FISHERY BULLETIN: VOL 86, NO 1 



70 r 



3 2 



Minutes prior to dive 







Figure 2. — Breath sequences prior to 5 dives lasting from 93 to 279 seconds. During the 90 seconds 

 immediately preceding dives, the mean interbreath interval was 15 seconds. Prior to this 90-s period 

 of hyperventilation the mean interbreath interval was 48 seconds. 



(A^ = 20, SD = 74.6). During this period of erratic 

 diving the whale continued to swim N, then 

 NNW. At about t = 140 minutes the whale 

 stopped traveling NNW and began a series of 10 

 dives, the second being the longest, followed by 

 successively shorter dives. These dives were fol- 

 lowed by rather uniform surface intervals and all 

 10 lasted significantly longer (x = 183.5 seconds, 

 N = 10, SD = 89.2) than the previous mean of 75 

 seconds. At the end of the dive sequence, at 182 

 minutes, the whale stopped swimming entirely 

 and floated motionless at the surface, occasion- 

 ally moving its jaws. This inactivity lasted about 

 12 minutes and then the whale began a second 

 series of dives. We called these dive sequences, 

 which consisted of regular length surface inter- 

 vals interspersed with a series of longer dives of 

 progressively decreasing duration, "feeding 

 bouts" because at ^ = 140 seconds the whale had 

 reached the only major aggregation of krill in the 

 vicinity, as verified by sonic records (Fig. 3). We 

 saw dense schools of krill and isolated krill at the 

 surface from the bow of the ship, and we captured 

 krill in three successive hauls with the 1 m 

 Isaacs-Kidd midwater trawl. 



During the first feeding bout the whale slowed 



from its steady 3-knot swimming speed and 

 moved slowly at about 1 knot, but no longer in 

 any specific direction, finally swimming some 

 400 m to the south before beginning the second 

 feeding bout. The whale had fed on krill earlier 

 also, because it defecated during the feeding se- 

 quence and the feces, as determined by later mi- 

 croscopic examination, were composed entirely of 

 well-digested euphausiids. 



The display of a false fluke prior to the high 

 fluke initiating a long dive did not necessarily 

 indicate presence or absence of krill, but when 

 krill were present, it was a highly significant pre- 

 dictor of the length of the dive. In the presence of 

 prey, when the whale showed its flukes once (i.e., 

 did not false-fluke preceding the dive), dive dura- 

 tion averaged 91.2 ± 13.0 seconds {N ^ 5), 

 whereas when both a false fluke and a high fluke 

 preceded the dive, the dive averaged 234.7 ± 64.4 

 seconds (N = 1). 



In March and April 1986 we saw a total of eight 

 southern right whales. Of these we distinguished 

 four as individuals on the basis of video tapes and 

 photographs of callosities and body markings. 

 One of these whales was the same individual that 

 we had observed in January some 70 miles fur- 



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