Prince et al.: Movements and spawning of Tetropturus albidus and Makaira nigricans 



667 



6-7 7-8 8-9 



Length (mm) 



9-10 10-11 11-12 12-13 



Figure 6 



Length-frequency distribution for larval white marlin 

 (Tetrapturus albidus), blue marlin, [Makaira nigricans), 

 and unidentified istiophorids collected in the vicinity 

 of Punta Cana. Dominican Republic, April and May 

 2003. 



the present study is the first to provide direct evidence 

 of springtime spawning activity in this area. Histologi- 

 cal assessment of the captured female ovarian tissue is 

 consistent with the premise that the adult white mar- 

 lins in the aggregation that we located during fishing 

 and PSAT tagging operations participated in spawning 

 activity. This contention is strengthened by the presence 

 of very small, presumably very young, white (and blue) 

 marlin larvae in the same location. 



The presence of larvae is the most direct way of docu- 

 menting that a spawning event has actually occurred. 

 This is particularly relevant to highly mobile species, 

 such as billfishes, that can cover large distances in a 

 short time (Prince and Brown, 1991). Serafy et al. (2003) 

 used a similar approach to identify blue marlin spawning 

 grounds in the area of Exuma Sound, Bahamas. In their 

 neuston collections, 90 blue marlin, no white marlin, and 

 three sailfish larvae were captured. Because Serafy et 

 al., (2003) sampled during the entire month of July, it 

 seems possible that larval sampling in Exuma Sound 

 took place after the majority of white marlin spawning 

 had already occurred. Subsequent neuston sampling of 

 Bahamian waters yielded white marlin larvae in Exuma 

 Sound in April and in the Old Bahama Channel and 

 just east of Long Island in March, but no blue marlin 

 during these months (D. E. Richardson and S. A. Lu- 

 thy, unpubl. data). Extensive sampling of the Straits 

 of Florida (SOF) over four years resulted in sporadic 

 captures of white marlin larvae in May and June. Blue 

 marlin was the more common larval marlin in the SOF 

 and was captured from June to September (S. A. Luthy, 

 unpubl. data). In the present study, white marlin larvae 

 were twice as abundant in larval samples as blue marlin 

 larvae (which had been captured earlier in Punta Cana) 

 than in other areas where blue marlin larvae had been 

 found. These results are consistent with reports that 

 white marlin is primarily a spring-time spawner but 



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Figure 7 



Mean displacement per day (in nautical miles) for blue 

 marlin iMakaira nigricans), white marlin {Tetrapturus 

 albidus), black marlin iMakaira indica). and striped 

 marlin {Tetrapturus audax) monitored with pop-up sat- 

 ellite archival tags by Gunn et al. (2003) [Australia], 

 Domeier et al. (2003) [Mexico], Graves et al. (2001) 

 [Bermuda], Kerstetter et al. (2003) [Northwest Atlantic], 

 Graves and Horodysky 4 [Punta Cana, Dominican Repub- 

 lic, La Guaira, Venezuela, U.S. Mid-Atlantic region], 

 and present study. In all studies, displacements were 

 computed from the point of tag release to the point of 

 first transmission from PSAT tags and are not meant to 

 infer tracks taken by the fish. Means are accompanied 

 by ± one standard deviation for each species identified as 

 follows: blue marlin (BUM, stippled bar), white marlin 

 (WHM, empty bar), black marlin ( BLK, solid bar), and 

 striped marlin (STM, cross hatched bar). 



mark an expansion of the July to October spawning 

 season reported for blue marlin in the North Atlantic by 

 Erdman (1968) and de Sylva and Breder (1997). 



