No description available.

The main purpose of this study was to produce and test the reliability of predictive models of cetacean distributions off the west coast of Scotland. Passive acoustic and visual surveys were carried out from platforms of opportunity between 2003 and 2005. Acoustic identifications were made primarily of harbour porpoises (Phocoena phocoena), delphinids, and sperm whales (Physeter macrocephalus). Generalised Additive Models (GAMs) were used to relate species’ distributions to a range of environmental variables over a range of temporal and spatial scales. Predictive models of delphinid distributions showed both inter-annual and inter-month variations. Combining all data for all months and years resulted in a model that combined the environmental influences from each monthly and yearly model. Overall, delphinids were found to associate with the deep (> 400m) warm water (10.5°C-12.5°C), and in areas of deep thermocline. Relationships between sperm whales and environmental variables were consistent over changes in grain size (9 km or 18 km), but not between areas. Although sperm whales were distributed in deep water characterised by weak thermoclines and strong haloclines in the most northerly area (Faroe-Shetland Channel), they were found in deep productive areas with cold surface temperature in the more southerly waters (Rockall Trough). Within the southern Inner Hebrides, high use areas for harbour porpoises were consistently predicted over time (in years) and with differing survey techniques (acoustic versus visual), but not over space (southern Inner Hebrides versus whole of the Inner Hebrides). Harbour porpoises were mainly distributed in areas with low tidal currents and with higher detection rates during spring tides. The use of prey as a predictor variable within models of delphinid distribution shows some promise: there were correlations between delphinid and herring (Clupea harengus) in shelf-waters in 2005 but not in 2004. These models can be used in mitigating acoustic threats to cetaceans in predicted high use areas off the west coast of Scotland.

The objective of this thesis was to determine if there were any correlations in the distribution of cetaceans, especially sperm whales (Physeter macrocephalus), pantropical dolphins (Stenella attenuata), bottlenose dolphins (Tursiops truncatus), and Risso’s dolphins (Grampus griseus) in the northern Gulf of Mexico because of the influence of oil and gas production and exploration. This research is important because of the lack of knowledge about the impact of anthropogenic sounds from oil and gas exploration and production (E&P) on cetacean distribution in the Gulf of Mexico. I analyzed cetacean visual line-transect survey results from the Gulf of Mexico for period of 1992 – 2001. I divided this time span into an early period (1992 – 1997) and a late period (1998 – 2001). I overlayed the locations of cetacean sightings and the locations of oil and gas E&P platforms to demonstrate their close association in space, and tested a hypothesis that distribution would shift south correlated with changes in distribution of E&P. I compared the distributions of cetacean sightings in the entire Gulf of Mexico, and separated the Gulf of Mexico into east and west, between the early period and the late period. The east Gulf of Mexico represents an area without oil and gas E&P platforms and the west Gulf of Mexico is the area where oil and gas E&P platforms are located. The null hypothesis for these tests was that there was no difference in cetacean distribution between the early period and the late period. I also compared the distribution of sperm whales, pantropical dolphins, bottlenose dolphins, and Risso’s dolphins in the entire Gulf of Mexico, both east and west, between the early and late periods. I expect if distribution changes were correlated with changes in E&P distribution, then there will be a shift south in the western Gulf. Changes in distribution in the eastern Gulf would not be correlated with E&P. I found that the sightings per unit effort (SPUE) of all cetacean sightings in the entire Gulf of Mexico shifted to the south in the late period, as compared to the early period .The distribution of all cetacean sightings for the late period (1998-2001) was significantly different compared to the distributions of all cetacean sightings in the early period (1992-1997). The SPUE of sperm whale and bottlenose dolphin distributions were shifted to the north in the late period (1998-2001) compared to the early period (1992-1997). While pantropical dolphin distributions were significantly shifted to the south between the two time periods. I observed that the SPUE of all cetaceans sightings in the east Gulf of Mexico for the early period (1992-1997) were shifted to the south compared to the west, which were not different. The SPUE for sperm whales in the east for the early period were marginally shifted to the north in comparison to the west, which were also shifted further north. The SPUE for Risso’s dolphins in the east were shifted further north while in the west SPUE were shifted to the south. The SPUE for pantropical dolphin sightings were shifted to the north in both the east and west regions. While the SPUE for bottlenose dolphin sightings were shifted to the north in both the east and west Gulf of Mexico. My SPUE results suggest that pantropical dolphins, like the total cetaceans examined here, have shifted their distributions in the entire northern Gulf of Mexico to the south. However, in areas of high oil and gas E&P platforms the distributions of sperm whales and bottlenose dolphins did not shift their distributions from the early period to the late period to the south even though these E&P activities have shifted to the south over the past two decades as they expanded into the deeper waters of the northern Gulf of Mexico. Therefore, there is little evidence that large scale changes in the latitudinal distribution of marine mammals in the Northern Gulf have occurred as a result of greater offshore E&P activity.

The subpopulation of sperm whales (Physeter macrocephalus) in the Mediterranean Sea is presently list as “Endangered”. This study is an attempt to provide detailed data on sperm whale Bachelor Groups surrounding Ischia, Italy in the Tyrrhenian Sea (Mediterranean Sea). 24 hours, 38 minutes, and 38 seconds of sperm whale Bachelor Group acoustic data was analyzed in order to describe acoustic repertoire, classify behavioral associations to acoustic types, and identify habitat-use. The data showed that the acoustic repertoire of sperm whale Bachelor Groups is dominated by Usual Clicks. Additionally, a click type that maintains an inter-click interval (ICI) in between Usual Clicks and Creaks was identified during acoustic analysis and named “Transition Clicks”. Acoustic events were categorized into Single Code and Combination Code events; representing situations where one acoustic code was heard versus situations where two or more different acoustic codes were heard simultaneously. Analysis revealed that Single Code events represented 71.25% of the sperm whale Bachelor Group acoustic repertoire. The Usual Click/ Transition Click combination represented 73.74% of Combination Code events. A significant difference was shown between time spent in Single Code versus time spent in Combination Code for Usual Clicks and for Squeals. Acoustic repertoire data revealed the possibility for a strong collaborative acoustic structure and a speculated strategy for evolutionary success among sperm whale Bachelor Groups in Ischia, Italy. Additionally, the study showed that sperm whale Bachelor Groups spend 77.87% of the analyzed time engaged in orientation/searching/foraging behavior and 1.09% engaged in socializing behaviors. Event maps revealed a ‘hotspot’ of sperm whale Bachelor Group activity in the waters to the northwest of Ischia, Italy, within the submarine Canyon of Cuma, and outside of the boundaries for the Regno di Nettuno Marine Protected Area (MPA). It is recommended that the results of this study be utilized in extending the Regno di Nettuno MPA to include the ‘hotspot’, and possible critical area, for sperm whale Bachelor Groups. The results of this study and published literature of the sperm whales in this area could be utilized to create population-specific management strategies for more effective measures in ending population decrease and preserving the species. Further research should be carried out to analyze in detail the role of Transition Clicks in sperm whale acoustics and the possibility of a collaborative acoustic structure that has yet to be displayed in any other sperm whale population worldwide.

Behavioural responses can reveal important fitness trade-offs and ecological traps in evolutionarily novel contexts created by anthropogenic stimuli, and are of increasing conservation concern due to possible links to population-level impacts. This thesis illustrates the use of proxies for energy acquisition and expenditure within multivariate and state-based modelling approaches to quantify the relative time and energetic costs of behavioural disturbance for a deep-diving marine mammal (Physeter macrocephalus) in foraging grounds in Kaikoura Canyon (New Zealand) and near Lofoten Islands (Norway). A conceptual framework is first developed to identify and explore links between individual motivation, condition and external constraints to behavioural disturbance [Chapter 1]. The following chapters then use data from behavioural response studies (BRS) to: 1) derive biologically relevant metrics of behaviour [all chapters], 2) investigate effects of boat-based focal follows and tagging procedures [Chapters 2-3], and 3) relate responses to specific disturbance stimuli (distance, approach, noise) from whale-watching [Chapter 2], naval sonar and playback of presumed natural predator (killer whale Orcinus orca) sounds [Chapter 4]. A novel hidden state model was developed to estimate behavioural budgets of tagged sperm whales from multiple streams of biologging (DTAG) data [Chapter 3]. Sperm whales traded off time spent at foraging depths in a non-foraging and non-resting state in response to both tag boat presence, 1-2 kHz naval sonar (SPL 131-165 rms re 1μPa) and mammal-eating killer whale sound playbacks, indicating that parallel non-lethal costs were incurred in both anthropogenic disturbance and presumed antipredatory contexts. While behavioural responses were highly variable by individual, biologically informed state-based models appeared effective to control for variability in energy proxies across different functional contexts. These results and Chapter 5 “linking buzzes to prey” demonstrate that behavioural context is a signal that can aid understanding of how individual non-lethal disturbance responses can impact fitness.

Species distribution maps can provide important information to focus conservation efforts and enable spatial management of human activities. Two sympatric marine predators, grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina), have overlapping ranges but contrasting population dynamics around the UK; whilst grey seals have generally increased, harbour seals have shown significant regional declines. A robust analytical methodology was developed to produce maps of grey and harbour seal usage estimates with corresponding uncertainty, and scales of spatial partitioning between the species were found. Throughout their range, both grey and harbour seals spend the majority of their time within 50 km of the coast. The scalability of the analytical approach was enhanced and environmental information to enable spatial predictions was included. The resultant maps have been applied to inform consent and licensing of marine renewable developments of wind farms and tidal turbines. For harbour seals around Orkney, northern Scotland, distance from haul out, proportion of sand in seabed sediment, and annual mean power were important predictors of space-use. Utilising seal usage maps, a framework was produced to allow shipping noise, an important marine anthropogenic stressor, to be explicitly incorporated into spatial planning. Potentially sensitive areas were identified through quantifying risk of exposure of shipping traffic to marine species. Individual noise exposure was predicted with associated uncertainty in an area with varying rates of co-occurrence. Across the UK, spatial overlap was highest within 50 km of the coast, close to seal haul outs. Areas identified with high risk of exposure included 11 Special Areas of Conservation (from a possible 25). Risk to harbour seal populations was highest, affecting half of all SACs associated with the species. For 20 of 28 animals in the acoustic exposure study, 95% CI for M-weighted cumulative Sound Exposure Levels had upper bounds above levels known to induce Temporary Threshold Shift. Predictions of broadband received sound pressure levels were underestimated on average by 0.7 dB re 1μPa (± 3.3). An analytical methodology was derived to allow ecological maps to be quantitatively compared. The Structural Similarity (SSIM) index was enhanced to incorporate uncertainty from underlying spatial models, and a software algorithm was developed to correct for internal edge effects so that loss of spatial information from the map comparison was limited. The application of the approach was demonstrated using a case study of sperm whales (Physeter macrocephalus, Linneaus 1758) in the Mediterranean Sea to identify areas where local-scale differences in space-use between groups and singleton whales occurred. SSIM is applicable to a broad range of spatial ecological data, providing a novel tool for map comparison.