The spill scenarios developed for the revision of the

Management plan [27] predicted that on average even the worst-case scenario would have little adverse effects, but that there was a certain probability it could affect a large proportion of the yearclass of cod and especially herring. These effects would be further magnified if that occurred during a year with high recruitment, further diverging the worst possible outcome from the expected one. The experience from the 1989 Exxon Valdez oil spill in the Gulf of Alaska shows that long term effects are not only difficult to predict, but also challenging to determine even with the benefit of hindsight [50]. Before this oil spill, it was assumed that acute mortality was the key concern, but experience from this oil spill indicates an unexpected long-term effect on wildlife www.selleckchem.com/products/Etopophos.html [51]. On the other hand, uncertainty still remains on whether the oil spill was the major Ganetespib in vitro cause of the herring stock collapses [49]. Present efforts of refining risk assessments have the potential to reduce some of the associated uncertainties. For example, including cod larvae’s diurnal migration pattern may offer new insight in potential overlaps between an oil slick and cod larvae. However, including more detailed information will introduce new layers of uncertainty: Is the model resolution

sufficiently fine to assess the exposure of larvae during their migration up and down the water column? What other factors determine survival of larvae to later life stages? There are several sources of uncertainty that make the associated uncertainty challenging to reduce: (i) Major oil spills are rare, and hence empirical knowledge is scarce. The conditions have rarely been the same from one blowout to another, and

almost oil tanker accidents and recent blowouts reveal unpredicted dispersal or phenomena that have not been observed before, for example the fate of an oil slick [52] and [53]. (ii) Ocean currents and other environmental conditions are influenced by stochastic processes and will affect the distribution of an oil slick, on fish stocks and other marine life in a non-predictive way [8]. (iii) Political, cultural, natural and technical conditions change and will always be unpredictable to some extent. Taken together, uncertainty will necessarily remain, both on the probability and the size of a worst-case scenario. The uncertainty is thus reducible only to some indeterminate extent. Concerning the presentation of risks, there is a structural issue on how the “worst case” is defined. The “worst case” could be related only to the size of the oil spill, but it could also be defined as the worst case in terms of fate, weather conditions, time of year, overlap with fish larvae, etc. As a result, the risk assessment for an equally large oil spill is driven by the choice of how that “worst case” is defined. A second issue relates to the low probability, high impact and nature of the risk.