FISHERY BULLETIN: VOL. 69, NO. 3 



pure tone (Table 1) did flee the killer whale 

 source when we projected it to them before they 

 passed by the sound projector. We did not pro- 

 ject killer whale sound to the other contacts 

 that did not avoid random noise and pui-e tone. 



Observers on board noted how little of the 

 avoiding whales' bodies showed above the sur- 

 face and their unusually small surface distur- 

 bance. In many instances their blows were in- 

 visible and even blows at close range were 

 scarcely audible. In contrast, the surfacing of 

 undisturbed whales involved the simultaneous 

 appearance of head and blow accompanied by 

 a well-defined surface wake. Their blows were 

 generally visible, and they were audible at close 

 range. After their first appearance, the undis- 

 turbed whales showed their backs and sometimes 

 tossed their flukes high into the air. On the 

 other hand, it was diflicult to spot the fleeing 

 whales. 



We thought that if gray whales associated 

 the projected killer whale "screams" with po- 

 tential danger, they would have left the area 

 silently to lessen their chance of detection. For 

 example, Schevill (1964) noted that belugas, 

 Delphinapterus leucas, became silent in the 

 vicinity of two killer whales. Upon analyzing 

 our data, it turned out that only 2 gray whale 

 phonations appeared on the tapes during killer 

 whale periods, whereas 47 occurred during the 

 control periods. 



Gray whales on the breeding grounds fre- 

 quently exhibit a behavior termed "spying-out" 

 (Gilmore, 1961) wherein the head comes ver- 

 tically out of the water for several seconds. "Spy- 

 ing-out" in the breeding lagoons seems to be 

 associated with searching for channels; it is also 

 done when the whales are pressed by small boats 

 (communication from Dr. Joseph R. Jehl, San 

 Diego Natural History Museum) . Since we have 

 seen this behavior over the past 6 years only 

 three times, we assume that migrating gray 

 whales rarely "spy-out." However, gray whales 

 in the present experiments inevitably "spied- 

 out" after fleeing into the thick kelp following 

 killer whale playbacks. 



As a result of these experiments we conclude 

 that gray whales apparently recognize the voice 

 of a killer whale, that they can easily localize 



the sounds underwater, and that they flee killer 

 whale phonations probably as a sign of potential 

 danger. Such avoidances consist of several be- 

 haviors that appear to function as protective 

 mechanisms — sound localization, silence, rapid 

 escape, i-educed exposure, and visual search. 



DISCUSSION 



Walker (1971) has expressed the opinion that 

 the function of "spy-hopping" ("spying out") 

 by gray whales is not that ". . . the whale looks 

 around, spying out possible dangers such as 

 ships, or even spotting shore landmarks as aids 

 to navigation." In reply he points out that "In 

 the vertical posture the law of gravity takes 

 over, conveying food from the whale's mouth to 

 a capacious four-chambered stomach. Although 

 a gray whale can swallow when horizontal, the 

 vertical position allows it to clean entangled de- 

 bris from the filter and to wash food down to the 

 throat for quick ingestion." Walker further re- 

 ported ". . . that in the 'spy-hopping' position 

 their [gray whales'] range of vision is limited 

 and that they navigate mostly by echolocation, 

 . . . ." On the other hand, in the same report is 

 the following portion of a caption to a photo- 

 graph showing a breaching gray whale. "The 

 catapulting action, he [Dr. Walker] believes, 

 enables the animals to scan the waters around 

 them and make course corrections when inter- 

 fering noises prevent them from navigating by 

 echo-location." 



We ai-e not aware of any experimental evi- 

 dence that shows whether a gray whale "spy- 

 hops" to look around or to swallow food. Nor 

 is there any substantial evidence that migrating 

 or breeding gray whales feed very much. To 

 the contrary, there is hard evidence (summa- 

 rized by Gilmore, 1968) that gray whales fast 

 on their way to the breeding grounds, at the 

 grounds, and on the return triii north. 



Relative to the killer whale attack cited earlier, 

 Baldridge reported that the mother frequently 

 "spy-hopped" from a distance as the killer whale 

 chewed on her dead calf. 



In view of the above, the context of "spy- 

 hopping" exhibited by gray whales during our 

 experiments would seem to imply that this be- 



528 



