Testing the Efficacy of Ship Strike Mitigation for Whales in the Hauraki Gulf, New Zealand

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dc.contributor.advisor Constantine, R en
dc.contributor.advisor Riekkola, L en
dc.contributor.author Ebdon, Philippa en
dc.date.accessioned 2017-08-02T02:39:23Z en
dc.date.issued 2017 en
dc.identifier.uri http://hdl.handle.net/2292/34693 en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Evidence-based policy, with proven efficacy, is key to the mitigation of human-wildlife conflict. Voluntary agreements to implement actions are popular as they take less time to formulate than mandatory policies and foster cooperation between stakeholders. Mandatory and voluntary agreements have been used globally to reduce ship-whale collisions, or ship strike. Ship strike threatens a resident population of Bryde’s whales (Balaenoptera edeni) in the Hauraki Gulf, New Zealand. In response to this issue the Hauraki Gulf Transit Protocol for Commercial Shipping was developed and the aim of this study was to test the efficacy of the voluntary ship strike mitigation measures implemented in 2013. Automatic Identification System (AIS) is a system used by vessels for maritime safety purposes, which can also be used to track vessels. AIS and whale sightings data were used to determine the distribution and density of ships and whales throughout the Gulf to quantify and assess compliance to the voluntary 10kt speed limit, and subsequently the risk of a lethal ship strike to whales. From October 2014 – September 2016, the location of 189 groups of Bryde’s whales and shipping routes of 703 vessels >70 metres in length were plotted using ArcGIS. This showed hotspots of preferred whale habitat that differed from previous years, but shipping traffic density did not. Ship speeds were determined from 1.58 million AIS data points were used to calculate the relative probability of encounter between whales and ships throughout the Gulf. Probability of lethal ship strike to Bryde’s whales in the Hauraki Gulf has nearly halved (26%) since 2013 (51%). This is due to a drop in average vessel speeds from 13.2kt to 10kt. Events of potential ship strike, as determined by the Gulf’s Large Whale Warning System (LWWS), were analysed at a fine scale using AIS data to examine reactions to this real-time ship strike mitigation measure. From 13th May 2015 to 6th January 2017 a total of 37 LWWS notifications were transmitted to ships transiting through the Gulf. Of these, 15 involved one or more ships passing within either a five kilometer potential danger zone or within one kilometer of the reported whale sighting - a distance at which the Transit Protocol requires the watch-keeper to undertake action to mitigate a potential ship strike. Of the five events where a ship passed within one kilometer of a whale, the AIS tracks showed no change of course or speed in reaction to the whale warnings. Reports of whale sightings were very low, with only 15% of whale sightings reported to the LWWS; a reflection of technical difficulties, challenges with maintaining motivations to report, and the likelihood of inexperienced observers onboard ships. Mariners were surveyed via a questionnaire to determine knowledge of mitigation measures in the Gulf and their motivations to comply with them. Overall, mariners were aware of ship strike mitigation measures and adhered to the 10 knot speed limit, but had little motivation to heed the LWWS due to incomplete transmission of the message or perception of the response required, resulting in poor compliance. However, due to the high compliance to the voluntary 10 knot speed limit, other mitigation measures may no longer be necessary to protect Bryde’s whales. Ascertaining motivations of key user groups to comply with conservation agreements can determine whether a mitigation measure is effective, has the potential to be effective if it is altered, or if it is likely to be ineffective regardless. This study highlights the importance of testing the efficacy of conservation mitigation measures, as highly effective actions may eclipse the need for less effective techniques. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.rights.uri http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ en
dc.title Testing the Efficacy of Ship Strike Mitigation for Whales in the Hauraki Gulf, New Zealand en
dc.type Thesis en
thesis.degree.discipline Biological Science en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 643864 en
pubs.org-id Science en
pubs.org-id Biological Sciences en
pubs.record-created-at-source-date 2017-08-02 en

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