(ESTIMATED PUB DATE) INVESTIGATION OF ELECTRIC FISHES -- FINAL REPORT - PHASES 1 AND 2

• Document Type: SPECIALCOLLECTION
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): 00173971
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 110
• Document Creation Date: January 21, 2025
• Document Release Date: January 15, 1983
• Publication Date: August 1, 1974

. INVESTIGATION OF ELECTRIC FISHES
FINAL REPORT - PHASES 1 AND 2
by
Prepared under
Contract
August 1974
SUMMARY
Electric fishes have one or more transmitting electric organs and an
array of electroreceptors. The system is controlled by special nuclei lo-
cated in the brain. The elements of the electric transmitting organs, called
electroplates, are described; and the electromotive force (EMF) generated
by each electroplate and of the entire organ is discussed. The waveform of
the signals was studied and the structure of the electric organs investigated.
The biochemistry of the chemotransmitter and the metabolism of the electro-
genic tissue is discussed. The physiology of the electric transmitting organs
was studied, and their common properties described. Analogy has been made
between the electrogenic properties of muscular tissue and the electric organs
of fishes. The transversal and lateral resistance of the electric tissue of
the electric eel and torpedo is mentioned.
Electroreceptors are special sensors of the lateral line system. Some
fishes possess electroreceptors and no electric transmitting organ. The dif-
ferent kind of electroreceptors are mentioned. The physiology of some of
the electroreceptors of Sternarchus albifrons, a South-American fresh water
weakly electric fish were investigated. The electroreceptors of the mormyrid
Gnathonemus petersii were mapped and counted.
Tonic and phasic electroreceptors were studied. The nervous control
and function of the electroreceptors is discussed and the functional character-
istics of six different kinds of lateral line organs have been considered.
The location of objects by the electroreceptor system of elettric fish
is discussed and communication between electric fishes mentioned.
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The electric field pattern around the electric fish Sternarchus albifrons
has been plotted and compared with the theoretical pattern of a dipole. The
perturbing effects of various confinement cages on the electromagnetic field
pattern were determined. Distortions of the wave form with distance were
recorded.
The maximum detection range of the electric fishes Gnathonemus sp.
and Gymnotus carapo to stainless steel, iron, brass and nylon is presented.
At the critical separation between the fish and sample, (assumed to be the
threshold detection distance) the fish increased the rate of its signals or
ceased transmission entirely. The effects of sample material, sizes, form
and azimuth on the threshold detection distance are presented. Behavioral
experiments have been formed using Gymnarchus niloticus to determine the
threshold of detection distances. These experiments were also performed in
the fiberglass tank with and without an aluminum foil liner. Photos and movie
films were made to record the fishes behavior.
Gnathonemus sp. is a fresh water, low rate, high frequency pulse
weak electric African mormyrid fish. Gymnotus carapo is a fresh water,
medium rate, medium frequency pulse, weak electric South-American
gymnotid fish. Despite their physiological and electric differences, both
these fishes stopped transmitting electric signals if the object was of high
conductance and was brought close to the fish (