Electromagnetic Fields in the Ocean and Electroreceptive Fish
Research rept. Jul 1975-Jul 1976
NAVAL UNDERSEA CENTER SAN DIEGO CA
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This report considers the possibility of the detection of dipole fields by electrosensing fish. In particular, a skateRaja clavata which is sensitive to threshold electric fields of 1 microvoltmeter has been examined. The results indicate that skates detect electric dipole fields at short distances approximately 100 m at f0, 1, or 10 Hz and for dipole source current moments on the order of 60 A-m. A comparison between the electric dipole sensing capabilities of skates and artificial systems is also made. In general, it appears that the optimum single-element manmade sensing system is superior to the skate for purposes of long-range detection of narrowband, extremely low-frequency signals.