Composite Training Unit Exercises and Joint Task ... - Govsupport.us

COMPTUEX/JTFEX EA/OEA Final Appendix A(Perrin et al., 1994); the northern limits are the Sea of Japan, Hokkaido, Washington state, and alongroughly 40°N across the western and central Pacific (Reeves et al., 2002).Striped dolphins are gregarious (groups of 20 or more are common) and active at the surface (Whiteheadet al. ,1998). Wade and Gerrodette (1993) noted a mean group size of 61 in the ETP, and Smith andWhitehead (1999) reported a mean group size of 50 in the Galápagos.In and near the SOCAL Range Complex, striped dolphins are found mostly offshore, and are much morecommon in the warm-water period (Fig. A-13).Common DolphinTwo species of common dolphin occur off California, the more coastal long-beaked dolphin (D. capensis)and the more offshore short-beaked dolphin (D. delphis). The long-beaked common dolphin is lessabundant, and only recently has been recognized as a separate species (Heyning and Perrin, 1994). Thus,much of the available information has not differentiated between the two species. Neither species is listedunder the ESA, and neither the California/Oregon/Washington Stock of the short-beaked commondolphin nor the California Stock of the long-beaked common dolphin is considered depleted or strategicunder the MMPA. The minimum population estimates are 365,617 (CV=0.25) and 25,163 (CV=0.72),respectively (Carretta et al., 2005).Available data regarding trends in population size in California and adjacent waters suggest an increase innumbers of both the short-beaked and long-beaked forms, likely because of gradual warming of watersoff California (Heyning and Perrin, 1994; Barlow et al., 1997; Forney, 1997).Common dolphin distributions are related to bathymetry; high-relief areas known to be associated withhigh concentrations of anchovies (Hui, 1979) are used more frequently than are low-relief areas. Shortbeakedcommon dolphins have been sighted as far as 300 nm (556 km) from shore, and are likely presentfurther offshore (Barlow et al., 1997). Long-beaked common dolphins are usually found within 50 nm(92.5 km) of shore (Barlow et al., 1997) and have not been sighted further than 100 nm (185 km) fromshore (Perrin et al., 1985; Barlow, 1992 in Heyning et al., 1994).The short-beaked common dolphin is abundant in the waters of the SOCAL Range Complex (Fig. A-14),and the long-beaked common dolphin is much less common, occurring there mostly in the warm-waterperiod (Fig. 15). The abundance of common dolphins has been shown to change on both seasonal andinter-annual time scales in southern California (Dohl et al., 1986; Barlow, 1995; Forney et al., 1995;Forney and Barlow 1998). The common dolphin is the most abundant cetacean in the SCIRC; itcomprised 74.6% of the estimated number of cetaceans in cold-water months and 98.0% in warm-watermonths (Carretta et al., 2000).The available data show a mean group size of 353.6 animals (based on n=61 groups) within the SCIRC(Carretta et al., 2000). The largest group of common dolphins seen there was 2,700. A mean group sizeof 141 (based on 417 groups) was found within the Point Mugu Sea Range, and a mean group size of 306(based on 110 groups) was found in areas east of the Point Mugu Sea Range (U.S. Navy, 1998). Thelargest groups seen in the above areas were 2,000 (Point Mugu Sea Range) and 3,000 (Santa BarbaraChannel).A-35 February 2007