Sea of Cortez: Saving the World's Aquarium
Nov 20, 2019 | 10 minute read
Reading Time: 10 minutes

For decades, the Gulf of California was revered as one of the world’s most incredible marine ecosystems. Also known as the Sea of Cortez, the 700-mile-long gulf is home to nearly a thousand fish species, 5,000 types of invertebrates, as well as a variety of rare marine mammals and sea turtles. But for all its beauty, the Gulf of California is an ecosystem in decline.

Aerial panoramics from Espiritu Santo Island, Baja California Sur, Mexico

The variety and abundance of sea creatures have made the Sea of Cortez a very lucrative fishery. In fact, fishing is one of the key drivers of the local economy. The commercial shrimp fishery alone is responsible for 37,000 Mexican jobs. Tourism, with the sportfishing industry as its main driver, generates around $500 million in expenditures each year.

On the flip side, the fishing industry has arguably become too reliant on the resource. This has led to overfishing across the sea and pushed many native creatures to the brink of extinction. As commercial fishing continues and tourism expands, pollution is likely to impact even the deeper waters of the gulf.

an entire coral trapped in a fishing net

Today, we’ll explore the wonders this bountiful sea has to offer, the dangers it faces, and what we can do to preserve it.

The Aquarium of the World

The Sea of Cortez, one of the most biologically diverse bodies of water on Earth, is also among the world’s youngest. The gulf was formed some 4–5 million years ago, thanks to a tectonic rift between Baja California and the North American Plate. To this day, the sea separates Baja California from mainland Mexico.

Who lives here?

The Gulf of California is home to an astounding number of sea creatures. Almost a thousand resident and migratory fish species swim in these waters, many of them endemic. In fact, one in 10 of these fish live here and nowhere else on the planet!

One of these is the critically endangered vaquita, a porpoise whose numbers have diminished drastically over the last couple of decades. Recent estimates say that there are only 12 of these creatures left!

the Vaquita Porpoise

The gulf is home to a wide range of game fish. From various types of Tuna and Billfish, to Sharks, Groupers, and Snappers, this place is an angler’s paradise. There’s also a variety of Rays, as well as Lobsters, Sardines, Squid, and others.

And it’s not just fish. The Sea of Cortez also houses thousands of invertebrates, as well as a wide range of rare marine mammals. As many as 36 species of marine mammals inhabit the gulf. To put that into perspective, the entire coast of the state of Alaska has 29 such creatures.

A baby humpback whale
A baby Humpback Whale.

Goliaths like the Humpback, Killer, and Sperm Whale often migrate to the Sea of Cortez to feed and reproduce. On occasion, the gulf is even visited by the largest creature in existence, the Blue Whale. And some, like the Fin Whale, have made this sea their permanent residence.

With all this in mind, it’s easy to see why French explorer Jacques Cousteau famously dubbed the area “The Aquarium of the World.”

The diversity of wildlife is not the only thing that makes the Gulf of California special. These waters are home to many oceanic processes that normally occur in very different locations. This makes the Sea of Cortez even more interesting to marine biologists and researchers.

A Gourmet Dining Table

As it usually happens in nature, thousands of sea creatures didn’t come to call the Sea of Cortez home by accident. Thanks to a number of oceanic processes, the gulf consistently serves up a feast of nutrients for its resident sea creatures. 

a Californian Sea Lion in the Sea of Cortez

Fifty years ago, the Gulf had a steady influx of nutrients and minerals from the Colorado River. Nowadays, the river has diminished significantly, but the Gulf continues to produce its food. How is this possible?

The Tides

The Gulf of California holds an immense amount of water. When Pacific tidal movements happen, the waters move in and withdraw in a massive movement. So massive, in fact, that the northern part of the gulf sees an incredible 32′ tidal range! 

the low tide in the gulf of california

This colossal movement results in waters mixing at depths as deep as 1,500 feet, thus creating a strong continuous current. When water from the surface moves away from the coastline, it is replaced by “new” water from below. This is called an upwelling. Upwelling doesn’t just bring new water; it brings huge amounts of nutrients, as well. 

These nutrients attract crustaceans and small fish, which, in turn, attract larger fish, birds, and sea mammals. 

