NOAA's Response and Restoration Blog

An inside look at the science of cleaning up and fixing the mess of marine pollution


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A Final Farewell to Oil Tankers with Single Hulls

January 1, 2015 marks a major milestone in preventing oil spills. That date is the deadline which the landmark Oil Pollution Act of 1990 (OPA-90) specifies for phasing out single-hull tankers in U.S. waters. That act, passed after the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, required that all new tankers and tank-barges be built with double hulls.

Recently constructed single-hull tankers were allowed to operate, but 25 years after the Exxon Valdez, those vessels are now at the end of their operational life and will no longer be able to carry oil as cargo. The requirement was phased in gradually because of the difficultly of converting existing single-hull tankers to double hulls, and retiring the single-hull tankers more rapidly would have been a major disruption to world shipping.

Counting Down to a New Era

There won’t be a dramatic change-over on New Year’s Eve; most of the tankers calling on U.S. ports have had double hulls years before this deadline. However, one ship which was not switched over to a double hull soon enough was the tanker Athos I. This ship, carrying 13.6 million gallons of heavy crude oil, struck a submerged anchor in the Delaware River and caused a relatively large, complicated oil spill near Philadelphia, Pennsylvania, 10 year ago.

In 1992, two years after the Oil Pollution Act, the International Convention for the Prevention of Pollution from Ships (the MARPOL Convention) was amended to require all newly built tankers have double hulls. MARPOL has been ratified by 150 countries, representing over 99 percent of merchant tonnage shipped worldwide.

Stay out of Trouble by Going Double

So, what is the big issue around single vs. double-hull ships? Historically, tankers carrying oil were built with a single hull, or single shell.

While we measure oil in barrels, it is not actually shipped that way. Instead, oil is pumped into huge tanks that are part of the structure of tankers and barges. For vessels with a single hull, one plate of steel is all that separates the oil on board from the ocean. If the hull were punctured from a collision or grounding, an oil spill is pretty much guaranteed to follow. On the other hand, a ship with a double hull has two plates of steel with empty space in between them. The second hull creates a buffer zone between the ocean and the cargo of oil.

Naval architects have debated the merits of various hull designs in reducing oil spills, and using a double hull, essentially a hull within a hull, was selected as the preferred vessel design.

Close up of gash in hull on Cosco Busan cargo ship.

The cargo ship Cosco Busan lost 53,000 gallons of fuel oil when the single-hull ship hit the San Francisco-Oakland Bay Bridge in 2007. (U.S. Coast Guard)

However, the double hull requirements only apply to tankers and tank barges. Container ships, freighters, cruise ships, and other types of vessels are still built with single hulls. While these ships carry a lot less oil than a tanker, a large non-tank vessel can still carry a lot of fuel oil, and some have caused some pretty big spills, including the 2007 oil spill caused by the cargo ship Cosco Busan in San Francisco Bay.

Of course, double hulls don’t prevent all oil spills from tankers either, but the design has been credited with reducing the amount spilled, especially in the cases of low-speed groundings and collisions.

And some pretty spectacular collisions have resulted in double-hull tankers not spilling a drop.

Twenty years after the Exxon Valdez oil spill, the Norwegian tanker SKS Satilla collided with a submerged oil rig in the Gulf of Mexico. The collision tore a huge hole in the side of the oil tanker, but, thankfully, none of the 41 million gallons of crude oil it had on board was spilled.


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Latest Research Finds Serious Heart Troubles When Oil and Young Tuna Mix

This story was first published on March 26, 2014. It was updated April 9, 2015 to reflect additional research.

Atlantic bluefin tuna prepares to eat a smaller fish.

Atlantic bluefin tuna are a very ecologically and economically valuable species. However, populations in the Gulf of Mexico are at historically low levels. (Copyright: Gilbert Van Ryckevorsel/TAG A Giant)

In May of 2010, when the Deepwater Horizon rig was drilling for oil in the open waters of the Gulf of Mexico, schools of tuna and other large fish would have been moving into the northern Gulf. This is where, each spring and summer, they lay delicate, transparent eggs that float and hatch near the ocean surface. After the oil well suffered a catastrophic blowout and released 3.19 million barrels of oil into the Gulf, these fish eggs may have been exposed to the huge slicks of oil floating up through the same warm waters.

