Table 7. — Meristic counts of larvae and juvenile wahoo ' 



Myomeres 



Teeth ■' 



Standard length 



Pre- 

 anal 



Mm. 



9 ._ 



2 



6 



6 (est.)- 



8 



9 (est.)- 



4 



7 







2 



2 



No. 

 26 

 29 

 28 

 28 

 30 

 27 

 27 

 29 

 29 

 29 

 30 

 29 

 27 

 27 

 27 

 27 

 27 

 26 

 27 

 28 

 30 

 27 

 26 

 32 

 27 

 31 

 26 

 27 

 29 

 26 

 28 

 26 

 26 

 30 

 27 

 23 

 29 

 26 



Post- 

 anal 



No. 

 39 

 35 

 37 

 37 

 35 

 37 

 37 

 35 

 36 

 35 

 35 

 35 

 37 

 38 

 37 

 37 

 38 

 38 

 38 

 36 

 35 

 36 

 39 

 32 

 36 

 34 

 38 

 37 

 35 

 38 

 37 

 37 

 39 

 35 

 37 

 36 

 36 

 38 



Total rays 



Bran- : 

 chio- I 

 stegal Upper 



No. 



jaw 



I 



65 



64 



65 



65 



65 



64 



64 



64 



65 



64 



65 



64 



64 



65 



64 



64 



65 



64 



65 



64 i 



65 



63 



65 



64 



63 



65 



64 



64 



64 



64 



65 



64 



65 



65 



64 



64 



65 



64 



Lower 

 jaw 



No. 



Pala- 

 tine 



No. 



Fin spines and rays 



No. 



dorsal 



No. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 2 

 3 

 4 

 5 

 5 

 6 

 



Second 



dorsal 



plus 



flnlets 





 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 3 

 5 



9 

 11 



12 

 12 

 15 

 16 

 20 

 20 

 21 

 21 

 23 

 23 

 24 



Anal 

 plus 

 flnlets 



JVo. 































































































4 



4 



7 



8 



10 



11 



11 



14 



16 



18 



19 



20 



20 



22 



22 



22 



Pec- 

 toral 



No. 































































































4 



5 



4 



5 



6 



6 



7 



10 



11 



11 



11 



12 



11 



14 



19 



23 



Pelvic 



No. 







































































































Bud 



Bud 















Bud 



Bud 



Bud 



Bud 



1,2 



1.4 



1,5 



1,5 



1,5 



Caudal fin rays 



Dorsal 

 (princi- 

 pal and 

 second- 

 ary) 



JVo. 















































































3-hO 



3-1-0 



3-1-0 



4-1-0 



5-1-0 



5-1-0 



7-1-0 



^+o 



7-t-O 

 6-1-0 

 7-1-0 

 9-1-2 

 9-1-4 

 9-1-3 

 9-1-4 

 9+4 

 9-1-4 

 9-t-7 

 9-1-9 

 9-1-15 



Ventral 

 (princi- 

 pal and 

 second- 

 ary) 















































































3-1-0 



2-)-0 



2-1-0 



3-1-0 



4-(-0 



4-1-0 



i+0 



5H-0 



6-1-0 



5-1-0 



5-(-0 



8-1-0 



8-1-2 



8-1-1 



84-3 



8-h3 



8-f-3 



8-H6 



8-1-9 



8-1-15 



1 Standard length (mm.) and numbers of precaudal vertebrae and caudal vertebrae for each of three specimens in which vertebrae were counted were as 

 follows: 13.2 mm.— 33, 31: 17.8 mm.— 32, 31: 23.7 mm.— 32, 31. 



2 D= damaged. 



T obtained a premaxillary length to skull length 

 ratio of 0.11 :1 for the S. scomber illustrated by 

 Allis (1903), and ratios of 0.12:1, 0.12:1, 

 0.11:1, and 0.10:1 for four S. japonicus that 

 were 220, 271, 284, and 386 mm. fork length, 

 respectively. These ratios vary considerably 

 from the 0.23:1 which Conrad reported for 

 Scoyyiber. 



Strasburg (1964) has mentioned the pres- 

 ence of a small, cartilaginous pad at the tip of 

 the lower jaw in juvenile wahoo. The pad is 

 barely noticeable in the 4.2-mm. larva but is 

 clearly developed in the 4.3-mm. larva. The pad 

 assumes its characteristic conical shape in 

 larvae more than 5.8 mm. long. 

 Body Depth 



In many fish larvae, body depth at the pec- 

 toral fin is greatly influenced by the amount of 

 food in the digestive tract. Furthermore, the 

 distention of the gill cover and the bending of 



the body at the junction of the head and trunk 

 also distort the body depth of fish larvae at the 

 pectoral fin. The variability produced by this 

 distortion can be eliminated by discarding all 

 distorted specimens, but this measure was not 

 possible because few wahoo larvae were avail- 

 able. Consequently, body depth of wahoo 

 larvae was measured at the posterior edge of 

 the anus, where distortions caused by bending 

 are minimal. 



Body depth follows a different course of 

 growth from that of premaxillary length. Dif- 

 ferences between the two growth curves are 

 seen mainly in larger larvae (fig. 4 and table 

 4) ; where the premaxillary grows at a uniform 

 rate in larvae 6.6 to 10.7 mm. long, the body 

 depth increases abruptly when the larvae are 

 about 9 mm. long, and where the premaxillary 

 grows relatively slower than standard length 

 in larvae larger than 10 mm. (a = 0.276), the 



MORPHOLOGY AND DISTRIBUTION OF LARVAL WAHOO 



311 



