Sacramento perch

The Sacramento perch (Archoplites interruptus) is a species of freshwater sunfish endemic to California, and transplanted to other parts of the western United States. It is the only extant species within the genus Archoplites. It is the only species of freshwater sunfish whose native habitat resides west of the Rocky Mountains, while all the other species are native to the east. Due its small range and the impact of introduced species on it, it is considered Endangered on the IUCN Red List. While there is no updated analysis of their populations in these states, it is certain that they still exist throughout California. However, there is speculation of viable populations in Utah, Nevada, and Colorado. The Sacramento perch's native habitat is in sluggish, heavily vegetated waters of sloughs and lakes. It can reach a maximum overall length of 73 cm (29 in) and a maximum weight of 1.4 kg (3.1 lb), and it has been reported to live as long as nine years. Its adaptability to different habitats is variable, and it can survive on various food sources, from insects, bottom-dwelling snails, phytoplankton, and small fishes. As young perch, they consume mainly small crustaceans and eventually move on to insect larvae and then smaller fish as adults.

Taxonomy

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Archoplites interruptus belongs to the family Centrarchidae, within the order Centrarchiformes. Although called the Sacramento perch, A. interruptus is not a perch strictly speaking. The perches are members of the genus Perca in the family Percidae. Being the only native centrarchid west of the Rockies, the Sacramento perch is believed to closely resemble the ancestral fish that split from the rest of the other species residing in the east. However, a reevaluation of this using DNA sequences shows that it is most closely related to the Rock Bass.

A. interruptus is currently the only species of the genus Archoplites, but Girard, an ichthyologist, originally assigned it to Centrarchus. The genus name comes from the Greek words that mean anus and armor, which refers to the anal spines. The species name, interruptus, refers to the irregular stripe pattern on its sides.

†Archoplites clarki Smith & Miller, 1985 (Middle Miocene of Clarkia fossil beds, Idaho)
†Archoplites langrellorum Van Tassel & Smith, 2019 (Pliocene of eastern Oregon)
†Archoplites molarus Smith, Morgan & Gustafson, 2000 (Early to Late Pliocene of the Ringold Formation, Washington)
†Archoplites taylori Miller & Smith, 1967 (Late Miocene of Idaho, including Poison Creek Formation)

The earliest fossils of the extant A. interruptus itself are from the Early Pleistocene-aged Cache Formation of California. The females, however, tend to have these bars less prominent and have more of an even coloration with the silver scales. There are about 25–30 gill rakers in its gills, and has black spots on the operculum.[<nowiki/>verification needed] The largest of this species ever recorded was 73 cm total length. It inhabited sloughs, slow-moving rivers of the Pajaro and Salinas rivers, and lakes with emergent vegetation such as Clear Lake. This species has been eliminated from 90% of its natural habitat due to habitat destruction, egg predation by invasive fish species, and interspecific competition with other centrarchids, mainly bluegill. Sacramento perch are quite rare in their native range and are found primarily in warm, turbid, and alkaline farm ponds, reservoirs, and recreational lakes that it has been introduced into. Sacramento perch populations exist in six California watersheds, including Clear Lake Reservoir, Cedar Creek, Walker River, upper Owens River, Mono Lake, and Abbotts Lagoon. However, eating mosquito larvae is rare because these fishes are mainly midwater swimmers and do not usually feed on terrestrial or flying insects. The younger and smaller adult perches mostly feed on small benthic crustaceans. As they grow, they move on to chironomid larvae and other fish, including their own species on rare occasions. Sacramento perch of Pyramid Lake have been found feeding on Tui chubs and Tahoe suckers. Based on experimental designs in aquariums, they usually hunt alone and will slowly stalk their prey for a period of time. The Sacramento perch reaches breeding age at two to three years old. The perch lay their eggs in 8–12 inch diameter nests in shallow waters, usually with rock piles, submerged roots, or other substrates nearby. These nests are not created but found, differentiating them from all the other centrarchid species that create their own nests. Nesting sites are scouted by males about 12 hours before nesting, and once obtained, they begin defending their territory. The main threat to this species' survival is interspecific competition with other introduced centrarchid species that are typically larger in size and prey upon it. One in particular is the bluegill since its diet is similar, and they have the same preferred nesting areas. The bluegill's advantage is not so much in size but in its aggressive behavior. Field observations in small ponds and experimental observations in aquariums consistently show the dominance of the bluegill over the Sacramento perch by aggressively chasing them.

References

External links

Bay Delta Fish You've Never Heard Of: Sacramento Perch; by Chris Clarke; July 9, 2015