ABSTRACT
On 13th of April 2022, a ship-to-ship fuel transfer operation off the Swedish West coast resulted in a spill of VLSFO into the ocean. The spill traveled just below the surface and was invisible to the surveillance of the Swedish Coast Guard, until it ended up on the coast a day later, spreading around the archipelago outside Gothenburg and North of it. The Swedish Coast Guard estimates that around 1,000 L of oil were collected when the response operation was concluded. This is one of the first VLSFO spills in temperate waters. The behavior of this VLSFO spill was different to normal HFO spills. The oil clustered together into smaller and very sticky lumps to a larger degree, there was little to no oil sheen visible, and the oil was difficult to remove from the rocky shores and the abundance of algae on the coast. An environmental assessment was performed after sampling on the 3rd of May. The biological samples usually target blue mussels (Mytilus edulis), but they have become rare on the Swedish West coast and the invasive Pacific oyster (Magallana gigas) was instead sampled together with algae and sediment. Results showed increased levels of benzo(a)pyrene in the oysters, but no other thresholds were exceeded. Since the oysters are eaten, there is a need to develop guidelines and thresholds of hydrocarbons for human consumption, for which none exists in Sweden today. In order to make informed response decisions, more knowledge and research on the environmental impact of these new fuels are needed.