The bigmouth buffalo is a fish native to North America and it is in decline. It is the largest North American species in the Catostomidae or "sucker" family, and is one of the longest-lived and latest-maturing freshwater fishes, capable of living beyond 110 years and reproducing infrequently. It is commonly called the gourdhead, marblehead, redmouth buffalo, buffalofish, bernard buffalo, roundhead, or brown buffalo. The bigmouth buffalo is not a carp, nor is any other fish in the sucker family. Although they share the same order, each belong to different suborders and are native to separate continents. The bigmouth buffalo is typically a brownish olive color with dusky fins, but can vary greatly in color across individuals. Like other catostomids it has a long dorsal fin, but unlike all others it has a terminal mouth reflecting its unique, pelagic feeding ecology. It is the largest of the buffalo fish and can reach a length of more than and in weight. Generally, it lives in sluggish areas of large rivers and in lakes. Bigmouth buffalo populations have been in decline in the northern extent of their range since the 1970s, including parts of Minnesota, North Dakota, and Canada. A 2019 study documented that several populations in northwestern Minnesota are comprised mainly of individuals more than 80 years old, suggesting recruitment failure since the 1930s because of dams. Management of bigmouth buffalo is in urgent need of reevaluation, at least in the northern part of their US range where populations are declining, there are no limits on harvest, and night bowfishing was recently legalized allowing a new and growing form of exploitation.
Geographic distribution
The bigmouth's native distribution is confined to the countries of Canada and the United States of America. It is native to the Red River of the North and Mississippi River drainage basins, from Manitoba, Canada, and North Dakota, United States, to the Ohio River and south in the Mississippi River system to Texas and Alabama. 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 Montana, North Dakota, Minnesota, Wisconsin, and down to southern states including eastern Texas, Oklahoma and Louisiana. The major systems where they are found in include the Hudson Bay and Mississippi River drainages. The introduction of bigmouth has largely been done for commercial purposes. Regions of reintroductions include some reservoirs along the Missouri River drainage of North Dakota and Montana. Regions of introduction include some reservoirs in Arizona, and within California, they have also been introduced to the aqueduct system of Los Angeles.
Ecological, cultural, and economic importance
Native to North America, bigmouth buffalo are integral to ecosystems therein. Bigmouth buffalo young are prey for several predatory fish including walleye, northern pike, catfish, alligator gar, etc. Bigmouth buffalo filter-feed on invasive zebra mussels during the mollusk's larval planktonic stage. They form the native counterpart to the invasive bighead and silver carp, and they compete with the invasive common carp. However, these invasive species are outcompeting native bigmouth buffalo. Native Americans utilized bigmouth buffalo, Lewis and Clark harvested them on their journey in 1804, and the inland commercial fishing industry has valued them as a prized catch since the 1800s. The bigmouth buffalo is a popular foodfish throughout the United States, and has been introduced into a few southwestern states. Commercial harvesters have to obtain annual permits to net from designated waterbodies, which are rotated among on a year-by-year basis, and they must report harvest from each haul to their respective state agency. Bigmouth buffalo are then trucked in oxygenated water tanks to markets where they are sold alive. Though it has small bones suspended in its muscle tissue like northern pike, its good flavor makes it one of the most valuable of the traditional, non-game freshwater fish. In addition to being a foodfish, the bigmouth buffalo has recently become a sportfish, as night and day bowfishing have become increasingly popular since 2010. In this sport catch and release is not legal nor possible since fish are lethally wounded with an arrow. Bowfishers do not have to report their kill, which typically ends up discarded as fertilizer or wanton waste.
Ecology
The bigmouth buffalo has a rather unique, pelagic ecology of shallow-water systems. The larval bigmouths are pelagic and sometimes benthic feeders of copepods and cladocerans mostly, but also eat phytoplankton and chironomids. Bigmouth buffalo, unlike its close relatives the black and smallmouth buffalos, is a pelagic filter-feeder, using its very fine gill rakers to strain zooplankton from the water. It sometimes feeds near the bottom, using short up-and down movements to filter from the water the animals that hover near the bottom or rest lightly on it. The juveniles and adults are mostly limnetic plankton feeders that also eat cladocera, copepods, algae, Chironomidae, ostracods, and other insect larvae and invertebrates depending on availability. The optimum habitat for spawning bigmouth buffalo is highly vegetated waters. They are a very resilient fish that can tolerate high turbidity and low oxygen levels. They can be found in waters with turbidity levels over 100 ppm. 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 migrates upstream to spawning in the spring, usually April to June, where it lays its eggs on plants to which they adhere. More than one male will assist in spawning by moving the female to the top of the water to help mix eggs and milt. This species of buffalo will also occasionally spawn in rock and gravel in the spring. Bigmouth buffalo are susceptible to anchor parasites which can lead to secondary infections which can be harmful in poor water conditions.
Life history
At 112 years of age, the bigmouth buffalo is the oldest known freshwater teleost by nearly 40 years, shattering all previous records for this group. With a previous maximum longevity estimate for this species at 26 years, supercentenarian longevity came as a surprise and was initially met with skepticism. Thorough bomb radiocarbon dating was conducted on their otolith microstructure and confirmed the old age estimates generated from thin-sectioned otoliths, making bigmouth buffalo the oldest age-validated freshwater fish in the world. 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 highly submergent and emergent vegetation, which is ideal habitat for the hatching of their eggs. 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 mostly unknown and likely varies with latitude. In southern Minnesota, females begin to mature once they are around 10 years old, while males around 6 years old. This is substantially older than previously assumed using inadequate aging techniques, indicating a much slower life pace than previously realized. Bigmouth buffalo have a tendency to accumulate unique pigmentation as they age. The bigmouths are group spawners which produce 250,000 eggs/kg of adult weight; their eggs are about 1.5 mm in diameter.
Conservation status
Bigmouth buffalo's conservation status is in urgent need of reassessment. The bigmouth buffalo is an endangered fish species in Pennsylvania. Besides this state, the bigmouth buffalo is not currently listed as threatened or endangered in any other region of its native distribution, even though they have had Special Concern status in Canada since the 1980s, and have been known as declining in the northern extent of their US range since the 1970s. Surprisingly, several longstanding US populations are composed almost totally of individuals hatched before 1940, while harvest limits do not exist in these same areas - this despite the rapidly-growing new sport of modernized night bowfishing that exploits this species. Clearly, management of bigmouth buffalo needs to reevaluated. The fingerlings are susceptible to a parasite, 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 protozoan Epistylis and bacteria Flavobacterium columnare are both attached to serious parasite infestations. 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. The fish is vulnerable in shallow water and is often captured by bow and arrow. It is commercially caught on trotlines, setlines, hoop and trammel nets, and seines. There are currently no found specific management plans for the bigmouth buffalo either privately or governmentally funded in the US. In some place like the southern US, progeny have been reared in hatcheries.
Records
On June 21, 2013, Noah LaBarge caught the Wisconsin state record bigmouth buffalo fish. It measured and weighed. 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 bigmouth buffalo while fishing on Percy Priest Lake. The fish, caught by Jeff Wilkins in late March, was 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 bigmouth buffalo on June 8, 2000, in a sand pit located in Dodge County.
