FISHERY BULLETIN: VOL. 70, NO. 2 



(Table 3, Figure 5). The indicated mortality 

 rate was 21 ^/c per year, with 95 percent confi- 



dence limits of 14 



<"; 



and39Sr 



(Z, the coefficient 



of instantaneous total mortality = 0.32 ± 0.17). 



Table 3. — Summary of recaptures of tagged white mar- 

 lin (to December 31, 1969). Dashed lines enclose data 

 used for mortality estimates. 



Year 



Months at large 



Number Number 



tagged recaptured^ q_,2 12-24 24-36 36-48 >48 



1954 

 1955 

 1956 

 1957 

 1958 

 1959 

 1960 



4 

 145 

 413 

 145 

 41 

 202 

 111 



1966 

 1967 

 1968 

 1969 

 Unknown 



508 



521 



883 



1,395 



2 



Total 6,590 



Total, 1961-^5 only 



9(11) 



3(4) 



9 



5(6) 



2 



58(65) 



4(6) 3 

 1 (1) 



6 3 



5(6) 



28(33) 13(15) 

 11(13) 7(3) 



' Number recaptured ore for groups A-C (see Appendix); numbers for 

 groups A-D, If different, are shown in parentheses. 



0-12 12-24 24-36 36-48 

 MONTHS AT LIBERTY 



Figure 5. — Number of returns of white marlin tagged 

 from 1961 to 1965 in waters north of lat 32 °N, plotted 

 by time at liberty. 



BLUE MARLIN 



Since 1954, 486 blue marlin have been tagged 

 in the western North Atlantic; 3 have been re- 

 covered, all near their respective release points. 

 One blue marlin released oflF Chub Cay, Bahamas, 

 in August 1968, was recaptured oflF nearby An- 

 dros Island the following December; one re- 

 leased off La Guaira, Venezuela, in August 1966, 

 was recaptured in the same area in October 1968; 

 and one released off Biloxi, Miss., in June 1969, 

 was recaptured 5 months later off Sabine Pass, 

 La., 350 miles to the west. The returns indicate 

 that meaningful information about blue marlin 

 can be obtained if sufficient numbers are tagged. 



LONGLINE CATCHES 



METHODS 



Data on the catch of marlins by the Japanese 

 longline fishery in the Atlantic Ocean have been 

 published by Shiohama, Myojin, and Sakamoto 

 (1965) and by the Fisheries Agency of Japan 

 (1966, 1967a, b, 1968, 1969). Catches of white 

 and blue marlins, and those of other billfishes 

 and tunas, are listed in those publications by 5°- 

 quadrangles for each month, beginning in June 

 1956. Although catches in the categories "black 

 marlin" and "striped marlin" also are listed, 

 systematists do not presently recognize that 

 black marlin, Makaira indica,^ and striped mar- 

 lin, Tetrapturus audax, occur in the Atlantic 

 Ocean. We do not know whether those catches 

 were misidentified or whether these species do, 

 in fact, occur in the Atlantic. The catches listed 

 in the two categories were too few to affect the 

 conclusions of our study even if they were really 

 white or blue marlin. 



For each species, the catch per unit of effort 

 (CUE), in fish per 100 hooks, was calculated 

 for each 5°-quadrangle-month stratum in the 

 period 1956-67 for which data were available. 

 These CUE's were computed by dividing the 

 number of fish caught in each such stratum by 

 1 % of the number of hooks fished in it. To show 

 seasonal distribution, average (unweighted) 



^ Ueyanagi et al. (1970) report occasional catches of 

 M. indica in the equatorial and southeastern Atlantic. 



290 



