Impacts from maritime transport

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Estimating the Non-Market Environmental Damages caused by the Prestige Oil Spill


Maria L. Loureiro, John B. Loomis, and Maria Xosé Vázquez

On November 13, 2002, the single-hull 26 year-old oil tanker, Prestige, suffered a serious accident just 46 kilometers away from the Finisterra Cape, in the Northwest of Galicia (Spain). The Prestige had a complicated parentage. It was owned by a Liberian company, registered in the Bahamas, and was operated by a Greek captain with a Filipino and Greek crew. It carried about 77,000 metric tons (MT) of heavy low-quality oil. Six days after the accident, and after traveling without a clear direction outside the Atlantic coast of Galicia, the Prestige sank 222 Kilometers away from the Cies Islands on November 19, 2002, after splitting in two during a storm. On its way to the bottom of the sea it spilled more than 60,000 MT of oil, polluting more than 1,300 kilometers of coastline. Its spill was the most serious environmental accident ever suffered in Spanish waters. It began in November 2002 and lasted for about 4 months, affecting the coasts of Northern Portugal, Northern Spain and Southern France. The spill from the Prestige arrived at the Spanish coast in three large “black waves,” contributing to the extended agony of all affected individuals. The first large wave arrived at the Galician coast on November 16, 2002, and at the time the regional authorities of Galicia issued a prohibition for inshore fishing as well as shellfish extraction (fishing and shellfish ban) in the affected area. The lack of cleaning equipment and qualified personnel made it difficult to articulate a quick and proper response to clean such large affected area. While the oil was piling up on seashores and beaches, the second wave of oil arrived on November 20, 2002, being the worst in magnitude (with 30 kilometers in length according to satellite images). Almost the entire Galician littoral was closed for fishing and shellfish extraction, and in most cases, the affected areas would not be re-opened until a few months later. When the Prestige sank, it was estimated that it took around 50,000 MT of its cargo of heavy oil down to the sea bed. However, posterior estimations showed that only 11,000 MT were kept inside, spilling the rest into the waters. The third oil wave arrived at the coasts on December 19, 2002, after the tanker sank. However, until February 1, 2003, the Prestige kept leaking oil from its tanks while on the sea bed, creating multiple smaller spills arrived at the seashores.

The cleaning operations continued for many months, although by summer time 2003 most of the affected beaches were cleaned. In December 2004, and after all cleaning operations were completed on the coast, a total of 97,000 MT of waste coming from the Prestige had been collected along the coast of Galicia only, from which 78,000 MT were solid materials, and 19,000 MT were oiled waters collected by the cleaning ships.

The environmental damage caused by the Prestige oil spill was very severe, seriously affecting commercial fisheries, recreational activities, and other marine mammals and birds. On August 31, 2003, a total of 13,221 birds were collected along the Galician coast, from which 2,466 (20%) were still alive and 9,242 (69.90%) were dead. From the birds alive, about 629 were cleaned and sent back to their natural habitats. This represents a recovery rate of about 10%. Three bird species were heavily affected by the oil spill: razorbill (Alca torda), common mure (Uria aalge), and Atlantic puffin (Fratercula arctica), which jointly account for 80.5% of the total birds soiled. Among all, the common murre was the most affected specie with 4,492 oiled birds (36.8% of the total collected in Galicia). In total, about 23,181 birds were collected in all the affected Spanish regions, while the total amount of birds killed was about 15,610, including those also collected in the French and Portuguese coasts. However, previous estimations consider that the number of killed birds could be even much larger. In January 2003, the Spanish Society of Ornithology and Birdlife estimated that the number of birds killed by this oil spill was between 65,000-130,000, which would make the Prestige the second worst oil spill in history with respect to the number of killed birds. Other international studies conducted after the Erika, Braer, and Exxon Valdez oil spills present even a more negative outlook, showing that the percentage of collected birds is usually between 15-50% of the total affected. Consequently, we could expect that the number of killed birds may add to 115,000-230,000.

Valuation of all environmental damages is a complex task. In this empirical exercise we focus on the so-called passive use values of ecosystem services. We use the contingent valuation (CV) method as Carson et al. (1992) in the valuation of the environmental damage caused by the Exxon Valdez Oil Spill. The survey employed in the environmental damage assessment followed the guidelines suggested by Carson et al (1992), although incorporated important changes in order to deal with socio-economic and cultural differences of the targeted samples. In addition, other methodological refinements were included.

The contingent valuation survey was carried out in a representative sample of the Spanish population during the spring and early summer 2006. In total, about 1110 completed surveys were collected. The main objectives of the present survey were: a) to assess the total lost passive value in this environmental accident, as it has been done in previous oil spills, such as in the Exxon Valdez oil spill; and b) to assess the sensitivity of WTP estimates under different scenarios.

The survey had different sections: in the first section, the environmental consequences of the Prestige oil spill were described in great detail; the second section presented a program designed to prevent future oil spills. Photographs and graphics were used to facilitate the participants´ understanding. The third section contained information about the expected effects of a prevention program specifically designed to reduce the magnitude and frequency of oil spills in the Northwest coast of Spain. The fourth section included the WTP question for the described prevention program. Right after the WTP question, a follow-up certainty scale was presented. Finally, the last section contained the socio-economic questions and other attitudinal questions. Surveys were administered at private homes at different hours during the week days and weekends. The response rate was 44%, which is fairly high for CV studies conducted in Europe.

Results from this survey show interesting results. About 67% of the respondents consider than the environmental losses were far more important than any other economic or related losses. Survey participants were also worried about the health effects caused by the Prestige oil spill, and about 26,84% of them declared to have reduced fish consumption in the months after the Prestige oil spill, and 15,18% of them did not still recover their full trust in the fish quality. Mean willingness to pay for a program to avoid a similar oil spill as the Prestige was estimated with a logit model, and it amounts to about 35 € per Spanish household. This implies that total passive use losses caused by the Prestige are at least equal to the amount individuals wish to pay to avoid future spills. These estimates reflect significant societal losses, which are equivalent to 9,800,000 €. In future analysis we will analyze the sensitivity of our results. This study reflects the importance of considering the environmental damages that go beyond the traditional market or commercial losses into the total damage assessment valuation.

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