Orange roughy

Description

The orange roughy (Hoplostethus atlanticus), also known as the red roughy, slimehead and deep sea perch, is a relatively large deep-sea fish belonging to the slimehead family (Trachichthyidae). The UK Marine Conservation Society has categorized orange roughy as "vulnerable to exploitation". It is found in 3 to 9 °C (37 to 48 °F), deep (bathypelagic, 180-to-1,800-metre (590 to 5,910 ft)) waters of the Western Pacific Ocean, eastern Atlantic Ocean (from Iceland to Morocco; and from Walvis Bay, Namibia, to off Durban, South Africa), Indo-Pacific (off New Zealand and Australia), and in the eastern Pacific off Chile. The orange roughy is notable for its extraordinary lifespan, attaining over 200 years. It is important to commercial deep-trawl fisheries. The fish is a bright, brick-red color, fading to a yellowish-orange after death. Like other slimeheads, orange roughy is slow-growing and late to mature, resulting in a very low resilience, making them extremely susceptible to overfishing. Many stocks (especially those off New Zealand and Australia, which were first exploited in the late 1970s), became severely depleted within 3-20 years, but several have subsequently recovered to levels that fisheries management believe are sustainable, although substantially below unfished populations. The orange roughy is not a vertically slender fish. Its rounded head is riddled with muciferous canals (part of the lateral line system), as is typical of slimeheads. The single dorsal fin contains four to six spines and 15 to 19 soft rays; the anal fin contains three spines and 10 to 12 soft rays. The 19 to 25 ventral scutes (modified scales) form a hard, bony median ridge between the pelvic fins and anus. The pectoral fins contain 15 to 18 soft rays each; the pelvic fins are thoracic and contain one spine and six soft rays; the caudal fin is forked. The interior of the mouth and gill cavity is a bluish black; the mouth itself is large and strongly oblique. The scales are ctenoid and adherent. The lateral line is uninterrupted, with 28 to 32 scales whose spinules or 'ctenii' largely obscure the lateral line's pores. The eyes are large. The orange roughy is the largest known slimehead species at a maximum standard length (a measurement that excludes the tail fin) of 75 cm (30 in) and a maximum weight of 7 kg (15 lb). The average commercial catch size is commonly between 35 and 45 centimetres (14 and 18 in) in length, again, varying by area.