How can a potential oil pollution affect the recruitment to fish stocks?

Abstract

Eggs, larvae and the larvae's first search for food are the most critical stages in a fish life, both to threats from natural causes and pollution. Based on experimental studies of several species of fish eggs, larvae and zooplankton, and their in situ abundance, calculations of potential reduction of the affected year class or stock are demonstrated. The organisms exposed to oil concentrations likely to be found in the marine environment show considerably variation from species to species. While our experiments show little or no impact on herring eggs and larvae, eggs of saith and cod do not tolerate even short term (2-24 hour) exposure to low oil concentrations (50 ppb WSF). In some areas the majority of the years spawning products are restricted both in time and space, and therefore the potential for reduction in the recruitment of these stocks is considerable. Based on registered distributions of fish eggs and larvae, our calculations show a fairly low percentage of potential reduction using a worst case concept. Although the statistically calculated risk for an accident resulting in serious oil pollution is very low, real and severe accidents remind us that this may happen every so otten regardless of the statistics. It is our hope that the experimental results presented can be used in predicting and assessing the impact of serious oil spills.