Irish Pompano, Diapterus auratus
Irish Pompano, Diapterus auratus. Fish caught from coastal waters off Boca Raton, Florida, November 2023. Length: 14 cm (5.5 inches). Catch, photograph and identification courtesy of Chris Moore, Peoria, Arizona.
Irish Pompano, Diapterus auratus. Commercial fish courtesy of Soriana’s Mercado, Cabo San Lucas, Baja California Sur, March 2015. Length: 21 cm (8.3 inches). Sold as “Mojarra.” Fish identification courtesy of H.J. Walker, Jr., Scripps Institute of Oceanography, La Jolla, California.
Irish Pompano, Diapterus auratus. Fish caught from coastal waters off Tampa, Florida, May 2018. Length: 20 cm (7.9 inches). Catch, photograph and identification courtesy of Ben Cantrell, San Diego, California.
Irish Pompano, Diapterus auratus, Protrusible Snout. Fish caught from coastal waters off Sanibel Island, Florida, March 2017. Catch, photograph and identification courtesy of Marc Eberlein, Grand Rapids, Michigan.
The Irish Pompano, Diapterus auratus, is a member of the Mojarra or Gerreidae Family, that is also known as the Irish Mojarra and in Mexico as mojarra guacha. There are four global members in the genus Diapterus, and all four are found in Mexican waters, two in the Atlantic and two in the Pacific Ocean. Its common name “Pompano” is simply weird!
The Irish Pompano has a rhomboidal deep compressed body with a depth that is 43% to 47% of standard length. They are uniformly silvery olive in color. Their dorsal fin has a thin black margin and their anal and pelvic fins are yellow. Juveniles have 3 vertical bars on their sides. Their head has a pointed snout and their lower head profile is significantly concave. Their mouth is extensible and points downward when extended. The margin of their gill cover is serrated. Their anal fin has 3 spines, the second being thick and longer than the third, and 8 rays; their caudal fin is deeply forked; their dorsal fin is set high on the body and has 9 spines and 10 rays; the second spine being the longest; their pectoral fins are long and reach past the anal fin origin. They have 12 to 15 gill rakers on their lower arch. Their lateral line is prominent and slightly curved on the front of the body. Their head and body are covered with rough scales.
The Irish Pompano is a schooling species that reside in shallow coastal areas including protected sandy bays, seagrass meadows, lagoons, and freshwater estuaries at depths up to 30 m (100 feet). They reach a maximum length of 34 cm (13 inches). As of January 1, 2024, the International Game Fish Association world record stood at 0.68 kg (1 lb 8 oz) with the fish caught in coastal waters off Port St. Lucie, Florida in December 2000. They feed on plant materials, copepods, nematodes, ostracods, and other small invertebrates. The Irish Pompano is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction..
The Irish Pompano is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean.
The Irish Pompano can be easily confused with a series of other Mojarras noting that they differ in head profiles, gill raker counts, body depths, gill cover serration, and second anal spine thickness. These include the Brazilian Mojarra, Eugerres brasilianus and the Rhombic Mojarra, Diapterus rhombeus (different gill raker counts), the Maracaibo Mojarra, Eugerres awlae (very long second anal fin spine), and the Striped Mojarra, Eugerres plumieri (concave upper head profile).
From a conservation perspective the Irish Pompano is currently considered to be of Least Concern with stable, widely distributed populations. They are fished commercially via cast nets, beach and boat seines, gill nets, trammel nets, beam trawls and traps. In Mexico they are caught primarily as a by-catch by shrimp trawlers. In the State of Florida, they are sold fresh and whole at a level of 100,000 kg per year.
NOTE. There are eighteen members of the Mojarra or Gerreidae Family currently Included in this website, ten are from Mexican waters of the Pacific and eight from the Atlantic. They are all very similar in appearance and difficult to identify. As an aide to this challenge I have assembled a Mojarra Body Depth Chart that presents these seventeen mojarras from thin bodied to deep bodied which is useful in identification work. In addition, I have also assembled a Mojarra Maximum Length Chart which I have also helpful in the identification work for these eighteen mojarras. Both charts can be found at the end of the Mojarra Family Page.