Orange roughy

Slimehead

The orange roughy is a long lived fish that grows slowly, matures late (~30 years) and lives up to 130 years. Orange roughy lives in very deep waters from 500-1500m worldwide, but is most abundant off the coasts of New Zealand, Australia, southwest Africa (Namibia) and in the northeast Atlantic Ocean. Individuals aggregate around prominent topographic features such as seamounts, particularly during spawning and feeding. This species is thought be an opportunistic predator, using currents and eddies around marine features to prey on prawns, squid, and small fishes.

Orange roughy is extremely vulnerable to fishing pressure because it grows slowly, does not reproduce until 30 years of age, and lives up to 130 years. This species also aggregates during spawning, a behaviour that makes them vulnerable to opportunistic fishing.

Catch of orange roughy has shown a series of successive crashes in individual fisheries around the world, giving the impression of a cumulatively constant supply. Catches in New Zealand and Australia peaked around 1990 and have declined since. Small fisheries in the northeast Atlantic and in Namibia/Chile also peaked in the early ‘1990s, the late 1990’s respectively. All are now in decline or have restricted limits.

Bycatch in orange roughy fisheries tends to be low because fish gather around seamounts and are captured as schools. However, a study from the oldest fishery in New Zealand showed declines in the abundance of 10/18 of the species that have been regular bycatch in orange roughy fisheries between 1979 to 1997 (e.g. black oreo, smooth oreo, deepwater dogfish, slickheads, rattails and basketwork eels and sharks).

Boats fishing for orange roughy use destructive heavy trawl gear that destroys ocean habitat. Bycatch from orange roughy trawls in New Zealand and Australia have shown that trawling kills slow-growing corals that may take more than a century to recover and that the average benthic biomass from seamounts was 106% greater in unfished than in heavily fished areas and contained 46% more species.

Management is addressing the issue of overfishing by limiting entry and allowable catch while monitoring stock recovery. New Zealand and Australia implemented individually transferable quota (ITQ) management for orange roughy in 1986 and 1992 respectively, when gear and fish size restrictions were ineffective in the face of increasing effort. Each ITQ represents a portion of the total allowable commercial catch for a year (TACC), which is adjusted each year based in stock assessments and best available science. However, management has failed to address the overall effect of trawling and loss of considerable orange roughy biomass in deep-sea ecosystems.

Consumption advisory due to mercury.

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