Colorado Grouper, Mycteroperca olfax
Colorado Grouper, Mycteroperca olfax. Fish photographed in Chedraui Mercado, San Jose del Cabo, Baja California Sur, May 2021. Length: 40 cm (16 inches). Identification reconfirmed by Dr. Matt Craig, NOAA, La Jolla, California. Photograph taken of the fish in the display case. Regretfully I failed to purchase the fish which would have provided a badly needed world class photo of this species.
The Colorado Grouper, Mycteroperca olfax, is a member of the Grouper or Epinephelidae Family, that is also known as the Bacalao Grouper and the Sailfin Grouper and in Mexico as garropa parda and mero bacalao. Globally, there are fifteen species in the genus Mycteroperca, of which eleven are found in Mexican waters, seven in the Atlantic and four in the Pacific Ocean.
The Colorado Grouper has an elongated, robust, and compressed body with a depth that is the same at the origin of the anal and dorsal fins with a standard length of 2.9 to 3.1 times the body’s depth. They are dark to olive brown in color with purple or light brown spots or they are dark brown and they have 10 to 12 thin dark bars on the upper body. The margins of the fins have dark margins with narrow white borders. A small percentage of the population is a xanthic morph that has an overall bright yellow color.
The adult Colorado Grouper is found among rock walls, rocky reef drop-offs, underwater lava ridges and vertical rock structures at depths up to 100 m (330 feet). The juveniles are found in shallow sandy lagoons, seagrass beds, mangrove and shallow lava reefs. They reach a maximum length of 1.20 m (3 feet 11 inches). A Grouper Family Weight From Length Conversion Table has been included in this website to allow the accurate determination of a fish weight and a return to the ocean unharmed. Juveniles are found in shallow sandy lagoons, seagrass beds, mangrove lagoons, shallow lava reefs and inland lava ponds. The males are normally found further offshore within banks than the juveniles and females which are found in coastal inshore reefs. They head has a long snout with a projecting lower jaw that is equipped with depressible teeth with canines at the front of the jaws. Their anal fin has 3 spines and 11 rays; their caudal fin is emarginate in adults and truncate in juveniles; their first dorsal fin has 11 spines with the second and third spines being elongated and the second being longer than the third; and, their second dorsal fin has 16 or 17 rays and is rounded. They have 24 to 29 gill rakers. They are covered with scales above the lateral line. Adults are mainly piscivorous, and large adults feed primarily on Pacific Creolefish, Cephalopholis colonus. The Colorado Groupers are protogynous hermaphrodites commencing life as females and changing to males midlife. The females becoming sexually mature at four years of age and then transition to males around twelve years of age. Females outnumber males by more than 50 to 1. Reproduction occurs in spawning aggregations of 40 to 60 individuals. They have life spans of twenty-one years.
The Colorado Grouper is known primarily within a small range in three remote, offshore island localities in the eastern tropical Pacific – the Cocos Islands, the Galapagos Islands and Malpelo Island. From discussions with Matt Craig, who reconfirmed the identification of the above photographed fish, the Colorado Grouper is also known to the southeast coastal line of the Baja south of La Paz.
The Colorado Grouper can be confused with the Leopard Grouper, Mycteroperca rosacea (greenish gray-brown covered with small red spots) and the Parrot Sand Bass, Paralabrax loro (third dorsal spine 3X second dorsal spine; 17 gill rakers).
From a conservation perspective the Colorado Grouper are currently considered to be VULNERABLE. They reside in a small geographic range, slow growth rates, late maturity and reproductive cycles and are targeted by both commercial, recreational and spearfishermen during spawning aggregations in April and May. Once abundant their populations are currently in significant decline which has been attributed to overfishing. Their removal from the native environment will no doubt cause a significant impact on the balance within their native habitat. In addition, the size of the catch is significantly smaller being composed primarily of females and sexually immature juveniles. They are an excellent food fish and are utilized in a traditional Easter dish in Ecuador called fanesca.