An international team of researchers from NOAA, Stanford University, the University of Miami, and Australia recently published a study in the journal Proceedings of the National Academy of Sciences exploring what happens when tuna mix with oil early in life.

“What we’re interested in is how the Deepwater Horizon accident in the Gulf of Mexico would have impacted open-ocean fishes that spawn in this region, such as tunas, marlins, and swordfishes,” said Stanford University scientist Barbara Block.

This study is part of ongoing research to determine how the waters, lands, and life of the Gulf of Mexico were harmed by the Deepwater Horizon oil spill and response. It also builds on decades of research examining the impacts of crude oil on fish, which began after the 1989 Exxon Valdez oil spill in Alaska. Based on those studies, NOAA and the rest of the research team knew that crude oil—including oil from the Deepwater Horizon oil spill (Incardona et al. 2013)—was toxic to young fish and taught them to look carefully at their developing hearts.

“One of the most important findings was the discovery that the developing fish heart is very sensitive to certain chemicals derived from crude oil,” said Nat Scholz of NOAA’s Northwest Fisheries Science Center.

This is why in this latest study they examined oil’s impacts on young bluefin tuna, yellowfin tuna, and amberjack, all large fish that hunt at the top of the food chain and reproduce in the warm waters of the open ocean. The researchers exposed fertilized fish eggs to small droplets of crude oil collected from the surface and the wellhead from the Deepwater Horizon spill, using concentrations comparable to those during the spill. Next, they put the transparent eggs and young fish under the microscope to observe the oil’s impacts at different stages of development. Using a technology similar to doing ultrasounds on humans, the researchers were able create a digital record of the fishes’ beating hearts.

All three species of fish showed dramatic effects from the oil, regardless of how weathered (broken down) it was. Severely malformed and malfunctioning hearts was the most severe impact. Depending on the oil concentration, the developing fish had slow and irregular heartbeats and excess fluid around the heart. Other serious effects, including spine, eye, and jaw deformities, were a result of this heart failure. (Incardona et al. 2014 [PDF])

Top: A normal young yellowfin tuna. Bottom: A deformed yellowfin tuna exposed to oil during development.

A normal yellowfin tuna larva not long after hatching (top), and a larva exposed to Deepwater Horizon crude oil as it developed in the egg (bottom). The oil-exposed larva shows a suite of abnormalities including excess fluid building up around the heart due to heart failure and poor growth of fins and eyes. (NOAA)

“Crude oil shuts down key cellular processes in fish heart cells that regulate beat-to-beat function,” noted Block, referencing another study by this team, (Brette et al. 2014).

As the oil concentration, particularly the levels of polycyclic aromatic hydrocarbons (PAHs), went up, so did the severity of the effects on the fish. Severely affected fish with heart defects are unlikely to survive. Others looked normal on the outside but had underlying issues like irregular heartbeats. This could mean that while some fish survived directly swimming through oil, heart conditions could follow them through life, impairing their (very important) swimming ability and perhaps leading to an earlier-than-natural death.

“The heart is one of the first organs to appear, and it starts beating before it’s completely built,” said NOAA Fisheries biologist John Incardona. “Anything that alters heart rhythm during embryonic development will likely impact the final shape of the heart and the ability of the adult fish to survive in the wild.”

Even at low levels, oil can have severe effects on young fish, not only in the short-term but throughout the course of their lives. This is why the research team, composed of scientists from NOAA, Stanford University, and the University of Miami, is studying fish exposed to low levels of crude oil as embryos that subsequently grow into juveniles and adults in clean water. Initial research has shown that subtle disruptions of the embryonic heartbeat can produce permanent changes in heart shape that negatively affect swimming performance and other behaviors critical for fish survival. The team has shown similar underlying effects on juvenile mahi mahi (Mager et al. 2014), and studies are ongoing using zebrafish.

