Sea Otters Finally Rebound From Exxon Valdez
Thousands of otters died after the Exxon Valdez oil tanker disgorged more than 10 million gallons of crude oil onto the Alaskan coast. Now, 4,277 sea otters swim in western Prince William Sound. Continue reading →
The sea otter population of Prince William Sound, Alaska took 25 years to recover after the Exxon Valdez oil tanker disgorged more than 10 million gallons of crude oil onto the Alaskan coast on March 25, 1989.
Thousands of otters likely died immediately as they soaked in sludge. For the next two decades, a filthy oil residue poisoned otters as they fed, slowing the recovery process.
In 2013, though, approximately 4,277 sea otters (Enhydra lutris) swam in western Prince William Sound, up from 2,054 in 1993, according to a recent U.S. Geological Survey (USGS) report. Even Knight Island, one of the most heavily polluted areas in 1989, had recovered to pre-spill otter occupancy levels. The otters now abound at near the maximum number the region can support sustainably.
"Although recovery timelines varied widely among species, our work shows that recovery of species vulnerable to long-term effects of oil spills can take decades," said lead author and USGS biologist Brenda Ballachey, in a press release. "For sea otters, we began to see signs of recovery in the years leading up to 2009, two decades after the spill, and the most recent results from 2011 to 2013 are consistent with recovery as defined by the Exxon Valdez Oil Spill Trustee Council."
Prince William Sound sea otters live normal life spans now, too. In a healthy ecosystem, the oldest and youngest otters die more frequently than adult animals in the prime of life, from two to eight years old. However, between 1989 and 2008, biologists counted an abnormally high number of adult otter corpses washed up on the beach, compared to the numbers from before the spill. However, in the three most recent counts, otters death rates seemed to be returning to a normal range of ages.
Ongoing adult otter death may have occurred because, after the spill, the surviving otters suffered from near-constant exposure to toxic chemicals as the animals foraged for mussels and other shellfish in the crude-soaked sand and gravel beds of the Sound. USGS scientists found genetic signs in the otters bodies indicating that they experiences chronic long-term exposure to oil residues, compared to otters from other areas.
Although the biologists still observed these genetic warning signs in 2012, the levels had dropped significantly since 2008.
Photo: Sea otter, Enhydra lutris, mother with nursing pup in the Morro Bay harbor. Credit: "Mike" Michael L. Baird, Wikimedia Commons
If we judged the worst oil spills in history only by gallons leaked, the Exxon Valdez disaster -- which occurred 25 years ago today -- would not make the list. However, adding in environmental impacts and clean-up efforts, it's still recognized as one of most damaging spills to date. In 2009, Exxon Mobil Corp. was ordered to pay about $500 million in interest on punitive damages for the oil spill off Alaska, nearly doubling the payout to Alaska Natives, fishermen, business owners and others harmed by the 1989 disaster. Debate continues over what qualifies as an oil "disaster," but here are 10 that would certainly make the list.
As the largest oil spill disaster in U.S. history, the
incident continues to leave an incredibly damaging black mark. Shortly after midnight on March 24, 1989, the tanker was traveling outside of normal shipping lanes to avoid ice, when it struck the Blight Reef in Prince William Sound, Alaska. Out of the 53 million gallons of crude oil onboard, 11 million gallons were lost in the accident. The size of the spill and its remote location in the pristine Alaskan wilderness made clean-up a horrendous task. Ten million birds, whales, otters and other animals were placed immediately at risk and thousands died.
On March 18, 1967, the
entire cargo of 119,000 tons of Kuwait crude oil was lost after the tanker ran aground on Pollard Rock on the Seven Stones Reef off of Lands End, England. The Royal Navy dispatched a clean-up response team within four hours of the grounding. By March 26, the entire vessel had broken apart, putting an end to any hopes of towing the ship off the reef. The British government eventually decided to bomb it.
