Using epoxy to affix transmitters to the carapace is an effective method. You might find this paper on low-cost construction of GPS loggers to complement traditional (VHF) radio-telemetry useful: Article An Open-Source Hardware GPS Data Logger for Wildlife Radio-T...

thank you@Sasha_Tetzlaff

Agree with Sasha. Epoxy works well for affixing transmitters. I used a 5-minute epoxy to affix Holohil RI-2B transmitters to spotted turtles. It withstood extreme weather conditions, underwater movements, and general wear/tear for about 6-8 months. I recommend patching/replacing the epoxy every 4-5 months depending on the species.

We used epoxy (TUNZE® Coral Gum 104.74/104.75) to fasten GPS/GSM transmitters (Ecotone® Saker T) T. scripta, here in EU an invasive species. After we released individuals to track their migrations. Unfortunately, approx. half of transmissions stopped probably because sliders lost their devices (or failure of solar batteries).

I think that O'Bryan is right, but sometimes is difficult to recapture the animal depending on which body of water it is located.

Dear Vishal,

depending on your aim you can use different tracking systems. If you need fine scale monitoring you can use microGPS together with VHF transmitter. It would give you better idea about the daily movements and home range tortoise. As suggested by other colleagues epoxy is good option for attaching. We used it and found one of our tortoises after there years letter we lost it with microGPs still on the tortoise.

Know a project in Western Australia wetlands had a challenge with moving around the boggy ground, Dr Debbie Saunders drone solution solved the problem