2 
immediately began to thicken. Its base sank steadily to l80 meters 
$ 
4 
depth, and the temperature at 150 meters rose correspondingly, reaching 
a high of 27«2® at 4®N(PigTxre 1), 
At this latitude, the ship crossed the southern boxindary of the ECC 
into the weetwardly flowing Gouth Equatorial Current (SEC). %e 
temperature at 150 meters began to cool again, the deeper portions of the 
mixed layer were replaced by cooler 'water, and a new base to the 
r 
surface mixing formed near 75 meters depth, gradually rising to 50 meters 
* 
as the aftiip entered the Southern Grid at 2®N, 
Figure 1 also shows a plot of total birds sighted each day, for 
comparison with sea temperature at the surface and at 150 meters depth* 
Bird numbers were moderate from Johnston island to 14®1J, then dropped 
significantly in the HEC and the northern edge of the ECC, However, 
the birds then increased southward to a peak (falue near the southern 
boundary of the ECC, and dropped off again as the ship passed into the 
SEC and approached the Southern Grid, Bird numbers show a very good 
correlation with the 150 meter temperature, but do not correlate well 
with surface temperature, The 150 meter temperature itself is not the 
property of significance to the birds, father, the temperature at this 
depth is probably a good indicator of differing water aaases, whose 
differences in food content at the surface are the more likely amami 
reason why birds are concentrated in favored zones. 
The temperature plots in Figure 1 are baaed on a preliminary 
aualysia of the BT data performed at sea* A refined analysis will be 
performed by the Honolulu Laboratory, Bureau of Coraraeroial Fisheries, 
which may be expected to modify the temperature data negligibly if at ^1* 