These subtle but serious impacts are a lesson still obvious in the recovery of marine animals and habitats still happening 25 years after the Exxon Valdez oil spill.

Find the most up-to-date summary of NOAA-funded research on crude oil’s potential effects on fish in the Gulf Mexico.


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Detecting Change in a Changing World: 25 Years After the Exxon Valdez Oil Spill

Life between high and low tide along the Alaskan coast is literally rough and tumble.

The marine animals and plants living there have to deal with both crashing sea waves at high tide and the drying heat of the sun at low tide. Such a life can be up and down, boom and bust, as favorable conditions come and go quickly and marine animals and plants are forced to react and repopulate just as quickly.

But what happens when oil from the tanker Exxon Valdez enters this dynamic picture—and 25 years later, still hasn’t completely left? What happens when bigger changes to the ocean and global climate begin arriving in these waters already in flux?

Telling the Difference

Two people wearing chest waders sift for marine life in shallow rocky waters.

In 2011 NOAA marine biologist Gary Shigenaka (right) sifts through the sediments of Alaska’s Lower Herring Bay, looking for the tiny marine life that live there. (Photo by Gerry Sanger/Sound Ecosystem Adventures)

In the 25 years since the Exxon Valdez oil spill hit Alaska’s Prince William Sound, NOAA scientists, including marine biologist Gary Shigenaka and ecologist Alan Mearns, have been studying the impacts of the spill and cleanup measures on these animals and plants in rocky tidal waters.

Their experiments and monitoring over the long term revealed a high degree of natural variability in these communities that was unrelated to the oil spill. They saw large changes in, for example, numbers of mussels, seaweeds, and barnacles from year to year even in areas known to be unaffected by the oil spill.

This translated into a major challenge. How do scientists tell the difference between shifts in marine communities due to natural variability and those changes caused by the oil spill?

Several key themes emerged from NOAA’s long-term monitoring and subsequent experimental research:

  • impact. How do we measure it?
  • recovery. How do we define it?
  • variability. How do we account for it?
  • subtle connection to large-scale oceanic influences. How do we recognize it?

What NOAA has learned from these themes informs our understanding of oil spill response and cleanup, as well as of ecosystems on a larger scale. None of this, however, would have been apparent without the long-term monitoring effort. This is an important lesson learned from the Exxon Valdez experience: that monitoring and research, often viewed as an unnecessary luxury in the context of a large oil spill response, are useful, even essential, for framing the scientific and practical lessons learned.

Remote Possibilities

As NOAA looks ahead to the future—and with the Gulf of Mexico’s Deepwater Horizon oil spill in our recent past—we can incorporate and apply lessons of the Exxon Valdez long-term program into how we will support response decisions and define impact and recovery.

The Arctic is a region of intense interest and scrutiny. Climate change is opening previously inaccessible waters and dramatically shifting what scientists previously considered “normal” environmental conditions. This is allowing new oil production and increased maritime traffic through Arctic waters, increasing the risk of oil spills in remote and changing environments.

If and when something bad happens in the Arctic, how do scientists determine the impact and what recovery means, if our reference point is a rapidly moving target? What is our model habitat for restoring one area impacted by oil when the “unimpacted” reference areas are undergoing their own major changes?

Illustrated infographic showing timeline of ecological recovery after the Exxon Valdez oil spill.

Tracking the progress of recovery for marine life and habitats following the Exxon Valdez oil spill is no easy task. Even today, not all of the species have recovered or we don’t have enough information to know. (NOAA) Click to enlarge.

Listening in

NOAA marine biologist Gary Shigenaka explores these questions as he reflects on the 25 years since the Exxon Valdez oil spill in the following Making Waves podcast from the National Ocean Service:

[NARRATOR] This all points back at what Gary says is the main take-away lesson after 25 years of studying the aftermath of this spill: the natural environment in Alaska and in the Arctic are rapidly changing. If we don’t understand that background change, then it’s really hard to say if an area has recovered or not after a big oil spill.

