DISTRIBUTION AND GENERAL NOTES ON THE SPECIES 291 



that males become increasingly scarce towards the south, and it is probable that this exception is due 

 merely to insufficient sampling of the more southerly males caused by this scarcity. 



Table 13. Observed differences in populations 0/ Merluccius hubbsi sampled in different latitudes 

 between 21 March and 30 March, 1932, in long. 64° 15' W 



Stations considered 

 Mean latitude 

 Hake per hr. trawling 

 Sex ratios, % males 



Males: 



No. measured 

 Mean length 



Northern region 



WS853 and WS855 



45° 39' S 

 702 

 76-4 



544 

 35-2 cm. 

 5-1676 

 0-0491 



Intermediate region 



WS857, WS862 and WS864 

 48° 21J' S 

 37 

 37-8 



Southern region 



WS866 and WS868 

 Si-iol'S 

 27 

 16-7 



42 



39-3 cm. 



5-6454 

 0-7588 



9 



42-4 cm. 



1-5720 

 0-2746 



Difference mMl{ = d) 



.'■ djaa = 

 Significance 



Females: 



No. measured 

 Mean length 

 aMl 



Difference in Ml ( 



<^d 



.'. djaa = 



Significance 



--d) 



4-1 cm. 

 0-8988 



4-56 

 Clear 



3-1 cm. 

 1-0166 



3-p4? 

 Just significant 



332 

 39-9 cm. 



10-3011 

 0-3196 



69 



48-3 cm. 

 11-0042 



1-7550 



45 



56-0 cm. 



9-1894 



1-8765 



8-4 cm. 

 1-4404 



5-832 

 Strong 



7-7 cm. 

 1-9057 

 4-041 

 Clear 



Table 13 shows a similar consideration of more limited data from each of the three regions m the 

 last ten days of March 1932 in one longitude. This array of the data also permitted comparable figures 

 for relative abundance (hake per hour's trawling) and sex ratios to be given at the head of the table 

 Both show marked diminution towards the south. This falling off in the proportion o males is the 

 third important feature associated with increasing latitude in populations of M. hubbsi It would 

 seem to imply that spawning activity must be much reduced near the southern limits of the range of 



*FurthlTdemonstration of the effect of latitude upon size is given by Fig. 22. Here the length 

 frequencies for either sex, m each of the three regions, have been summed into 5 cm. §-"?«' -^uced 

 to percentages, and the results plotted graphically. The curves show quite clearly how small fish 

 become mo?e are, and larger fi^l. commoner, as one proceeds southwards. Incidentally the figure 

 p vrds a good iUustration'of the unusually large discrepancy in size between the sexes oi MMbbn 

 L has already been mentioned. Females are significantly larger than males among a large majority 

 of fishes, but it is unusual to find differences as great as these. 



THE RELATION BETWEEN LENGTH AND WEIGHT OF MERLUCCIUS HUBBSI, AND 

 THE RELATION m.^i ^^ ^^ INDICATOR OF THE SPAWNING SEASON. AND 



FOR OTHER PURPOSES 



During our third survey the weights of male and female M. hubbsi were reeorded m the form of bulk 

 Durmg our tmra s J ^ . , ^,^„^^^ b,; 3ed. Hieklmg (.930*, PP- 7. 8) has proved 



Zf A^S 1 d remaSly rat'e figurl at sea. even 'when used for much more delicate weighings 



tn anTaUempted by us^The lengths of our fishes were known individually, so that a '.rue mean 



