152 
PACIFIC SCIENCE, VoL XVII, April 1963 
TABLE 1 
Response of Sharks to Extracts of Natural Food at Hawaii Marine Laboratory (hml) 
and Eniwetok Marine Laboratory (embl) 
SHARKS, LABORATORY, AND 
RESPONSE* 
YEAR 
MATERIAL 
RR 
R-R? 
O-S 
A-A? 
AA 
Total 
1959 
Tiger, HML 
Fresh tuna extract 
3 
2 
2 
7 
Aged shark extract 
- 
1 
1 
2 
1959 
Blacktips, EMBL 
Various extracts 
! 5 
21 
32 
32 
90 
Aged shark extract 
- 
- 
7 
8 
3 
18 
1960 
Blacktips and greys, EMBL 
Fresh extracts 
12 
18 
30 
Aged eel extract 
- 
4 
8 
6 
2 
20 
Aged shark extract 
- 
- 
- 
1 
1 
2 
Total 
- 
9 
39 
62 
59 
169 
* RR, strong repulsion; R-R?, weak or doubtful repulsion; O-S, no apparent response or sensing; A-A?, weak or doubtful 
attraction; AA, strong attraction. 
sponses, some of which were classed as doubtful 
repulsion. The notes indicated that the material 
smelt foul. Similar results were obtained with 
the same material on July 18. The sharks were 
tested with freshly prepared standard eel ex- 
tract on July 20 and both species showed a 
strong attraction response. 
In direct contrast to the above results are those 
with extracts of decayed shark flesh, which after 
a week in the hot sun smelt particularly foul. 
Our material consisted of extract of decayed 
hammerhead and of decayed tiger shark tested 
on the tiger shark at the Hawaii Laboratory (two 
tests) and of extracts of decayed blacktip shark 
flesh and skin tested on blacktip sharks at Eni- 
wetok ( five tests ) . In addition, we tested black- 
tips at Eniwetok on an alleged shark repellent, 
supplied by a fisherman, which contained ex- 
tract of decayed shark flesh as the principle 
component ( six tests ) . We also tested fractions 
of extract of decomposed shark flesh which were 
supplied by Dr. M. A. Steinberg, Bureau of 
Commercial Fisheries Technological Laboratory, 
Gloucester, Mass. (11 tests ) . No repellent ef- 
fects were noted in any of the tests. On the con- 
trary, the majority yielded responses which were 
classed as either weak or strong attraction. Our 
results with the fractions of extract were in 
agreement with those reported by Steinberg 
(I960) when his material was later tested on 
the lemon shark ( Negaprion hrevirostris) , the 
reef shark ( Carcharhinus falciformis ) , and the 
bull shark ( Carcharhinus leucas ) at the Lerner 
Marine Laboratory, Bimini, Bahamas, B. W. I. 
Our results with extracts of decomposed shark 
flesh seem to be at variance with those of 
Springer (1955), who found that the feeding 
of the dogshark ( Mustelus canis ) was consist- 
ently inhibited by the presence of decayed shark 
flesh. Although several hypotheses might be 
formulated to account for the difference in re- 
sults, no convincing explanation can be made 
at the present time, particularly in view of the 
apparent repulsion noted with decomposed eel 
and other extracts noted in preceding para- 
graphs. 
BEHAVIOR OF STARVED SHARKS 
In considering shark predation, the questions 
arise as to how long a shark can exist without 
food and whether its olfactory response is modi- 
fied by starvation. Some information on these 
points was obtained for small sharks at the Eni- 
wetok laboratory. 
In 1959, following the summer’s work, AEC 
personnel at Eniwetok volunteered to keep track 
of the fate of four small blacktips under starva- 
tion conditions. Three of the sharks died after 
about 2 months in captivity. One survived for 
3 months but it was not known to what extent 
it had maintained itself by feeding on the sharks 
which had died. 
