Body length 



■10.0 



20. - 



60.0- 



-10. - 



20.0 



■10.0 



20.0 



100 120 140 160 10 20 30 



cm 



kg 



Figure 6.— Body (eye-fork) length and weight compositions of 

 shortbill spearfish caught by longline fishery in the central 

 South Pacific Ocean (lat. 16°-28°S, long. 166°E-174°W), 

 November-December 1969. M = male; F = female; white tri- 

 angle = average (Koga, Imanishi, and Tawara, 1972). 



Figures 6 and 7, the average length of fish caught by 

 the longline fishery is about 135 cm in the central 

 South Pacific and about 150 cm in the eastern Pacific, 

 suggesting an increasing tendency in size toward the 

 east. 



Kume and Joseph (1969b) report the weight-length 

 relation for the shortbill spearfish taken in the Pacific 

 Ocean east of long. 130° W. To describe the relation- 

 ship, they use the equation log,,, Y = log,„ a + log 10 X 

 and fitted the data by the least squares method, 

 where Y is the weight in kilograms and X the eye-fork 

 length in centimeters. The data employed are of two 

 types, 1) gilled and gutted and 2) whole, both from the 

 Japanese longline fishery. The regression coefficient 

 (b) and the Y intercept (log,„ a) they obtained are 

 3.9195 and -7.2239 for the gilled and gutted, and 

 3.7242 and -6.8146 for the whole, respectively. The 

 number of fish and the size range of specimens ex- 

 amined are 89 fish and 102.4-167.0 cm long for the 

 gilled and gutted, and 19 fish and 128.0-156.0 cm for 

 the whole, respectively. Koga et al. (1972) use the 

 same weight-length relation and obtain the value of 

 4.5926 as the regression coefficient for the South Pa- 

 cific shortbill spearfish. 



4.2 Abundance and Density (of Population) 

 4.21 Average abundance 

 The population size is not yet estimated. 



Figure 7.— Size composition of 63 shortbill spearfish captured 

 in the eastern Pacific Ocean during 1963 and 1964 by the RV 

 Shoyo Maru. Number and location of fish measured are shown 

 by 1° areas. (From Kume and Joseph, 1969b). 



4.22 Changes in abundance 



Because of the inadequacy of the catch statistics of 

 this species (see 2.1), the changes in abundance can- 

 not be considered at present. 



4.23 Average density 



Annual mean density for any given area or any 

 given year has not been calculated. 



4.24 Changes in density 



The apparent relative abundance is low throughout 

 areas of the longline fishery compared with the striped 

 and blue marlin. In 1958, it ranged from 0.16 fish to 

 0.3 fish per 100 hooks depending on areas of the 

 fishery in the South Pacific between lat. 20° and 30° S 

 and between long. 170°E and 170°W (Koga, 1959). 

 Concerning variation with depth, there is an indica- 

 tion in the equatorial western Indian Ocean that the 

 highest catch rate for this species was in the 501-1,000 

 fathoms range (Merrett, 1971; see 2.3). Merrett in- 

 dicates the value of approximately 0.03 fish per 100 

 hooks in this depth range. 



4.3 Natality and Recruitment 



4.31 Reproduction rates 

 No information is available. 



4.32 Factors affecting reproduction 



No information is available, except for the general 

 recognition that the transportation, dispersion, and 

 mortality of the larval fish population may be greatly 



50 



