My current research focuses on the great sperm whales in eastern North Pacific.
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The sperm whale, the largest of the toothed whales, is a globally distributed, deep-diving marine mammal generally inhabiting continental slope or oceanic waters (Rice, 1989). They prey primarily on mesopelagic and bathypelagic squid; males are more likely than females to prey on fish, sharks and rays (Rice, 1989). Sperm whales exhibit pronounced sexual dimorphism and sexual segregation of adults and a complex, hierarchical social structure (Rice, 1989; Whitehead, 2003).
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In the Pacific, the foundation of female social structure consists of long-term social units of approximately 10.4 females and their dependent young (range = 3–24, SD = 6.23) (Whitehead, 2003). Units may travel with one or more other units forming temporary “groups” (Whitehead et al., 1991; Whitehead and Kahn, 1992) which, in turn, are structured into acoustic clans (Rendell and Whitehead, 2003; Hersh et al., 2022). In the Pacific, units and groups appear to be comprised of clusters of both related and unrelated individuals (Mesnick 2001).
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Males leave their natal units between four and 21 years of age and form “bachelor groups.” As they mature, they disperse from these groups and the largest males tend to be solitary (Best, 1979). In the North Pacific, females and their dependent young typically occur at latitudes less than 40° and are occasionally found at latitudes up to 50°N (Rice, 1989). Males move to higher latitudes to feed, returning to lower latitudes to mate (Rice, 1989).
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Sperm whales were targeted during two periods of commercial whaling that peaked in the 1840s and 1960s, respectively, and largely ended in the mid-1980s with the International Whaling Commission’s moratorium on commercial whaling.  The hunt was global in scale, with over 300,000 sperm whales estimated to have been killed in the North Pacific alone during the 20th century (Rocha et al., 2014; Ivashchenko et al., 2014).
 
Today, sperm whales are a species of conservation concern because of both historical and contemporary anthropogenic impacts, including ship strikes, fishery interactions, pollutants, plastics, noise, and environmental change. Efforts by the National Marine Fisheries Service (NMFS) to assess conservation status and to mitigate current threats relies are complicated by the species’ wide distribution, nomadic nature and hierarchical social structure. There are many unknowns when it comes to knowledge of sperm whale movements, population structure and behavior. In my work I seek to unravel these mysteries and provide insights to open questions.
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