Fixing the Broken Aquarium of the World

How the collaborative effort of scientists, fisherfolk, and natural resource managers to protect rocky reef habitats is the key to restoring and preserving the uniquely biodiverse and productive Gulf of California (Sea of Cortéz)

Written and illustrated by Alan Ruiz Berman

The Gulf of California, commonly known as the Sea of Cortéz, is one of the planet’s most biodiverse and productive bodies of water. A long and turbulent sea it lies between the Mexican mainland and the Baja Peninsula – a finger of arid, but in some unique places lush, mountainous land, three times the length of Florida. With around one hundred commercial fisheries in the northern Gulf alone, the Sea is of critical socio-economic importance to both Mexico and the United States. In the early 1970’s, world famous marine explorer, Jacques Yves Cousteau dove the Gulf of California’s reefs and dubbed this Mexican sea, “The Aquarium of the World,” because so much of Earth’s marine biodiversity could be found here.

But worrying trends have revealed that the World’s Aquarium has long been broken. An overall and persistent decline in reef health speaks to the urgent need to save the Gulf of California from the sort of total ecological collapse that previously vibrant seas like the Mediterranean underwent decades ago. The key to this conservation effort lies in a crucial habitat – the Gulf of California’s rocky reefs, which foster much more than their share of biological diversity and abundance. Indeed, it is the Gulf’s reefs that allow for recreational and commercial fishing activities to continue today, along with a still thriving eco-tourism industry that caters to boaters, snorkelers, and divers.

Furthermore, to restore and protect the Gulf’s crucial reefs we must continue the long-running project of monitoring ecological changes, year after year, and well into the future. By keeping tabs on a wide diversity of species (vs. fisheries monitoring which focuses only on the commercial catch), above and below the water, Marine Ecological Monitoring allows decision makers to make wise decisions about where limited resources are best spent. The goal is to create an effective network of interconnected Marine Protected Areas – places of refuge and recovery for marine life that are supported both by local communities and by the Mexican government and its international partners.


(history and ecology of the Gulf of California and the critical importance of its rocky reef habitats)

The name “Sea of Cortéz,” though popular still, is appropriately going out of style; the infamous conquistador, Hernan Cortés, never once explored the sea but instead sent one of his finest captains, Francisco de Ulloa, to do so in 1539. On a note that will become relevant later in this article, Ulloa noted that the northern Gulf was so full of sharks that a man could practically walk to shore across their backs. The Indigenous resident must have watched Ulloa arrive with considerable fear and hostility toward the unknown enemy. They had never seen the likes of a Spanish Galleon, but the northern Comcaac/Seri regularly crossed kilometers of their sacred sea on balsas of braided reeds with nothing but a harpoon and paddle. The Seri hunted sea turtles, and like the northern Plains Indians, wasted not a single strand of ligament or organ – relying on the bladders to store their freshwater. They are one of only two cultures on the planet to have been sustained so heavily by the sea turtle – the other being the Aboriginals of Australia’s far northeastern Tora Strait, not far from the tropical seas of New Guinea. Today, these groups visit one another regularly on cultural exchange. 

For tens of thousands of years before European adventurers braved its unruly waters and rugged coastlines, the Gulf was inhabited and held sacred by millions of resident Indigenous people, both on the Baja Peninsula and Mexican Mainland – including the Tohono O’odham, Cocopah/Papago, Comcaac/Seri, Mayo, and Yaqui Nations. In addition to hunting deer and foraging edible and medicinal desert plants, some of these highly mobile groups lived directly from the marine life in nearshore waters, including sea lions, fish, and shellfish. Many were bold warriors – never giving up their sovereignty to New Spain, nor to the Church, nor to Mexico, and were thus brutally persecuted well into the 20th century. Indeed, the survivors were forced to hide in the most inaccessible and arid region of their homeland, Isla Tiburón, to avoid capture and/or death. For the traditional stewards of the Gulf, and for thousands of small-scale fisherfolk today, the sea remains their very lifeblood.

By land, the first westerner to explore the Gulf was the Italian Father Usebio Francisco Kino, better known as Padre Kino, a Tyrolean Jesuit missionary and explorer extraordinaire, who from the high volcanoes of what is now the Pinacate Biosphere Reserve, noted that the Baja Peninsula was not, as was previously considered, a large island. The Gulf is also known as the Vermillion, or Crimson Sea, so called for the rich silt deposits that for millions of years flowed freely into its head from the mighty Colorado River. In the 1930’s, this great River, the main artery watershed of the American Rockies, was dammed up to what is now just a small trickle allocated to the Delta’s diminished wetlands. This large-scale damming, most apparent in the massive walls of the Hoover Dam, changed the sea from a freshwater dominant estuary to a saline or “negative estuary.” Other smaller tributaries that once ran into the Gulf, such as the Sonoita River, have also dried up due to the overuse of groundwater further North, and with them native plants and animals like minnows, frogs, insects, clams, and turtles have perished, some now extinct. The new border wall was recently erected directly across the remains of Sonoita Creek, and the project disgracefully pumped water from the precious fossil springs of Quitobaquito in Organ Pipe National Monument.

