Conservation success story

Hunted to near extinction

Elephant seal at Piedras Blancas, California. Image courtesy photographer - Nichole Dillon-Lee.
More photos at PBASE
Inside this section
• Hunted to near extinction
• A century of progress
• New threats from a changing environment

Title - What's worth diving down there?

"Hundreds of thousands of northern elephant seals once inhabited the Pacific Ocean. They were slaughtered wholesale in the 1800s for the oil that could be rendered from their blubber. By 1892, only 50 to 100 individuals were left. The only remaining colony was on the Guadalupe Island off the coast of Baja California." - according to California State Parks [12].

Hunters weren't after their fur. They wanted their blubber.

Blubber and lamps • Video - Quilliq Oil Lamp • Quilliq: Lessons from a Stone Oil Lamp
Complexity of history • The "Whale Oil Myth"
It was sold and processed into high-quality lamp and machine oil. When elephant seals hauled out, they were easy to harvest.

Blubber had also been used by indigenous people such as the Inuit to light stone oil lamps called quilliqs.

By the turn of the century, the scarcity of elephant seals and the arrival of alternative fuels such as petroleum-based products made blubber-based oils obsolete.

Return of the elephant seal

Haulout at Piedras Blancas. Photographer - Wolf Berger.

"By 1922, the Mexican government gave protected status to elephant seals, and the U. S. government followed suit a few years later when the seals began to appear in Southern California waters." - [12].

A century of progress - From a single known colony at Isla de Guadalupe off the Pacific coast of Baja California, colonies expanded all along the coast of the Californias. Where there were only 100 or so individuals, there are now over 100,000.

Distribution of northern elephant seal breeding colonies then and now, at 2005 and circa 1900. Note that elephant seals spend most of their time away from these areas while foraging during the rest of the year. Data provided by Richard Condit, Mark S. Lowry, Amy Betcher, Sarah G. Allen, Dawn Adams, Brian Hatfield,
Derek E. Lee, Patricia A. Morris, David Aurioles, Maria-Concepcion Aguilar and Burney J. LeBoeuf.

Living with a genetic bottleneck - Like the California condor, this once endangered species reestablished itself from just a few survivors. As a result, there isn't much genetic variation between individuals, although there are many individuals.

Title - What's worth diving down there?

A genetic bottleneck is a temporary reduction in population size that causes the loss of genetic variation in future generations. When the number of individuals has been low, no matter how populous the next generation becomes, all the individuals in that generation are drawn from the same limited gene pool. Studies confirm the expectation of low genetic variation within groups of living northern elephant seals. It might seem redundant, but comparing what we expect with what actually occurs is important because surprises do occur. The elephant seals we find today might have been the descendants of more survivors than just the one colony at Isla de Guadalupe. This apparently didn't happen.

The downside of low genetic variability is less resilience to environmental stress as a group. Since genetic variation is low, the genetic solutions that these animals possess is limited. Should a critical stress occur, large numbers of these animals could be susceptible to its negative effects until greater genetic variability reestablishes itself over time. Modern conservation efforts seek to preserve the rich genetic variation of natural populations as well as total numbers of individuals.

New threats

Citizen scientist

See for yourself - Compare migration movies with sea surface temperature (SST) and chlorophyll concentration at the sea surface for different years. You can analyze the relationship between climate, food supply and elephant seal migrations.
• TOPP - Migration movies
• TOPP - Home

Climate change - It didn't hurt the northern elephant seal's recovery when people lost interest in their blubber because they favored the new fossil fuels.

Title - What's worth diving down there?
Over a century later, the situation has changed and CO2 emissions from fossil fuels may threaten the northern elephant seal by reducing its food supply. Some scientists think that a warmer climate will cause problems similar to those observed during El Niño.

Research scientist Dan Costa at TOPP comments on the potential impact of climate change on elephant seals -

"we examined the response of both sea lions and elephant seals to the 1998 El Niño event. We think of future climate changes as being more like an El Niño event. During this event elephant seal females foraged in the same places and in the same way, but did not gain as much mass as over normal years. We also examined the foraging patterns of sea lions during the 2005 warm period. This was not an El Niño, but the coastal waters were warmer than usual. During this period both male and female sea lions foraged farther at sea and took longer trips. Males changed their diet and ate more sardines and no squid. The general picture is that a warmer climate will have an adverse impact on both elephant seals and sea lions."

More boys in a warmer world Scientists have observed that the ratio of male-to-female northern elephant seal pups changes with climatic conditions in the North Pacific [42]. During warmer times, more males are born than females. It may be an advantageous adaptation to produce fewer female young relative to males when food is harder to find in areas where females forage.

Obviously elephant seals and other marine mammals are biologically adapted to survive episodes of natural climate variability such as El Niño. Just how well they survive on low genetic variability, and whether they experience stresses beyond their capacity to rebound will determine their continued success or decline.

Resting weaners. Photographer - Jessica Meir.

Elephant seals help us to understand the oceans - Now that satellite-based technologies let us know where they forage for food - in the deep North Pacific and along the continental shelf of the Pacific Northwest, we can see that elephant seals rely on food sources that are vulnerable to climate change.

So how do they help us to help them? We can monitor the sea surface by using satellite technologies but it's much harder to get readings from below the surface in this way.

The same equipment that allows us to track elephant seal migration can monitor key conditions in the oceans by letting the elephant seals carry instrumentation for us. Elephant seals travel to places that are difficult for even remote vehicles to access and they spread out across large areas of some oceans. The information collected by elephant seals helps us understand how the oceans and atmosphere work together to set the Earth's climate. That understanding has the potential to positively impact the well-being of both elephant seals and humans.