FISHERY BULLETIN: VOL. 72. NO. 3 



nature indicate about 8 to 11 mo for palinurids 

 (Johnson, 1960; Lazarus, 1967; Chittleborough 

 and Thomas, 1969). In some scyllarids shorter 

 periods are indicated (Saisho, 1962; Robertson, 

 1968), but in others, including Scyllarides 

 astori, a length comparable to that of palinurids 

 is suggested by the wide dispersal of the larvae. 

 These long drifting periods provide ample 

 time for far and wide dispersal. Coincident with 

 this, the number of larvae caught in a plankton 

 tow is always small especially for the later 

 stages and this precludes close statistical 

 analysis for short surveys. But the presence of 

 even small numbers of larvae when scattered 

 over a large area or period of time are 

 significant in indicating major outlines of the 

 type of drift and dispersal by currents from 

 adult spawning areas. 



PROCEDURE 



In view of the scarcity of larvae and the pres- 

 ence of only later developmental stages VI-XI 

 (the final phyllosoma stage) in far offshore wa- 

 ters, the collections most generally useful were 

 those from nets filtering large quantities of 

 water: a 15 x 15 m mid-water trawl with a 

 section of 3-mm bar mesh and towed obliquely 

 in steps from 100 to m or from 30 to m for 

 about 1 h 30 min; and a Blackburn micronekton 

 net 5.8 m long constructed of nylon with mesh 

 apertures of about 5.5 x 2.5 mm, and cod end of 

 no. 56 XXX grit gauze. This net attached to a 5 

 X 5 foot (1.52 X 1.52 m) frame was towed about 

 60 min obliquely from 200 to m. Samples 

 were also analyzed from tows taken with a 5-m 

 long "neuston" net constructed of nylon with 

 mesh apertures of about 0.65 mm, and cod end 

 of no. 56 grit gauze. This net was attached to a 

 1-m ring bent to form a narrow opening and 

 buoyed to tow at the immediate surface for 

 15 min. For David Starr Jordan cruise 65, 

 analyses were also made of all samples taken 

 with a similar net attached to a regular 1-m 

 ring towed obliquely from 200 to m for 20-25 

 min simultaneously with the neuston net. 



RESULTS 



David Starr Jordan Cruise 57 



and Townsend Cromivell Cruise 51 



5 N0V.-2I Dec. 1970 



In Figure 1 is shown the station pattern 



640 



I5°N 



10' 



.i)_ 



o 



■(•f A« A» 



NORTH EQUATORIAL CURRENT 





• • •! O 



EQUATORIAL COUNTERCURRENT 



> l--h-- ^ 



'^S. astori post larva 

 0^:__.O ! 



SOUTH EQUATORIAL CURRENT 



S'S 



II5°W 



JORDAN 57 and CROMWELL 51 

 Stations with available 

 plankton samples: 



• Jordan 5'x 5' net 



A " midwater trawl 



n " neuston net 



O Cromwell 5x5' net 



A " midwater trawl 



/ ptiyllosoma larvae taken 



Figure I.— RV Townsend Cromwell cruise 51 and RV David 

 Starr Jordan cruise 57 station pattern in unit areas 1-6. Neuston 

 net tows are shown only where larvae were taken. 



where net tows, positive or negative for phyl- 

 losoma larvae, were taken by the trawl or the 5 

 X 5 foot net. The stations occupied fall into 

 more or less distinct unit areas as designed for 

 the tuna study to correlate with the prevailing 

 major elements of the Equatorial Current Sys- 

 tem. 



The number and stages of larvae caught in 

 the various nets are given in Table 1 for each of 



