Fewer Pacific Sardines Means Fewer Boobies
SANTA CRUZ, Galapagos Islands, Ecuador – Where have all the blue-footed boobies gone?
For centuries, it was easy to see flocks of the iconic sea birds throughout the Galapagos archipelago. But since the mid-1990s, their numbers have been dropping radically. Today it’s more likely to see just one or two of the boobies clinging to a rock with their Tiffany blue feet.
Scientists estimate that the number of blue-footed boobies has dwindled by 68 percent in the last 50 years to about 6,400. They have many predators: Galapagos hawks, rats, cats and dogs. But researchers say the main reason for their decline is the lack of their prime source of nourishment, the Pacific sardine.
“If the sardine numbers don’t rise in the next 10 years, then it is predicted that the population size will drop from the currently estimated 6,400 boobies to about 1,500,” said David Anderson, a seabird biologist at Wake Forest University and the lead researcher on a blue-footed booby population analysis sponsored by the Charles Darwin Research Station on Santa Cruz Island.
|Booby on the rocks||Videos by Alexandra Stone Coren|
The southern Pacific waters have suffered the worst sardine population crash since the mid-1900s, according to the Pacific Fishery Management Council in Portland, Ore., one of eight federally established organizations that help the National Ocean And Atmospheric Administrations oversee the conservation, protection and regulation of marine resources in the United States.
The main culprit is the El Niño phenomenon, which over the last two decades has been occurring twice as often. El Niño reduces the schools of sardines that the blue-footed boobies depend on. And whatever sardines survive an El Niño often get swept up by commercial fishermen.
With El Niño comes rain.
The Pacific warms up, causing plankton, the main food source for sardines, to die out. The sardines must move to colder regions further south or starve.
“El Niño used to come every 15 years, but in recent years it’s every seven to eight years, which doesn’t give the plankton enough time to recover between El Niño cycles, affecting the entire food chain,” said Washington Parades, a national park guide on the island of Santa Cruz. Paredes can do an almost perfect imitation of the blue-footed booby’s cry.
Sea lions suffer from a decline in sardines, too, said Dave Acuna, a marine biologist at the Charles Darwin Research Station. But they “are really good at hunting so it doesn’t affect them as much,” he said.
Blue-footed booby looking for food
Sea lions can dive more than 600 feet and stay underwater for several minutes, Acuna said. But blue-footed boobies make shallow dives of no more than 2-feet and pop up for air immediately.
Frigate birds, black with wide wing spans and often seen gliding high in the sky on wind currents like buzzards and hawks, eat a lot of sardines, too.
The frigate birds often chase the boobies, catch them by their tail feathers and shake them until they regurgitate whatever they’ve caught.
“In a duel between the boobies and the frigatebirds, the frigatebirds usually win,” said Boris Baker, a National Park guide on the island of San Cristobal.
Some conservationists believe the problem is made worse by overfishing by commercial fishing fleets.
“There are more boats, and more people in recent years who eat sardines, and there are no limitations on managing or conserving the species,” said Gustavo Jimenez, a marine bird survival and reproduction specialist with the Charles Darwin Research Station. “Fishermen in the Galapagos are more artisanal with smaller boats and do not fish for sardines. But, off the coasts of Chile, Peru and Japan, industrial fishermen will take all the sardines they can get.”
National Oceanic and Atmospheric Administration researchers point to unsustainable fishing in the Pacific, like the high catch limits and a focus on catching older, breeding-age fish. After an El Nino, the agency says, commercial fishermen often haul away many sardines that would otherwise reproduce and replenish sardine schools.
Diet directly affects the reproduction of blue-footed boobies.
Just as the flamingo gets its pink color from the shrimp it eats, the blue-footed booby gets its blue feet – hence its name – from the sardines it eats. The bluer the feet, the more attractive males are to females. Without vibrant blue feet, the males are just not that interesting to the females.
“They only want the male boobies with the bluest feet because that shows strength and good health,” said Baker, the park guide. “The girl boobies have standards.”
Many researchers feel there isn’t a lot that man can do to help blue-footed boobies. “It’s mostly a natural cycle,” said Anderson, the seabird biologist at Wake Forest.
It will be nearly impossible to get funding for a conservation plan to save the sardine or the blue-footed booby, Acuña said.
“There are only two or three fish species that have been managed in terms of limiting size and the season for fishing and this took tons of work and fighting for,” Acuña said. “The only bird that has received attention so far is the mangrove finch.” A pilot program for the conservation of the mangrove finch has been running for two years, he said.
But no conservation can reduce the tremendous impact of El Niño, Acuna said: “Nobody knows the magic.”
El Niño has been taking place for millions of years, and creatures have either adapted or perished.
Charles Darwin discovered that as he was developing his theory of evolution from his explorations in the Galapagos in the 1830s. “It is not the strongest of the species that survives, nor the most intelligent that survives,” he said. “It is the one that is most adaptable to change.” #
Riding out a sardine shortage