Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Filters

2012 - 20152

Settings

Has files: YesSubject: search.filters.subject.Whales, New Zealand

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    An analysis of marine anthropogenic noise in New Zealand : sources, policies, and implications for cetaceans : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Science, Massey University, Auckland, New Zealand
    (Massey University, 2015) Patin̋o-Pérez, Jessica
    In recent decades, anthropogenic noise has become recognised as a major pollutant worldwide and the study of its impacts has increased due to the potential for adverse consequences on wildlife. For marine environments, where sound is transmitted very efficiently through water, underwater noise has increased, mainly, at low and medium frequencies. Of all marine organisms, cetaceans may be the most affected, as they depend primarily on sound to communicate, navigate and find food. Accordingly, the general aims of this thesis are to identify the types of anthropogenic noise facing New Zealand’s cetaceans, the potential impacts, review current legislation, and to propose improvements to enhance current mitigation measures of impacts. My systematic review showed that 90% of the information about impacts of noise pollution on cetacean comes from peer-review journals and, although available from 1975, studies of marine noise pollution substantially increased after 1997. In addition, I identified the limited information on this topic in important areas such as Latin America, Africa and Southeast Asia, as well as regions in the Arctic and Southern Ocean. I also found that most effort has been focused on the impact of vessels, and bottlenose dolphin and harbour porpoise are, by far, the most studied species, showing a disparity in research coverage of both sources of noise and species. For New Zealand, there is a striking lack of knowledge of the range of sources of noise on cetaceans (excluding vessels). The information I compiled on New Zealand’s cetacean distributions showed that three main groups are well represented: baleen whales, delphinids and beaked whales. Nonetheless, the information available for these species varies greatly. While there are some species very well studied, for others New Zealand species, the available information is scarce, as in the case of beaked whale. Current mitigation measures can only be effective if comprehensive data are used to inform them. For example, planning surveys at different spatiotemporal scales are crucial to increase the effectiveness of mitigation measures. In particular, spatial modelling techniques can support mitigation measures by helping managers to identify areas of conflicts between marine mammal conservation and the development of activities such as dredging, drilling and seismic surveys. I used opportunistic sighting data collected from different platforms, and several environmental variables biologically important for cetaceans and/or their prey, to create maps of habitat suitability for seven species of cetaceans in New Zealand. These maps were created using maximun entropy modelling (MaxEnt), a model system that does not require absence data and performs well with small sample size. Models validations were done using the Receiver Operating Characteristic curve (ROC) and the Area Under the Curve (AUC) values. The models for all seven species had excellent discriminatory power (AUC > 0.9). The environmental variables depth and sediment had the most explanatory power for the distribution of these species. Comparisons of the areas of current and designated areas for exploration activities with the marine mammal distributions generated using MaxEnt show significant and wide-ranging conflicts. Of particular concern is the designated area for exploration in the northern part of the North Island, this area overlaps with the distribution of the highly endangered Maui’s dolphin, and will add new pressures on this already diminished population. Expanding noise related research in this region (as elsewhere) will help stakeholders to support future decisions for planning when human activities enter into conflict with cetaceans. Finally, the development of effective laws that adequately regulate the anthropogenic noise impacts on marine mammals has been a task that has taken many years to advance. To assess the effectiveness of New Zealand’s legislation to mitigate impacts from seismic surveys and whale-watching activities, I described and compared methods prescribed by international associations. Strengths of The Code of New Zealand are that it presents a set of comprehensive guidelines with specific mention of biologically important aspects such as mother/calve pair priority. Nonetheless, improvements could be made regarding the enforcement of these guidelines. In addition, I suggest that New Zealand’s whale-watching guidelines, could be improved through the inclusion and implementation of an Impact Assessment, the creation of separate guidelines to protect specific species and/or areas and, as with seismic activities, ongoing enforcement of guidelines.
  • Thumbnail Image
    Item
