270 DISCOVERY REPORTS 



larger-sized animals are mixed with the small in the surface layers, but large animals descending to 

 breed are found in the deeper layers. The mature animals are normally only found below 750 m., in the 

 warm deep water. 



5 10 15 20 25 30 35 40 45 50 55 60 65 

 SIZE GROUPS 



Fig. 24 



10 

 9 



8 



7 



6 



5 



4 



3 



2 

 UJ 



5 i 



< 



a o 



UJ 



|-' 



UJ 



1- -2 



336 7 

 SALINITY 



9 34 I 2 -3 4 5 6 7 8 9 35 



Fig- 25 



Fig. 



Fig. 



24. The vertical distribution of size groups of 5. gazellae in early winter, from shallow and intermediate oblique i m. nets. 



25. The distribution of mature specimens of 5. gazellae in relation to temperature and salinity. 



VERTICAL DISTRIBUTION OF MATURE ANIMALS 

 Table 14 shows the depth distribution of all mature specimens taken in closing nets (N450, TYF, 

 N 100, N70). Here I class as 'mature' those specimens in which the seminal vesicles have grown to 

 full size, and these include all in the stages of maturity from II/III to V. It is evident from the data 

 that the advanced stages are very rare at depths above 750 m., and probably most common in the 

 1 500-1000 m. layer. The number of hauls made below 1000 m. is small compared with the number 

 made in the shallower layers, and therefore the one stage III individual taken in the top 250 m. is the 

 only mature specimen from approximately 35,000 immatures observed from this layer, whereas the 

 fifteen mature specimens from the 1500 to 1000 m. layer represent a high percentage of the total 

 numbers taken in this layer. Deep hauls have been searched for mature specimens, and Table 1 5 has 



