Benson et a\. Abundance, distribution, and habitat of Dermochelys conaceo off California 



343 



(Keinath and Musick, 19931 and applied to 

 aerial survey density estimates for Atlantic 

 leatherback turtles (Keinath et al., 1996). The 

 correction used in the Keinath and Musick 

 study, however, was based on the proportion 

 of time the transmitter was above the water 

 surface (and wave action), not the estimated 

 proportion of time a turtle would have been 

 visible to an aerial survey team (to about 

 1 m depth), as in this study. Furthermore, St. 

 Croix represents a nesting area, and leath- 

 erback diving behavior may differ between 

 nesting and foraging areas. 



Average uncorrected densities of leath- 

 erback turtles off California during our 

 study (0.75 turtles/100 km^) are within the 

 range of 0.21 to 2.2 leatherback turtles/ 

 100 km2 reported during 1978-82 along 

 the U.S. Atlantic coast (Shoop and Kenney, 

 1992), although the Atlantic study reported 

 monthly estimates, not a seasonal average, 

 and encompassed a larger study area. Av- 

 erage uncorrected densities in a smaller 

 foraging area off North Carolina during 

 August-November 1986-91 (0.80 leatherback 

 turtles/100 km^; Keinath et al., 1996), were simila 

 those observed in this study. 



Leatherback turtles along the U.S. West Coast 

 part of the western Pacific genetic stock (Dutton et 



.M 



£ 10 - 



 South Central Califomi.1 



□ Monterey Bay 



n Gulf of the Farallones 



S Point Arena 



D North Coast 



i 



Seplcmhcr 



October 



No\ember 



Figure 4 



Average monthly leatherback turtle (Dermochelys coriacea) encounter 

 rates (turtles / 1000 km surveyed) by geographic stratum, 1990-2003. 

 Error bars indicate one standard error. 



r to 2000, 2007), which is known to nest in Papua (Indo- 



nesia), Papua New Guinea, Solomon Islands, and on 

 are other western Pacific islands (Dutton et al., 2007). The 



al., western Pacific metapopulation was estimated to contain 



