NOTES Holland et al.: Capture and release behavior of Pacific blue marlin off Hawaii 



399 



this fish and the other five marlin are summarized in 

 Table 1. 



In terms of vertical behavior, this fish dove when 

 released and spent the next 4 hours in the top 3 or 4 

 degrees of the thermocline at depths varying between 

 50 and 70 m. The fish then moved closer to the sur- 

 face, spending 92% of the last 3 hours of the track 

 within the surface mixed layer, moving between the 

 surface and 35 m. 



Fish 8803 (60 kg) was caught and tagged 2 nmi off 

 Keahole Point at 1120, 8 August 1988, by a team par- 

 ticipating in the HIBT. The fish was fought for ~20 

 minutes and described as tired but in good condition 

 when released by the anglers. This marlin moved 

 steadily west for ~ 12 hours before curving north dur- 

 ing the night (Fig. 2). The fish was moving northwest 

 when the track was terminated after 24 hours because 

 of deteriorating sea conditions. The vertical movements 

 of this fish (Fig. 3A) had a consistent "floor" where 



50 

 100 

 150 



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J 100 

 •i 



150 



50. 



I 100 



I 



150- 





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r 



--W -n 26 C 



12 13 14 15 16 17 18 19 20 21 22 23 



2 3 4 5 6 7 



irnrr 



9 10 11 12 



13 15 17 19 21 23 I J 



^•^•^•^ 



^r 



rr26 c 



m^ 



9 11 13 15 17 19 21 23 1 3 5 7 9 11 13 15 17 19 21 23 1 3 



iT^:^. 



w 



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^ii""P 



9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 1 2 3 4 5 6 7 



n 



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"To i'i 12 13 14 15 16 17 18 19 20 21 22 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 



REAL TIME 



Figure 3 



Vertical movements of marlin tracked off Keahole Point and Keauhou, Hawaii. A = fish 8803; B = 8804; C = 8807; D = 8903; E = 8904. 

 Solid horizontal line represents the sharpest inflection in water temperature at the bottom of the mixed layer, whereas dashed horizontal 

 lines represent 1°C isotherms, starting at 1°C below surface temperature. Horizontal bars represent nighttime. 



