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Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Washington State Parks and Recreation Commission's Marine Facilities Replacement Program in North Puget Sound, Washington
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Federal Register Documents published on or after 08/24/2025
For pinnipeds in water, measurements of TTS are limited to harbor seals, northern elephant seals ( Mirounga angustirostris), bearded seals ( Erignathus barbatus), and California sea lions (Kastak et al., 1999, 2007; Kastelein et al., 2019b, 2019c, 2021, 2022a, 2022b; Reichmuth et al., 2019; Sills et al., 2020).
Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses are well-studied through controlled experiments and for both laboratory and free-ranging animals ( e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005; Ayres et al., 2012; Yang et al., 2022).
Several studies have demonstrated that impulse sounds might affect the distribution and behavior of some fishes, potentially impacting foraging opportunities or increasing energetic costs ( e.g., Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999; Paxton et al., 2017).
However, some studies have shown no or slight reaction to impulse sounds ( e.g., Peña et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et al., 2012).
Therefore, the receiving animal's hearing, motivation, experience, demography, life stage, and depth can be difficult to predict ( e.g., Southall et al., 2007; Southall et al., 2021; Ellison et al., 2012).