88 



Fishery Bulletin 103(1) 



We conducted bootstrapping simulations 

 to examine the effect of sample size on the 

 95% confidence intervals of the release mor- 

 tality estimates using software developed by 

 Goodyear (2002). Distributions of estimates 

 were based on 10,000 simulations with an 

 underlying release mortality equivalent to 

 that observed for straight-shank ("J") hooks 

 for experiments containing 10-200 tags and 

 no sources of error (e.g., no premature re- 

 lease of tags, no tagging-induced mortality, 

 and no natural mortality). 



Results 



Forty-one white marlin were tagged in four 

 geographic locations during 2002-2003 

 (Table 1). Information for each fish is summa- 

 rized in Table 2. Fight times were fairly typi- 

 cal for this fishery (mean: 15.8 min, range: 

 3-83 min), although two animals required 

 more than 30 minutes before they were suf- 

 ficiently calm at boatside for tag placement. 

 Overall, forty tags (97.6%) transmitted data 

 to the satellites of the Argos system and of 

 these, thirty-seven tags remained attached 

 to study animals for the full five- or ten- 

 day duration. One five-day tag was released 

 prematurely from a surviving white marlin 

 after 2.5 days, presumably because it had 

 not been attached securely. This individual 

 showed behavior similar to other surviving 

 white marlin while the tag was attached 

 and was presumed to have survived for the 

 purposes of our study. Additionally, two 10- 

 day tags attached to moribund white marlin 

 disengaged from the carcasses prior to the 

 expected date after an extended amount of 

 time at a constant depth and temperature 

 on the seafloor. Approximately 61% of data 

 (range: 19-95%) were successfully transmit- 

 ted from reporting tags. 



Overall, 33 of 40 tags (82.5%) returned 

 data that indicated the survival of tagged 

 animals throughout the duration of tag de- 

 ployment. Surviving white marlin exhib- 

 ited daily variations in water temperature 

 and depth data while carrying PSATs (Fig. 

 2A). The net movement of surviving ani- 

 mals could not be explained by the speed or 

 direction of current patterns alone over 

 the course of the tag deployment (Table 2, 

 Fig 3A). In contrast, moribund white mar- 

 lin (Fig. 2B) sank to the seafloor (237-1307 

 m) and to constant water temperatures (3.7-12.5°C), 

 where they remained until the tags disengaged and 

 floated to the surface not far from the initial tag- 

 ging location (Fig 3B). Five of the seven moribund 

 white marlin died within the first six hours of release; 



Surviving white marlin 



30 

 25 



15 

 10 



rr 



S. "60 



80 



120 



08/22 08/23 08/24 08/25 08/26 08/27 08/28 08/29 08/30 08/31 09/01 09/02 



Moribund white marlin 



08/18 08/19 08/20 08/21 08/22 08/23 08/24 08/25 08/26 08/27 09/28 09/29 



Figure 2 



Depth and temperature tracks for a surviving (A) (MA12) and 

 moribund (B) (MA01) white marlin (Tetrapturus albidus). Filled 

 symbols correspond to measurements taken while tags were attached 

 to animals, hollow symbols refer to measurements taken after pop- 

 up while tags were transmitting data to Argos satellites. Gray bars 

 denote periods of local night. 



four of these five animals died within the first hour 

 (Table 2). 



The two white marlin that experienced the longest 

 fight times (46 and 83 min) died more than 24 hours 

 following their release. White marlin VZ03-11 had a 



