Opah, Lampris guttatus, caught off the Southern California Bight. Image Credit: Elea Medina NOAAThe opah (Lampris guttatus), or "moonfish", is a large pelagic fish found worldwide in temperate and tropical waters from 70° N to 45° S and occurs seasonally off the coast of California and Mexico. Opah are deep-ranging fish known to inhabit mesopelagic waters and have been shown to swim and forage beneath the thermocline from the surface down to depths near 500 meters. They have large, laterally-compressed, oval bodies shaped like discs and grow to an average 3 feet and 100 pounds, though have been recorded up to 5.25 feet and 196 pounds ( Hawn & Collette, 2012). Although opah are considered elusive and solitary fish, they are often caught incidentally in recreational tuna fisheries off Southern California, longline fisheries targeting tuna around the world, and in the commercial California drift gillnet fishery. Their rich meat has become popular and most opah bycatch is now kept and sold to seafood markets and restaurants. Although their commercial value is increasing and the fish is a prized recreational catch, the species is not targeted by any fishery and is not currently managed under a Fishery Management Plan (FMP). In fact, little is known about the biology, population status, and ecology of opah in the California Current. To begin to better understand this data-poor species, scientists at the Southwest Fisheries Science Center began opportunistically collecting biological samples from opah in 2009 and initiated an electronic tagging program in 2011. Sampling and tagging efforts are helping researchers to better understand the behavior, physiology, occurrence, and foraging ecology of opah in the SCB.



SWFSC Opah Biology Research SWFSC Opah Foraging Ecology Research SWFSC Opah Distribution Research NOAA FishWatch: Opah SWFSC Opah Image Gallery Opah Publications



Meet the SWFSC scientists involved with opah research:

Recent SWFSC opah publications:

  • Wegner, N.C., Snodgrass, O. E., Dewar, H., and J. R. Hyde. 2015. Whole-body endothermy in a mesopelagic fish, the opah, Lampris guttatus . Science, 348 (6236): 786-789.

  • Hyde, J. R., K. E. Underkoffler, and M. A. Sundberg. 2014. DNA barcoding provides support for a cryptic species complex within the globally distributed and fishery important . Mol Ecol Res,14:1239–1247.

  • Runcie, R. M., Dewar, H., Hawn, D. R., Frank, L. R. and Dickson, K. A., 2009. Evidence for cranial endothermy in the opah (Lampris guttatus). Journal of Experimental Biology. 212, 461-470.


Opah and our Large Pelagics team  in the news: