Influence of natural factors and anthropogenic stressors on sperm whale foraging effort and success at high latitudes

• Main Author: Isojunno, Saana
• Other Authors: Miller, Patrick
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of St Andrews 2015
• Subjects: Physeter macrocephalus; Cetacea; Behavioural disturbance; Behavioural response studies; Whale-watching; Naval sonar; Risk-disturbance hypothesis; Functional state; State-switching model; Time-series model; QL737.C435I8; Sperm whale; Whales > Behavior; Whale watching; Sonar; Lofoten; New Zealand; Norway; Killer Whale; Orca; Orcinus orca; Killer whale
• Online Access: http://hdl.handle.net/10023/6760

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 ...