[GARY SHIGENAKA] “I think we need to really keep in mind that maybe our prior notions of recovery as returning to some pre-spill or absolute control condition may be outmoded. We need to really overlay that with the dynamic changes that are occurring for whatever reason and adjust our assessments and definitions accordingly. I don’t have the answers for the best way to do that. We’ve gotten some ideas from the work that we’ve done, but I think that as those changes begin to accelerate and become much more marked, then it’s going to be harder to do.”

 

Read a report by Gary Shigenaka summarizing information about the Exxon Valdez oil spill and response along with NOAA’s role and research on its recovery over the past 25 years.


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After the Big Spill, What Happened to the Ship Exxon Valdez?

This is a post by Gary Shigenaka, a marine biologist with NOAA’s Office of Response and Restoration.

Close-up of the ship's name on side of Exxon Valdez.

The last days of the Exxon Valdez: in the San Diego shipyard before the first name change. Photo from the collection of Gary Shigenaka, NOAA.

A popular myth exists that it is bad luck to rename a boat.  It is unclear whether this applies to “boats” as big as a 987-foot-long oil tanker, but it is possible that the ship originally known as the Exxon Valdez might be used to argue that the answer is “yes.”

When the Exxon Valdez was delivered to Exxon on December 11, 1986, it was the largest vessel ever built on the west coast of the U.S. On July 30, 1989, four months after it ran aground in Alaska’s Prince William Sound and caused the then-largest oil spill in U.S. waters, the crippled Exxon Valdez entered dry dock at National Steel and Shipbuilding in San Diego—its original birthplace.

The trip south from Prince William Sound had not been without incident. Divers discovered hull plates hanging from the frame 70 feet below the surface that had to be cut away, and a 10 mile oil slick trailing behind the ship for a time prevented it from entering San Diego Bay.

New Law, New Name

Ship Exxon Mediterranean in Trieste, Italy, July 1991.

Exxon Mediterranean in Trieste, Italy, July 1991. Photo by Arki Wagner, used with permission.

Nearly a year and $30 million later, the ship emerged for sea trials as the Exxon Mediterranean.  The Exxon Valdez had suffered the ignominy—and corporate hardship—of effectively being singled out in U.S. legislation (the Oil Pollution Act of 1990 [PDF]) and banned from a specific U.S. body of water:

SEC. 5007. LIMITATION.

Notwithstanding any other law, tank vessels that have spilled more than 1,000,000 gallons of oil into the marine environment after March 22, 1989, are prohibited from operating on the navigable waters of Prince William Sound, Alaska.

(33 U.S.C. § 2737)

With this banishment institutionalized in U.S. law, Exxon Shipping Company shifted the operational area for the ship to the Mediterranean and the Middle East and renamed it accordingly.  In 1993, Exxon spun off its shipping arm to a subsidiary, Sea River Maritime, Inc., and the Exxon Mediterranean became the Sea River Mediterranean.  This was shortened to S/R Mediterranean.

In 2002, the ship was re-assigned to Asian routes and then temporarily mothballed in an undisclosed location.

A Ship Singled Out?

Exxon filed suit in federal court challenging the provisions of the Oil Pollution Act of 1990 that had banned its tanker from the Prince William Sound trade route.  In November 2002, the Ninth Circuit Court of Appeals upheld the Oil Pollution Act and its vessel prohibition provision (the Justice Department noting that to that time, 18 vessels had been prevented from entering Prince William Sound).  While Sea River had argued that the law unfairly singled out and punished its tanker, and that there was no reason to believe that a tanker guilty of spilling in the past would spill in the future, the three-judge panel disagreed unanimously.

The Oil Pollution Act of 1990, the landmark law resulting from the Exxon Valdez oil spill, legislated the phase-out of all single-hulled tankers from U.S. waters by 2015. On October 21, 2003, single-hulled tankers carrying heavy oils were banned by the European Union.  A complete ban on single-hulled tankers was to be phased in on an accelerated schedule in 2005 and 2010. There remains pressure to eliminate single-hulled tankers from the oil trade worldwide, so their days are clearly numbered.