The Mangroves 

The edges of the Sea of Cortez are dotted with mangrove forests. Providing shelter and nutrients, these forests serve as feeding and nursing grounds for a variety of fish species. In fact, a recent study has shown that mangrove forests are strongly associated with the number of fish landings in the Gulf of California. 

an estuary in the mangroves

Scientists went so far as to put a dollar value on what the mangrove forests bring to the local economy. According to the data, a single hectare of mangrove forests brings $37,500 to the local fishing industry. 

Sadly, mangrove forests have come into grave danger in recent years. With the aggressive expansion of the tourist trade, more and more mangrove forests are being cut down in favor of resort areas and boat launches. Worse still, the government fails to realize the ecological and existing commercial value of these coastal areas, often selling them for pennies on the dollar.

Leaving the coastal regions behind and venturing into deep waters, the Sea of Cortez becomes even more fascinating.

A Whole Other World

Due to its position between two shifting tectonic plates, the Sea of Cortez has seen its share of remarkable geological occurrences. Perhaps most bewildering is the fact that the Baja Peninsula still hasn’t stopped moving away from mainland Mexico. Every year, the 800-mile strip of land moves another 2 inches towards the Pacific, expanding the Sea of Cortez.

the map of the gulf of california
Long ago, the Baja Peninsula was a part of mainland Mexico.

For the world below the water surface, this means a lot. For instance, recent diving expeditions in the Gulf have uncovered astounding new lifeforms that thrive in the harshest of environments. 

While exploring hydrothermal activity, researchers from the Schmidt Ocean Institute found large venting mineral towers reaching over 75 feet in height. These towers not only came in an incredible array of colors, they featured what you could only describe as “upside-down burning mirror-pools.” If that sounds a little out there, that’s because it is.

a reverse mirror pool caused by Hydrothermal vents in the Sea of Cortez
Source: Schmidt Ocean Institute

As SOI Chief Scientist Dr. Mandy Joye puts it: “Hydrothermal vents are caused by magma beneath the Earth’s surface heating water that has seeped into the rocks on the seafloor. As the water gets hot, it rises, and shoots out of the seafloor into the ocean.”

Scientists also found patches of seabed oozing with methane gas. What’s even more impressive is that there are organisms that not only survive in these volatile conditions, they thrive. Understanding these organisms can help science, medicine, and technology for years to come.

If they’re still there, that is. On their dives, SOI researchers often found plastic bags and other human-created debris lying on the sea bottom. For all the beauty the bottom the Sea of Cortez offers, one can’t help but feel disheartened by the piles of rubbish on its seabed. 

A Golden Goose

For decades, the Sea of Cortez was one of Mexico’s prime sources of income. Be it from commercial fishing, sportfishing, or tourism, these waters were a treasure trove for the local economy. After years of unregulated fishing however, Mexico is dangerously close to losing its golden eggs.

Commercial Fishing

With an annual $260 million in landings, shrimping is Mexico’s most important fishing industry. Shrimping is also the largest contributor to employment in the Gulf area, with 37,000 direct jobs and 75,000 indirect ones. Boasting the single largest fishing fleet of 711 bottom trawlers and about 16,000 small-scale vessels, commercial shrimpers bring in a whopping 40,000 tons of shrimp annually.

shrimps in a fishing net

At the same time, the commercial shrimping industry is one of the most ecologically detrimental fisheries in the Gulf of California. For years, industrial bottom trawlers have decimated the seabed, gulping up century-old corals, fish, and anything else in their path. For every pound of shrimp caught, the trawlers pulled out 40 pounds of bycatch! 

a large trawling boat with its nets in the water

This meant that tens of thousands of tons of marine creatures were needlessly killed off. Fortunately, in 2006, Mexico introduced a fishery improvement plan, reducing the fleet by 50% and implementing new gear requirements to lower bycatch levels. Before a longterm stock assessment, we won’t know just how effective the initiative was. Still, after decades of almost unregulated fishing, this was a step in the right direction.

Smaller scale artisanal fishing, on the other hand, is much harder to regulate. For example, illegal gillnetting for the endemic Totoaba has all but wiped out the species. Totoaba, namely its swim bladder, is a prized delicacy in China, and there’s a large smuggling industry behind it. After years of overfishing, the Totoaba is now on the IUCN Red List of Threatened Species.

To make matters worse, Totoaba gillnetting has proven to be the primary cause of death for the already critically endangered vaquita porpoise. Today, even with the regulations in place, there’s a strong feeling that there is nobody to enforce them. If poaching continues to devastate the gulf, it’s safe to say that the vaquita’s days are numbered.

