Can the endemic bigmouth buffalo fish live 100 years?

Collaboration with North Dakota State University to determine the age, growth and longevity of bigmouth buffalo (Ictiobus cyprinellus) using otolith sections and bomb radiocarbon dating.

PUBLISHED: https://rdcu.be/bDQ2m

Centenarian longevity for Bigmouth Buffalo Ictiobus cyprinellus

Authors: Alec R. Lackmann, Allen H. Andrews, Malcolm G. Butler, Ewelina S. Bielak-Lackmann, and Mark E. Clark.

North Dakota State University, Department of Biological Sciences & the Environmental and Conservation Sciences Program 

Website: www.bigmouthbuffalo.org

The Bigmouth Buffalo fish (BMB; Ictiobus cyprinellus) is endemic to the Mississippi and Hudson Bay drainages and belongs to the Catostomidae, an especially diverse family in North America. From Native Americans to inland commercial fishing, BMB have been a valued food-fish for centuries. Since 2010, they have been a prized sportfish as night bowfishing became a multi-million dollar industry. All harvest is virtually unregulated and not studied, even though BMB are declining and little is known about their biology. Using thin-sectioned otoliths and bomb radiocarbon dating, we found BMB to reach 112 years of age, quadrupling previous estimates of longevity and making BMB the oldest known freshwater teleost (~12,000 species). We show that numerous extant populations are heavily comprised (85-90%) of individuals over 80 years, suggesting long-term recruitment failure since dam construction in the 1930s. Our findings indicate that commonly used fish-ageing methods are inadequate, BMB and other catostomids require urgent attention, and there are broader consequences of ecological neglect. 

Thin-sectioned lapillus and asteriscus otoliths from four Bigmouth Buffalo (Ictiobus cyprinellus) with age estimates ranging from 3, 36, 85, and 112 years at the time of collection. White dots indicate annual growth bands and yellow triangles decade counts. All otolith composite images set to same scale bar = 1 mm. Note the well-defined annuli. This mircostructure was sampled with a series of extractions made with a New Wave Research micromilling machine (Elemental Scientific Lasers, Bozeman, MT, USA; http://www.nwrlasers.com/milling/micromill/).

Distribution of the endemic bigmouth buffalo (Ictiobus cyprinellus). The species has been extirpated from much of its distribution and recruitment success may have been compromised from river diversions and alterations that began in the 1920s and 1930s. Bowfishing now threatens this species because people either mistake it for an invasive Asian carp species or feel that the species is not of any importance (classified as rough fish). Map also shows the freshwater 14C chronologies in North America. Chronologies have been determined from otoliths of Arctic salmonids, Freshwater Drum of Lake Winnebago (western white circle) and Lake Ontario and Lake Oneida (eastern most white circles; U.S. Fish and Wildlife Service unpublished data). Bigmouth Buffalo (Ictiobus cyprinellus) of Minnesota (diamonds; present study). Bigmouth Buffalo were also taken from the points marked with an “X”, but these were not analyzed for radiocarbon. The dark-gray shaded area within the USA and Canada represents the endemic range of Bigmouth Buffalo. Scale bar = 400 km.

Caution is encouraged as this sport bowfishing industry develops. Salient observations of fishers using this fishing method have have indicated that significant changes in lengths and numbers of these fish for a given fishing area have decreased markedly in just 5-10 years.