In 2005, the S/R Mediterranean was reflagged under the Marshall Islands after having remained a U.S.-flagged ship for 20 years (reportedly in the hopes that it eventually would have been permitted to re-enter the Alaska – U.S. West Coast – Panama route for which it had been designed).  The ship’s name became simply Mediterranean.

In 2008, ExxonMobil and its infamous tanker finally parted ways when Sea River sold the Mediterranean to a Hong Kong-based shipping company, Hong Kong Bloom Shipping Co., Ltd. The ship was once again renamed, to Dong Fang Ocean, and reflagged under Panamanian registry.  Its days as a tanker also came to an end, as the Dong Fang Ocean was converted into a bulk ore carrier at Guangzhou CSSC-Oceanline-GWS Marine Engineering Co., Ltd., China.

The Dong Fang Ocean labored in relative anonymity in its new incarnation until November 29, 2010.  On that day, it collided with another bulk carrier, the Aali in the Yellow Sea off Chengshan, China. Both vessels were severely damaged; the Dong Fang Ocean lost both anchors, and the Aali sustained damage to its ballast tanks.  The Dong Fang Ocean moved to the port of Longyan with assistance by tugs.

The End Is Near

With this last misfortune, the final countdown to oblivion began in earnest for the vessel-formerly-known-as-Exxon-Valdez.  In March 2011, the ship was sold for scrap to a U.S.-based company called Global Marketing Systems (GMS). GMS in turn re-sold it to the Chinese-owned Best Oasis, Ltd., for $16 million.

Exxon Valdez/Exxon Mediterranean/Sea River Mediterranean/S/R Mediterranean/Mediterranean/Dong Fang Ocean/Oriental Nicety being dismantled on the beach of Alang, India, 2012.

Exxon Valdez/Exxon Mediterranean/Sea River Mediterranean/S/R Mediterranean/Mediterranean/Dong Fang Ocean/Oriental Nicety being dismantled in Alang, India, 2012. Photo by ToxicsWatch Alliance.

Intending to bring the Oriental Nicety, as it had been renamed yet one last time, ashore at the infamous shipbreaking beaches of Alang, Gujarat, India, Best Oasis was blocked by a petition filed by Delhi-based ToxicsWatch Alliance with the Indian Supreme Court on the grounds that the ship could be contaminated with asbestos and PCBs. ToxicsWatch Alliance invoked the Basel Convention, which restricts the transboundary movements of hazardous wastes for disposal. However, an environmental audit required by the court showed no significant contamination, and in July 2012, the Oriental Nicety was cleared to be brought ashore for its final disposition. The ship was reportedly beached on August 2, 2012.

Shanta Barley, writing for Nature, penned a wry obituary as a lead-in to her article about the last days of the ship:

The Oriental Nicety (née Exxon Valdez), born in 1986 in San Diego, California, has died after a long struggle with bad publicity.

Editor’s note: Use Twitter to chat directly with NOAA marine biologist Gary Shigenaka about the Exxon Valdez and its impacts on Alaska’s marine life and waters on Monday, March 24 at 3:00 p.m. Eastern. Follow the conversation at #ExxonValdez25 and get the details: http://1.usa.gov/1iw2Y6W.

Gary Shigenaka.

Gary Shigenaka.

Gary Shigenaka is one of the original biological support specialists in the Emergency Response Division of NOAA’s Office of Response and Restoration. Even though his career with NOAA has spanned decades, Gary’s spill response experience began with the Exxon Valdez. He has worked countless spills since then, in the U.S. and internationally. He also currently oversees a number of response-related research efforts and represents the U.S. Department of Commerce on the Region 10 Regional Response Team.


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Do Bigger Oil Spills Require More Restoration?

This is a post by NOAA intern Franziska Economy.

Quick, can you name ten major oil spills?

