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PACIFIC SCIENCE, Vol. XVII, April 1963 
more realistically than the "time index.” Special 
techniques used in studying the response of the 
sharks to living fish will be discussed later. 
Haivaii Marine Laboratory 
At the Hawaii laboratory several grey sharks 
of two species {Car char hinus spp. ) , hammer- 
head sharks {Sphyrna lewini ) , and tiger sharks 
{Galeocerdo cuvier ), all 5 to 7 ft in length, 
were readily caught by set line in the adjacent 
waters of Kaneohe Bay. They were established 
in large seminatural ponds (Fig. 3), screened 
by gates and flushed slowly by tidal action. Three 
grey sharks and one tiger shark were success- 
fully maintained in captivity for 3 years and 
were still alive and healthy at the time of writ- 
ing (October 1961). Hammerheads were suc- 
cessfully maintained in captivity for periods 
from 3 months to 1 year. It is suspected that 
their death was due either to injury caused by 
the other sharks or lack of food. They were un- 
able to compete successfully with the fast, ag- 
gressive grey sharks; often our efforts at pre- 
ferential hand-feeding failed when the food was 
taken persistently by the other species. The 
sharks were fed sparingly about once or twice a 
week on cut or whole fish. 
Several experiments were undertaken on a 
tiger shark and a grey shark following their re- 
spective establishment in Ponds 2 and 3, both 
of which were about 100 ft long, 60 ft wide 
and 3-4 ft in maximum depth. Observations 
were conducted from a 16-ft tower between the 
ponds. By means of a pump and hose a continu- 
ous flow of water was taken from one pond, 
led to the top of the tower, and thence led into 
a test area of the other pond. Following a series 
of 3 -min control periods, during which quanti- 
tative data were collected on the activity of the 
shark, notes were made of overt responses and 
the path of the shark was diagrammed. The ma- 
terial to be tested was then introduced into the 
stream of salt water after dilution in a suction 
funnel on top of the tower, and the observations 
were repeated during a series of 3 -min test 
periods. 
During the winter of 1959-60 both the grey 
and the tiger shark were transferred to Pond 5 
(Fig. 4), a much larger enclosure about 360 ft 
long and 66 ft wide. Other grey and hammer- 
head sharks were added to this pond; eventually 
