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40 80 120 160 200 240 



TIME (days from release) 



Figure 10.— Regression plot of black marlin recover) distances, by number of days 

 at large. 



August or December were recaptured within the first 60 d from 

 release. The average rate of movement during the first 60 d from 

 release for black marlin tagged in September was 1.46 nmi/d; Oc- 

 tober, 4.58 nmi/d; and November, 10.06 nmi/d. The average rate 

 increased 3.1 times from September to October, and 2.2 times 

 from October to November, with the November rate being 6.9 

 times that recorded for September. An increasing average rate of 

 movement (nmi/d) was shown for black marlin tagged during the 

 later part of the season. This may indicate that black marlin fre- 

 quenting the general area of tagging early in the season may not 

 migrate out of the area as rapidly as those black marlin tagged 

 later in the season. 



Vector analysis used distance and directional data determined 

 by examination of tagging and recovery locations (straight-line 

 distance), time of release (number of days), and direction 

 (number of degrees, true bearing) from tagging point to recovery 

 point. Vector mean bearings and distances were calculated 0-730 d 

 in five time periods as shown in Figure 1 1 . This analysis indicated 

 a reduced rate of movement for the first time period after tagging 

 (0-60 d) compared with the two following time periods (61-120 

 and 121-240 d). For the second period an acceleration of move- 

 ment of 6.2 times the first period was noted. A reduced rate of 

 movement of mean vector distance of 2.8 times the second period 

 was observed for the third period (121-240 d). 



® 0-60 days N = 26 



120.8° vector mean bearing 

 72.0 nm vector mean distance 



® 61-120 days N=7 



134.3° vector mean bearing 

 445.4 nm vector mean distance 

 121-240 days N=4 

 097.1° vector mean bearing 

 1255.8 nm vector mean distance 



241-365 days N = 7 

 190.9° vector mean bearing 

 38 4nm vector mean distonce 

 366-730 days N = I4 

 108.0° vector mean bearing 

 58.3 nm vector mean distance 



Figure 11.— Vector mean bearings and distances for five recovery periods: 0-60 d, 

 61-120 d, 121-240 d, 241-365 d, and 366-730 d. 



Arcs showing mileage limits were plotted, using both the 

 average distance traveled from tagging to recovery per day by 

 period, times the midpoint for each time period; the vector mean 

 distance for each period is given in Figure 12. The differences be- 

 tween the plots of average nautical miles per day and the vector 

 mean distance are relatively small. Vector mileage arcs are smaller 

 due to the method of calculation. The black marlin covering the 

 most distance from the point of tagging (2,100 nmi in 235 d) to 

 the recapture site northeast of New Zealand (see Fig. 12) had an 

 average daily rate of travel of 8.94 nmi. 



Figure 12.— Nautical mile arcs for average distance traveled from tagging to 

 recovery by time periods, (1 = 0-60 d, avg. 30 d; 2 = 61-120 d, avg. 90 d; 3 = 

 121-240 d, avg. 180 d). V is the vector mean distance for each period, m is the 

 measured distance. Only long distance recoveries (< 500 nmi) are also shown. 



12 



