312 ANNUAL REPORT SMITHSONIAN INSTITUTION, 194 7 



ply. They left their hiding places for more oxygen, thus exposing 

 themselves under a weakened condition and simplifying their capture. 



Shallow tidal pools that trap fish at low tide are simple to work, 

 but the use of rotenone in the ocean surf on the ocean reef of a coral 

 atoll requires special technique. 



Rotenone was used successfully along the lithothamnium ridge in 

 the ocean surf. The "mud" was administered a few minutes after the 

 low point of the tidal cycle. An area was selected where pools oc- 

 curred but which were not completely connected with the surge chan- 

 nels. These pools were desirable as settling basins for the sick and 

 dying fishes. The area between two or three surge channels, where 

 the waves flow inward across the ridge was the place where we placed 

 the rotenone mixture. Big handfuls of the thick mud were thrown 

 out as far as possible into the backwash of a wave. The next moment 

 the oncoming breaker churned the water into foam and carried the 

 water-laden cloud of rotenone inward, spreading it over the area and 

 into the numerous crevices; then it flowed out the surge channels. 

 Soon the rotenone cloud was distributed along the ocean edge of the 

 reef, and some was brought back again over the lithothamnium ridge. 

 The continual surging inward of the water brought in the sick fish. 

 Men were stationed along the surge channels to take fishes that were 

 being swept out to sea and perhaps lost. After the pools and channels 

 cleared, the bottoms were searched for fishes by the skin divers. 



The use of a face mask in skin diving and swimming enables one 

 to see clearly for 50 to 100 feet in the lagoon and ocean waters. Look- 

 ing down in the surge channels between the corals, one sees a gorgeous 

 display, a colorful marine garden of coral algae and fishes. Some of 

 the corals are fan-shaped, others resemble the antlers of deer. They 

 are blue, bright green, red, brown, yellow, and purple, contrasting 

 with the white foraminiferal sand of the bottom. 



The light from the tropical sun flickers down into these enchanted 

 caverns, filled with the blue sea. The trembling shafts of light illum- 

 inate the green, brown, and red algae, waving in the dim light. Fan- 

 tastically shaped fishes, as if from another world, dart about, reflect- 

 ing their weird color combinations of brilliant blues and sapphires, 

 greens, and yellows, red or scarlet, and with black and white markings 

 contrasting sharply. Some have big red spots, others sapphire-blue 

 bars and dazzling yellow and crimson stripes. 



Butterfly, damsel, surgeon fishes and wrasse lazily swim about in the 

 aquatic caverns and channels, but the moment a large predaceous fish 

 appears they seek protection, disappearing there, reappearing here, 

 among the coral growths. Some swim as easily sidewaj's and upside 

 down as in a vertical position. The view of this gorgeous marine 

 garden fades away into nothingness a hundred feet or more below. 



