The effect of land based seal watching tourism on the haul-out behaviour of harbour seals (Phoca vitulina) in Iceland

•Harbour seals (Phoca vitulina) were affected by the presence and behaviour of tourists.•The vigilance of seals increased when tourists were present in the area.•However, the seals were less vigilant when tourists behaved in a passive way.•The presence of tourists affected the spatial distribution of the harbour seals.•Single tourists and couples behaved calmer than families and other tourist groups.

The effect of land-based seal watching on the haul-out pattern of harbour seals (Phoca vitulina) was investigated between June and August of 2008–2010 on Vatnsnes, NW Iceland. The results showed that the behaviour and spatial haul-out pattern of seals was affected by the tourists. In 2009 the seals were more likely to be vigilant during periods when tourists had access to the area, compared to a period when tourists were not allowed in the area. Also, in 2010 the likeliness of the seals being vigilant increased as the number of tourists in the area increased. In addition, seals were more likely to be vigilant when tourists behaved in an active way. During the post weaning period, which coincided with the peak of the tourist season, a significantly higher proportion of seals hauled out on the skerry located farthest away from land, compared to a skerry closer to land. Seals also preferred to haul out further away from land when the number of tourists in the area increased. Single tourists and couples behaved more passively compared to families and tourist groups of more than two adults. All tourist group types were significantly more active in an approaching zone than in the seal watching zone. Education of tourists, for example through a code of conduct built on these results, is advisable to minimise disturbance of seals in the area.