Halfbanded Rockfish

Halfbanded Rockfish, Sebastes semicinctus

The Halfbanded Rockfish, Sebastes semicinctus, whose common Spanish name is rocote inspector, 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 Halfbanded Rockfish have slender bodies with a depth that is 28 to 32% of standard length. They vary in color from orange to deep red or brown and transition quickly to white ventrally. They have a diamond-shaped dark mark that runs from under their spiny dorsal fin to below their lateral line. They also have two additional bands toward the rear of their body. Their body is heavily blotched and saddled. Their caudal fin has brown and green streaks and is covered with dots. They have the ability to change colors and patterns. They have a long head with a short snout, disproportionately large eyes, and a relatively small terminal mouth. Their anal fin has 3 spines and six to 8 rays; their caudal fin is slightly forked; their dorsal fin has 13 spines and 12 to 14 rays; their pectoral fins have 16 to 18 rays; and they have 36 to 42 gill rakers. Their body is covered with scales.

The Halfbanded Rockfish are bottom dwellers found in a wide variety of habitats ranging from muddy floors to hard rockscapes at depths between 50 and 1,320 feet. They are found as individuals or in schools that number in the thousands and are one of the most abundant species in mid-depth reefs. They reach a maximum length of 25 cm (10 inches), with females being larger than males. They feed on zooplankton including amphipods, copepods, crustacean larva, and kril. Reproduction is oviparous with each female releasing between 3,000 and 31,000 pelagic eggs. They have a lifespan of up to fifteen years, however, very little is known about their behavioral patterns.

In Mexican waters the Halfbanded Rockfish have a limited distribution being found from Guerrero Negro northward along the central and northwest coasts of Baja.

The Halfbanded Rockfish is easily confused with the Stripetail Rockfish, Sebastes saxicola (lacks dark mid-body diamond-shaped bar).

The Halfbanded Rockfish are not fished commercially. They are caught with some regularity by recreational fishermen but their small mouths reduce their quantities significantly.

Halfbanded Rockfish (1)

Halfbanded Rockfish, Sebastes semicinctus. Fish provided by the commercial fishermen of the greater San Diego area, San Diego, California, October 2014. Length: 18 cm (7.1 inches). Identification courtesy of Milton Love, University of California, Santa Barbara, Santa Barbara, CA.

Halfbanded Rockfish (3)

Halfbanded Rockfish, Sebastes semicinctus.  Both fish caught from coastal waters off Long Beach, California, , July 2015. Length of each: 12.7 cm (5.0 inches). Photo courtesy of Chris Wheaton, Loreto, Baja California Sur.