- The recent “Assessment of the Ecological Health of the Gulf of California” report shows a decline in several populations of animals throughout the narrow sea flanked by the Mexican mainland and Baja California.
- The report was compiled by the Next Generation Sonoran Desert Researchers (N-Gen) in the U.S. in collaboration with Prescott College’s Kino Bay Center field station in Mexico, and draws on long-term monitoring studies.
- Many of the assessed groups, such as seabirds, whales, giant squid, crabs, starfish and fish, are in decline.
- Basic primary productivity, which nurtures species diversity and abundance in the Gulf of California, remains stable.
Lorayne Meltzer has lived along the Gulf of California for 30 years. As an ecologist and director of a binational field station, she’s supported many scientists in their research into this biodiverse region of northwestern Mexico. Over time, she’s observed changes in the region’s ecosystems and species firsthand. Most of these changes, she said, haven’t been positive.
“I’ve noticed concerning changes,” Meltzer told Mongabay Latam. “Even on recreational trips to the islands, these changes were visible. So, we had the idea of getting in touch with researchers with long-term databases on various taxa, from the smallest animal in the world to the largest whale, to see if this decline is general or only among certain species.”
The result was a new collaborative report produced by Meltzer’s field station, the Kino Bay Center at Prescott College, and the binational organization Next Generation Sonoran Desert Researchers (N-Gen). The report brings together decades of scientific research showing an alarming decline in populations of species at the top of the food chain throughout this Mexican sea.
Among the groups in decline, according to the report’s findings, are seabirds, whales, flying squid, crabs, starfish and fish.
“Unfortunately, their health is declining on average,” Meltzer said. “Some groups, such as sea turtles, seem to be recovering, and at the plankton level, the ecosystem is quite healthy. However, it’s very normal for megafauna to be the most impacted within ecosystems, which are animals that take longer to reproduce.”
The report brings together the findings of 41 long-term ecological research projects, most of them running since 2000, conducted by 32 scientists and encompassing diverse biomes, ecosystems and species across the region. The experts were convened by the organizations through an open survey launched in 2024 as a first step to identify high-priority knowledge gaps to be addressed in future versions of the report.
“The aim of this report was to provide a snapshot of the Gulf of California’s ecological health status. We know that it isn’t a complete picture — there are gaps, and it isn’t entirely clear — but it is a starting point in 2025 so that we know which animal groups and regions are really at risk and need attention,” Meltzer said. “This will let us know whether it’s time to sound the alarm and really be concerned.”
The most affected
The studies reviewed for the report find that only three groups were improving. These are almost exclusively terrestrial or have a land-sea connection: the darkling beetle (family Tenebrionidae), the hawksbill sea turtle (Eretmochelys imbricata) and the Mexican giant cactus (Pachycereus pringlei). Seven groups remain stable, according to the report, including the fish-eating bat (Myotis vivesi) and the California sea lion (Zalophus californianus). Populations of zooplankton, krill and other small animals — critical components of the marine food web — also appear stable.
By contrast, the report lists 11 species as “degrading” in the region, such as the Humboldt squid (Dosidicus gigas, also known as the jumbo flying squid), the warrior swimming crab (Callinectes bellicosus) and several seabird species, including the double-crested cormorant (Nannopterum auritum). In addition, the report finds two groups to be “rapidly degrading”: cetaceans (whales and dolphins) and rocky reef communities (echinoderms and corals).
“For example, it takes a shark seven years to reach reproductive age,” Meltzer said. “In these seven years, they have to navigate many threats: a shrimp boat, a sardine boat, a net … the largest mammals and sharks are generally very vulnerable.”
According to biologist Héctor Pérez Puig, ongoing monitoring studies has revealed a marked decline in sightings of whales and dolphins in the Midriff Islands region over the past eight years. Sperm whales (Physeter macrocephalus) and short-finned pilot whales (Globicephala macrorhynchus) have “effectively disappeared” from the region due to the population collapse of their prey species, the Humboldt squid, in the Midriff region and Gulf of California more widely.
“Another disturbing trend is the increased observation of emaciated individuals in most cetacean species observed; most notably in Blue Whales (Balaenoptera musculus) and Bottlenose Dolphins (Tursiops truncatus),” the report states.
According to the report, the Gulf of California’s ecosystems have undergone changes due to anomalous warming events in recent decades. Large- and small-scale fishing have also significantly impacted marine communities, contributing to population declines of several species.
“Why are we, as conservationists or scientists, leaving out all the social dynamics, especially in coastal areas?” said ecologist Ben Wilder, director of N-Gen and co-chair of the report. “The social context is so complex at all scales, from villages to communities to coastal areas to the whole gulf region, that when we were forming this effort, we were thinking about how we can touch on social questions at the same time as biological ones, and we found that there wasn’t really a way to do it well.”
Wilder said researchers are now working to bring together other experts who can explain these social dynamics and prepare a second report to understand them.
With the publication of this first report, the compilers invite the scientific community, conservation organizations and decision-makers to join in the effort to continue collecting data, strengthen conservation in the Gulf of California, and protect the biodiversity that sustains local communities.
The situation is currently unstable for those involved in scientific research due to wide-reaching budget cuts in the U.S., according to Wilder.
“I think the situation is a bit dangerous, increasingly so on a daily basis given what’s happening on this side of the border, because we’re heading in the direction of losing our ability to maintain critical long-term monitoring efforts that allow us to prepare for future changes,” Wilder said.
The future of the Gulf of California
The Gulf of California, also known as the Sea of Cortés, faces problems linked to overfishing, warming waters and pollution from plastics and abandoned fishing nets, as well as the impacts of aquaculture. Meanwhile, natural gas exploitation and mega cruise ships loom on the horizon.
“The data show that species are suffering,” Wilder said. “We know there’s vulnerability, significant stress and changes within populations, especially higher up the food chain. If we put more stress on the system, I think we can expect to see further declines in trends.”
According to Meltzer, future impacts are unimaginable, so it’s important to ensure that companies promoting new projects in the region comply with environmental laws and base their activities on scientific data.
“I’ve dedicated my career to marine conservation,” Meltzer said. “What I want to see in the future is the Gulf of California as an exemplary marine system, and it truly is: the islands, reefs, estuaries and deep-sea areas still have incredible biodiversity, but we have to protect it because it’s threatened.”
Meltzer urged the involvement of all sectors of society, from scientists and academia to governmental and financial, before further declines occur.
“I’ll say it again: we all need to pay attention because we all depend on a healthy ocean,” Meltzer said. “The health of human society is linked to ocean health.”
According to Wilder, more work is still needed within the scientific community to develop strategies that will lead to a stronger relationship with decision-makers and other stakeholders in the region.
“The Gulf of California is resilient, but we need to give it room to recover,” Wilder said. “We’re seeing a lot of changes, but there’s still plenty of productivity and capacity for restoration — we just need to let it happen and give it time to recover.”
Banner image: The common bottlenose dolphin is one of the most abundant species in the region, but monitoring studies in the Gulf of California have observed malnourished individuals. Image courtesy of Héctor Pérez Puig.
This story was first published here in Spanish on Feb. 25, 2025.
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