Schaefer and Fuller: Movemenis, behavior, and habitat selection of Ihunnus obcsus 



in 



Time (CTZ) 

 12 00 12 00 12 00 12 00 12 00 12 00 12 00 12 00 



22 00 02 04 06 08 10 12 14 16 18 20 22 00 02 



■21 

  15 

 14 

 13 

 ■13 

 12 

 12 



Figure 2 



Depth and temperature records for a bigeye tuna carrying an archival tag 

 (tag 99-889), exhibiting unassociated type-1 behavior. Approximate area. 

 1°N 97°W. is based on geolocation estimates from the archival tag. CTZ = 

 central time zone. 



/?=9), even though the larger fish (mean=16.2'7(, n=12) still 

 had an obvious affinity for floating objects. 



Deep-diving behavior 



Deep-diving behavior was defined as dives in excess of 500 m 

 (Fig. 7). The mean duration of deep-diving behaviors for 

 individual fish ranged from 0.3 to 2.3 h (grand mean=1.2 

 h, 95% CI=0.3 h) (Table 2). The distributions of the time of 

 day, duration, and maximum depth of the 115 deep-diving 

 events are shown in Figure 8. The majority of the deep dives 

 occurred during daylight hours (mean=ll:56 central time 

 zone |CTZ| ), although some deep dives were made at night. 

 The prominent mode in the maximum depth distribution 

 was about 650 to 850 m. The estimated maximum depth and 

 minimum temperature reached by three bigeye tuna (99- 

 801, 99-803, and 99-889) were 1500 m and 3°C, respectively 



Reliability of the geolocation estimates 



The estimated mean accuracy and precision in the geolo- 

 cation estimates of latitude were 2.04 and 0.79 degrees, 

 respectively (Table 3). The associated uncertainty in those 

 estimates averaged 2.57 degrees (95% CI=0.85) for the 

 south error and 3.40 degrees (95% CI=1.00) for the north 

 error The estimated mean accuracy and precision of the geo- 

 location estimates for longitude was 0.46 and 0.26 degrees, 

 respectively (Table 3). The associated uncertainty in those 

 estimates averaged 0.33 degrees (959; CI=0.13) for the west 

 error and 0.17 degrees (95% CI=0.13) for the east error 



Additional information on the accuracy and precision of 

 the estimates from the processed archival tag light-level 

 data was obtained by comparing the differences between 

 estimates and actual latitudes and longitudes of recapture 

 for tags 99-864 and 99-874 (Table 3). The two bigeye tuna 



