In 2004 and 2005, fishermen and fishery biologists reported unusual catches of fish and invertebrates, including opah, 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. The long-term implications of this ocean warming and these changes of distribution and abundance to Alaskan fisheries are not clear. READ MORE
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LAUNCH THE MAPOpah
Lampris guttatus
ALSO KNOWN AS:
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Moonfish
SOURCE:
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U.S. wild-caught from Hawaii and surrounding high seas
STATUS
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POPULATION
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FISHING RATE
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HABITAT IMPACTS
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BYCATCH
Click the icons to learn more about each criteria
OVERVIEW
This opah, also known as the moonfish, was caught and released on a longline set off of the Channel Islands near California.
LAUNCH GALLERYOpah has been caught incidentally in Hawaii longline fisheries for years. Fishermen once thought that this unusually colorful fish brought good luck, and would give it away as a goodwill gesture rather than sell it. There also wasn’t much of a market for the fish. In the late 1980s, the state of Hawaii started promoting opah to build a market among U.S. consumers for this underutilized species. Today, the demand is rising for opah and its rich, tasty meat.
Opah do not swim in schools, so they’re not caught in great numbers. Individual fish are regularly caught by longliners fishing in the deep ocean for tunas and billfish. While almost all opah sold in the U.S. market are from Hawaii, this species is found worldwide in tropical and temperate waters and is often taken as bycatch by longliners targeting tuna from New Zealand to California. When domestic supplies are low, the United States imports opah, predominantly from Fiji, Tahiti, and New Zealand.
Looking Ahead
LOCATION & HABITAT
Opah are found in tropical and temperate waters around the world. They live in deep open ocean waters. Opah are capable of traveling long distances, often in response to changing oceanic conditions, such as temperature.
BIOLOGY
Because opah are not a major commercial seafood species and they live in the deep ocean, scientists know very little about their biology and ecology. They assume opah share general characteristics with other Pacific Ocean pelagic fish (PDF). Scientists estimate that opah grow quickly. Although they’re not sure of opah’s exact life span, scientists age opah by their fin rays, assuming fin ray marks are formed annually. Most opah caught in longline fisheries are estimated to be between 1 and 6 years old. They average about 100 pounds with a diameter of 3 feet.
Opah spawn in warm surface waters throughout the year in the tropics and more seasonally in cooler waters. Opah seem to be very productive, potentially spawning many times throughout the spawning season.
PHYSICAL DESCRIPTION
Opah are an unusual looking fish – they have round, flat, body that’s silvery gray in color. Toward the belly, the silver shades to a rose red, dotted with white spots. Its fins and mouth are red, and their large eyes are encircled with gold.
OVERVIEW
Despite the opah's value to commercial and recreational fishermen, little research on the basic biology and ecology of opah has been conducted. To begin to fill some of the data gaps, NOAA's Southwest Fisheries Science Center began collecting biological samples from opah in 2009 and initiated an electronic tagging program in 2011. Analyses of the biological samples and the data provided by the tagging program have revealed a plethora of information. For example, genetic analysis has determined that there are multiple species of opah—those caught off California are a different species than those caught off Hawaii. Opah also appear to have a unique gill arch structure which has never been seen before.
Scientists plan to continue their study of opah, processing stomachs to identify the species' diet and dissecting gills and whole fish to learn about their anatomy and swimming mechanics. Scientists also hope to continue tagging opah to learn about their movements and range. This research will provide the basic life history information necessary for future population assessments and management. Historical catch data may also show correlations between opah catch and abundance with changes in sea surface conditions such as El Niño and La Niña.
POPULATION STATUS
Unknown, but there is no evidence that opah populations are in decline or that fishing rates are too high.
ADDITIONAL RESEARCH
With funding from NOAA's Office of Ocean Exploration, scientists at NOAA's Pacific Islands Fisheries Science Center have conducted tagging studies on opah to learn more about where they live and where they travel. When they catch opah, they tag this fish with a Pop-up Archival Transmitting (PAT) tag then release it back into the ocean. 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 while the tag was attached. From these data, scientists have gained new insights into the depths and water temperatures opah occupy as well as their migration routes. Several opah have showed curious patterns.
Harvesting Opah
There is no directed fishery for opah. In Hawaii, opah is caught on longlines set deep below the surface to target bigeye tuna. Off California, they're taken incidentally in the California drift gillnet fishery targeting swordfish. Since they're highly marketable, fishermen rarely throw opah back.
Management
Who’s in charge? NOAA Fisheries and the Western Pacific Fishery Management Council
Current management: Fishery Ecosystem Plan for Pelagic Fisheries of the Western Pacific Region
Annual Harvest
Compared to targeted tuna, opah are harvested in small but still significant quantities. In 2010, U.S. commercial fishermen harvested more than 1.8 million pounds of opah.
Economy
Opah are particularly valued by the restaurant trade in Hawaii and the continental United States for their high-quality white flesh. The 2010 commercial harvest was valued at nearly $2.6 million.
Recreational
Although not commonly caught, opah are prized by deepwater recreational anglers for their unique colors and light flavor.
OVERVIEW
Opah has four types of flesh, each a different color. The tender meat behind their head and along the backbone is orange. Toward the belly, the flesh pales to pink. Opah’s cheeks are dark red. All of meat turns white when cooked, except a small amount of red or liver-colored flesh inside the breastplate, whichcooks to a brown color and is somewhat stringy and difficult to fillet.
Opah has a rich, creamy taste and firm, fatty texture. The flavor is distinctive, a cross between tuna and swordfish. The opah’s flesh is rich with healthy oils, and is great grilled, broiled, sautéed, raw, or smoked.
(
Seafood Business, 2011 
;
Hawaii Seafood Council, 2011
)
SEASONAL AVAILABILITY
Year-round, but landings seem to peak in April–August
NUTRITION
Opah is a rich source of protein, niacin, vitamin B6, vitamin B12, phosphorus, and selenium. It is also low in sodium. Opah provides about 1,800 mg of omega-3s (DHA and EPA) per 4-ounce serving of fresh fish.
| Servings | 1 |
| Serving Weight | 4 oz. (raw) |
| Calories | 170 |
| Protein | 24 g |
| Fat, total | 8 g |
| Saturated fatty acids, total | 2.5 g |
| Carbohydrate | 0 g |
| Sugars, total | 0 g |
| Fiber, total dietary | 0 g |
| Cholesterol | 60 mg |
| Selenium | 49 mcg |
| Sodium | 80 mg |
Opah Table of Nutrition
RECIPES
- Coming Soon...