The Gulf of California’s diverse waters comprise a wide climatic range – from a temperate and sub-tropical ecosystem in the Northern Gulf, to a “Panamic,” or tropical marine ecosystem in the Southern Gulf. The beginning of the Gulf is the Colorado River Delta (just South of San Diego) and it continues South to an imaginary line that is typically drawn by marine ecologists from the tip of the Baja Peninsula (Cabo San Lucas) to near Puerto Vallarta on the Mexican mainland. This vast area includes 4,000 km of arid coastline and in its deep blue heart lie 3,000-meter-deep ocean trenches – among the deepest parts of our planet. These trenches are being formed by the Baja Peninsula, which rides atop the North American Plate, splitting away from the Pacific Plate on a northwesterly track along the famed San Andreas Fault. The tectonic split occurs at a geologically good clip of around one inch per year, and along the fault hydrothermal vents open along the seafloor – named so because they vent gases heated by friction and the magma seeping up from under the Earth’s crust. Recently discovered around these vents and their “smoking” mineral towers is a vast chemo-synthetic biological community – organisms existing entirely without oxygen. These giant tube worms, crabs, clams, and other high-pressure adapted critters can provide us with insights as to what life on other planets might look like. 

Marine ecologists have divided the Northern, Central, and Southern Gulf into three, distinct biological regions (see map above), each comprising a specific latitudinal range and containing a wide array of distinct habitats, including sandy sea bottoms, mangrove estuaries, rocky reefs, and deep-oceanic trenches. The Gulf’s overall habitat diversity, together with its circulating currents that flow clockwise in summer and counterclockwise in winter – like a giant washing machine, foster an impressive diversity and mass of life – transferred by these same surface currents across extensive areas.

The Gulf’s highly interconnected web of life includes 185 invertebrate species in 14 major groups: the sponges, sea pens, stony-corals, sea fans, flat worms, sea worms, sea stars, sea urchins, sea cucumbers, snails, clams, sea spiders, crabs, and sea squirts (or ascidians). Typically, the number of unique marine and terrestrial species increases as one moves southward towards the tropics, however, the Gulf shows a reversed trend. Occurring throughout the Gulf, the most abundant invertebrate groups are the sea fans, sea urchins, corals, sea pens, and sea squirts, with the greatest diversity of species occurring in the Central and Northern Gulf primarily in an area known as the “Midriff Islands.” The Central zone is home to somewhere between 106 – 129 invertebrate species, where in the Southern Gulf, invertebrate diversity decreases by around 38%. Even southern biodiversity hotspots are less diverse, with the Islas Marias hosting only 62 invertebrate species – mainly sea fans and corals, and Bahia Banderas and the Revillagigedo Islands hosting only around 49. In the rocky reefs of Revillagigedo, currents are so powerful that for the most part only hardy sea urchins can survive clinging atop the mostly bare rocks. 

Researchers conducting underwater Marine Ecological Monitoring have discovered that the cause for the Gulf’s latitudinal reversal in biological diversity is mostly due to a lack of rocky reef habitats further South, as well as to the Southern Gulf’s less nutrient-loaded and warmer waters (which range from 23 – 30°C or 73 – 86°F). Simply put, food is scarcer in the Southern Gulf, so while sea fans and corals – using their millions of tiny polyps to filter particles from passing swells and currents thrive, many other invertebrate and fish species lack both the food and shelter that currents and rocky reefs further North generously provide. 

Northern reefs also have the advantage of sitting in colder waters (14-23°C or 57-73°f), which not only contain more oxygen but, as they rise from the ocean floor – pushed horizontally then vertically up against the walls of deep ocean trenches like the Guaymas Basin, become laden with nutrients from the seafloor. The cold, nutrient-rich water being brought up from the deep sea to the surface allow, in the sunlit (200m deep) “photic zone” which is home to 90% of marine life, for algal (phytoplankton) blooms so large they can be seen from space – appearing like a neon-green, aquatic aurora borealis. These algal blooms, in turn, form the foundation of the Gulf’s entire marine food web. In addition to these deep-sea nutrients, the Colorado River for millions of years deposited nutrient rich silt into the Northern Gulf, such that even with the river having been dammed, there is still a residual supply of nutrients in this basin. 

