A major oil spill in the Lofoten area during the spawning season can affect eggs, larvae and the spawning behaviour of mature fish. If possible, bigger fish

can escape a polluted area, but eggs and fish larvae are far less mobile [8]. With mature cod spawning in a concentrated area, a major oil spill could more easily overlap the whole distribution area of the resulting larvae [8] and possibly affect an entire yearclass of cod. Simulations of oil dispersal and the probability of various levels of population loss for several species of marine birds and mammals are presented in the Management plan, while improvements are requested on the consequences for fish species [8] and [28]. The current improvements include coupling an oil LBH589 chemical structure dispersal model and a distribution model for Northeast Arctic cod eggs and larvae [42]. The simulated diurnal migration of larvae and PCI-32765 cell line the refined modelling of vertical location of fish eggs are expected to improve the estimated exposure of larvae and eggs to toxic oil components [42]. Also, there are efforts to simulate the effects of egg and larvae mortality on the future cod stock [43]. These projects are financed by the Research Council of Norway and the petroleum sector [29], [42] and [43]. In spite of expected improvements, uncertainty will remain. The simulated overlap

between oil spill and mature cod, eggs and larvae is still uncertain. How much will the, partly unknown, diurnal pattern of larvae, moving up and down the water column, increase or decrease their chances of getting affected by an oil slick? How does cod in early life stages follow ocean currents? To what extent can mature cod avoid an oil slick? Species such as cod, and especially herring, have variable recruitment success between years. Typically a few

good yearclasses dominate the population, whereas most years produce only a moderate level of recruitment. This variability increases the potential harm that a spill in a single year can inflict on the stock [8]. And although spawning fish may avoid an oil spill, they may choose less favourable spawning Thymidine kinase locations or the spawning ritual may be affected. It is also an open question whether the majority of the successful recruits come from only a few portions (limited in space and time) of the spawned eggs or whether there is a relatively homogenous contribution from different spawning sites and times [8]. An entire yearclass could potentially be killed although only a part of the spawning stock is affected. Further, the abundance of a stock and its distribution prior to a major oil spill will influence the impact of a major oil spill, but the abundance fluctuates significantly from one year to another, resulting in uncertain assessments and predictions, even before taking effects from an oil spill into account.