Korean rockfish, Northern black seaperch, Black rockfish
Sebastes schlegelii, also known as the Korean rockfish, northern black seaperch, and black rockfish, is a predatory species of marine ray-finned fish belonging to the subfamily Sebastinae, the rockfishes, part of the family Scorpaenidae It is found in the Northwest Pacific Ocean.
S. schlegelii are blackish with black pelvic, anal and caudal fins. The seaperch has a total of 8 weak head spines. It is black when young and turns a mottled gray on the sides with age, often nearing white. This species can vary greatly in size between bodies of water. They can live for up to 18 years, and older individuals are often much larger than average; the maximum recorded length is 60 cm (24 in). The record is 6.6 lb (3 kg).
The species is found in the Northwest Pacific Ocean, off China, the Korean Peninsula and Japan.
It is a pelagic fish, occurring on the continental shelf. Like other pelagic fish, they spend most of their time amid the water columns and are generally associated with rougher terrain. Juveniles are often associated with rafts of seaweed.
Lepeophtheirus elegans is a species of sea lice reported on S. schlegelii.
S. schlegelii is ovoviviparous and breed via internal fertilization, females storing sperm until the development of the eggs. The phases between the start of the process and the end are separated by several months. The majority of the young are reared in late winter to early spring. Females produce between 125,000 and 1,200,000 eggs every breeding season. However it has been noted that not all of the eggs are released every year. It has been occasionally observed that the female may absorb the eggs back into her system.
Along with other close related Sebastes species in the Northwest Pacific Ocean, a duplicated copy of the amh gene (called amhy) is the master sex-determining gene for S. schlegelii. In vitro experiments demonstrate that the overexpression of amhy causes female-to-male sex reversal in S. schlegelii.
