DISTRIBUTION OF EGGS AND LARVAE OF JACK MACKEREL 269 



Table 24. — Percentage of each size class of jack mackerel larvae, occurring in each region, 19SS-S4 



Table 25. — Annval estimates of abundance and survival of jack mackerel eggs and larvae, 1952-54 



[ In billions] 



Category 



Size range 

 (mm.) 



Abim- 

 dance 



Survival 



per 100.000 



eggs 



1953 



Abun- 

 dance 



Survival 



per 100,000 



eggs 



Abtm- 

 dance 



Survival 



per 100.000 



eggs 



Eges 



Larvae: 



2.0 mm.. 



2.5 mm.. 



3.0 mm.. 



3.5 mm.. 



4.0 mm.. 



4.5 mm.. 



5.0 mm._ 



6.75 mm. 



6.76 mm. 

 7.75 mm.. 



8.75 ram. 



9.76 mm. 

 10.76 mm 

 11.75 mm 



12.75 mm 



13.76 mm 

 14.76 mm 



1. 90- 2. 25 



2. 26- 2. 75 



2. 76- 3. 25 



3. 26- 3. 75 



3. 76- 4. 25 



4. 26- 4. 75 



4. 76- 5. 25 



5. 26- 6. 25 



6. 26- 7. 25 



7. 26- 8, 25 



8. 26- 9. 25 



9. 26-10. 25 

 10. 26-11. 25 

 11.26-12.25 



12. 26-13. 25 



13. 26-14. 25 

 14.26-15.25 



593. 100 



28.300 



48, 100 



63.600 



11, 100 



9.400 



6,900 



6,500 



2.600 



780 



320 



170 



100 



42 



25 



17 



43 



37 



736, 100 



462. 300 



4.711 



8.109 



10, 706 



1,871 



1,648 



1,163 



927 



438 



131 



63 



28 



16 



7 



4 



2 



7 



6 



29,600 



3.300 



3,300 



3.200 



2.200 



1.600 



860 



660 



150 



150 



28 



60 



60 



20 



81 



4.007 



448 



448 



434 



298 



203 



115 



76 



20 



20 



3 



8 



8 



2 



11 



59.300 



6.800 



6.700 



3.800 



4.100 



1.600 



830 



480 



160 



71 



30 



12.827 



1,470 



1,232 



821 



886 



324 



179 



97 



34 



15 



GROWTH RATE OF LARVAE 



Tlie growth rate of jack mackerel larvae was 

 obtained by direct observation of material taken 

 from station 70 on line 97 (97.70) during March of 

 1957 (Farris, 1959). Eggs were taken from the sea 

 with a plankton net, sorted according to develop- 

 mental stage, placed in jars of fresh sea water, and 

 observed daily until they hatched. After hatching 

 the larvae were measured daily until they died. 

 No attempt was made to feed the fish. The 

 measurements were averaged daily and plotted as 



log average length against days (fig. 12). Such 

 a plot suggested that growth during the first 3 

 days was more rapid than for the next 4 daj's. 

 The yolk sac was absorbed and the eyes became 

 pigmented on the sixth day of larval life. The 

 growth rates for the first 3 daj^s (section A) and 

 for the following 4 days (section B) were then 

 compared by regression analysis (table 26), where 

 X=days past hatching, F= length in miUimeters, 

 log Y=a+bX, Si)=standard deviation of slope, 

 and .Sy/i= standard deviation of sample points 



