On the policy aim to reduce illegal discharges by 25% between 1990 and 1995 (WL), the question arose how the success of measures would be evaluated (JAF). It appeared that at present there was no method of measuring the reduction (WL). The only available database at this moment were number of oil slicks from aerial surveillances (KJB), but it is possible that from Beached Bird Survey (BBS) results equally valuable information could be derived (KJB, WL). The use, value and establishment of an Exclusive Economical Zone (EEZ) were questioned (CA, AG). KJB explained that in an EEZ national laws can be enforced, including environmental regulations. The EEZ is not yet established because an international agreement has not been achieved so far. KJB stated that if such an agreement will not be reached soon enough, the Netherlands will proceed on there own. In 1989, the North Sea Working Group proposed to make the use of oil reception facilities in harbours free, and to include the costs for these facilities in harbour dues (RG). KJB answered that other measures are preferred. Rather worrying was the conclusion from TK that at present, despite measures and aerial surveillance, there are no signs of reduction in the amounts of oil spilled in bilgewater operations at sea (chronic oil pollution). The possibility to intensify aerial surveillance by using the navy (AG) was considered too costly in impractical in the Netherlands (TK), but is taken more serious in Norway (AF). TK further commented that the presence of an aircraft apparently did not stop illegal discharges; there does not seem to be a strong prevention from discharges from the aerial surveillance. BW asked whether or not ’illegal’ discharges according to the MARPOL convention could be separated from allowed operational discharges during aerial surveillance. At the North Sea Directorate, it is the impression that any visible slick, or any slick detectable in the SLAR image, is an illegal discharge; 15 ppm is definitely not visible (TK). As soon as a vessel is detected with a visible trail of oil, it must have been an illegal discharge according to the MARPOL Convention. The next step will be to lay down this opinion in an official document to convince judges that these visible slicks are all violations of the law. KJB adds that this is the reason why within IMO, North Sea states have proposed to decrease the amount of oil to be discharged legally from 100 to 15ppm within Annex I of the MARPOL Convention. JAF raised the problem that with tankers, being allowed to discharge 60 litres per mile, it will remain very hard to see the difference between legal and illegal discharges. TK remarks that mineral oil discharges from tankers are nowadays seldom observed. If discharging tankers were observed, it often referred to vegetable oils or bilge waters. The majority of vessels found to discharge illegal amounts of oil are ordinary cargo ships like container vessels. On average, 80 vessels per year are caught red-handed. JAF and GD remark that this may be true for the Dutch continental shelf, but certainly not for the entire North Sea. The second subject of discussion concerned knowledge of the presence of vulnerable concentrations of seabirds when the decision has to be made to clean up a spill or leave it. CJC remarks that todays policy, to combat a slick when it comes ashore but to leave it when it remains offshore, is nice for beaches but hazardous for seabirds. TK answers that mud-flats, as vulnerable areas, are certainly taken into account. Up to date information on vulnerable concentrations of seabirds is not available. The British way of dealing with these matters was considered interesting and worthy to follow.