LAGUNA SAN IGNACIO, Mexico — Monday, March 31, 2008 | In the darkness of night, he could hear the whales calling. From out there, out across the lagoon’s barren expanse, came the sound of gray whales surfacing, spouting a misty breath of air, then gasping for more before diving.

Four decades have passed since Pachico Mayoral first encountered the eastern Pacific gray whales that come each winter to this isolated lagoon 475 miles south of San Diego. In the years since he traded an itinerant existence on a merchant freighter for life as a fisherman, he has seen changes in the whales that pass by San Diego’s shores annually to nurse their young in the predator-free waters here for four months.

What scientists have concluded from research spanning decades, the 67-year-old has observed anecdotally from his home on the lagoon’s sandy shores. Since 1985, Mayoral says fewer whales have used the lagoon. And while the whales once returned from their Alaskan feeding grounds at the start of December, they’ve gradually begun showing up in late December, he says, spending less time before returning north to the Arctic.

Scientists studying the whales in the lagoon confirm Mayoral’s observations. The whales’ fall migration south past San Diego is peaking five days later than it once did. Once they get to Baja, they’re staying two weeks less than they did in the late 1970s. Back then, scientists conducting occasional population censuses here counted as many as 400 adult whales in a day. Last year, censuses found half that. And 12 percent of the whales that did stay in the lagoon in 2007 showed signs of malnutrition, a phenomenon dubbed “skinny whale syndrome.”

Gray whales, massive barnacle-encrusted mammals about the same weight and length as a large school bus, swim nearly 12,000 miles each year, spending summers feeding in the rich waters near Alaska and winters raising calves in four lagoons on Baja California’s Pacific coast. The whale known as Eschrichtius robustus lures curious tourists to San Diego, inspires crowds at Cabrillo National Monument and fuels both the local whale-watching industry as well as small ecotourism camps in coastal Baja.

But the gray whales are changing, and scientists studying them in Laguna San Ignacio say they believe climate change is responsible for causing a subtle shift at the base of the Arctic food chain that has magnified as it has rippled upward, forcing the whales to switch their feeding and migration patterns.

Here along the lagoon’s shores, the shift highlights nature’s delicate balancing act and the potential threat the warming climate poses thousands of miles away from the Arctic, where some of climate change’s most profound effects are being felt.

“It’s all connected,” says Sergio Gonzalez, a graduate student from the Autonomous University of Baja California Sur studying the lagoon’s whale population. “If you affect something up there, you affect it down here. We are watching a lot of skinny whales here.”

While the connection to climate change hasn’t been definitively proven and researchers don’t fear for the whale’s survival, its migration habits are changing, and the effects are being felt in San Diego and around the lagoon’s shores.

Many of the 500 villagers who live here rely on the whales. They have increasingly turned to whale-watching and ecotourism as an alternative to fishing, a back-breaking task that holds little promise in the lagoon, where overfishing has left once-vibrant fish stocks struggling for survival. Sitting inside a green canvas tent on the lagoon’s shore, Mayoral gestures outside the flap when asked how far he once traveled to fish.

“Aquí,” he says, pointing at the aquamarine water. Here.

Today, the windswept expanses of salt flats and desert around Laguna San Ignacio are littered with hundreds of stacks of scallop shells, two-foot-tall reminders of those who migrated here from mainland Mexico and harvested scallops until there were no more.

The seas are emptying. Mayoral says today fishermen must go as far as 30 miles offshore, catching less each season while the cost of fuel increases.

But as villagers’ livelihoods increasingly rely on tourists coming to watch whales, they worry that they’re exposing themselves to the uncertainties of a global shift: cambio climatico.

Scientists who have studied the lagoon’s whales say the whale-watching season has been shortened two weeks since the late 1970s, a shift they blame on climate change. Villagers say they have seen skinny whales before but not to the extent they have recently. They worry that if fewer whales use the lagoon, fewer tourists will come.

“What are we going to do?” asks Daniel Aguilar, a 25-year-old fisherman and whale guide. “Are we going to start fighting over the few whales that are here?”

Karen Ivey, owner of Baja Discovery, a Chula Vista-based whale-watching company that operates a camp at the lagoon, no longer offers tours in January, eliminating two five-day trips in the last five years. “I don’t want people to come from far and wide and not see whales,” she says.

Ten years ago, she booked tours as early as Jan. 17. Today, the five-day all-inclusive trips that cost $2,275 per person don’t start until Feb. 4. Ivey worries whether the season will continue shortening in the future.

“It’s scary,” Ivey says. “The local people, this has been very good for them. But Mother Nature is changing.”

Scientists observing the whales last year found that 12 percent showed signs of malnutrition. Some appeared concave, their bodies curving inward, instead of convex, curving out. Others had shoulder blades evidently bulging outward or showed a depression in the fatty area behind the skull.

Steven Swartz, a Maryland-based marine biologist with the National Marine Fisheries Service, says climate change-induced warming of the frigid waters off the Alaskan coast has sharply reduced the food source on the ocean floor that whales historically fed on to fatten up for the migration south to Baja.

