Longspine Thornyhead, Sebastolobus altivelis
The Longspine Thornyhead, Sebastolobus altivelis, whose common Spanish name is chancharro espinoso, is a species in the Rockfishes and Scorpionfishes or Scorpaenidae Family, known collectively as escorpiónes or lapóns in Mexico. Globally, there are only three species in the genus Sebastolobus, of which two are found in Mexican waters, both in the Pacific.
The Longspine Thornyheads have elongated bodies with a depth that is 25 to 29% of standard length. They have a red to orange-red coloration with white patches on their back, cheeks, and spiny dorsal fin. Their gill chambers are dark in color. They also have black patches on their sides. They have a large head, cheeks with 8 to 10 strong spines, and a large terminal mouth. Their anal fin has three spines (the second being much longer than the third) and 4 to 6 rays; their caudal fin is square; their dorsal fin has 15 to 17 spines (the third being the longest) and 8 to 10 rays; their pectoral fins are notched with 22 to 24 rays; and they have 21 to 26 gill rakers. Their body is covered with scales.
The Longspine Thornyheads are bottom dwellers that reside over muddy bottoms adjacent to small rocks and sponges at depths between 530 and 5,760 feet. They reach a maximum length of 39 cm (16 inches), with females being larger than males. They are found as solitary individuals and known to lay motionless on the bottom for long periods of time. They feed on other fish and invertebrates including amphipods and shrimp. Reproduction is oviparous with each female releasing between 2,000 and 50,000 pelagic eggs. They have a lifespan of up to forty-five years, however, very little is known about their behavioral patterns.
In Mexican waters the Longspine Thornyheads have a limited distribution being only found along the entire west coast of Baja.
The Thornyheads can be distinguished from other Rockfish by the spiny ridges across their cheeks. They also have 15 or 16 dorsal spines while other Rockfish have 13. The Longspine Thornyhead is similar to and found mixed in with the Shortspine Thornyhead, Sebastolobus alascanus (short third dorsal spine).
The Longspine Thornyheads are an expanding part of the west coast commercial fishery with fish taken primarily by deep water bottom trawls and the majority being exported to Japan. In domestic markets many are sold live as they lack a swim bladder and can survive after being hauled up from the deep. They are caught occasionally by recreational anglers but the equipment needed to reach their depth make them a poor sportsfish.