There are about 17 000 shipwrecks along the coasts of Sweden and the Swedish Maritime Administration, in collaboration with among others Chalmers and SwAM classified 300 of them as hazardous for the environment. About 30 of the shipwrecks pose an acute environmental threat. They contain large amounts of oil that may leak. Shipwrecks leaking oil pose risk to marine life in Swedish waters. Organisms living in the vicinity of the shipwreck are mainly affected but the oil can also spread to other areas with the water currents.
SwAM has since 2016 had the responsibility to coordinate the investigations and the recovery of oil and ghost nets (old fishing gear that has remained in the sea and lakes that can continue to fish and catch birds, and other marine animals) from shipwrecks. With the help of Chalmers model, they have been able to prioritize among the wrecks.
“Before we decide which shipwreck to be recovered from oil, we can use the model to estimate the probability of a leak, the volume of oil in the wreck and where the oil is likely to end up in case of an oil leakage” says Fredrik Lindgren, an analyst at SwAM who previously worked on VRAKA during his doctoral studies at Chalmers.
To date, 360,000 litres of oil have been recovered
Since 2017, the model has been used for investigation and oil recovery operations of the six wrecks Thetis, Skytteren, Sandön, Hoheneichen, Lindesnäs and Finnbirch. They are all close to sensitive natural areas where oil leaks could have major, negative impacts on the environment, outdoor life and tourism.
Sandön and Hoheneichen proved to be empty of oil but from Thetis, Lindesnäs and Finnbirch they managed to recover a total of about 360,000 litres of oil and a large amount of ghost net. From Thetis, they also manage to recover 12 tonnes of purse seine (a kind of fishing gear) and during the recovery operation of Lindesnäs, a 46-meter long ghost net was found which was stuck to the wreck. The ghost net was recovered and left ashore for recycling or destruction.
The purpose of the investigation of Skytteren was, among other things, to get data to VRAKA for assessment. SwAM's assessment, however, was that an oil recovery operation is very likely to cost more than SwAM's annual budget for environmentally hazardous shipwrecks in Swedish waters. SwAM has requested funding from the government to increase the budget during a financial year, so that they can recover oil from Skytteren as well.
From 2018, SwAM was granted SEK 25 million per year until 2027 for research and oil recovery operations. Starting in 2020, the budget is SEK 30 million per year. VRAKA made the funding possible. Carrying out oil recovery operations is costly, from five to hundreds of millions. It is important to make qualified assessments of which wrecks that should be prioritized for oil recovery operations. VRAKA made the prioritization possible and SwAM can now use the funds to make the greatest environmental benefit by removing the threats to the environment from the wrecks that pose the greatest risk.