brownish olive color with dusky fins. Like other suckers it has a long dorsal fin, but unlike others it has a large oblique and terminal mouth. It is the largest of the buffalo fish and reaches a length of more than 4 ft (1.2 m) and 65 lb (29 kg) in weight.
It is distributed from the Red River of the North, Manitoba, Canada, and North Dakota, United States, to the Ohio River and south in the Mississippi River system to Texas and Alabama in the United States. It lives in sluggish areas of large rivers and shallow lakes and streams.
The bigmouth buffalo migrates upstream to spawn in the spring, usually April to June, where it lays its eggs on plants to which they adhere. Bigmouth buffalo, unlike its close relatives the black and smallmouth buffalos, is a filter-feeder, using its very fine gill rakers to strain crustacean zooplankton from the water. It sometimes feeds near the bottom, using short up-and down movements to swirl the water and thus be able to filter from the water the plants and animals that hover near the bottom or rest lightly on it. More than one male will assist in spawning by moving the female to the top of the water to help mix eggs and milt.
The fish is vulnerable in shallow water and is often captured by spearing. It is commercially caught on trotlines, setlines, hoop and trammel nets, and seines. Though it has numerous small bones, its good flavor makes it one of the most valuable of the nongame freshwater fish.
The bigmouth buffalo is naturally found throughout the United States from the Great Lakes south to Alabama and Louisiana drainages and west to Texas and Minnesota. They generally live in shallow swells, large slow-moving rivers or swamps, since they seem to be adept at dealing with these low-oxygen habitats. This species of buffalo spawns in rock and gravel (open substrata) sometime in the spring.
The bigmouth buffalo is a popular foodfish throughout the United States, and has been introduced into several states. No known impact on their population would harm their population numbers drastically in the near future. The bigmouth has certain ecological needs to live, though. They prefer shallow, slow-moving water like flooded vegetation. Bigmouth buffalo is also susceptible to anchor parasites which can lead to secondary infections which can be harmful in poor water conditions.
The bigmouth's native and introduced distribution is confined to the countries of Canada and the United States of America. In Canada, they inhabit the Milk River which flows through Alberta and the Qu'Appelle River which flows through Saskatchewan and Manitoba into Lake Winnipeg. Beginning in the northern United States, they are native to Iowa, South Dakota and, Minnesota, more southern states include eastern Texas and Oklahoma. The major drainages where they are found in include Lake Erie, the Ohio River, and Mississippi River drainages. From these drainages, they are found into Arkansas, the Gulf region of Louisiana, and down the Tennessee River into Alabama. The introduction of bigmouth has been largely done for commercial purposes. Regions of introduction include reservoirs in Arizona and Missouri River drainage reservoirs of North Dakota and Montana. Within California, they have also been introduced to the aqueduct system of Los Angeles.
The bigmouth buffalo has numerous ecological needs. The larval bigmouths are benthic feeders of copepods and cladocerans mostly, but also eat phytoplankton and chironomids. The juveniles and adults are benthic and limnetic plankton feeders that also eat cladocera, copepods, algae, Chironomidae, ostracods, and other insect larvae and invertebrates depending on availability. The optimum habitat for bigmouth buffalo requires highly vegetated and turbid waters. Turbidity levels over 100 ppm are optimal, they also like muddy bottoms. A minimum total dissolved solids is 200 ppm during the growing season. During spring and summer, 50–75% pools should be present, with backwaters, and marsh areas and 25-75% littoral area and protected embayments during summer for the habitat to be suitable. Bigmouth can be found in waters from 22.5–38.0°C, but their preferred temperature is between 31 and 34°C. The optimal temperatures for incubation and hatching of eggs are from 15-18°C, but they can develop in temperatures reaching up to 26.7°C. The bigmouth prefers slow-moving water that does not reach a velocity over 30 cm/s. Salinity can be a problem for reproduction. Spawning can occur from 1.4-2.0 ppt of salinity which eggs and yearlings not being able to survive a salinity of over 9 ppt. The minimum dissolved oxygen during the spring and summer is 5 mg/l.
The bigmouth buffalo is a spring spawner generally spawning between April and June when the water temperature is between 13 and 26°C. The bigmouth is a broadcaster that has adhesive eggs which it lays in highly vegetated waters. Females seek high submergent and emergent vegetation and high turbidity to keep their eggs safe and in ideal habitat for hatching. The substrate found is generally a mixture of a medium amount of rubble and gravel and a high amount of sand and silt. The water levels substantially rise before spawning and stabilize afterwards. The sexual maturity of bigmouths is dependent on their size. Females mature once they are over 475 mm, while males begin to mature around 305–328 mm and should be mature by the time they are 356–379 mm. The bigmouths are group spawners which produce 250,000 eggs/kg of adult weight; their eggs are about 1.5 mm in diameter. The ages of bigmouths are around 2 years when they reach sexual maturity, but they have been found as old as 20.
The bigmouth buffalo is not listed as threatened or endangered in any region of its native or introduced distribution. The fingerlings are susceptible to aparasite, Lernea cyprinacae, but most are unaffected by the time they reach a length of 30 mm. They are anchor parasites that insert themselves between scale margins and fin insertions. The real problem is a secondary infection that may arise due to these parasites, the protozooan Epistylis and bacteria Flavobacterium columnare are both attached to serious parasite infestations. Bigmouth hybridizes. The bigmouth has been seen to hybridize in the wild with smallmouth buffalo, and it is possible that some fish identified as black buffalo are indeed these hybrids. The hybridization does not seem to be negatively impacting their populations but makes it difficult to determine how many hybrids and how many black buffalo are actually in certain reservoirs and therefore difficult to manage for either species. There are currently no found specific management plans for the bigmouth buffalo either privately or governmentally funded. Bigmouth buffalo are seen as a commercial foodfish for the most part and do not seem to be in any danger of decreasing in population. They are very readily reproduced by hatcheries and if ever needed could be easily stocked.
Overall, no need exists to protect or set aside conservation easements for the bigmouth buffalo; it seems to be a very well adapted species to its range and maintains its population well naturally. Since the bigmouth is a food fish commercial catching seem to be a way to sample the population, but knotted nets can harm the fish, causing hemorrhages and scale loss. Seining for the bigmouth through oxbows and other regions of their range is ideal. This should be done in multiple locations where the fish are known to be caught.
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On June 21, 2013, Noah LaBarge (13 years old) caught the Wisconsin state record bigmouth buffalo fish. It measured 49.5 in and weighed 76.8 lb. It was caught on an 8-lb-test line on the Wisconsin River at Devil's Elbow, which is on the north end of the Petenwell Flowage. It was officially recognized to be the new world record by the National Fresh Water Fishing Hall of Fame as both 8-lb-line class and all tackle. A Mt. Juliet, Tennessee, a man caught a record 62-pound (28 kg) bigmouth buffalo while fishing on Percy Priest Lake. The fish, caught by Jeff Wilkins in late March, was 45 inches (110 cm) in length and snagged in the Seven Points area of the lake. The Tennessee Wildlife Resources Agency said it took him 35 minutes to reel in the fish. The new record surpasses the previous mark of 52 pounds, 2 oz, previously held since April 6, 2001, by Greg Megibben. The giant fish also came from Percy Priest Lake. After the record was certified, Wilkins released the fish back into the lake. In Omaha, Nebraska, Joe Slavic caught a 64-pound (29 kg) buffalo bigmouth on June 8, 2000, in a sand pit located in Dodge County.
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