In the early morning hours of Dec. 15, 1976, the crew of the aging Liberian oil tanker
could not keep control in the rough waves and 50-knot winds during a storm off the coast of Nantucket. The ship ran aground among the Nantucket shoals. On Dec. 16, the crew was evacuated, and by Dec. 22, the ship had broken into three pieces, spilling all of its 7.7 million barrels of oil into the ocean. Constant bad weather made salvage attempts very difficult, but environmentalists said damage to local waters were minimal. Strong currents carried the oil away from the Massachusetts shoreline and forced it out to sea.
Stormy weather, rough seas and a faulty piece of steering equipment proved to be a fatal combination for the
on March 16, 1978. The enormous vessel -- carrying almost 2 million barrels of oil -- was sailing from the Arabian Gulf to Le Havre, France when it ran aground on Portsall Rocks, three miles off the coast of Brittany, during a severe storm. The entire cargo spilled into the water, creating an oil slick 18 miles wide and 80 miles long, and it wasn't long before the force of the storm caused the ship to break apart.
The only thing worse than one oil tanker exploding and sinking while at sea, is two oil tankers colliding at sea. During the rage of a tropical storm in the Caribbean, two giant supertankers, the
, each carrying over 200,000 tons of crude oil, collided near the islands of Trinidad and Tobago on July 19, 1979. The impact caused enormous, violent fires to break out over both ships. Between the two ships, 26 crew members died and 280,000 tons of crude oil were spilled into the Caribbean. Fortunately, the spills never reach shorelines.
In the Bay of Campeche off the coast of Mexico, 600 miles south of Texas, the company Petroleos Mexicanos (PEMEX) was drilling a 2-mile-deep oil well called IXTOC I. On June 3, 1979, a loss of drilling mud circulation forced a blowout, causing oil and gas to spew out of the well and ignite. The platform holding the drilling equipment and collecting the oil immediately caught fire and collapsed into the water. Several rescue crews worked for days to try to reach the Blowout Preventer (BOP) -- a large valve used to seal off the surface of a wellhead -- but poor visibility, debris and a long pipeline made it difficult. The IXTOC I well continued to spill oil at a rate of 10,000 to 30,000 barrels per day until it was finally capped on March 23, 1980 -- nine months after the initial incident. By the time it was capped, over 140 million gallons of oil had seeped into the bay, making it the second worst oil spill disaster in history.
Kuwait oil spills during the Gulf War remain the worst examples of eco-terrorism and are by far the worst oil disasters in history. Beginning in January 1991 during the Gulf War, the Iraqi Army deliberately spilled millions of barrels of oil in the Persian Gulf. Over 500 Kuwaiti tankers, oil fields and refineries were torched, and 3 to 6 million barrels of oil went up in smoke on a daily basis at the peak of the burnings. One 6-million-barrel spill covered over 600 square miles of water and the oil traveled as far as 20 miles away out into the Indian Ocean. The environmental and health risks were enormous, with over 90 million barrels of oil lost. Environmental experts deemed the incident 25 times more toxic than the Exxon Valdez.
On April 11, 1991, while unloading crude oil onto a floating platform seven miles off the coast of Genoa, Italy, the MT
exploded, burned for three days and then sank, spilling over 42 million gallons of oil in its wake into the Mediterranean Sea. The Italian and French coastlines were polluted for 12 years after the accident.
When the huge oil tanker
wrecked about 130 miles of the coast of Galicia, Spain during a storm on Nov. 19, 2002. The ship broke apart and sank to the bottom as it spilled over 1.5 to 2 million gallons of oil into the Atlantic Ocean. Three massive "black tides" soiled 125 miles of Spanish coastline within two weeks after the accident. Considered to be twice as big as the
accident, the Prestige accident remains the worst oil spill in Spain's history.
An oil well blow out in the Gulf of Mexico on April 20, 2010, caused an offshore oil drilling platform to explode and sink, killing 11 men onboard. Government scientists declared the Deepwater Horizon spill the largest in U.S. history -- with twice as much oil spilled than in the Exxon Valdez disaster.