Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Species spotlight: The Sicklefin chub
Midwest Region, October 1, 2011
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The swift current near the shipping channel of the Missouri River is a rough environment for most fish. This torrent of water carries with it a large debris load and creates a perpetual sandstorm of sorts. Out on the edge of the main channel there aren’t many places for fish to find refuge from the constant onslaught of the current. This is a realm for only the toughest of fish, like monster blue catfish and pallid sturgeon, certainly not a habitat for small fish – unless that small fish happens to be the sicklefin chub (Macrhybopsis meeki).

This small minnow species rarely exceeds four inches in length, but is uniquely adapted for the swift currents adjacent to the main channel of the Missouri River. In fact, of all the Missouri River fish species, adult sicklefin chubs may be the best suited for the swift current. We routinely capture sicklefin chubs in habitats where current velocities exceed one meter per second – areas where we rarely see other small fish. One look at the sicklefin chub and you can quickly see why it is so well suited for the fast current. Its streamlined body, elongated snout, flattened ventral surface and long sickle shaped pectoral fins are all part of a body plan tailor made for swift current. The species tiny eye and the presence of barbels and external taste buds suggest that it locates foods mainly by taste and doesn’t rely much on its eyesight – another adaptation to life in the turbid Missouri River.

The sicklefin chub was selected as one of the “target species” for the pallid monitoring program, because it shares similar habitats with pallid sturgeon and has been shown to be a prey item for pallid sturgeon. Although it is not rare to capture sicklefin chubs in the Missouri River, they are never overly abundant. The species is classified as “vulnerable” globally and within the state of Missouri.
Over the years we have learned much about the sicklefin chub, but many questions remain unanswered. Currently we are collecting chubs for a USGS study that will hopefully add to our understanding of the life history of this unique species.

Contact Info: Colby Wrasse, 573-234-2132 x30, colby_wrasse@fws.gov
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