Table 3. — Tag return rales by year and tag type for black marlin tagged off 

 north Queensland, Australia, as part of the Cooperative Marine Game Fish 

 Tagging Program— Pacific Area (NMFS/WHOI). (For tagging 1968-78.) 

 Total tag recovery rate (%): FM67 305T/4R = 1.3%; H 2.267T/56R = 

 2.4% (1 H tag recovered, tagging date unknown); no recoveries for either 

 A or B tags. 



Year Type No. tagged No. recovered 



Recovery rate (%) 



1968 



1969 



1970 



1971 



1972 



1973 



1974 



1975 



1976 



1977 



1978 



FM67 



26 



H 







A 







B 







FM67 



51 



H 







A 







B 







FM67 



110 



H 







A 







B 







FM67 



57 



H 



127 



A 







B 







FM67 



1 



H 



287 



A 







B 







FM67 



60 



H 



378 



A 







B 







FM67 







H 



335 



A 



1 



B 



1 



FM67 







H 



409 



A 



1 



B 



1 



FM67 







H 



501 



A 







B 







FM67 







H 



170 



A 







B 







FM67 







H 



60 



A 







B 







1 



17 

 

 



9 

 

 



10 



2,576 



59 



3.1 



1.9 



0.9 



1.7 

 0.8 



0.0 

 2.4 



0.0 

 2.4 



5.1 

 0.0 

 0.0 



2.2 

 0.0 

 0.0 



2.0 



1.2 



0.0 



Table 4. — Black marlin weights as recorded by year, 1 September through 31 De- 

 cember 1970-78, at Cairns and Lizard Island, Queensland, Australia. 





Number Total 



weight 



Average 



Heaviest 



Lightest 



Year 



marlin kg 



lb 



kg 



lb 



kg 



lb 



kg lb 



1970 



47 12,271 



27.053 



261 



575 



558 



1,231 



35 77 



1971 



69 21,078 



46,468 



305 



673 



514 



1,133 



40 89 



1972 



107 34,177 



75,346 



319 



704 



576 



1,271 



78 172 



1973 



134 46,000 



101,411 



343 



756 



654 



1,442 



20 45 



1974 



64 22,775 



50,210 



356 



784 



535 



1,180 



98 215 



1975 



78 28,023 



61,778 



359 



792 



620 



1,367 



99 218 



1976 



59 22,043 



48,596 



373 



823 



583 



1,286 



84 186 



1977 



49 21,273 



46,899 



434 



957 



600 



1,323 



110 243 



1978 



37 15,036 



33,149 



406 



896 



616 



1,358 



118 261 



Total 



644 222,676 



490,910 















; 346 kg (762 lb) average 













weight for a release time of 0-60 d, was 16 kg (35 lb). For recap- 

 tures made 61-120 d after release, the average angler overestimate 

 at tagging was 21 kg (46 lb). Estimated weights at tagging and 

 recapture were compared within release time periods, and the 

 results listed in Table 5. These calculations assume no growth, 

 therefore an increase in recapture weight vs. weight at tagging 

 would be expected as time progressed. However, the average 

 recaptured weight decreased when compared with estimated 

 weight at tagging during periods 0-60 and 61-120 d after release. 



Table 5. — Average weights of black marlin as 

 estimated by the angler at time of tagging and 

 compared with weights reported upon recovery': 

 estimated tagging weight vs. recorded weights by 

 time periods. 





No. of 

 fish 



\.<, ::u'c 



weigh 1 



Period 



kg 



lb 



0-60 d 



16 



'+20.6 



'+45.5 



61-120 d 



4 



'+41.9 



'+92.5 



121-240 d 



5 



= -2.7 



2 -6.0 



241-365 d 



7 



--3.8 



= -8.4 



366d-2 yr 



9 



' + 19.5 



' + 43.0 



2-3 yr 



3 



' + 14.3 



' + 31. 6 



3^tyr 



1 



'+36.2 



' - 80.0 



'Overestimate ( + ), fish recovered at weights < 

 reported tagged. 



Underestimate { - ), fish recovered at weights > 

 reported tagged. 



SEX RATIO OF RECAPTURED MARLIN 



Some longline vessel crews recorded the sex of tagged black 

 marlin upon recapture. One angler also gave this information on a 

 recaptured marlin. Sex information was given for 28 recoveries in- 

 cluding two recaptures from black marlin tagged with NSWF 

 tags, and of this number, 25 (89%) were reported as males and 3 

 (ll°7o) as females. The average weight of the 25 males recovered 

 was 91 kg (193 lb), and 221 kg (449 lb) for the three females. The 

 average weight for the small sample of females recovered was 

 determined from black marlin weighing 45 kg (100 lb), 95 kg (209 

 lb), and 479 kg (1,056 lb). 



MIGRATORY PATTERNS AND RATES 



Black marlin occur throughout the Pacific Ocean between 

 about lat. 40°N and 45°S, but their population density, as 

 measured by the Japanese longline catch rate data, is low except 

 in certain geographical areas. The stock structure of black marlin 

 is not fully understood. Isolated high catch-rate areas are observ- 

 ed in the western and eastern Pacific. It has been suggested that 

 two stocks (eastern/western) or three stocks (eastern/northwest- 

 em/northeastern) may be present (Shomura 1980). There is a 

 strong possibility of mixing between black marlin stocks in the In- 

 dian Ocean, Indo-Pacific, and the western Pacific. 



Figures 4-8 show plots of black marlin tag and recovery loca- 

 tions, grouped by release time periods. All recoveries >500 nmi 

 from the tagging location off the Great Barrier Reef, Queensland, 

 Australia, regardless of release time period, are shown in Figure 9. 

 Information on recovery number, month of tagging, and number 

 of days from release to recovery are included in these figures and 

 lines connecting the tagging and recapture points do not indicate 

 the exact migratory path of the tagged fish. 



When these recovery distances over time (as measured by days 

 from release to recapture) are presented, it can be seen that 



