Rosethorn Rockfish

Rosethorn Rockfish, Sebastes helvomaculatus

The Rosethorn Rockfish, Sebastes helvomaculatus, whose common Spanish name is rocote moteado, is a species in the Rockfish and Scorpionfish or Scorpaenidae Family, known collectively as escorpiones, lapons or rocotes in Mexico. Globally, there are 124 species in the genus Sebastes, of which 49 are found in Mexican waters, all in the Pacific.

The Rosethorn Rockfish have small and elongated bodies with a depth that is 28% to 32% of standard length. They vary in color from crimson, orange, yellow or yellowish-green arranged in a series of diffuse stripes. Their anal and dorsal fins are usually striped in pink or green and the top of their head may be green with white stripes. They have four or five white blotches on their back. Their anal spines are shorter than, or equal in length to, the anal rays. Their head is relatively narrow and spine-laden with a short pointed snout, large eyes, and a small terminal mouth. Their anal fin has three spines and five to seven rays; their caudal fin is square; their dorsal fin has 12 to 14 spines and 12 to 14 rays; and their pectoral fins have 15 to 18 rays. They have 27 to 33 gill rakers.

The Rosethorn Rockfish are found demersal in benthic environments over mixed rock and mud substrate at depths between 260 and 1,150 feet with water temperatures as low as 4.1oC (39oF). They are typically solitary or found in small aggregations. They reach a maximum length of 43 cm (17 inches) and weight of 1.5 kg (3.3 pounds). They feed on a wide variety of invertebrates and small fish. In turn they are preyed upon by Lingcod and Yelloweye Rockfish. Reproduction is oviparous with pelagic eggs. They have a lifespan of up to 87 years, however, very little is known about their behavioral patterns.

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

The Rosethorn Rockfish is most likely confused with the Pinkrose Rockfish, Sebastes simulator (bright red or red with yellow tinges; 17 or more pectoral rays), the Rosy Rockfish, Sebastes rosaceus (purple on head, back, and sides), and the Swordspine Rockfish, Sebastes ensifer (extended second anal spine).

The Rosethorn Rockfish are not important as food fish. They are caught as a by-catch of trawl and longline fisheries as well as by deep water recreational anglers with good frequency.

Rosethorn Rockfish, Sebastes helvomaculatus. Fish caught from coastal waters off Tijuana, Baja California, October 2016. Length: 15.2 cm (6.0 inches). Catch, photo, and identification courtesy of Eli (obsessiveangling.wordpress.com).