“The gray whales and a number of Arctic species are all suffering from the result of this regime change,” says Swartz, who has studied the lagoon’s whales since 1977. “They’re going through a transition where they figure out the new carrying capacity of the population.”

While climate change is the likely cause, proving the connection is difficult, says Wayne Perryman, a fisheries biologist at the National Marine Fisheries Service’s Southwest Fisheries Science Center in La Jolla. Because Swartz is monitoring only one lagoon in Baja, what happens there may not be reflective of the whole population, Perryman says. The skinny whales spotted may be lactating females, he says, which have lost weight while nursing their young.

Perryman, who leads an annual population count from the shores near San Simeon, says he feels strongly that the shifts are climate-change related, even without large amounts of data to prove it. The warming climate is having its most profound impact in the Arctic, where climbing temperatures have begun melting once-impassable ice in summer.

Perryman says the whales offer an important window into those shifts because scientists along the length of the Pacific coast can monitor gray whales without fielding Arctic research teams.

“Gray whales are interpreting climate change,” Perryman says. “We have a lot of clues. But budgets are tight, and we’re lucky these are coastal animals because we can see them from the beach.”

Scientists trace the change in the whales’ habits to the fundamental building blocks of the Arctic food chain. Gray whales once feasted on amphipods, a shrimp-like crustacean found in the Chirikov Basin, just south of the Bering Straits, the passageway into the Arctic Circle nestled between the Alaskan and Russian coasts.

The muddy ocean floor in the basin served as a feeding trough for the whales, which have little to eat in Baja and must bulk up before leaving. Females depend on the extra blubber to provide enough energy to carry a pregnancy and nurse their calves. While that trough was once overflowing, the basin’s amphipod population has dropped, and the whales that once clustered there are now fanning out throughout the Arctic Circle, continuing their migration hundreds of miles north through the Bering Strait into the Chukchi and Beaufort seas above Russia and Alaska.

Scientists attribute the amphipod decline to the extreme melts of Arctic sea ice that have occurred in recent years. In the whales’ historic feeding ground, winter ice was once a solid, thick sheet. Today, the winter ice is thinner and breaks up earlier in spring, giving way to a warmer ocean in summer.

The warmer waters increase competition for food, allowing more fish to migrate into the whales’ former feeding grounds, which were once too frigid for many fish. The faster ice breakup also reduces the growth of algae, which serves as the fundamental building block of the Arctic food chain.

Amphipods historically fed on bits of algae that grew beneath the ice and sunk to the ocean bottom. Gray whales dove to the bottom, grabbed a mouthful of mud and amphipods and forced sediment out through their brush-like baleen, chomping on the tiny crustaceans left over.

But as algae growth has declined, so have amphipods. That has driven the whales to search for new food sources that scientists believe may be less nutritious, a switch that makes the whales vulnerable to disease and parasites.

“They have some flexibility and can use these other food items, but the question is how far they have to search to find them,” Swartz says.

Some Arctic experts disagree that climate change is responsible for the shift. Ken Coyle, a researcher at the Institute of Marine Science at the University of Alaska, Fairbanks, says the gray whale population, which peaked at 30,000 in 1998, may have exceeded its historical pre-whaling levels and overgrazed the Chirikov Basin’s amphipod habitat. The population has since dropped to about 20,000 whales.

“When whales were being hunted, they knocked those populations way down,” Coyle says. “If the population exceeds the carrying capacity of the environment, you might find them in poor condition.”

Because the historic feeding grounds have declined at the same time that summer ice has retreated unprecedented distances in the Arctic, he says the whales may be swimming farther to eat because they can feed in new parts of the ocean.

“The whales may just be able to stay a lot longer and feed a lot longer,” Coyle says. “They may be taking advantage of a food resource that was blocked because of the ice.”

Because the whales are swimming farther north in the summer, they’re arriving later in Baja each winter. Dave Rugh, a National Oceanic and Atmospheric Administration wildlife biologist in Seattle, says the middle of their southbound migration happened five days later last year than it had since the 1980s. The timing was similarly late this year, says Rugh, who monitors the annual migration.

The whales are likely leaving for Baja California at the same time they always have, but arrive later because they’re migrating farther, Rugh says.

While the whale continues adapting to the changing Arctic, scientists say they are not worried about its long-term prospects. The species dates back at least 120,000 years, Swartz says, and adapted through the last ice age, which ended 12,000 years ago. It survived whale hunters and in 1994 became one of the first species to be removed from protection under the federal Endangered Species Act.

“Gray whales are called robustus for a reason,” Swartz says, referring to their scientific name. “The stuff that’s going on currently in the Arctic is accelerated, but it’s nothing new for a species like a gray whale. They’re having to adjust, they’re doing what they’re programmed to do.”

Tomorrow: San Diego conservation and philanthropic groups hope to address the challenge and opportunity posed by land preservation in Baja.

Please contact Rob Davis directly with your thoughts, ideas, personal stories or tips. Or send a letter to the editor.

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