Do Tour Boats Affect Fur Seals at Montague Island, New South Wales?

Abstract

Interactions between fur seals (Arctocephalus pusillus doriferus and A. forsteri) and tour boats at Montague Island were investigated between November 1997 and November 1998. The fur seals were in four haul-out sites, which are referred to here as colonies. The study was instigated by the management requirement of the National Parks and Wildlife Service of New South Wales to determine effects of disturbance from tour boats on the fur seal colonies. At each of 84 inspections, distance between the boat and the colony was measured and seal behavior (or response) was recorded 11 times at 15-second intervals as the boat moved toward the seals. This period of 2.5 minutes was approximately the time tour boats stayed at a colony. Behavior of the fur seals ashore was recorded in four categories of increasing disturbance from "Resting" to "Many moving." From analyses using multinomial models, the probability of observing a given response by the fur seals and the pattern of the responses as a function of distance from the colony were both influenced by the colony under observation. In general, fur seals' responses were significantly correlated with distance between the study boat and the colony, and with the size of the colony (i.e., number of fur seals visible ashore). In all cases, the probability of the colony remaining in the "Resting" category decreased as the distance between the colony and the study boat decreased. Similarly the probability of the colony showing the maximum response ("Many moving") increased as the distance decreased. The probability of New Zealand fur seals "Resting" was higher than for Australian fur seals. Tour boats approaching the colonies had a relatively small effect on the fur seals; few or none of them ran to the sea. Based on results from this study, we recommended that the minimum approach distance of tour boats to the fur seal colonies at Montague Island should be 40 m; other recommendations involved how tour boats approach the fur seal colonies. The former has been gazetted as a government regulation and the other recommendations have been incorporated into the license conditions for the tour boats operators.