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Fishery Bulletin 90(3). 1992 



behavioral focal samples. A significant decrease in 

 the ratio of surface interval to dive time followed 

 the biopsy procedure. Although not statistically sig- 

 nificant, increases in trumpet blows and, to a lesser 

 extent tail slashes and sounding dives, were noted 

 following biopsy strikes, as were decreases in the 

 amount of slow swimming and some nonessential 

 behaviors. 



Two of the behavior types that were noted to in- 

 crease, trumpet blows and tail slashes, have been 

 previously suggested to be agonistic (Baker and Her- 

 man 1984, Watkins and Wartzok 1985). A tail slash 

 may be used by a humpback whale as a means of 

 aggression against another whale in what has been 

 interpreted as courtship battles (Baker and Herman 

 1984). Norris and Reeves (1977) identify "tail 

 swishing" (our "tail slashing") as one of the more com- 

 mon behavioral responses to harassment. 



The behaviors elicited by the biopsy procedure in 

 most cases are not intrinsically different from those 

 behaviors which occur naturally in this species. Thus 

 we emphasize that it may be the change in frequency 

 of behaviors that should be viewed as indicative of 

 "affected" behavior, rather than the occurrence of such 

 displays per se. The one notable exception is the hard 

 tail flick, which rarely has been observed other than 

 in response to the biopsy procedure. 



The possibility exists that the hard tail flick reaction 

 we observed is a reflex response. This reaction typically 

 occurred at the instant of dart impact and thereafter 

 was rarely repeated. Moreover, in some individuals a 

 single hard tail flick at the time of the biopsy was 

 followed by a period during which no other behavioral 

 change was observed. A reflex response is consistent 

 with our finding of no correlation of respiratory varia- 

 tion with the occurrence of this reaction. 



While some of the hard tail flicks may have been 

 purely reflexive, the same behavior was seen once in 

 response to an extremely close vessel approach when 

 no physical contact was made. Further, a similar reac- 

 tion was reported by Watkins (1981), who labeled it a 

 "startle response." Hence it is uncertain whether this 

 behavior is reflexive or cognitive. It may have both 

 components. 



In other studies of whale disturbance in response to 

 noxious stimuli, both Watkins (1981) and Mathews 

 (1986) mention the approach of the vessel as con- 

 tributing to the reaction of the animal. We made every 

 effort to diminish vessel effects. Both previous studies 

 were conducted from power-driven vessels approaching 

 at moderate to rapid speeds. In over half of our paired 

 samples, data were collected from the relatively silent 

 approach of a sailboat. Those approaches made under 

 power in paired samples were done at slow speed. Fur- 

 ther, we limited movement of the research vessels near 

 whales, except in the brief approach for the biopsy, to 

 lessen effects of vessels. While the effect of the vessels 

 was minimized, this approach is a necessary part of the 

 biopsy procedure and need not be considered separately 

 in an analysis of responses. 



Our results are comparable with those found by 

 Mathews (1986), who examined the response of eight 

 gray whales to a similar biopsy procedure. Both studies 

 established great variability in the reaction of whales 

 to biopsy procedures. One clear difference is that the 

 blow interval of gray whales showed a significant in- 

 crease in the postbiopsy period, while that of the hump- 

 back whales we studied did not. Even so, four of the 

 eight gray whales studied by Mathews (1986) showed 

 a reduction in their surface-interval/dive-time ratios, 

 as did 57.0% of the larger sample; only one gray 

 whale showed an increased surface-interval/dive-time 

 ratio. 



