Sperm whales at Kaikoura and the effects of whale-watching on their surface and vocal behaviour
Richter, Christoph Friedrich
Whale-watching has become a globally successful branch of the tourism industry. While there is ample information on its economic importance, there is only scant data on the environmental, social and cultural impact. Kaikoura, a small coastal community on the South Island of New Zealand, serves as an example to describe the development of a whale-watching industry. Off Kaikoura, male sperm whales (Physeter macrocephalus) are the focus of the whale-watching industry, which uses boats and aircraft to view the animals year-round. The objective of this thesis was firstly critically to review the literature on. Whalewatching impacts on cetaceans and propose a more unified study approach. Sixty papers were reviewed for field methods, study design and statistical analyses. None of the studies were readily comparable due to lack of information and/or varying design and analysis. By drawing on the vast experience of land-based environmental impact assessment and by considering carefully the choice of observation platform, control conditions, study design, and the issues of pseudoreplication and balance between Type I and II errors, more comparable and effective studies on the impacts of whalewatching could be carried out. Secondly this thesis assessed the influences of current whale-watching activities off Kaikoura on the surfacing and vocalisation patterns of the sperm whales. This study employed boat-based and shore-based observations to determine the impacts of current whale-watching activities on the whales. From the independent research vessel, blow intervals, surface time, number of blows during a surfacing, aerial behaviours and time to first click were recorded. In addition, whales were individually identified from fluke photographs. Shore-based observations focused on blow intervals. Over four years ( 1998-2001 ), we recorded 1,676 sightings from the research vessel and 435 from shore. Several aspects of whale behaviour were significantly affected by the presence of whale-watching vessels. Data collected from shore showed that blow interval (mean and median) decreased in the presence of the research vessel and/or whale-watching platforms. Data collected from the research vessel showed that both whale-watching boats and planes, individually or together, caused increases in time spent at the surf ace, the frequency and amount of heading changes, and in the case of boats, a decrease in the time to the first click. Aerial behaviours were more frequent when only the research vessel was present, which is likely due to the closer positioning of the research vessel to surfacing whales after acoustic tracking. Two groups of sperm whales are distinguishable off Kaikoura: resident whales, which typically stay in the study area for weeks or months at a time, often returning in different seasons and/or years, and transients, which are seen on one day only. From this study, it is clear that transients react more frequently and more strongly to vessels. However they are rarely visited by whale-watching trips, owing to their distribution further offshore. Residents react less and bear the majority of whalewatching activity. Taken together, our analyses show that reactions to whale-watching vessels vary significantly among different individuals, some of which are very tolerant. Reactions also vary with season, for reasons that are not understood, but which may reflect prey distribution or availability. On balance, effects on resident whales, while statistically detectable, appear to be sustainable, and of no serious biological consequence. However, current whale-watching effort on residents is high, individuals are likely to spend approximately half of their surfacings during the busy summer season with one or more accompanying vessels.
Advisor: Dawson, Steve; Slooten, Liz
Degree Name: Doctor of Philosophy
Degree Discipline: Zoology
Publisher: University of Otago
Research Type: Thesis