Keeljaw Needlefish, Tylosurus melanotus
Keeljaw Needlefish, Tylosurus melanotus. Fish caught from coastal waters off Puerto Los Cabos, Baja California Sur, December 2003. Length: 60 cm (2 feet 0 inches).
Keeljaw Needlefish, Tylosurus melanotus. Fish caught from coastal waters off Loreto, Baja California Sur, May 2019. Length: 62 cm (2 feet 1 inches). Catch courtesy of Marty Dufek, Huntington Beach, California. Photograph and identification courtesy of Chris Wheaton, Fullerton, California.
The Keeljaw Needlefish, Tylosurus melanotus, is a member of the Needlefish or Belonidae Family, that is also known as the Agujón Needlefish and in Mexico as marao isleño. It was once thought to be the Pacific equivalent of the Atlantic Agujón, Tylosurus acus, a species only found in the Atlantic and lacking the keeljaw. Some of my scientific friends believe that this is form of the Pacific Needlefish, Tylosurus pacificus, but others recognize it as a separate species. Globally, there are six species in the genus Tylosurus, of which three are found in Mexican waters, one in the Pacific and two in both the Atlantic and the Pacific Oceans.
The Keeljaw Needlefish has a slender elongated rounded body with a dark blue upper body, silvery sides, and a white belly. They also have a light blue stripe along their flanks. Their jaws are prolonged and their upper and lower beaks are of equal length, relatively long (18% to 20% of standard length), slender, and up-curved with many long pointed teeth. The key to identification is a keel found near the tip of their lower beak (pictured above). Their caudal fin is deeply forked with the lower lobe being much longer than the upper lobe; their dorsal fin has a long base; and, their pectoral and pelvic fins are short.
The Keeljaw Needlefish is an oceanic pelagic fish found in the first 9 m (30 feet) of the water column. They reach a maximum length of 1.00 m (3 feet 3 inches). As of January 1, 2023, the International Game Fish Association world record stood at 1.47 kg (3 lbs 4 oz) with the fish caught in coastal waters off Tanzania in January 2019. The Keeljaw Needlefish 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 Keeljaw Needlefish is a resident of Mexican waters of the Pacific Ocean and was thought to be found only around the various oceanic islands including Clipperton, Cocos, Malpelo, Revillagigedos, and Tres Marias, however, I have made catches in the coastal waters in the greater Los Cabos area, and the photo above documents they are found as far north as Loreto within the Sea of Cortez, extending the known range for this species.
The Keeljaw Needlefish is easy to identify due to the keel under its chin and therefore cannot be confused with any other species, but it is otherwise very similar in appearance to the Giant Mexican Needlefish, Tylosurus fodiator and the Pacific Needlefish, Tylosurus pacificus. There is some controversy about this species in the scientific fish community, with some believing that it is a standalone species and others believing that it is a variation of the Pacific Needlefish. The differences between the two include: the keel under the tip of the chin (not present in the Pacific Needlefish), 24 to 26 dorsal fin rays (versus 21 to 23), 21 to 24 anal fin rays (versus 18 to 21), and 89 and 92 vertebrae (versus 74 to 80).
From a conservation perspective the Keeljaw Needlefish has not been formally evaluated. Although uncommon in Mexican waters it is viewed by locals as a pest with “too many bones” to be utilized for food. They are either a “catch and release” or retained for use as cut bait for bottom fishing. When hooked they like to make mad, short dashes. They are excellent bait stealers inflicting major damage to and weakening monofilament lines with their many teeth. When hooked they become acrobatic, making spectacular jumps while bending themselves into complete circles, and make mad, short dashes.