Abstract
Toothed whales (odontocetes) are abundant, globally distributed animals that play key trophic roles in ecosystems and may overlap with potentially harmful human activities. Data on odontocete habitat use are necessary for informing ecosystem-based management plans and for predicting and mitigating human impacts, yet such data is often scarce. The Stellwagen Bank National Marine Sanctuary (SBNMS) and the Hawaiian Islands Humpback Whale National Marine Sanctuary (HIHWNMS) are areas of national importance that lack critical biological and ecological data on odontocetes within their management areas. This thesis addresses knowledge gaps in toothed whale ecology in two marine protected areas by gathering baseline biological data to improve habitat use monitoring and by directly studying spatial and temporal occurrence of odontocete species. Digital acoustic recording tags (DTAGs) were deployed on spotted dolphins off Hawaii to characterize whistle parameters and dive behavior, enabling future acoustic monitoring of species occurrence and improving our understanding of 3-dimensional habitat use. These same data were used to discuss advancements in deploying suction cup tags on small delphinds and illustrate advantages of acoustic tags in studying individual and group whistle repertoires. Year-round odontocete habitat use in SBNMS was addressed using two complimentary methods: species distribution modeling of visual sightings and passive acoustic monitoring. Long-term opportunistic sighting data and point process models were used to investigate environmental influences on the spatial distributions of Atlantic white-sided dolphins and harbor porpoise from April through October in SBNMS. To study winter occurrence of odontocetes, passive acoustic monitoring and habitat characterization were conducted using autonomous ocean gliders. The opportunistic sightings, resultant models and innovative passive acoustic recordings showed a year-round odontocete presence. Spatial distributions differed between months and years and were strongly influenced by static and bathymetric features. Together, these studies improve our understanding of toothed whale habitat use in two important marine protected areas, providing valuable, new data on understudied, but potentially ecologically important species. This work also provides a baseline to begin assessing the ecological role of odontocetes and overlap with human activities in these respective national marine sanctuaries.