The effects of oil-base drilling mud and crude oil on demersal fish eggs

The Norwegian spring spawning herring and the Barents Sea capelin both with demersal eggs, spawn in relative small and concentrated areas on the Norwegian continental shelf. Besides potential impact on the fish resources from oil pollution, drilling of oil wells can in some cases, where oil-base drilling mud is used, have an impact on the development of demersal eggs. This paper presents the biotest setup at the Institute of Marine Research in Bergen for testing effects from oil hydrocarbons and other water soluble toxicants on marine organisms. Methods for testing effects of oil and oil-base drilling mud on fish eggs and larvae are discussed. It also shows results from experiments, where capelin and herring eggs/larvae are exposed to oil (200 ppb WSF) and to drill cuttings (1,3 gram/liter) where oil-base drilling mud is used, and elaborate further how the findings can be used in advising the authorities how to avoid possible conflicts from drilling activities