Megamouth Shark # 38: The First Megamouth Shark, Megachasma pelagios, Found in Mexican Waters

November 16, 2006

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Sources of Information:
M. en C. José Leonardo Castillo Géniz
Centro Regional de Investigación Pesquera de Ensenada
Instituto Nacional de la Pesca
Carr. Tijuana-Ensenada km 97.5
El Sauzal de Rodríguez, A.P. 1306
Ensenada. B.C., Mexico. Phone: (646) 174-6135 y 174-6140
with photographs taken by José Leonardo Castillo-Geniz
On November 16, 2006, the crew of the F/V "Corina del Mar" (a commercial shark boat based in Ensenada, B.C., Mexico), under Captain Edén Magaña, and his crewmen Eleazar Murillo, Jesús Molina y Samuel Van-Borsted, accidentally caught a "very rare" shark in waters in front of Tortugas Bay (BCS), on the Pacific coast of the Baja California Peninsula, Mexico.

Location were the megamouth was incidentally caught in front of Tortugas Bay, B.C.S., Mexico.
courtesy José Leonardo Castillo-Geniz

After their return to the Port of the Sauzal in Ensenada, convinced of the rarity of the shark, and its possible scientific importance, the owner of the ship Saúl Romero and the Captain Magaña invited José Leonardo Castillo-Géniz, a shark specialist from the Ensenada's Regional Fisheries Research Center of the National Fisheries Institute of Mexico, on November 27 to examine and possibly identify the shark species. According to the shark biologist Castillo-Géniz, he observed the elongated and flabby body of the animal, its particularly huge and terminal mouth, and a group of black circular spots over its ""inferior lip" of its jaw. These observations gave him the first hint about the possible identity of the specimen, and some minutes after the initial shock from the excitement, he identified the shark and confirmed it as the first record of the megamouth shark ("tiburón bocón" in Spanish), Megachasma pelagios to be captured and documented in the waters off of Mexico.

According to Captain Magaña, the megamouth was captured off Tortugas Bay, in B.C.S., Mexico. This is a region that also includes Cedros Island and Sebastían Vizcaíno Bay in the western coast of the Baja Peninsula and is considered by the fishermen as a traditional fishery ground for sharks, including makos Isurus oxyrinchus, and thresher sharks Alopias vulpinus.

With the support of the local fishery company "Pesquera Cortés", the megamouth was frozen and conserved immediately for posterior examination. In the morning of November 28th, a team of technicians and students (Arturo Ocampo, Carmen Rodríguez, Alfonso Medellín, Ely Cuevas, Miguel Olvera, Santa Rodríguez, Erick Oñanate, Omar Santana, Jenny Chong y Nadia Olivares) from the fishery ecology laboratory of CICESE, lead by Castillo-Géniz, conducted the first examination of the shark. The specimen was determined to be an immature female with a total length of 214.9 cm and body weight of 27 kilograms. Several morphometric measurements were taken as well as samples of the stomach content, teeth, and dermal denticles. This information and data will be generated in the next weeks, allowing specialists to describe in detail the first record of Megachasma pelagios in Mexican waters. Given the stage of sexual immaturity of the shark, the shark team decided not to conduct a dissection of the body, because there is the intention of maintaining the shark intact for future public exhibition in Mexico.

The presence of the megamouth shark confirms the enormous diversity of sharks and rays that inhabit in Mexican waters.

© José Leonardo Castillo-Geniz

Research team INP-CICESE that conducted the first examination of the Megachasma pelagios
© José Leonardo Castillo-Geniz

The first megamouth shark found in Mexican waters
© José Leonardo Castillo-Geniz

Head of the megamouth
© José Leonardo Castillo-Geniz

Mouth and tooth of the megamouth
© José Leonardo Castillo-Geniz