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This study contributes to the development of harvesting procedures for Nile tilapia under
pond culture system. A total of 13 LED light traps (blue, green, yellow, orange, red, white
and control) were used to examine phototactic response of Nile tilapia in the pond
experiment. The traps were made of polyamide (PA) nylon monofilament (31.75 mm mesh
size), fastened around two wire ring frames (490 mm) with a net height of 270 mm. A lamp
was placed on the bottom of the trap. There were no significant differences in the CPUE
(catch per unit effort) and YPUE (yield per unit effort) among light traps and control. The
CPUEs for continuous, blinking light traps and the control ranged from 0.21 to 1.07, 0.14 to
0.79, and 0.57 fish trap-1 night-1, respectively. While the YPUEs for continuous, blinking light
traps, and the control varied from 2.43 to 43.36, 1.00 to 27.21, and 10.50 g trap-1 trial-1
respectively. 105 individuals (2,376 g) consisting of 59 males (641 g) and 46 females (1,735 g)
were analysed. The body size of catch ranged from 43-193 mm (97.14±34.61 mm) total length
and 1-133 g (22.98±27.87 g) weight. Nile tilapia grew isometrically and fish are in good
condition (K = 1.79). Positive group responses of fish were more pronounced in the middle
size classes between 90 and 99 mm total length. Nile tilapia responded positively to all
colors of light tested. In addition, efforts to sample Nile tilapia from the wild sources may
benefit from this study. |
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