    The occurrence and habitat use of common dolphins (Delphinus sp.) in the central Bay of Plenty, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, Auckland, New Zealand
    (Massey University, 2012) Gaborit-Haverkamp, Tania
    This thesis investigated the occurrence and habitat use of common dolphins (Delphinus sp.) inhabiting the central Bay of Plenty (BOP), North Island, New Zealand. Although common dolphins are the most prevalent species of dolphin found off the east coast of the North Island of New Zealand, there has been no long term empirical investigation of the species in the central BOP area. Behaviour of common dolphins in the presence of the observation platform was also assessed to investigate habitat use. Additionally, data describing other cetacean species occurring within this region are presented in order to place into context the importance of these waters for Delphinus. Sightings data were collected between March 1998 and May 2011 during 2364 boat-based surveys on board platform of opportunity, tourism vessel Gemini Galaxsea (a 60 ft ketch sailboat). Variables examined included location, group size, composition, water depth, time of day, seasonality, behaviour and the presence of associated species. Common dolphins were encountered during 54% (n = 1265) of surveys, in water depths ranging from 5.0 to 197.0 m. Delphinus sightings primarily occurred in the area between Motiti Island, Mayor Island and Waihi on the mainland. Group size ranged from one to 500+ individuals and was significantly affected by the time of day, month and depth of sightings. The most frequently recorded group size involved 50 to 100 animals, with larger aggregations more frequent during the warmer austral months when nutrient upwelling leads to increased prey availability in coastal waters off the BOP. Groups containing immature animals accounted for 16% of total sightings and occurred throughout the year, although neonate calves were only reported during the warmer austral summer months, supporting the concept of reproductive seasonality in this population. Common dolphin groups sighted within the central BOP were reported in association with five marine mammal species and 14 avian species, most frequently with various species of petrel (Procellariiformes) and the Australasian gannet (Morus serrator). The year round occurrence of common dolphins within central BOP waters indicates that this region maybe important for Delphinus. Behavioural data were collected from 162 independent dolphin groups. Overall, forage, social and travel accounted for the majority of recorded behavioural states, while mill and rest were less frequent. Behaviour was influenced by water depth, with foraging dolphins encountered in the deepest waters. Behaviour also varied significantly according to group size, with 4 foraging occurring more often than expected in large groups and resting, socialising and milling occurring more often in smaller groups. The presence of immature animals also had a significant influence on common dolphin behaviour, with foraging occurring more often than expected in groups containing immature animals. The presence of associated species varied according to behaviour, with the majority of foraging groups occurring in the presence of Australasian gannets. Seasonal and diurnal peaks in behaviour were not evident. Social behaviours primarily occurred during summer when large nursery groups were also reported in the central BOP. In order to place into context the use of central BOP waters for Delphinus, an investigation of other cetacean species using these waters was undertaken; eleven cetacean species (6 Mysticeti and 5 Delphinidae) were identified as utilising central BOP waters. Sightings primarily occurred in the area between Karewa Island, Mayor Island (Tuhua) and Motiti Island in the central BOP. The majority of delphinid sightings occurred in spring and involved the bottlenose dolphin, Tursiops truncatus (50.5%) and killer whale, Orcinus orca (42.9%). Pilot, Globicephala spp. (3.8%) and false killer whale, Pseudorca crassidens (2.9%) sightings were less frequent. Group sizes ranged from solitary to 200+ individuals. Calf presence was recorded for bottlenose dolphins during summer and autumn and killer whales during spring and autumn. Pilot and false killer whale calves were not recorded during the study period. The majority of baleen whale sightings occurred during winter and spring and involved minke, Balaenoptera acutorostrata/bonaerensis (44.3%), blue, B. musculus (19.0%) and Bryde’s whales, B. edeni (16.5%). Humpback, Megaptera novaeangliae (10.1%), sei, B. borealis (8.9%) and southern right whale, Eubalaena australis (1.3%) sightings were less frequent. Group sizes ranged from solitary to four individuals, with results highly skewed towards solitary animals (79%). Cow-calf pairs were observed during spring for all baleen whales except sei and humpback. Cetaceans were primarily observed in association with the Australasian gannet as well as various species of petrel and shearwater (Puffinus spp.). Bottlenose dolphins and false killer whales were sighted together in mixed species groups. Bryde’s whales were also sighted in association with common dolphins.