Having a hard time? Until recently, I would have been scratching my head after:

  1. Deepwater Horizon/BP spill in the Gulf of Mexico (2010)
  2. Exxon Valdez tanker spill in Alaska (1989)
  3. … ?

Maybe some of you managed to come up with a couple of the other major spills from the last few decades, but this seems to be a tall order for the average person.

Oil spills actually happen just about every day, but most don’t make the news. I was surprised to learn that there are nearly 14,000 oil and chemical spills reported to the National Response Center every year.

Even crazier to me was the discovery that sometimes the best recovery option for small oil spills is actually taking “No Action.” This can be the case when cleaning up the oil would cause more harm to a sensitive ecosystem than just leaving it there to break down naturally. Sometimes, however, an oil spill can be relatively large and present real dangers to the plants and animals in the area without attracting much attention from the greater public.

Learning all of this prompted me to delve into the treasure trove of information on the oil spill cases NOAA’s Office of Response and Restoration handles. As the lead science agency for oil spills, NOAA is asked to respond to about 100–200 of the more significant marine and coastal spills every year to provide scientific support to help with the cleanup. A much smaller subset of those spills require a legal assessment of environmental monetary damages to restore those natural resources. This is known as a Natural Resource Damage Assessment or NRDA.

When studying these NRDA spill cases, I focused on two particularly interesting factors: the size of the oil spill and the “restoration cost,” or how much money the oil spiller has to pay to restore the public’s injured natural resources. Take a look at the top ten oil spill cases in each category and see how they compare:

Graph of the top ten NOAA oil spill NRDA settlements by dollar amount needed to restore injured environmental resources.

Figure 1. The top ten NOAA oil spill NRDA settlements by dollar amount needed to restore injured environmental resources. Note: each color in this graph corresponds to a spill found on both Figure 1 and Figure 2; gray spills are only found on one graph. Source: http://www.darrp.noaa.gov/ Click to enlarge.

Graph of the top ten NOAA oil spill NRDA settlements by the volume of oil spilled in gallons.

Figure 2. The top ten NOAA oil spill NRDA settlements by the volume of oil spilled in gallons. Source: http://www.darrp.noaa.gov/ Click to enlarge.

Right off the bat, it is easy to spot that bigger oil spills don’t always result in the highest restoration costs, and even if the restoration cost of a spill is relatively high, it is not necessarily related to the size of the spill. The Cosco Busan and Athos place first and second among oil spill settlements by restoration cost (Figure 1), but they are not big enough to land in the top ten by spill size (Figure 2; they are 12 and 23, respectively).

Furthermore, before the Deepwater Horizon/BP incident, the spill Barge Morris J. Berman was the largest spill that OR&R had responded to; yet it ranked only the fifth highest among restoration settlements, not even one-third the amount of the highest settlement, the Cosco Busan. In general, only half of the spills on each graph appear on the other, showing a lower correlation between these two variables than I originally thought.

So, why do you think that is? I’ve been brainstorming what factors could influence why gallons of oil spilled do not necessarily result in the most money required to restore natural resources. A single variable—such as the amount or type of oil spilled—isn’t by itself an accurate indicator of how much money it takes to respond to, clean up, and restore the environment after an oil spill. We have to examine a variety of factors to understand the bigger picture.

Other factors which might affect the restoration cost of an oil spill include:

  • the properties of the oil spilled (was it thick like tar that would sink to the bottom? Or was it light and likely to evaporate quickly from the water’s surface?)
  • the type and effectiveness of cleanup methods (was very little oil able to be recovered?)
  • the type of ecosystem affected (was it an estuary full of sensitive marsh grass and bird nesting sites or in an lower quality industrial area with a bulkheaded shoreline?)
  • the cultural and economic values of nearby cities and towns (was the spill close to a population with strong ties to the outdoor environment?)

What other issues do you think might play a role in how much restoration is required to offset the impacts of an oil spill on the environment?

