Bigmouth buffalo

The bigmouth buffalo (Ictiobus cyprinellus) is a fish native to North America that 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 127 years and reproducing infrequently. Even at a century old they show no age-related declines, but instead improvements relative to younger individuals, making this species a biological marvel. 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 including melanistic, golden, and even xanthic color morphs. Like other catostomids it has a long dorsal fin, but unlike all other extant species it has a terminal (forward-facing) mouth reflecting its unique, pelagic feeding ecology. It is the largest of the buffalofishes and can reach a length of more than 4 ft (1.2 m) and 80 lb (36 kg) in weight. Generally it lives in lakes, or in sluggish areas of large rivers. Bigmouth buffalo populations have been in decline in the northern extent of their range since the 1970s, including Minnesota, North Dakota, and Canada.

A 2019 study documented their late maturity, centenarian longevity, and that several populations in northwestern Minnesota are composed mainly (85–90%) of individuals more than 80 years old, indicating recruitment failure since the 1930s. This newfound life history information published in 2019 defied pre-conceived notions of the species. A 2021 study from North Dakota also revealed a slow pace of life including late maturity, decadal episodic recruitment, declining population, and a relatively large group of old-growth individuals. A 2022 study from Saskatchewan, Canada revealed remarkable tendencies of the bigmouth buffalo including a supercentenarian lifespan, skip-spawning related to water levels, proximate mechanisms underlying failed recruitment, extreme episodic recruitment, and late maturity—all characteristics that make this species extremely vulnerable to overfishing, habitat degradation, and invasive species. Indeed, bigmouth buffalo are declining in Canada, and have been in steep decline in contiguous areas of the US, temporally associated with the rise of modern wasteful bowfishing in the 21st century. Their life history attributes, including the ability to survive several decades with no successful recruitment (i.e. episodic recruitment), are more pronounced than other long-lived freshwater fishes, including sturgeon and paddlefish. Such long-lived species require time to successfully sustain themselves by surviving to periods in which favorable environmental conditions arise for booms in reproduction and subsequent recruitment. Unregulated, unmanaged and wasteful lethal fisheries are not compatible with their biology, yet such fisheries exist in the United States and the species is declining. Canada on the other hand, has long-enforced protections for bigmouth buffalo.