The amount of life in our oceans is commonly estimated by scientists and fisheries managers in terms of Biomass (B), which is a measurement of living organisms in an area over a selected period of time. Biomass can refer to species biomass, which is the mass of a population of one or more species based on the weight of sized individuals, or to community biomass, which is the mass of all the species existing in an ecological community, and which can include microorganisms, plants, and/or animals. The central and northern Gulf’s weighty planktonic biomass can feed a great diversity of fishes and invertebrates, and even a healthy population of blue whales (Balaenoptera musculus) – the largest animal ever to inhabit our planet on land or sea. Also at the Gulf’s dining table are half of Earth’s diversity of marine mammals including sea lions, orca, dolphins, sperm whales, and the other two largest baleen whales, the fin and grey whale. Baleen Whales reciprocate for their food source, irrigating the water with their feces and returning to it abundant nutrients, namely phosphorous, that are critical to maintaining the planktonic biomass along with its crucial role producing half of all the air we humans enjoy breathing. 

The Gulf’s robust food web also supports five of the world’s seven sea turtle species and diverse forms of coastal and open-ocean avian life, like godwits, brown and blue-footed boobies, Herman’s gulls, and red-billed tropic birds to name just a few. Visiting an Island like San Pedro Martír, the furthest out from either of the Gulf’s rocky shores, feels much like going back in time, as one finds him/herself surrounded by feeding frenzied whales, sharks, sea lions, sea birds, and fish breaking the surface among a cacophony right out of the Jurassic period. If you visit in 2022, you will also see a frightening amount of sardine purse-seining boats, busily netting ton after ton of the silvery clupeid fishes. As I sat on a panga and helplessly watched the great body of marine life’s base be depleted from the bottom-up I could not help but wonder, how exactly is this ecosystem being managed if at all? 

Fixing the Broken Aquarium 

Throughout the 1970’s, 1980’s, and into the present day, the Gulf of California – commonly known as the Sea of Cortez, has been severely overfished by Mexico, the United States, and further away nations like Russia, China, and Japan, emptied of everything from sea cucumbers to large sharks. To what extent the Gulf’s coastal and marine ecosystem has been diminished is difficult to say, as studying marine ecosystems let alone the impact of specific fisheries is a relatively recent phenomenon. Nevertheless, we do have an anecdotal baseline, and there are generations of people still alive today who can tell of the unbelievable abundance of the now stiller and more silent Gulf. One of these eyewitnesses is the author and photographer Carlos Eyles, one of the first people to spearfish on the Gulf’s rocky reefs and to witness the mind-blowing beauty, and tragic decline, of the grouper fish (Serranidae spp.) that once existed in astonishing size and abundance.

What we do know is this – the Gulf’s health and potential for recovery continues to be severely challenged by illegal, unregulated, and unreported (IUU) commercial fishing, sardine netting, shrimp trawling, sport-fishing, unchecked coastal development, agriculture, various extractive and polluting industries, trash, and sewage; in all, the compounding impacts of unsustainably subsidized industries and rapidly growing tourism on top of a burgeoning population of over eight million coastal residents. Only through a collective, community-based effort, with full support from the Mexican government, the United States, and international community at large, can we hope to preserve some of the Gulf’s incredible beauty, natural resources, and the critical ecosystem services that we all rely on – such as natural climate change mitigation provided by the Gulf’s few but sizeable coastal wetlands.

The plight of the Gulf of California is perhaps best illustrated by that of the world’s most endangered marine mammal, the critically endangered vaquita marina, or sea cow, sometimes called the “panda of the sea” due to its endangered status and dark ring around its eye. Formally known to science as the Gulf of California harbor porpoise (Phocoena sinus), the vaquita is endemic to, or lives only in the heart of the northern Gulf, where a pod of around ten individuals is swimming dangerously close to the edge of extinction. This is an elusive species that has been seen by very few people, as they inhabit the silty, shallow waters of what was once the broader Colorado River Delta – an outlet that has been reduced to a mere trickle. These waters, located near the significantly populated fishing town of San Felipe, also a popular tourism destination for Arizona residents, are saturated with gillnets pertaining to local (legal and illegal) small-scale fisheries, chiefly for shrimp, a US bound export, and Totoaba, a large drum-fish illegally fished for the astonishingly high, black-market value of its swim-bladder in China. 