Franziska Economy is an American University graduate with a Bachelors of Arts in Economics and Environmental Science. She is working as a Constituent and Legislative Affairs intern for NOAA’s Office of Response and Restoration and enjoys sharing the interesting facts she has learned and statistics she has uncovered. She hopes to help break down the acronym-filled, complicated world of responding to oil spills, assessing damages, and restoring broken ecosystems.


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What Happens After Abandoning Ship

Twenty three years after running aground on a reef in Alaska and causing one of the largest spills in U.S. history, the tanker Exxon Valdez is back in the news—this time to keep it from being intentionally grounded on a beach in India.

The Indian Supreme Court has ruled that the Exxon Valdez (now called the Oriental Nicety) cannot be grounded and cut apart on the shores of Gujarat until it can be cleaned of residual oils and other contaminants.

Workers scrap ships for parts and metal on a beach in Bhatiari, Chittagong, Bangladesh.

Workers scrap ships for parts and metal (“ship breaking”) on a beach in Bhatiari, Chittagong, Bangladesh. Credit: Naquib Hossain, Creative Commons License: Attribution-ShareAlike 2.0).

What’s known as “ship breaking” is a dirty business, and many of the world’s tired and obsolete vessels end up being grounded on beaches in India, Bangladesh, and Pakistan and cut apart for scrap steel.

In recent years the business of ship scrapping has become a major health and environmental concern. Many ship breaking yards in these developing countries have little or no safety equipment or environmental protections, and toxic materials from these ships, including oils, heavy metals, and asbestos, escape into the environment.

A derelict vessel grounded on a coal reef in Samoa.

A rusted-out derelict vessel still sits grounded on a coal reef in Samoa. (NOAA/Doug Helton)

Obsolete vessels and ship scrapping can also be a problem here in the U.S. Last year, the 431-foot S/S Davy Crockett made the news down on the Columbia River near Vancouver, Wash.

Mysterious oil sheens on the river were traced upriver to the former Navy Liberty ship that had begun leaking oil due to improper and unpermitted salvage operations.

Next week I will be at the Clean Pacific Conference in Long Beach, Calif., and presenting information on the challenges of dealing with abandoned and derelict vessels in the U.S. I know that the Davy Crockett and the issues it raised will come up.

Vessels are abandoned for all sorts of reasons, including storms (particularly hurricanes/typhoons which may damage large numbers of boats), community-wide economic stress or change (e.g., declining commercial fishing industries), and financial or legal issues of individual owners.  The high cost of proper vessel disposal can lead some folks to just walk away.

Hopefully we can help improve how we respond to these vessels and increase prevention programs to prevent abandonment. If you are interested in this issue, there is more information on NOAA’s Abandoned Vessel Program.


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More Than Two Decades Later, Have Killer Whales Recovered from the Exxon Valdez Oil Spill?

With input from NOAA’s Alan Mearns, Gary Shigenaka, and Marilyn Dahlheim.

Orca breaching.

Killer whale breaching (NOAA Marine Operations Center).

Does a killer whale instinctively know how to avoid oil spilled on the surface of its watery home? At the time of the Exxon Valdez oil spill twenty-three years ago, scientists and oil spill experts presumed that the answer was “yes.”

They thought marine mammals were “smart” enough to steer clear of spilled oil, which possibly could harm their skin and eyes or irritate their lungs with hazardous vapors.

Yet, within 24 hours of the tanker Exxon Valdez grounding on Bligh Reef, killer whales were photographed swimming through iridescent slicks of oil in Prince William Sound, Alaska. No one was quite sure then how this exposure to oil might affect the health of killer whales living there. For most oil spills, we don’t know how well individual species were faring before oil invaded their habitats, complicating our ability to understand health impacts after a spill. This time, however, was different.

“Orcas (killer whales) have been particularly interesting because they have been so well studied and are one of the few critters for which pre-spill information was available,” NOAA biologist Gary Shigenaka says of the 1989 Exxon Valdez spill, which he has worked on extensively.

