How Massive Cruise Ships and an Oversaturated Tourism Industry are Destroying This Once Pristine Whale Shark Habitat

It’s the largest shark in the world and weighs as much as an F-15 fighter jet, but the whale shark is nothing to be afraid of. Whale sharks are filter feeders and only eat plankton and other small creatures like krill, although they occasionally feast on larger animals such as tuna or squid. Whale sharks are peaceful and won’t attack humans. Sadly, the population levels of these magnificent sea creatures are in decline. Cruises and tourism in Mexico threaten them even more.

La Paz is a Quiet Tourist Destination … For Now

The Bay of La Paz on the southeastern coast of Baja California Sur in Mexico is an important refuge for whale sharks. It’s also often a stopover for travelers on their way to the busier Los Cabos. However, those looking for a quieter vacation may choose to stay in the smaller city of La Paz. The beaches are gorgeous. Its sheltered location in the Bay of Cortez, along the Sea of Cortez, is home to an amazing amount of diverse wildlife.

The Sea of Cortez hosts over 900 different species of fish. The marine life is supported by nutrient-rich waters, coral reefs, rocky outcrops, seagrass beds, and sandy bottoms. In addition to fish, you may see dolphins, sea lions, manta rays, gray whales, hammerhead sharks, and the massive and popular whale shark (Rhincodon typus).

But it’s the Sea of Cortez’s biodiversity and unique wildlife, along with the pristine beaches that line the shores, that are putting marine life in danger. As La Paz grows more popular as a tourist destination, cruise ships and tourism companies are working to bring in even more travelers.

The private company Aquamayan Adventure has an agreement with the government of Mexico to use 360,600 square feet of the port to build a commercial complex. The company’s goal is to attract 150,000 cruise passengers per year, which is significantly higher than the number of cruisers in recent years, which hovered as low as 11,000 in 2023. It’s about 50% of the total population of the city of La Paz.

The Bay of La Paz Has Been a Whale Shark Refuge Since 2018

Scientists have been monitoring the whale shark population in La Paz Bay since 2003. Since they began monitoring the area, researchers observed that 66% of juvenile whale sharks were being struck by boats. Researchers worked with the Mexican government to advise and educate tourist companies on strategies to minimize their impact on whale sharks. In 2018, the area was established as a critical habitat for whale sharks and was designated a whale shark refuge.

Whale sharks are migratory, and a report from 2021 estimated that around 125 individuals arrive in the bay each year. Around 1,700 individual whale sharks are estimated to live in the entire Sea of Cortez.

How Whale Sharks Protect Their Ecosystem

Whale sharks play an important role in the ecosystem. They eat plankton and algae, controlling the populations of both. An overgrowth of plankton would decrease the amount of oxygen and sunlight reaching the water. This would disrupt the environment for the many species that live within it. These peaceful giants also serve as mini-ecosystems for small fish. The fish feed on parasites on the whale shark’s skin and take shelter from predators swimming alongside the sharks.

How the Cruise Ship Shutdown Impacted Whale Sharks During the Pandemic

We already know what impact increased numbers of cruise ships would have on the area around La Paz. During the pandemic in December 2020, over a dozen mega cruise ships were stranded in the port. A report found that the sitting cruise ships released the equivalent of 3,224 Olympic-size swimming pools of scrubber washwater.

According to the World Wide Fund for Nature (WWF), “Scrubber washwater is toxic to marine life, with harmful effects observed at concentrations as low as 1 part per million (ppm). At 10 ppm, it causes significant malformations in the juveniles of some species. Scrubber washwater is also highly acidic, contributing to worsening ocean acidification and impacting the ability of shellfish like oysters and sea urchins to grow and maintain skeletons and shells.”

The cruise ships operate 24 hours a day. Experts think the constant engine noise and light, along with the polluted water, could have affected the plankton that whale sharks feed on. Scientists observed that after December 2020, whale shark sightings in La Paz dropped drastically, and by April 2021, they were no longer observed in the area.

Carlos Mancilla, director of an environmental organization working to protect the bay, told Focusing on Wildlife that the cruise ships “emit as much toxic gas as 10,000 to 30,000 cars.” Because of the dunes, which protect the bay, ocean currents do not carry the polluted waters out of the area.

Environmental Organizations and Researchers Are Working to Save the Whale Shark Habitat

Environmental organizations are urging the Mexican government to revoke its agreement with Aquamayan Adventure, which would permit the construction of a tourist center and an increase in mega cruise ships in the bay.

As environmental groups work to persuade the government to protect the area, researchers continue to observe and monitor the impact of tourism. A recent crowd-funded effort to use drones to monitor the whale sharks began in the spring of 2025.