Sea of Cortez (Flickr)

MEX - A Deep Dive with Sharks in Mexico's Sea of Cortez: Then and Now

How wildlife is fighting to thrive in the Mexican sea, which captured the hearts of Jacques Cousteau and John Steinbeck.

The French environmentalist Jacques Cousteau once described Mexico's Sea of Cortez, also known as the Gulf of California, as “the world’s aquarium”. The combination of the temperate waters to the north of the gulf and tropical, warmer waters to the south create incredibly productive waters, which have led to comparisons to the Galapagos Islands. Swimming beneath the surface you can see whale sharks, bull sharks, hammerheads, manta rays, dolphins, schools of tuna and an abundance of other species.

In total, around 900 species of fish have been recorded in the UNESCO World Heritage Site, which comprises 244 islands, islets and coastal areas in total.

Mexico is in a position to become a beacon for community-led management through ecotourism, stimulating a sustainable use of marine resources.

The city of La Paz, on Mexico’s Baja California coast, is the tranquil gateway to this beauty. The waterfront area, known as the Malecón, is soundtracked by seabirds and sprinkled with statues - of a mermaid, hammerhead sharks, whales and even Jacques Cousteau himself. From here, you can head out to the legendary Isla Espíritu Santo, an otherworldly archipelago where sea lions play amongst lush coral reefs.

While the waters remain amongst the most productive in the world today, the Sea of Cortez has seen drastic changes in the past century. Where once it would’ve hard to visit El Bajo - on the fringe of La Paz Bay - without seeing hammerhead sharks, this beautiful species and many others were largely eradicated from the area due to fishing licences handed out in the 1990s. This devastated both endemic species and the local economy - parts of which relied on the tourism to the area of divers wishing to see those sharks.

The area, to first-time visitors, seems simply abundant with life. But shifting baseline theory should be considered here - the theory that reminds us that conditions are generally only monitored, or judged, from their present state, rather than in their historical context. Seeing one hammerhead shark today would inspire romanticism in most, for example, but in the 70s and 80s, you could literally have seen hundreds of hammerheads on every single dive.

A school of Hammerhead sharks in the ocean near Ecuador, Galapagos
Hammerhead sharks were once commonplace in the Sea of Cortez, but have suffered from overfishing. Photo: Getty

Dr. James Ketchum is the co-founder of the environmental NGO Pelagio Kakunjawho work to protect marine life in the area. He told an International Ocean Film Festival panel: “I was a divemaster and I remember seeing hundreds of these hammerheads, and I remember seeing their decline. And the same with tuna and sailfish [...] This isn’t just happening here, either. It’s a worldwide problem.”

It’s not too late, though. The hammerhead nursery is regenerating thanks to the work of people like Dr. Ketchum, and with appropriate protection, this incredible area can return to the full wonder that made it so famous to start with.


It was in 1940 that John Steinbeck, author of The Grapes of Wrath and Of Mice and Men, journeyed along the Gulf of California with marine biologist Ed Ricketts, later immortalising his experiences and the place itself in the non-fiction book The Log from the Sea of Cortez.

“Below the Mexican border the water changes colour,” he wrote. “It takes on a deep ultramarine blue - a washtub bluing blue, intense and seeming to penetrate deep into the water.” Steinbeck writes of a large shark which “cruised about us, his fin high above the water,” of large horned sharks, hammerhead sharks, basking sharks and “great numbers of sand sharks,” as well as great manta rays, sting rays, tuna, swordfish, urchins, morays and so very much more.

Read more.