The two killer whale pods unlucky enough to swim in or near Exxon oil were from two different eco-types of killer whales, known as “resident” and “transient.”  Eco-types differ in several aspects of morphology (shape and structure), ecology, behavior, and genetics.  For example, resident whales primarily feed on fish while transient killer whales feed on marine mammals.

Since the 1989 oil spill, scientists have followed closely the killer whale populations of Southeast Alaska. They have examined both the two pods of whales exposed to the oil in Prince William Sound as well as the other resident and transient pods which were not in the oiled areas at the time. The differences are stark.

Killer whales swimming alongside boats skimming oil from the Exxon Valdez oil spill.

Killer whales swimming in Prince William Sound alongside boats skimming oil from the Exxon Valdez oil spill (State of Alaska, Dan Lawn).

In the year and a half after the Exxon Valdez spill, both groups of killer whales swimming through Prince William Sound at the time experienced an unprecedented high number of deaths. The pod of resident killer whales lost 33% and the pod of transients 41% of their populations, according to a 2008 study by researcher Craig Matkin [PDF]. In general, killer whales tend to have very stable populations, usually losing only very young or very old whales when they lose any.

But in this case, the pods were losing a number of immature whales and breeding females as well. Missing these key members, the populations in the oiled areas were slow to bounce back, if they bounced at all. One pod of resident killer whales still hasn’t reached its pre-spill numbers, while the oil-exposed transient pod’s numbers have dropped so much that NOAA’s National Marine Fisheries Service has listed them as a “depleted stock” under the Marine Mammal Protection Act. Meanwhile, the other killer whale populations in Southeast Alaska have been growing since the mid-1980s.

Graph of killer whale populations exposed to oil after the Exxon Valdez spill.

Population trends in killer whales before and after the Exxon Valdez oil spill: AB Pod is the group of resident whales while AT1 is the transient group exposed to oil in Prince William Sound. Courtesy of Craig Matkin.

Still, because researchers were unable to examine either live or most of the dead whales after the spill (and thus confirm oil-related injuries), any direct link between the spill and killer whale health has been circumstantial. Even so, Shigenaka personally believes that this indirect evidence “stands the test of time.”

The crux of it lies in the fact that two pods of very different killer whale groups crashed suddenly and simultaneously after only one obvious disturbance to their environment—the Exxon Valdez oil spill.

Fast forward twenty-one years to April 2010 in the Gulf of Mexico. Taking these lessons about killer whales and oil from the Exxon Valdez, NOAA’s Office of Response and Restoration quickly partnered up with the NOAA Fisheries Service to do reconnaissance during the Deepwater Horizon/BP oil spill, especially in oiled areas. Twenty-one species of marine mammals live in the Gulf, and bottlenose dolphins in particular potentially could be suffering some significant impacts from this spill.

Since February 2010 (before the oil spill), nearly 700 bottlenose dolphins and other species of cetaceans (dolphins and whales) in the Northern Gulf of Mexico have been stranded. These marine mammals are experiencing what’s known as an “unusual mortality event,” defined as “a stranding that is unexpected, involves a significant die-off of any marine mammal population, and demands immediate response.” Federal and state agencies have been investigating this large die-off and any possible connections to its overlap with the Deepwater Horizon/BP oil spill.

These investigations are ongoing and the possible role of infection in these dolphins adds a twist that leaves us with plenty of questions still to answer. Nevertheless, every piece of information we learn helps create a fuller picture of how oil spills affect marine mammals, whether we’re looking at killer whales in Prince William Sound or bottlenose dolphins in the Gulf of Mexico.

For more information on killer whales and the Exxon Valdez oil spill, check out:

Matkin, C.O., Saulitis, E.L., Ellis, G.M., Olesiuk, P., Rice, S.D. 2008. Ongoing population-level impacts on killer whales Orcinus orca following the ‘Exxon Valdez’ oil spill in Prince William Sound, Alaska. Marine Ecology Progress Series, 356:269-281.

Loughlin, T. R. Ed. Marine Mammals and the Exxon Valdez. Academic Press, San Diego, 1994.