CAREY and ROBISON: DAILY PATTERNS IN ACTIVITIES OF SWORDFISH 



-I I I I I I I I I I I I I I I I 



Figure 4.— Track of swordfish no. 4, 5, 

 and 6, Baja California. These fish all 

 moved west during the first afternoon; 

 no. 5 and 6 then moved down the axis of 

 San Jose Canyon after sunset. Dots 

 represent sunset; circles represent sun- 

 rise. Ticks at 1-h intervals, bottom con- 

 tours in meters. 



I M I I I I I I I I I M I I I I III I, HI I 



-ri I I I I I 23° 20' 



23° 00' 



— 22° 40' 



' I I I ' I I I 1 I [ ] ] I ] J I I J L I I I I I I ] I I I J I I I I I ] I I I I I I 22° 20' 



110° 00' 109°40' 109°20' 



SUNRISE 



4 MAY 



24 6 



TIME. HOURS 



6 MAY 



Figure 5. — Depth record for swordfish no. 6 off the tip of Baja California superimposed on an isotherm pattern dravm from 

 bathythermograph lowerings. There was a full moon during this experiment and the usual nighttime depths were deeper than those on 

 the moonless nights during experiments with swordfish no. 2 and 3. The fish generally swam below the thermocline during the day and 

 was well into the oxygen-minimum layer, where oxygen concentration was estimated to be about 10% that on the surface. Isotherm 

 interval 1° F 



the northeast. At the end of the third day the flat- 

 tening of the deep isotherms (Figure 8) indicated 

 that it had crossed the center of the Gulf Stream 



and entered the Sargasso Sea. When we aban- 

 doned the fish it had gone a distance of 240 km 

 in 67 h. 



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