Eastern Pacific Flagfin

Eastern Pacific Flagfin, Aulopus bajacali

The Eastern Pacific Flagfin, Aulopus bajacali, whose common Spanish name is lagarto del Pacífico oriental, is a species in the Flagfin or Aulopidae Family, known collectively as aulópidos in Mexico. Globally, there are only seven species in the genus Aulopus, and one is found in Mexican waters, this species in the Pacific. First reported in the scientific literature in 1984, the Eastern Pacific Flagfin is extremely rare, only found around the tip of Baja (i.e. a bajacali), and seldom seen by humans.

The Eastern Pacific Flagfins have slender cylindrical bodies. They are overall brown in color and transition to lighter brown ventrally. They have four dark saddles on their upper body with irregular blotches between the saddles on their sides. Their head has dark blotches with a large dark blotch on the upper half of their gill cover. Their lower body has tinges of yellow. Females have a wide red band across the middle of their dorsal fin; males have a red-tipped dorsal fin with spines two to four being the longest. Their head has a pointed conical snout, a large mouth that opens at the front and ends under the eyes, and very large horizontal elliptical eyes. They have a prominent adipose fin located above their anal fin. Their caudal fin is strongly forked; their single high dorsal fin is located mid-body and originates just behind the pelvic fins; and their pectoral fins are mid-sized. They have 13 to 16 gill rakers and are covered with spiny and smooth scales that vary upon location.

The Eastern Pacific Flagfins are found at depths between 270 and 1,685 feet in sandy and muddy bottoms adjacent to heavy rock structures. They reach a maximum length of 31 cm (12 inches). They are a rare and poorly studied species and very little is known about their behavioral patterns.

The Eastern Pacific Flagfin has a very limited global distribution in Mexican waters being confined to Baja California Sur from Alijos Rocks (24o57’N, 115o45’W) and at the Uncle Sam Bank (25º34’N, 113o45’W) to at least thirty miles into the Sea of Cortez (Gordo I, 23.01oN, 109.31oW).  In October 2017, I caught one in coastal waters off Loreto (25.99oN, 11.35oW) extending the known range of this species well into the Sea of Cortez.

The Eastern Pacific Flagfin can be confused with a series of Lizardfishes including the Calico Lizardfish, Synodus lacertinus, the Iguana Lizardfish, Synodus sechurae, and the Spotted Lizardfish, Synodus evermanni; each have dorsal and adipose fins originating further back in the body.

This is a very rare small fish, of limited interest to most, and normally a “catch and release.”

Eastern Pacific Flagfin (4)

Eastern Pacific Flagfin (5)

Eastern Pacific Flagfin, Female, Aulopus bajacali. Fish caught from coastal waters off Point Palmilla, Baja California Sur, June 2015. Length: 16.5 cm (6.5 inches).

Eastern Pacific Flagfin, Female, Aulopus bajacali. Fish from coastal waters adjacent Gordo I Bank, Baja California Sur, January 2008. Length: 20 cm (7.9 inches). Fish identification courtesy of Dr. Ross Robertson, Smithsonian Tropical Research Institute, Panama.

Eastern Pacific Flagfin (1)Eastern Pacific Flagfin (2)

Eastern Pacific Flagfin, Male, Aulopus bajacali. Fish caught out of coastal waters off Point Palmilla, Baja California Sur, June 2015. Length: 13.0 cm (5.1 inches).