Redeye bass
The redeye bass, redeye, or Coosa bass is a species of freshwater fish in the sunfish family.The small bass is endemic to the Mobile and Alabama River systems, more specifically the Coosa River, which is a major tributary to the Alabama River in Georgia and Tennessee.
Systematics
Taxonomy and classification
Redeye historically have been under-described compared to other centrarchids. The osteology of M. coosae fits the general centrarchid pattern. These similarities in anatomy provide a gateway into understanding evolutionary relationships for future taxonomic and phylogenetic research. Etymologically, the redeye bass was named by American Ichthyologists Carl Hubbs and Reeve Bailey in 1940 upon discovery of the holotype. The species name “coosae” derives from the Coosa River system in Georgia, its native region. Prior to Hubbs's and Bailey's later research, M. coosae was taxonomically considered to be a small form of smallmouth bass. This misconception may be due to redeye bass's tendency to hybridize with smallmouth and spotted bass, as seen in California.Similar and co-occurring species
Two native species of fish have the most prominent similarity to redeye bass in terms of diet and habitat – the Rainbow Trout, and Sacramento Pikeminnow. These fishes can co-occur with redeye bass in small numbers below refuge areas. Additionally, redeye bass are often confused with the recently described shoal bass from Alabama, Georgia, and Florida, which is sympatric with redeye bass. Before the formal description of shoal bass by James Williams and George H. Burgess in 1999, shoal bass were often considered a type of redeye bass and were sometimes called the "Flint River form of Redeye Bass". In 2013, the redeye bass showed additional species-level variation: Micropterus cahabae, restricted to the Cahaba River system; Micropterus tallapoosae, restricted to the Tallapoosa River system; Micropterus warriorensis, from the Black Warrior River system; and Micropterus chattahoochae, from the Chattahoochee River system. Naturally, Micropterus coosae resides in the Coosa River system. The redeye bass’s most recent common ancestor can be dated to approximately 7.39 million years ago, with a potential range between 4.63 and ten Mya. The most recent speciation events from the largemouth and spotted bass likely happened between 0.68 and 0.76 Mya.Description
Body color and pattern
Redeye bass are distinguished from other species of black basses due to a couple of subtle, but diagnostic features; the presence of a distinct silver-white crescent on the posterior one-half of the eyeball, iridescent white, turquoise, or red on upper and lower margins of the caudal fin, a shallow emargination between the dorsal fins, and the absence of a dark mid-lateral stripe along the body. The upper and lower margins of the caudal fin are edged in white, a useful feature for separating redeye bass from both smallmouth bass and shoal bass. Unique from all other black basses, redeye typically have three dark bars on the cheek. Most individuals have 0–6 vertical black blotches near the front of the body, followed by softer spots toward the back. The back and sides of the fish are generally olive to brown with darker brown mottling.Fin shape and features
The anterior dorsal fin has dark green spines tipped in white with translucent green membranes, while the posterior dorsal fin is red with the front five or six rays tipped in white; the base is green, the upper half red, and the last few membranes are transparent. The caudal fin is green at the base and red at the tips, with translucent membranes and a thin white border on the top and bottom edges. The anal fin is dark green at the base, red toward the tip, and edged in white, with membranes shifting from greenish white at the base to red in the middle and clear near the edge. The pelvic fins are white with black streaks, and the membranes are translucent white, while the pectoral fins have red rays with transparent membranes.Sex and age differences
Notably, the red pigmentation in the fins occurs in both males and females throughout the year and is not linked to breeding or sexual dimorphism. Adults have several horizontal rows of dark spots on their lower sides, with breeding males have having a light bluish green color on the lower head and throat. On juveniles, the sides of the body usually have 10 to 12 dark blotches that do not join to form a lateral stripe across the caudal lobes, with red coloration on the fins and a rusty red base of a caudal fin.Anatomical features
The upper jaw extends to the back of the eye, which is usually red. The redeye is an elongate, slender fish with a large mouth that extends to or slightly behind the rear margin of the eye. The dorsal fin contains nine to 11 spines and 11 to 13 rays, and the area between the two is only slightly notched. The anal fin contains three spines and nine to 11 rays. The complete lateral line has from 63 to 74 scales. Scales above the lateral line number 12 or 13. A small tooth patch is present on the tongue. The fish has relatively small ctenoid scales, containing a range of 66 to 73 lateral line scales, 6–9 scales above the lateral line, 10–13 below it, and 28–32 around the caudal peduncle. A small tooth patch is present on the tongue, measured to be approximately 2 mm in size on average. Internally, the bass has a fairly narrow head and do not often exceed approximately 0.45 kg.Growing to a maximum reported overall length of, the redeye bass is one of the smaller black basses. The probable world record for redeye bass is from Lake Jocassee in South Carolina. Many redeye bass world record listings, especially those over are actually records for the shoal bass.
Image:RedEyeBassTallapoosaRiver.JPG|thumb|200px|left|Fly rod-caught redeye bass, Tallapoosa River, Tallassee, Alabama
The rock bass, a distinct species of Centrarchid, is sometimes called the redeye or redeye bass in Canada.
Species distribution
The redeye bass is a predatory fish that is endemic to the Coosa River system in the southeastern United States, including Georgia and Alabama. It can also be found in states such as Tennessee, Florida, South Carolina, and North Carolina. Its occurrence in Georgia includes the Alabama River system, and Chattahoochee, Oconee, and Savannah Rivers. Sheed's Creek and Cohutta Creek are the only two streams in Tennessee in which this fish occurs naturally. While native to the area, the redeye bass is not known to occur within the Apalachicola River basin, where it is often mistaken as a shoal bass. Redeye bass are limited to upland streams with canopy cover, cool water temperatures, vegetative cover, undercut banks, and rock ledges or large boulders. The species typically avoids impoundments and navigational pools, due to competition with the larger Alabama bass and largemouth bass.As an introduced species
In 1962 and 1964, redeye bass were introduced in California to provide angling in streams dominated by native fishes not favored by anglers, examples being introductions into the Stanislaus River, Feather River, Alder Creek, and Santa Margarita River. Now dominating in some California river ecosystems, the bass has eliminated native fishes. Introduced redeye bass additionally pose a threat to California's endemic frogs and the California tiger salamander. In 1969 redeye bass raised in the California Department of Fish and Wildlife’s Central Valley Hatchery were planted in Oroville Reservoir, where they became established and hybridized with smallmouth and spotted bass. The redeye bass is established in the Sisquoc River within the Santa Maria River basin. Introduced Micropterus coosae have displaced native hardhead in the Cosumnes River.Coosa bass were also introduced into the Verde River and it's tributaries, of North Central Arizona. The introduction of these fishes were mistakenly imported to the region from Alabama thought to be smallmouth bass, and have since become well established since their introduction during the mid 1950's; in around 2021 these fishes were genetically identified as Micropterus coosae. Elsewhere, the redeye bass was introduced to Tennessee in the 1950s and has hybridized extensively with native smallmouth bass.