Chinese Reeves Turtle Behavior

Question
Good Morning Jeannie,

I recently took over caring for my mother's Chinese Reeves Turtle as she is in the process of moving and it may take a few months. Gamera(turtle) is estimated to be at least 35 years old and has lived her whole life in capitivity. My parents got her at least that long ago. She is in a 40 gallon long tank. She has day/night heat lamps with UVA and a long UVB bulb. 1/3 of the tank is floating dock where she can fully exit the water. The substrate is medium-large river rocks. She has a heater and the water is ~78. The basking area is 90. She has an Eheim canister filter. These are all much better circumstances than she had previously(usually a weak filter, smaller tank, smaller basking area and no substrate).
My question:
Every once in a while(over the last few months) She seems to get very anxious and swims furiously around and tries to scale the tank. She also digs little "nests" in the river rocks. She has some skin shedding, but I can't tell if it is excessive. She also doesn't eat(but typically eats a lot). Based on the internet research I've done, I would guess she is gravid. However, my mother says she hasn't laid eggs in years.
Do turtles lay eggs their whole lives or do they stop with age? I would guess if she went through years of failed egg laying that her health would be very poor by now. Since she has never had this much room or circumstances, is this just behavior she hasn't had the chance to display? I want to make sure she is healthy. Mostly, I'm worried about her being stuck with the eggs in her.Otherwise she just looks anxious.
(I hope this was enough/not too much information)

Answer
Hi William,

Those symptoms could indicate she's gravid; restlessness is a very telltale sign.  They also get a kind of faraway look to them, but it's one of those things where you know it when you see it, but it's hard to explain.  When she's digging, is it with her hind legs at all, or do you see her making kicking/paddling motions with her hind legs?  Any apparent hind end weakness?  Is she eating well outside of these episodes?  Although she may not have laid any eggs in recent years, that doesn't mean she isn't gravid now.

You could try making a nesting box to see if she'll lay.  It can be a plastic bin or anything similar, filled with moist soil (it should hold its shape if you clench it in your fist) at least as deep as she is long.  Put her in it with a lamp over it (doesn't need to be too hot, but enough to warm her a bit) and see if she digs with her hind legs.  Some turtles will just lay in water if they don't have access to a nesting site, but others will retain the eggs and you don't want that.  

I don't know the upper end of egg laying as far as age goes.  I've known some pretty mature females to lay eggs, but can't think of any that were really ancient.  However, as long as they're healthy I'd guess that they could lay into relatively old age.  I'd suggest putting a cuttlebone in her tank to make sure she has access to extra calcium, just in case.  If you continue to be concerned, and the nesting box doesn't get any results, the definitive way to determine if she's gravid is to have her x-rayed.