Behavioural effects of tourism on oceanic common dolphins, Delphinus sp., in New Zealand: the effects of Markov analysis variations and current tour operator compliance with regulations.

Anna M Meissner,Matthew D M Pawley,Karen A Stockin,Fredrik Christiansen,Mark B Orams,Emmanuelle Martinez,Axel Cloeckaert

doi:10.1371/journal.pone.0116962

Anna M Meissner, Matthew D M Pawley + Show 5 more

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https://doi.org/10.1371/journal.pone.0116962

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Abstract

Common dolphins, Delphinus sp., are one of the marine mammal species tourism operations in New Zealand focus on. While effects of cetacean-watching activities have previously been examined in coastal regions in New Zealand, this study is the first to investigate effects of commercial tourism and recreational vessels on common dolphins in an open oceanic habitat. Observations from both an independent research vessel and aboard commercial tour vessels operating off the central and east coast Bay of Plenty, North Island, New Zealand were used to assess dolphin behaviour and record the level of compliance by permitted commercial tour operators and private recreational vessels with New Zealand regulations. Dolphin behaviour was assessed using two different approaches to Markov chain analysis in order to examine variation of responses of dolphins to vessels. Results showed that, regardless of the variance in Markov methods, dolphin foraging behaviour was significantly altered by boat interactions. Dolphins spent less time foraging during interactions and took significantly longer to return to foraging once disrupted by vessel presence. This research raises concerns about the potential disruption to feeding, a biologically critical behaviour. This may be particularly important in an open oceanic habitat, where prey resources are typically widely dispersed and unpredictable in abundance. Furthermore, because tourism in this region focuses on common dolphins transiting between adjacent coastal locations, the potential for cumulative effects could exacerbate the local effects demonstrated in this study. While the overall level of compliance by commercial operators was relatively high, non-compliance to the regulations was observed with time restriction, number or speed of vessels interacting with dolphins not being respected. Additionally, prohibited swimming with calves did occur. The effects shown in this study should be carefully considered within conservation management plans, in order to reduce the risk of detrimental effects on common dolphins within the region.

Highlights

Over the past two decades, an abundance of literature referring to boat based marine mammal tourism has clearly shown that cetacean-watching is seldom benign and that careful management is required to minimise potential negative effects on targeted populations [1, 2, 3, 4, 5, 6, 7]
We found that a vessel traffic intensity exceeding 34.0 and 56.0% would significantly affect common dolphin cumulative foraging and travelling behaviours, respectively (Fig. 4a)
Regardless of either Markov approach applied, our study provides further evidence that commercial tourism induces significant changes in the behaviour of common dolphins using open oceanic waters

Summary

Introduction

Over the past two decades, an abundance of literature referring to boat based marine mammal tourism has clearly shown that cetacean-watching is seldom benign and that careful management is required to minimise potential negative effects on targeted populations [1, 2, 3, 4, 5, 6, 7]. Vessel presence has for example been shown to increase dolphin travelling behaviour at the expenses of foraging [8, 9], resting [9, 10] or socialising [11, 12]. Viewing and swimming activities are regarded as relatively safe from an infectious standpoint [32], serious concerns have been raised as increased opportunities for disease transmissions exist and dolphins could potentially be infected by humans [33]

Results

Discussion

Conclusion