Recreational Fishing and Tourism

Sportfishing in the Gulf of California has always been a popular activity. Fishing in the Los Cabos area alone reels in an annual $57 million for the local economy. Each season, towns like Guaymas, Puerto Peñasco, La Paz, and Loreto come alive with anglers hoping to land “the big one.” Many of them do.

For all the bounty it’s known for, the Sea of Cortez boasts a fraction of the abundance it once had. With fewer small fish around, there’s less food for big game predators. Even the birds are fewer these days. Seasoned fishermen claim that today’s catches wouldn’t even make it to the boat 30 years ago. A week’s bounty was just a two-day effort back then. 

a fishing rod on a boat in the Sea of Cortez

Even so, sportfishing continues to bring big money to the region. So much so, that a number of “mega-resorts” were approved by the Mexican government recently. Each of these resorts was supposed to offer tens of thousands of rooms and suites, with multiple golf courses and marinas to boot. 

One such resort was Cabo Cortes, a giant 30,000-room complex that was to rise near the gulf’s lone coral reef, Cabo Pulmo. The resort was to feature two golf courses, a large marina, and an anti-salinity plant to provide all the fresh water for the complex. 

Luckily, this little coastal town is one of those special places where the local community repeatedly chooses to forgo an opportunity for profit in order to save its environment.

An Environmental Success Story

Twenty-five years ago, the families of Cabo Pulmo relied almost exclusively on fishing to make a living. During the 1980s, commercial and artisanal fishing was in full swing. As much as they fished, local fishermen began to notice that the area was not as abundant as it once was.

cabo pulmo corals

It was at that time that students and professors from the Autonomous University of Baja California Sur began to visit the coastal community. They wanted to educate the locals on just how important a healthy coral reef was. Even though they were dependent on fishing to make a living, locals realized the damage anchors and intensive fishing were doing to the reef.

Finally, in 1995, the families of Cabo Pulmo decided to ask the Mexican government to make the reef a protected area. Shortly after, the waters of Cabo Pulmo were declared a National Marine Park. As good as that sounded, the families were no longer able to fish. They needed another way to put food on the table. 

Progressive as they were, it didn’t take the locals long to figure things out. Some of them became snorkeling and diving instructors. Others opened up restaurants, and some continued to fish outside the park. Within a few years, the town blossomed to a popular resort community. Just a few miles away, something even more impressive was blooming. 

a school of fish in Cabo Pulmo, Sea of Cortez

Declaring the area protected meant that fish and all the other organisms were able to feed, grow, and mate across the 7,111-acre reserve. With no anchors or fishing lines, the reef started to grow back, too. After 20 years of no extraction, the biomass of sea life has increased by a whopping 460%! Just like that, Cabo Pulmo National Park became the most recovered marine reserve in the world.

It’s Not Too Late

The Sea of Cortez is a unique treasure trove of marine wildlife. From exciting goliaths to intriguing microorganisms, the Gulf of California provides sustenance for thousands of sea creatures. Not only that, but the expanding body of water is also home to some of the most remarkable natural phenomena we’ve ever seen.

Sadly, the Sea of Cortez is not what it once was. Through overfishing and poaching, many fish species have become critically endangered. Years of industrial trawling have ravaged much of the seabed. With no food to find, thousands of sea creatures have either migrated or perished.

For years, the Mexican government has tried to curb these dangers. Regulations are now in place, but enforcing them is not easy. Large scale commercial fishing is finally hitting sustainable levels, but illegal fishing is still raging unchecked.

Moreover, pollution had infested some of the most precious parts of the sea. With resorts continuing to sprout around the gulf, the local ecosystem seems to be heading to a cliff at a very fast pace. However, there is still hope. 

Through better enforcement, illegal fishing can be stopped. The manpower will cost money, but as Gandhi once famously said: “Action expresses priorities.” Cabo Pulmo, a shining example of successful conservation, can be a blueprint for many other future marine reserves. Tourism, the gulf’s lifeline, will still be able to flourish through watersports and sportfishing in unprotected areas.

the sea of cortez

For all the hardship it has endured, the Sea of Cortez has proven to be a remarkably resilient ecosystem. Like a poker player pulling an ace at the last moment, life in the incredible gulf has survived almost everything we have thrown its way. Hopefully, this will buy us just enough time to save it.

Have you ever visited the Sea of Cortez? What was your favorite thing about its beautiful waters? Let us know in the comments below.

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