Species Profiles: The Flathead Chub

Threatened and Endangered species tend to fall into one of the following categories: Rare to the point where they are never seen, abundant in certain locations, or just damned hard to find. The Flathead Chub (Platygobio gracilis) falls into that first category. For example, some researchers at K-State have been sampling the Kansas River for most of the last three years. In 2007, they pulled out >36,000 fish, but didn’t find a single flathead chub (Eitzmann and Paukert 2007). Needless to say, this one is on the list of Kansas T&E species that I haven’t seen.

The flathead chub is a member of the minnow family (Cyprinidae), otherwise known as the largest family of freshwater fishes in the world (~286 species in N. America alone). Like most members of this family, flathead chubs are small (typically 9-16 cm). This species has a relatively broad, wedge-shaped head with long, sickle-shaped pectoral fins. Coloration is greenish or brown on top, with plain, silvery sides. The species was first described way back in 1836 (McPhail and Lindsey 1970), although the name has changed a lot (the genus flipped back and forth from Hybopsis to Platygobio a few times from 1950-1989, so you will see some references to H. gracilis here and there).

This species has occasionally been broken up into two subspecies: A large-river variety (H. gracilis gracilis; primarily the Missouri) and a smaller stream variety (H. gracilis gulonellus; primarily in the Ark River drainages). The transition zone between these two subspecies was Kansas, and the possibility of distinct genetic lineages was disputed (some people disagree with designating these as subspecies). That question will probably never be resolved due to the species’ afore-mentioned “rare to the point where they are never seen” status in Kansas.

The absence of this species isn’t terribly surprising, although that doesn’t make it somewhat depressing. Like the Pallid Sturgeon, the Paddlefish, the Chestnut Lamprey, and a ridiculous number of other fishes, the flathead chub has been eviscerated as a part of the natural community in large portions of its range by the construction of impoundments. The species occurs widely throughout North America, but is only endangered in the southern extent of its range (see the pretty map from Natureserve). The large rivers in the Missouri/Mississippi Drainage have been extensively regulated, thus wiping out avenues for upstream migration, and also reducing the productivity associated with flood events and backwater areas.

Meanwhile, less regulated areas of the flathead chub’s range continue to support viable populations. In Wyoming, the occurrence of the chub may be declining (Patton et al. 1998), but at least it is still out there. NatureServe actually lists them as being ‘secure’ throughout Colorado, Nebraska, Wyoming, Montana, South Dakota and much of Canada.

Little is known about the spawning habits of this species, although in Kansas most spawning occurs between July 1^st and August 15^th. As an agency, Kansas Department of Wildlife and Parks is supposed to have a recovery plan for this species, but as yet none has been written. I have a hard time imagining such a recover plan that didn’t include propagation efforts, and KDWP currently does not propagate any fish species for non-game purposes. At this point, the agency primarily protects this species by restricting activities in waters where the species potentially occurs (the Kansas and Arkansas Rivers) during the spawning period.

Want to read more about this species? I recommend this conservation assessment by Rahel and Thel (2007; pdf).

Lit cited:

Eitzmann, J.L. and C. Paukert. 2007. Annual performance report: Distribution and Abundance of fishes in the Kansas River.

McPhail, J.D. and C.D. Lindsey. 1970. Freshwater Fishes of Northwestern Canada and Alaska. Fisheries Research Board of Canada, Bulletin 173. Ottawa, Ontario, Canada.

Patton, T.M., F.J. Rahel, and W.A. Hubert. 1998. Using historical data to assess changes in Wyoming’s fish fauna. Conservation Biology 12:1120-1128.

Rahel, F.J. and L. A. Thel. 2004. Flathead Chub (Platygobio grcilis): A technical Conservation Assessment. Rocky Mountain Region, USDA Forest Service.