The Niangua Darter
Like most darters, the Niangua darter is slender, having a long, thin body. However, it is rather large for a darter, averaging three to four inches from head to tail. The body is yellowish-olive and has eight dark bars across the back. Healthy specimens display orange spots scattered over their upper sides in addition. Also, a series of “U-shaped greenish blotches” alternate along its side with thin, narrow, orange markings (Missouri Department of Conservation).
The Niangua darter can be distinguished from other darters by the presence of two small, black spots at the base of its tail fin. Without these spots, the Niangua darter is nearly identical to many ...view middle of the document...
Also, it is known to predate upon the nymphs of stoneflies and mayflies (Missouri Department of Conservation).
The population of Niangua darters has been declining since the 1940s, according to the United States Fish and Wildlife Service. This can be attributed to the introduction of rock bass and spotted bass for game fishing in the darter’s territory. The darter has to compete with the highly predacious bass species for nutrients, as well as territory. Because of this threat and others, the state of Missouri has placed the Niangua darter on the endangered species list, signifying that “the prospects for survival of the species within the state are in immediate jeopardy.” Also, the fish is now listed as threatened on a national level. Despite the small numbers remaining in its population, the Niangua darter is still doing well in at least some of its native territory.
The darter is so endangered from extinction that it can only be found in 11 counties of the entire world: Benton, Cedar, Dade, Dallas, Greene, Hickory, Miller, Osage, Polk, St. Clair, and Webster (United States Geological Survey). All of these counties fall within the watersheds of either the Osage or Niangua river basin. In these areas, the Niangua darter lives mostly in clear upland creeks, but is also found in some small to medium-sized rivers. The darter was historically widespread and abundant in these rivers and streams (Magers). They require continuously flowing waters with slight to moderate currents and silt-free gravel or rock bottoms. Typically, these waters are the drainage from hilly areas (MDC). The most common types of bottom material found in streams containing the Niangua darter are chert and dolomite (MDC).
Mating season for most stream fish species is from late March to early June. The Niangua darter is not an exception to this, although most of its breeding is done in mid-April. Throughout most of the year, they are found in shallow pools, margins, and stream runs. During breeding though, they move into shallow gravel runs. The males change to bright colors and clear out areas for spawning with their tales. Breeding males are brilliantly colored, exhibiting an orange to red bottom-sides as well as series of blue and green bars along their sides (Northern Prairie Wildlife Research Center).
To spawn, males generally follow the females into shallow riffles where they may engage in threat displays with other males. This is common among fishes and has been observed in many species. Also during this time, males exhibit somewhat of a change in color. Along with the differences in color previously mentioned, they oftentimes lose the distinguishing dots found at the base of the tail. This is due to the clearing out of area with the tail. All markings do return to normal as soon as spawning has taken place.
The darter is a secondary consumer and can often times be found searching around in cracks of rocks for aquatic insect larva to eat. ...