Studies on imposex in the dogwhelks (Nucella lapillus) in Icelandic waters in 1998 show that the level of imposex has decreased considerably since 1992-1993, two years after implementation of restrictions on the use of tributyltin (TBT)-based anti-fouling paint. Vas Deferens Sequence Index (VDSI) and Relative Penis Size Index (RPSI) levels have declined considerably, both near large and small harbours. The impact area of a large harbour complex has decreased considerably, while lesser changes were seen in the impact areas near smaller harbours. (C) 2000 Elsevier Science Ltd.
I wish to thank the following persons for their aid in dissecting and/or sampling dogwhelks: Arja Kalvas, Bjarni K. Kristjánsson, Steinunn H. Ólafsdóttir and Menja von Schmalensee. I wish to thank Helgi Jensson and Davı́ð Egilsson for their help, Jóhanna Weisshappel for help in making Fig. 1 , AMSUM for financial support and Agnar Ingólfsson and an anonymous reviewer for valuable comments and advice.