These gill nets entangle and drown multiple vaquita every year, and though we cannot say with much confidence how many die each year, the precipitous decline of their population from over a thousand to just a handful of individuals has been demonstrated by population and mortality studies carried out since the early 1980’s. The first study on vaquita mortality in fishing nets was carried out by CEDO Director Emeritus Peggy Turk Boyer, then a graduate student at the University of Arizona, and we now know that the vaquita has been on a steady and accelerating path to extinction since it was first identified in 1958. A proverbial “canary in the coal mine,” the loss of the vaquita – a top predator in the northern Gulf, suggests that we may be losing the marine ecosystem in its entirety, even with a United Nations World Heritage Site and Biosphere Reserve protecting it.

Indeed, few of the Gulf’s protected areas, including the polygonal area designated as a Vaquita Refuge, have been very effective, largely due to a lack of enforcement and buy-in from the region’s artisanal and industrial fishing industries. What is more, the Sinaloa drug cartel now controls much of the northern Gulf’s small-scale fisheries operations, while at the industrial scale government subsidies maintain the most impactful and least sustainable fisheries – such as those for sardine and shrimp. In the latter fishery, again for a primarily US market, 90% of the catch is wasted “bycatch” – dead or dying marine life that is pushed out through the boat’s scuppers and back into the sea where it decomposes and releases unknown amounts of carbon gas. As the sea floor is consistently dredged by the heavy metal and wooden trawl gear, the mud itself also releases unknown amounts of carbon dioxide that would otherwise be stored in these anoxic sediments. If all this were not enough, the Gulf’s few remaining mangrove forests and other wetlands – verdant isles among vast deserts on both sides of the Gulf and critical “blue carbon ecosystems,” or natural carbon storage areas, are also threatened by compounding impacts, from sea level rise to the short-term exploits of greedy coastal developers. Fortunately, some of the largest wetlands, like Adair Bay near San Felipe, are internationally recognized, including by the RAMSAR Convention on Wetland Conservation. Given their importance to carbon sequestration, their critical role providing the base of the marine food web, and their capacity to lower the risk of pandemics and water-borne diseases, wetlands like these should literally be valued as emeralds among the shifting sands.

Now, let us now delve into what can be done to protect the Gulf’s incredible treasure trove of life – much of it unique to this inimitable part of the world. Scientists and conservation professionals largely agree that Community-Supported Marine Protected Areas Are the future of the Sea of Cortez. Effective Marine Protected Areas (MPA’s), including adaptable, community-led forms such as Mexico’s legally recognized “Fisheries Refuge Zones” and “Community Management Areas” are federally enforced and locally stewarded areas of biological and economic importance. Importantly, these areas need be chosen using the best available, ecological, and social science, according to their potential social, economic, and ecological value. Researchers have found that a truly “healthy” reef is not just biologically diverse, which it is too, but also home to MORE and LARGER species at the top of the food chain such as sharks and grouper – fish that also tend to be the most marketable. This trend pertains not only to the Gulf’s rocky reefs but also to coral reefs, most of which would be unrecognizable today to tropical fisherfolk living at the turn of the century. On reefs that become overfished and degraded by compounding human impacts we see large fish and other predators vanish, while herbivores and zooplankton-eating fish become more abundant, benefiting from an absence of predators. As far as invertebrates, some, like corals, clams, and sea cucumbers, thrive on healthy, protected reefs, while other less commercial inverts, like sea urchins and sea stars, proliferate on unhealthy reefs.

By identifying ecologically and economically important natural processes, together with the areas and seasons required for them to take place, co-management of the ecosystem becomes possible. Science has also demonstrated how protection will be most effective when the boundaries of these carefully selected areas are LARGER and more ABSOLUTE in their standards of protection, and when they are maintained for LONGER periods of time. The greater these three parameters, the better the chances that a protected area will be able to recover. Just as importantly, it is necessary to prevent a naturally occurring social phenomenon known as “shifting baselines” – dramatic changes in our perception of just what constitutes a thriving ecosystem and/or human community. Simply put, if we begin to settle for less every year, soon nothing will be left. On the other hand, by consistently tracking changes over time using scientific methodology, we are not only able to identify and recall what real indicators of ecosystem and human health look like, but we are also able to set realistic targets for a more hopeful tomorrow. 

