Opah (Lampris guttatus)

• Very little is known about opah. There is no evidence that opah populations are in decline, or that overfishing is occurring.
• There is no directed fishery for opah; they are incidentally caught in other fisheries.
• There are no published reports on the nutritional benefits of opah.
• All opah in U.S. markets come from U.S. commercial fisheries.

Sustainability Status

Biomass: Unknown
Overfishing: Unknown
Overfished: Unknown
Fishing and habitat: Opah are taken incidentally in other pelagic longline fisheries. Pelagic longlines generally have minimal impacts to habitat due to the lack of contact with bottom habitat.
Bycatch: There is no directed fishery for opah and no known bycatch concerns.
Aquaculture: There is currently no commercial aquaculture for opah in the U.S.

Science and Management

Opah is managed by the Western Pacific Fishery Management Council through its Fishery Management Plan for Pelagic Fisheries of the Western Pacific, originally implemented in 1987. There is no directed fishery for opah; the fish is caught incidentally on longlines for tunas and billfish in Hawaii and American Samoa.

Very little is known about the biology and ecology of opah. However, with funding from NOAA's Office of Ocean Exploration, scientists with NOAA Pacific Islands Fisheries Science Center have been deploying Pop-up Archival Transmitting (PAT) tags on opah caught and released from longlines. The PAT tags stay on the fish for several months then detach, float to the surface, and transmit data on the depth, water temperature, and location occupied by the fish, collected at regular time intervals while the tag was attached. From these data, scientists have gained new insights into the depths, and water temperatures opah occupy and their migration routes. Several opah have showed very curious patterns.

Life History and Habitat

Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed. Because opah represent a minor part of the fishery landings and dwell in deep oceanic waters, very little is known about their biology and ecology. Much of the information below is characteristic of Pacific Ocean pelagic fish in general.

• Geographic range: In tropical and temperate waters throughout the world's oceans
• Habitat: Open ocean; in the subtropical gyre northwest of the Hawaiian Islands, opah generally inhabit depths from 164 to 1,312 feet and water temperatures from 46 to 72 degrees Fahrenheit
• Life span: Unknown
• Food: Opah have a voracious appetite and are opportunistic carnivores, feeding on whatever prey available at the time. Juvenile opah feed on pelagic (in the water column) invertebrates such as crab larvae, isopods (a group of crustacean), and copepods (a group of small crustaceans). Adults feed on a variety of small fish, shrimp, and squid.
• Growth rate: Rapid during early years of life with a gradual slowing thereafter; varies considerably depending on ocean conditions and food availability
• Maximum size: From 60 to over 200 pounds
• Reaches reproductive maturity: Unknown
• Reproduction: Opah have high reproductive rates; individual females may spawn many times during the season at short intervals.
• Spawning season: Throughout the year in the tropics, and more seasonally at higher latitudes when sea surface temperatures are over 75 degrees Fahrenheit
• Spawning grounds: Over vast areas of the Pacific in warm surface waters
• Migrations: Opah are capable of long migrations that are related to oceanic environmental conditions, especially temperature. Migrations vary at different stages of life.
• Predators: Unknown
• Commercial or recreational interest: Commercial
• Distinguishing characteristics: Opah are round, flat, and silver in color with red fins and mouth.

Role in the Ecosystem

In 2004 and 2005, unusual catches of fish and invertebrates, including opah, were reported by fishermen and fishery biologists working in the coastal waters of the eastern and central Gulf of Alaska. These observations coincided with abnormally warm water in the eastern North Pacific Ocean resulting from an overall warming of the whole North Pacific Ocean, not an El Niño. The long-term implications of this ocean warming and these changes of distribution and abundance to Alaskan fisheries are not clear. For more information see the NOAA Alaska Fisheries Science Center Auke Bay Laboratory quarterly report.

Additional Information

Market name: Opah
Vernacular name: Moonfish

Biomass

Biomass refers to the amount of opah in the ocean. Scientists cannot collect and weigh every single fish to determine biomass, so they use models to estimate it instead. These biomass estimates can help determine if a stock is being fished too heavily or if it may be able to tolerate more fishing pressure. Managers can then make appropriate changes in the regulations of the fishery. A history of biomass estimates for opah is unknown.

Landings

Landings refer to the amount of catch that is brought to land. Opah are landed as bycatch in longline fisheries for tunas and billfish and are harvested in small quantities.

Note: U.S. commercial landings are presented in the graph.

Biomass and Landings

Are landings and biomass related? Landings are dependent on biomass, management measures in the fishery, and fishing effort.

Data sources:
Landings from NOAA's National Marine Fisheries Service Annual Commercial Landings Statistics site using"ALL STATES" as State

Important Dates

Notes and Links

General Information:
NOAA Ocean Explorer Census of Marine Life Studying Pelagics: Discovering the long distance migration and deep diving behavior for large pelagics in the central North Pacific with pop-up archival transmitting tags

NOAA Pacific Islands Fisheries Science Center Research, Fishery Monitoring, and Other Activities at the Pacific Islands Fisheries Science Center Related to Tuna and Tuna-Like Species During May 1, 2003-April 30, 2004

Vertical movement and habitat of Opah in the central North Pacific recorded with pop-up archival tags

Fishery Management:
Western Pacific Fishery Management Council's Pelagics Fishery Management Plan