Oil Spill Timeline and Sea Otters

Transporting oil across the sea in tankers and drilling for oil at sea can lead to devastating oil spills which are hard to contain and are detrimental to the marine environment and the organisms which inhabit it. As sea otters have such limited natural ranges, some of which coincides with oil tanker routes, one spill may be disastrous for a huge proportion of the sea otter population. One of the most catastrophic oil incidents to affect sea otters was the Exxon Valdez oil spill. On the evening of the 23rd of March 1989, the Exxon Valdez tanker left the port of Valdez bound for Long Beach California. At approximately 12.04 am on the 24th of March 1989 the tanker ran aground on Bligh reef after deviating from the shipping lanes. Eight of the eleven oil holding tanks were ruptured and 11 million gallons of Prudhoe Bay Crude Oil was spilt.

The oil spread over an estimated 470 -1000 miles of Alaskan coastline (Figure 2). The oil killed an estimated 250,000 seabirds, 300 seals, 22 killer whales, millions of fish eggs and nearly 3000 sea otters. Exxon Mobil the owner of the ship, failed to provide any recovery effort for 3 days due to lack of preparation. This meant that at the start of the recovery process the oil slick had become unmanageable and almost impossible to contain. The recovery effort included the work effort of 11,000 persons (some of who created small pop-up towns around the area), 58 aircraft, 1400 ships and vessels. The initial clean-up finished in 1992, taking 3 years.  Exxon Mobil claims to have spent $4.3 billion on the recovery effort and insists there has been no long-term impact, however, many Alaskan beaches have crude oil buried just below the surface (Plate 1)(Li and Boufadel, 2010). This suggests that oil is still present in the area and could be having long-term impacts on the environment (Golet et al., 2002; Kingston, 2002; Monson et al., 2000; Peterson et al., 2003; Short, 2003). 

Although the Exxon Valdez is the biggest oil contamination incident to affect sea otters it is not the first or last. The 1969 Santa Barbara Oil spill, was until the Exxon Valdez spill, the biggest oil spill in US history. In this incident, 3 million gallons of oil leaked into the sea over several months. This spill occurred at an offshore oil platform in the Santa Barbara Channel and was caused by an oil well explosion. This event killed many marine organisms but much of the impact was unrecorded, so it is not exactly known how many sea otters died in this incident. Then in 2015, the Refugio oil spill occurred, caused by another oil well blowout, and spilt 100,000 gallons of oil very close to the location of the 1969 Santa Barbara oil spill (Figure 3). Although sea otters were not listed as animals which had been affected by this spill, only 58 of the 99 marine mammals killed were recorded to species level. The spill was very close to an important area for the Southern Sea Otter, Cojo Anchorage near Point Conception, and with the spill reaching just 10 metres from this area, it is highly probable that it has affected sea otters.

It was also reported that in 1964 near the Kuril Islands 100 sea otters were contaminated with oil from a diesel spill, this was cited by(Geraci and Williams, 1990) from (Barabash-Nikiforov et al., 1968). There have also been isolated incidents of oil-contaminated sea otter carcasses washing ashore in both Alaska (Hess and Trobaugh, 1970) and California (Kooyman et al., 1976).