Musyl et al.: Postrelease survival, vertical and horizontal movements, and thermal habitats of five species of pelagic sharks 
353 
28 May 
14 June 
1 July- 
16 July 
1 Aug 
Temperature (°C) 
5 10 15 20 25 30 
Oceanic whitetip 
Carcharhinus longimanus E_ 
(«=13) 
15:00 10:00 23:00 03:00 07:00 11:00 
Time of day (HST) 
60% 40% 20% 0% 20% 40% 60% 
Percent of time (%) 
Figure 5 
Oceanic whitetip shark ! Carcharhinus longimanus), depth and thermal ranges as identified by pop-up satellite 
archival tags (PSATs). (A) Representative vertical movements. Dashed lines indicate expanded area shown in 
C. (B) Temperature-depth profiles obtained from the aggregated data from all sharks. (C) Expanded section 
from panel A with horizontal black bars representing nighttime. (D) Percentage of time spent in individual 
temperature strata for daytime and nighttime diving activities (all tags). (E) Average hourly depth (±standard 
deviation, SD) readings calculated for all samples, illustrating variability at crepuscular times (all tags). (F) 
Percentage of time spent in individual depth strata for daytime and nighttime diving activities (all tags). 
(Note: To prevent excessive clutter, SDs were not shown in some panel figures). 
Atlantic range from 10-32% (32%, Hoey and Moore 1 ; 
31%, Diaz and Serafy, 2005; 13.2%, Beerkircher et al., 
2008; -10%, Carruthers et al., 2009; 16%, Campana 
et al., 2009a). By contrast, in central Pacific longline 
fisheries, Walsh et al. (2009) reported that only 4% and 
6% of blue sharks were dead on retrieval from deep-set 
tuna and shallow-set swordfish gear, respectively. Our 
sample sizes, except for those for blue sharks, were 
not large enough to have a strong statistical impact; 
nevertheless, our estimates of at-vessel mortality 
appear to be species-specific and correlate with obser- 
vations for the shallow-set sector of the Hawaii-based 
longline fishery (Walsh et al., 2009). The at-vessel 
mortality estimates for blue sharks were also concor- 
dant with those reported in the Pacific by Yokota et 
al. (2006, 2-11%) and Hight et al. (2007, ~6%). 
Our reporting rate for PSATs attached to blue 
sharks (50%) was similar to that reported by Weng 
et al. (2005) for 28 PSATs (61%, CI*=43-79%). Non- 
reporting tags, however, cannot be considered syn- 
onymous with mortality because other factors can 
cause failure in electronic tags (Goodyear, 2002; 
Hays et al., 2007; Campana et al., 2009a; Musyl et al., 
2011. PSATs can, however, provide less ambiguous 
identification of mortality because they will auto- 
matically release from the animal at programmed 
depths (Moyes et al., 2006). This is especially true 
for sharks because dead sharks are negatively buoy- 
ant and sink, thus carrying the PSATs to depths 
where the pressure-activated release mechanism 
will be engaged (Moyes et al., 2006; Campana et al., 
2009a). 
