Saving Baja’s iconic biodiversity

The Mexican city of La Paz sits between the Sonoran Desert and the Sea of Cortez in Baja California, Mexico. In contrast to its landscapes, its turquoise waters teem with life—so much so that Jacques Cousteau described them as the "world's aquarium." This biodiversity hotspot is home to hammerhead sharks, sea lions, whale sharks and endemic species like the vaquita porpoise. The Sea of Cortez derives its richness from the convergence of ocean currents from both temperate and tropical ecosystems, creating nutritious upwells that support more than 900 fish species and critical marine mammal populations.

Between October and February, the waters off La Paz are a haven for whale sharks, with scores of the gentle giants cruising shallow, nutrient-rich waters close to the city. Juvenile whale sharks, typically 20-26 feet long (6-8 meters), congregate to feed on seasonal plankton blooms. The feeding aggregation has sparked a sustainable eco-tourism industry that allows snorkelers to swim alongside the docile filter-feeders, providing critical economic opportunities while raising awareness about the role of whale sharks within marine ecosystems and the need to protect them.

Marine biologist and whale shark expert Alberto Garcia Baciero heads up Whale Shark Mexico, a La Paz-based NGO committed to whale shark research and conservation. The Spanish native monitors both the juvenile whale sharks that congregate here and the plankton populations they feed on, gathering important data that can help us understand the long-term impacts of climate change on whale shark ecology. Over the years, Baciero has become extremely adept at spotting whale sharks from the bow of his research vessel.

Whale sharks have unique constellation-like skin patterns that are as individual as human fingerprints. Like whales, they are filter feeders, sifting up to 1,590 gallons (6,000 liters) of water every hour through specialized gill rakers. In the process, even a 20 foot (6 meter) juvenile consumes nearly 45 pounds (20 kilograms) of plankton daily. Nomadic by nature, whale sharks constantly migrate through tropical and warm temperate seas, tracking nutrient-rich currents from the Caribbean to the Indo-Pacific. Their expansive throat—barely wider than a human palm—paradoxically supports their immense size through precision feeding strategies that have evolved over millions of years. Researchers believe they spend a great deal of time feeding in the mesopelagic zone, sometimes diving over a mile in depth (1,928m).

Since 2016, whale sharks have been listed as “Endangered” by the International Union for the Conservation of Nature (IUCN), as a result of overfishing, bycatch, pollution and other human impacts. Now, whale shark populations are gradually recovering through targeted conservation efforts. International fishing restrictions and marine protected areas have helped stabilize their numbers, with populations showing signs of increased resilience. While challenges remain from bycatch and marine habitat changes, recent studies suggest the global population is slowly increasing, particularly in regions with strong marine conservation policies.

Alberto Garcia Baciero collects plankton samples at dusk off the coast of La Paz. Whale sharks' survival critically depends on plankton abundance and diversity. Studies have demonstrated that zooplankton density directly influences their feeding patterns and migration routes, and that climate change-induced fluctuations in both ocean temperature and chemical composition can disrupt plankton populations, reducing food availability. Like whales, whale sharks are often described as ecosystem engineers, since they are intrinsically connected to creatures at the bottom of the ocean food chain, managing numbers through their feeding habits and, as such, impacting the balance of marine ecosystems.

Giovanni Chimienti surfaces after an afternoon swimming with juvenile whale sharks in La Paz. As a Goodwill Ambassador for SEA BEYOND, the project by Prada Group in partnership with UNESCO-IOC, Chimienti helps support ocean literacy through his research and educational activities. SEA BEYOND contributes to the progress of ocean education on a global scale through a series of training initiatives for younger generations.

Located close to the US border in Baja California, Ensenada is close to the southern limit of a remarkable marine corridor—the Pacific Kelp Forest Highway. These towering underwater forests are among the most productive ecosystems in the ocean, and in the Americas they form a living pathway that stretches from Alaska to Mexico. Here, the cold California current meets warmer waters, creating unique conditions where giant kelp (Macrocystis pyrifera) thrives. The forest provides crucial habitat for countless species, and researchers now believe it played a crucial role in the migrations that populated the Americas.

When it comes to growth, kelp rivals bamboo for sheer speed—plants can increase their height by a whopping two feet (61 centimeters) per day in the right conditions. Yet it lacks conventional roots, instead staying anchored by intricate “holdfasts” whose sole function is to grip rocky seabeds. These underwater forests reach heights of up to 175 feet (53 meters), creating complex ecosystems that are among the most fertile in the ocean after coral reefs. Like their tropical counterparts, kelp forests shelter thousands of species, from microscopic organisms to marine mammals. A single holdfast can harbor 100 species and more, while the kelp's canopy creates essential nurseries for numerous fish species.

Kelp forests teem with life, from vibrant garibaldi and olive rockfish to playful harbor seals, and sea otters. Sea urchins graze the holdfasts, while sea lions weave through the towering stipes. Kelp forests serve as nurseries for over 800 species, including commercially important fish like bass and mackerel. Kelp's carbon-capturing prowess is remarkable—a single square mile can sequester more than 3,340 pounds (1,500 kilograms) of carbon per day. But around the world, kelp forests are struggling—and while there is a high degree of geographic variation, researchers estimate that between 40 percent and 60 percent of the world’s kelp forests have been damaged to varying degrees.

Marine biologist Rodrigo Beas prepares to dive in a small tract of kelp forest off the Punta Banda peninsula, south of Ensenada. Much of his research focuses on how warming waters and changing ocean conditions affect kelp forest resilience and recovery. Off Ensenada's coast, where cold and warm currents meet, a series of marine heatwaves has caused significant die-offs of kelp in the area, as warmer ocean temperatures affect the ability of kelp to photosynthesize. Typically, kelp can recover rapidly thanks to its speed of growth, but the frequency and severity of these heatwaves is disrupting the balance of the kelp forest ecosystem and threatening the capacity of kelp to recover.

Members of a local fishing cooperative bring in their catch of purple urchins in Punta Banda. These urchin populations have exploded as marine heatwaves have caused local kelp forests to retreat. Deprived of the kelp detritus they usually feed on when the forests are thriving, the purple urchins come out of their cracks and crevices in search of food, often aggressively feeding on immature kelp before it has a chance to grow. The rich biodiversity of the kelp forest is replaced by urchin deserts—an issue that affects California to the north and many other areas, too.

Factory workers process purple urchins, which have value as a food export, in Ensenada, Mexico. However, the market for purple urchins is relatively nascent compared to the more popular red urchins, which are being crowded out by their purple counterparts. Conservationists are working hard to encourage restaurants, supermarkets and consumers to turn their attention to the purple urchins in order to relieve the pressure on kelp forests, rather than relying solely on volunteer divers who work to clear tracts of seabed so that the kelp can recover. 

The Pacific coast of the Americas was once thick with kelp. Now, some kelp forest systems have virtually collapsed, with some in Northern California losing more than 95 percent of their coverage. It will require a concerted effort by governments, non-profits, scientists, volunteers and consumers to help the great kelp forest highway recover and continue to provide the valuable ecosystem services it has offered humans for thousands of years.

Find out more about how understanding our ocean can be the very thing to help save it; and more about Prada Group’s work with UNESCO-IOC here.