No abstract

The drastic changes in hydroelectric reservoir development created a completely new ecosystem that affects the river, particularly in the inundated area. In this study, five Neolissochilus soroides and Channa lucius were surgically implanted with a unique coded acoustic transmitter to observe the habitat utilisation and movement activity in Tembat Reservoir after the inundation process. All of the individuals were released into the transition zone of the reservoir and observed using passive and active acoustic tracking devices from April to December 2018. Kruskal-Walis test showed no significant difference between the average size of core area for N. soroides and C. lucius, x2(1) = 1.320, p = 0.251. The home range also showed a similar result for N. soroides and C. lucius where there was an insignificant difference, x2(1) = 0.273, p = 0.602. However, duration wise, N. soroides spend more time in the transition zone, R1 (M = 2.71 hrs, SE = 0.38), and C. lucius in the riverine zone, R5 (M = 7.14 hrs, SE = 6.13) and R6 (M = 3.85 hours, SE = 6.36). From the active tracking survey, PCA identified three (62.32%) and four (71.19%) components with eigenvalues greater than 1 for N. soroides and C. lucius, respectively. Three most important habitat parameters for N. soroides were the size of river (r = 0.97), existence of canopy cover (r = 0.77), and substrate type (r = 0.79).While, for C. lucius were mesohabitat type (r = 0.79), distance to riffle (r = 0.97), existence of canopy cover (r = 0.90), and elevation (r = 0.90). A 24-hour movement frequency analysis for both species revealed two active hours of movement at dusk and dawn for both species. From the study, it is known that N. soroides and C. lucius respond differently towards the inundation of the reservoir. The findings in this study can be implemented for effective aquatic management and conservation plan to ensure sustainable dam development.

Telemetry is an emerging method to study fish ecology and a reliable tool that provides useful information for managing and conserving aquatic fauna and river habitats. However, the reliability of telemetry depends on several technical factors. Implantation of the acoustic transmitter is one of the major aspects that ensure the survivability of the animal subject when released into the wild. Studies on the technicalities involving telemetry methods are limited; therefore, this study investigated the surgical insertion of an acoustic transmitter into the peritoneal cavity of Channa lucius and Neolissochilus soroides or locally known as Bujuk and Tengas. A severity index was used to rate the appearance of surgical wounds observed on the day of release into the river. Fish mortality and complications such as bleeding were not observed in both species post-surgery. The progress and prognosis of wound healing of C. lucius were better compared to N. soroides, with generally lesser inflammation and more sutures shed. Despite visually severe inflammation on N. soroides on day-12 and day-19 post-surgery, there was a good indication that skin integuments were healing. This data suggests that C. lucius has faster wound healing abilities compared to N. soroides. All fishes implanted with the acoustic telemetry method survived up to 244 days upon release into the Tembat River, Hulu Terengganu, Malaysia, and retained the tag throughout the tracking period.