PRELIMINARY OBSERVATIONS ON THE EFFECT Of A. C. CURRENT ON CATLA CATLA AND OPHICEPHALUS PUNCTATUS

Abstract

In order to evolve suitable electrical fishing gear for Inland
waters, preliminary experiments have been conducted to observe
effect of A. C. currents on Cat/a cat/a at voltages of 30, 90 and 120,
pH 7.3 and 8.4, temperature 48°F, 78°F and 105°F, distance between
electrodes 25 em, 50 em and 75 em, size range of :fish 100 mm, to
235 mm. Apparatus used was a 5 K. W; A. C., 60 cycles generator
with resistance control. Larger sizes of fish were more prone to
electric shock. Higher temperature increase the intensity of the
shock, while variation of pH between 7.3 to 8.4 did not materially
affect the intensity of the shock. Fishing with a mixed population of
Cat/a calla and Ophicepha!us punctatus gave a greater percentage of
mortality for the latter.