Common logperch

The common logperch (Percina caprodes), sometimes simply known as the logperch, is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. Like other logperches, it has the typical vertical barring along the flank and a subterminal mouth.

This is the most widespread logperch, commonly found in large parts of the eastern United States and Canada. Like other logperches, they inhabit clear, gravelly streams and lakes, reaching a maximum size of about 18 centimeters (7.1 in) and a maximum age of about 3 years. They play a key role in the reproduction of the snuffbox mussel (Epioblasma triquetra).

Habitat

The common logperch, like most darter species, dwells in benthic habitats where it forages for food. It prefers clear, swift water with rocky or sandy substrate; however, it may be found in any temperate water in their geographic distribution. Its diet consists primarily of benthic invertebrates, which it hunts by flipping over stones with its snout. It appears that logperches are not especially fastidious when foraging, and that they are actually very opportunistic feeders. That being said, chironomids constitute the largest part of a darter's diet (~54% volumetric contribution), whereas trichopterans and simuliids constituted roughly 15% and 22% volumetric contribution, respectively. However, prey consumption can vary largely by location and season. Some competition surely exists between the common logperch and other benthic species with the same native distribution and diet. It is an invasive species, Neogobius melanostomus (round goby), however, that poses the largest competitive threat to the common logperch. Studies indicate that this is most likely because Neogobius melanostomus better utilizes its space in the environment for shelter, decreasing the range of the common logperch, because Neogobius melanostomus is also a more aggressive than the relatively passive common logperch, and because N. melanostomus reproduces at a higher rate than the common logperch. Natural predators of the common logperch consist most notably of carnivorous piscivores from the Sander, Micropterus, and Esox genera.

Human induced changes that might reduce the abundance of the common logperch include the excess stocking of piscivorous fish species, the damming of rivers, introduction of chemicals into watersheds, and erosion caused from human activities. While the top-down effects the addition of excess predators can cause on prey species are relatively well studied, the effects and mechanisms of the other aforementioned human activities may not be so clear.

Distribution

The common logperch exhibits a rather large geographic distribution and range. The common logperch occurs naturally as far north as the St. Lawrence River system in Quebec, and as far south as the Rio Grande system in southern Texas and northern Mexico. Westwards, logperch are most heavily distributed in the Mississippi River drainage system, and their range extends eastward in freshwater habitats all the way to the Atlantic Ocean. Currently, however, the range of the common logperch has been artificially extended into California, where it was released into the wild in 1953. The range of the common logperch, while impressive, has nevertheless been reduced due to the construction of dams, the introduction of stocked predatory species such as walleye and sauger, the introduction of invasive competitors (specifically Neogobius melanostomus), and possibly by erosion around drainage systems.