Fish Identification Photos: Round Herring, Etrumeus teres: The Round Herring has a blue back with silver sides and belly. It has a long cylindrical slender body that is 5.8 to 6.0 times longer than its width. The mouth is at the front and the pelvic fin base is behind the dorsal fin base. Upon collection the color of the Round Herring changes rapidly to a deep blue black and the scales become highly visible.

The Round Herring is similar in size and appearance to the California Pilchard, Sardinops sagax sagax (series of black dots along its sides) and the Pacific Mackerel, Scomber japonicus (patterned back). The Round Herring reaches a length of 12 inches, but is more common at 8 inches. It is normally found in large schools very deep in the water column, between 200 and 400 feet, along rocky shorelines. The Round Herring is found in all Mexican waters with the possible exception being the oceanic islands.

The Round Herring is a member of the Clupeidae Family which consists of herrings, menhadens, pilchards, piquitingas, sardines, shads and threadfin herrings. In general, they are small silvery shallow water fishes that are found in all cold and warm waters of the seas. They normally travel in schools that consist of hundreds to thousands of individuals. They feed primarily on zooplankton. They are characterized by scuted keels along the entire belly, a single dorsal fin in the middle of the body, anal fins that are well back with a short base, pelvic fins on the abdomen below the dorsal fin, pectoral fins that are low on the sides, and fins with no spines. Herrings are of major importance to fisheries, comprising 50 percent of the global catch of fishes each year. Globally, 227 species of Clupeidae have been identified, of which only 11 are found in the tropical Eastern Pacific. For the genus Etrumeus only one species resides in Mexican waters.

The Round Herring is readily caught by the hundreds utilizing Sabiki Rigs, known locally in Mexico as "Lucky Joe Rigs," off the bottom in deep water over sandy terrain. They are a bycatch for those seeking Pacific Mackerel and viewed by locals as being of limited value. They are slow-trolled as a dead decoy to attract large surface fish or sent down deep with a cut down each side to expose the meat with a bottom rig attached to a 7/0 hook. The Round Herring has a limited value as a “cut bait.”