Many people are familiar with the Walleye, Yellow Perch and Sauger, but may not know about their smaller relatives, the Darters. Darters are often mistaken for young sport fish, but most of these little guys don’t get much bigger than 3 inches. Some can get up to 7 inches long, but that’s about it. Darters are native only to North America and are found east of the Rocky Mountains. They are ferocious little hunters; eating immature aquatic insects and larvae. Darters do not swim like other fish. They either lack a swim bladder or it is greatly reduced, so they sink as soon as they stop actively swimming. They swim by making a series of quick, darting, movements, and thus the name, Darter. They are well adapted to flowing water, and their body shape helps keep them down on the bottom and not washed away in the current. Not all of them live in fast current, but they can often be found along the bottom, hiding under rocks, or buried in the sand watching for prey1 (Figure 2).
There are several species in Illinois and Missouri, and they are often indicators of the water’s quality2. An indicator species is a species that is sensitive to changes in its habitat. Their disappearance from an area is often a first sign that something is wrong in that environment.
There are several Darter species, and I would like to highlight a few. The first is the Logperch (Figure 3), one of the bigger darters. It can reach up to 7 inches long. It is fairly common throughout Illinois2 and Missouri1 and is found in clear riffles (areas of the stream where the water is more turbulent and fast as it runs over larger rocks). It can also be found in lakes and large pools of streams. The Logperch prefers a rocky bottom with a mixture of sand and gravel and will hide in submerged brush or log jams, thus the name. Although it is still widely found, the Logperch has shown signs of decline. This is most likely due to habitat destruction and deterioration of the water quality in the area2.
The Blackside Darter (Figure 4) lives in similar habitats, firm-bottomed pools in creeks and small rivers with rocky, gravel bottoms. They can be found throughout Illinois2 and in parts of Missouri1. Although it is more tolerant of warmer and more turbid (cloudy) waters, it is also showing signs of decline2.
The Crystal Darter (Figure 5) is a very slender-bodied fish that lives in deep, fast-flowing water with sandy, gravel bottoms and is mostly nocturnal. Sadly, it is believed to be extirpated (locally extinct) in Illinois2, but can still be found in parts of Missouri1. The Slough Darter (Figure 6) is a lovely little fish that lives in swamps, floodplain lakes, ponds, and low-gradient streams with clay bottoms and debris. It lives in southern Illinois2 and parts of Missouri1, but it is sometimes confused with the Iowa Darter which lives in the northern part of Illinois.2 An interesting thing about this Darter is that breeding males will grow little bumps called nuptial tubercles on his chin, and he rubs them on the female’s head during courtship.
Darters, like many other animals undergo significant changes during the breeding season. For Darters, this mostly consists of males, and sometimes females becoming very colorful (Figure 1). Whoever says that only tropical fish are pretty has never seen Darters. The Slough Darter is doing fairly well2, but in Missouri, it is found in pockets of habitat. This broken distribution makes it vulnerable to extirpation in that state because if something devastating happens in that area like a chemical spill or drought, that population could be lost and have difficulty immigrating back into that area1. As you may have gathered from reading, one of the biggest threats to these incredible, beautiful little fish is poor water quality. Erosion of stream banks and off of fields increases the amount of silt (fine soil) in the water. Silt is so small that it stays in the water for a long time and doesn’t settle to the bottom. Increased sediment in the water can also alter the stream bed texture which not only affects the habitat for the fish, but also the fish’s prey. Lose the food and you lose the fish. Urbanization affects erosion and stream bed texture too. We will be discussing water quality and what affects it in August, so be sure not to miss that. There is a lot of monitoring and research being done on water quality and its effects on communities in the water. The hope is that as we all work to improve our water and environment, these fish and other species will be able to thrive once more. If this has peaked your interest in these fantastic fish check out The American Darters by R.A. Kuehne and Handbook of Darters by L.M. Page. References
- Pflieger, W.L. 1997. The Fishes of Missouri. Missouri Department of Conservation. Jefferson City., MO.
- Smith, P.W. 2002. The Fishes of Illinois. The Univ. of Illinois Press., Urbana and Chicago., IL.