LAURS ET AL.: SMALL-SCALE MOVEMENTS OF ALBACORE 



FIGURE 2. — Movements of albacore number 4 as indicated by 

 ultrasonic tracking and contoured field of sea surface tempera- 

 ture in degrees Celsius. Triangles on fish track indicate hourly 

 position. The time and date that tracking commenced is noted at 

 the starting location and shown above and below a slash mark, 

 respectively. The 0000 and 1200 h local time positions are also 

 indicated. Dots show where temperature observations were 

 made by David Starr Jordan. Temperatures below 15.0°C are 

 shaded. 



FIGURE 4. — Movements of albacore number 6 as indicated by 

 ultrasonic tracking and contoured field of sea surface tempera- 

 ture in degrees Celsius. Triangles on fish track indicate hourly 

 position. The time and date that tracking commenced is noted at 

 the starting location and shown above and below a slash mark, 

 respectively. The 0000 and 1200 h local time positions are also 

 indicated. Dots show where temperature observations were 

 made by David Starr Jordan. Temperatures below 15.0°C are 

 shaded. 



upwelled water and warmer, nonupwelled water 

 (Smith 1968). The effects that an upwelling front 

 may have on the movements of albacore were 

 indicated during the ultrasonic tagging experi- 

 ment. On 17 August, during tracking operations 

 for fish number 4, a relatively well-developed 

 upwelling surface temperature front was ob- 



served in the northeast portion of the tracking 

 area. The upwelling was caused by brisk north- 

 erly winds which had been blowing for several 

 days. The remainder of the area surveyed has a 

 rather simple surface temperature distribution 

 mostly within the temperature range considered 

 as the habitat preference for albacore (Figure 2). 



FIGLIRE 3. — Movements of albacore number 5 as 

 indicated by ultrasonic tracking and contoured 

 field of sea surface temperature in degrees Cel- 

 sius. Triangles on fish track indicate hourly posi- 

 tion. The time and date that tracking commenced 

 is noted at the starting location and shown above 

 and below a slash mark, respectively. The 0000 

 and 1200 h local time positions are also indicated. 

 Dots show where temperature observations were 

 made by David Starr Jordan. 



SO' 20' 



10' I22"00 



351 



