Longspine Thornyhead, Sebastolobus altivelis
Longspine Thornyhead, Sebastolobus altivelis. Fish provided by the commercial fishermen of the greater San Diego area, San Diego, California, October 2014. Length: 23.0 cm (9.1 inches).
The Longspine Thornyhead, Sebastolobus altivelis, is a member of the Rockfish and Scorpionfish or Scorpaenidae Family, and is known in Mexico as chancharro espinoso. Globally, there are three species in the genus Sebastolobus, of which two are found in Mexican waters, both in the Pacific Ocean.
The Longspine Thornyhead has an elongated body 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 3 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; and, their pectoral fins are notched with 22 to 24 rays. They have 21 to 26 gill rakers and their body is covered with scales.
The Longspine Thornyhead is a demersal species that resides over muddy bottoms adjacent to small rocks and sponges at depths between 160 m (530 feet) and 1,755 m (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 45 years. The Longspine Thornyhead is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Longspine Thornyhead is a resident of Mexican waters of the Pacific but has a limited distribution being found only 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).
From a conservation perspective the Longspine Thornyhead has not been formally evaluated. They are, however, an expanding component of the west coast commercial fishery with fish taken primarily by deep water bottom trawls. The majority of the commercial fish are 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.