The unsung heroes of marine conservation in the Gulf and beyond are the divers, fishermen, and scientists who consistently monitor the Gulf’s reefs, year after year without fail. Throughout the Gulf, these monumental efforts are being carried out by experts working in collaboration with local people who have the distinct advantage of experiencing their rugged and isolated ecosystems firsthand on a day-to-day basis. Experts and fishing communities can help one another to collect and apply spatial, temporal (seasonal), and biological data (such as knowing where, when, and how often fish and invertebrates reproduce), enabling an effective, long-term conservation process known as Coastal and Marine Spatial and Temporal Planning. Furthermore, budding technologies like E-DNA, or Environmental DNA sampling, used to identify the presence of individual species from water samples, are becoming ever more important to understanding the ecology and connectivity of living organisms in the Gulf and to creating networks of effective protection. What is more, local buy-in to protection regimes ultimately determines whether management decisions remain on paper or are successfully implemented, meaning that compromises must be reached. Having more scientists and social workers on-the-ground is essential to building inroads and establishing long-term working relationships – for only through broad collaboration around common goals can we hope to save rocky reefs, and then the Gulf in its entirety.

The good news in all of this is that relative to terrestrial habitats such as a temperate forest, the ocean has a remarkable ability to recover, growing back its food web in decades as opposed to centuries. Nevertheless, robust protection is needed before we can begin to observe the marine ecological community’s capacity to restore itself to a stable and productive state. What is more, the replenishment of life can only happen across interconnected habitats, and there is an obvious reason why; young larvae of both fish and invertebrates are for the first days to months of their lives floating freely on ocean currents – too weak to choose their own course. Connectivity means that these larvae can be successfully produced in one area and carried to another protected place where they can settle safely and mature successfully in conditions that promote survival during their most vulnerable stages of life. 

Once mature and able to swim freely, many fish tend to stay within the bounds of Marine Protected Areas, revealing the unmistakable though often overlooked intelligence of fish. At the same time, fishermen have learned to skirt the perimeter of protected areas recognizing the effect of “spillover” – when reproduction within a MPA begins to contribute to the fishable populations outside its borders. Because of the time scales involved in monitoring long-term population rebounds, evidence in support of the spillover advantage is compiling slowly, but surely. Provided fisherfolk don’t “cheat” by crossing into MPAs, the spillover effect can be used to encourage protection of rocky reefs and other critically interconnected habitats that fish and invertebrates rely on to reach reproductive age. Science has also shown that protecting large fish allows for much more successful reproduction and replenishment of the stock, as larger fish tend to be impressively more fecund than smaller ones.

The quintessential example of a rocky reef in the Gulf of California that has undergone a truly impressive recovery, is Cabo Pulmo – a yet undeveloped desert area of the Southern Gulf, smack between the rapidly growing cities of Cabo San Lucas and La Paz in Baja California Sur. This monumental conservation effort, led by a handful of local families of artisanal fisherfolk turned dive-tourism operators, resulted in a miraculous recovery; the overall Biomass (B) in Cabo Pulmo’s waters increased by over 400%, while the Biomass of top predators, a key indicator of the reef’s stability and health, also increased eleven-fold, and that of other carnivores increased four-fold (Aburto-Oropeza et al., 2011). As a result of this spectacular recovery, Cabo Pulmo reef was eventually able to transition from a popular fishing area to an international destination for divers seeking memorable encounters with giant grouper, tenacious bull sharks, and vast schools of silver-plated jacks. I have been one of these lucky dive tourists and can attest that it was well worth the trip! 

But before dive tourism took off in Cabo Pulmo, the local fisherman come reserve guides and stewards had to eke out their livelihoods and suffered considerable hardship, reminding us that marine protection requires sacrifice from local people and needed support from society at large. Though the threat of coastal development and encroachment of fishermen from outside the community threaten to walk back Cabo Pulmo’s hard-earned progress, protection there has been total and sustained, over a large area (27 square miles, or 71 square km) for more than 20 years. The success of Cabo Pulmo, where other MPAs have failed, can be attributed to this long term and large-scale effort, and other fortunate social and biological factors that made effective protection possible – such as the physical inaccessibility of the area to outside fisherfolk and, so far, tenacious developers. 

It is true that we have already pushed the Gulf’s fragile ecosystem to the edge, and that bringing it back will be no small feat, but many experts argue that there is yet good reason for optimism. In my own experience working with artisanal fishing communities, from the Northern Gulf south to La Paz, I have learned that Mexico’s fisherfolk are honorable and proud of their way of life. They care about the natural world and ultimately, they want their families to continue fishing for many generations to come. The Gulf’s deeply rooted traditional knowledge and fishing culture, in addition to the determination and resourcefulness of scientists and conservation professionals alike, gives me hope that one day we will be able to call this sea, once again, “The World’s Aquarium,” knowing that neither the sea nor our words are empty.


1. Dr. Aburto-Oropeza et al., 2011 & The Gulf of California Marine Program (@Scripps Institute of Oceanography in San Diego)

2. California Sea Grant Program

3. The Arizona Sonoran Desert Museum in Tucson, Arizona