Orange Roughy | Oceana
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Ocean Fishes

Orange Roughy

Hoplostethus atlanticus

Distribution

Worldwide in tropical to temperate latitudes except the western Atlantic Ocean

Ecosystem/Habitat

Deep seamounts

Feeding Habits

Active predator

Conservation Status

Unknown

Taxonomy

Order Beryciformes (squirrelfishes and relatives), Family Trachichthyidae (slimeheads)

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“Orange roughy” is the table name for a seafood species historically known to scientists as the “slimehead.”  The seafood industry correctly assumed that people would rather eat something called orange roughy instead of Slimehead, and now that is the generally accepted common name of the species.  The orange roughy is a predatory species that lives on deep seamounts (undersea mountains) in most ocean basins around the world.  This species is one of the longest living marine fish species, with individuals living for more than 150 years.  This longevity, and its other life history characteristics, makes the orange roughy vulnerable to overfishing.

Adult orange roughy are predators that live on or just over the seafloor, but near areas where strong currents bring their preferred prey (other fishes and squids) to them.  Deep seamounts provide the right oceanographic conditions to form these strong currents.  Orange roughy grow no bigger than a few feet (less than one meter) and are eaten by larger fishes and sharks that feed near the seafloor. 

This species reproduces through a behavior known as broadcast spawning, where several females release eggs and several males release sperm into the water column above the seafloor, all at the same time.  This method increases the likelihood that eggs will become successfully fertilized and that fertilized eggs will not be eaten by egg predators near the seafloor.  Scientists believe that, though orange roughy normally live in high densities, they migrate to form even denser aggregations for the purposes of spawning.  Individuals do not reach sexual maturity until they are least 20 years old (perhaps not until they are 30-40).

Throughout much of its range, the orange roughy is considered overfished by fisheries scientists and at risk of endangerment by conservation groups (though it has not been formally assessed for the most well recognized list of threatened species – the IUCN Red List).  The extremely long lifespan and the late age at maturity imply that a decimated population may take a half century or longer before it can recover.  Without careful fisheries management and conservation efforts when necessary, orange roughy numbers could reach very low levels without much fishing effort.  Furthermore, this species is captured primarily by bottom trawling, a method known to do extensive harm to bottom habitat (most notably long-lived deep-sea corals) and to accidentally capture high numbers of individuals of non-targeted species.  These fishing practices and orange roughy population trends need to be carefully assessed by scientists in order to avoid risking this species.

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