FISHERY BULLETIN: VOL. 85, NO. 4 



Table 2. — Size frequency of a) black and b) blue marlin and c) sailflsh larvae. If a block or cruise is not listed, no larvae were taken 

 there. X indicates a hiatus in the size sequence. A few larvae too badly damaged to be measured were omitted. Blanks indicate 

 zero. 



a. Black marlin 



Size class (mm) 



Block Cruise 2.5 .... 3.0 .... 3.5 .... 4.0 .... 4.5 .... 5.0 X 5.6 5.7 5.8 5.9 6.0 X 6.8 



E 1st 11 



C 1st 111 1 



2d 1 1 



8 1st 1111 11 11 



2d 1 1 



A 1st 328643213431 1 1 1 1 



2d 13 12 3 

 3d 1 



4th 1 1 



Lagoon 1st 11 1 



2d 1 1 



b. Blue marlin 



Size class (mm) 



Block Cruise 2.5 .... 3.0 .... 3.5 .... 4.0 .... 4.5 .... 5.0 . . . . 5.5 X 8.3 



E 3d 2 



4th 1 111 1 



C 2d 1 



B 2d 1 1 1 1 



3d 1 



A 3d 211 4212 11 11 11 



4th 1 112 



c. Sailfish 



Size class (mm) 



Block Cruise 2.5 .... 3.0 .... 3.5 .... 4.0 



C 4th 1 



B 3d 11 



4th 1 



A 3d 2 3 1 



4th 111 



composition of the larvae between areas. Larvae 

 on the fourth cruise were apparently larger than 

 those on the third, however it is doubtful that 

 only one cohort was involved because of the small 

 size difference between the two cruises which 

 were about 10 days apart (Table 2b). 



Sailfish larvae ranged from 2.5 to 3.8 mm, with 

 a mode at 2.6 mm (Table 2c). Only 12 larvae were 

 captured, but there is a suggestion that smaller 

 larvae were taken nearest the windward reef 

 face, and that the size of larvae increased with 

 distance into the Coral Sea. 



Vertical Distribution 



Our information on vertical distribution comes 

 primarily from samples taken within the Great 

 Barrier Reef Lagoon. It is limited, but it is consis- 

 tent. 



In the sampling with opening-closing bongo net 

 and neuston net, larvae of two species, sailfish 

 and blue marlin, were captured. No istiophorid 

 larvae were present in the neuston tows of the 

 vertical distribution sets. Sailfish larvae were 

 captured in 7 of 16 day-time vertical sets and 

 none of the 6 night-time sets. All the sailfish lar- 

 vae were captured in the 0-6 m stratum with the 

 exception of two larvae, one from each of the two 

 deeper strata, which came from two sets taken in 

 one of the turbulent interreef channels during a 

 falling tide (Table 3). Even with the inclusion of 

 the data from the interreef channel, sailfish lar- 

 vae were most concentrated in the 0-6 m stratum 

 while concentrations in the other strata did not 

 differ (Friedman test, SNK test, P < 0.05). Blue 

 marlin larvae were captured in only three of the 

 day-time vertical sets. All the blue marlin larvae 

 were captured in the 0-6 m stratum, with the 



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