Blackgill Rockfish, Sebastes melanostomus
The Blackgill Rockfish, Sebastes melanostomus, whose common Spanish name is rocote agalla negra, is a species in the Rockfishes and Scorpionfishes or Scorpaenidae Family, known collectively as escorpiónes or lapóns in Mexico. Globally, there are one hundred twenty four species in the genus Sebastes, forty nine of which are found in Mexican waters, all in the Pacific.
The Blackgill Rockfish are spiny fish with an enormous sloping head that continues into the mid-section and then tapers quickly to a thin tail. Their body depth is 34 to 38% of standard length. They have a red coloration with darker areas and white blotches. The gill covers have black margins for which they are named. Their clear lateral line becomes less apparent with maturity. Their fins and fin margins are similar in color to the body but with blank tinges. They have a disproportionately large head, large eyes, and a large terminal mouth. Their anal fin has 3 spines and 6 to 8 rays; their caudal fin is slightly lunate; their dorsal fin has 13 spines and 12 to 15 rays; their pectoral fins have 17 to 20 rays; and they have 27 to 35 gill rakers. Their body is covered with scales.
The Blackgill Rockfish are bottom dwellers found as solitary individuals or in small groups within boulders and rocky habitat at depths between 290 and 2,520 feet. They are normally found mixed in with Black Rockfish. They reach a maximum length of 61 cm (24 inches), with females being larger than males. They feed on small fish, primarily lanternfish. Reproduction is oviparous with each female releasing between 152,000 and 769,000 pelagic eggs. They have a lifespan of up to eighty seven years, however, very little is known about their behavioral patterns.
In Mexican waters the Blackgill Rockfish has a very limited distribution being found from Cedros Island northward along the central and northwest coasts of Baja.
The Blackgill Rockfish is fairly easy to identify when the black margins are present on its gill covers. When these are absent, it can be confused with the Darkblotched Rockfish, Sebastes crameri (five dark blotches above lateral line).
The Blackgill Rockfish are a strong component of the commercially fishery in coastal California waters with fish taken via both horizontal and vertical longlines and via trawls. They are sold in Asian markets in Southern California. Historically they were caught with some regularity by recreational fishermen but due to overfishing and lack of conservation the species populations have been drastically depleted and they are now seldom caught by recreational fishermen.