In our country (and probably in the whole world) the turtle kept most often is the red-eared slider. Their vitality depends both on correct living and feeding conditions. A matured turtle is cold-hardy and in a suitable garden pool can spend the winter outdoors here, the same as semiaquatic european pond turtle.
Marine turtles are about to become extinct. I have read an interesting article in National Geographics 1994/Feb. A long article is written about the fight of turtles and their fans - to survive. There are nice pictures, facts and interesting news.
The article described how some organizations buying out beaches and coasts, building fences and letting turtles lay eggs there - and turtles enjoy it, because their habit is to nest in the same place for the whole life.
Questionable turtle farms are also mentioned - turtles are bred, some are freed into sea, the rest are eaten. Some people say it's positive in spite of decrease of hunting for wild living turtles (because the demand is saturated), some say in opposite that this allow to loosefishes eat endangered creatures without penalty and support them in their lusts.
I like the Turtle excluder device which U.S. fishers are obliged to have (still). It allows the turtle to escape from a net. Before this became required, drowning in the net was the most common cause of death of marine turtles. I found snapshots from a video, showing how this device works at TURTLE TRAX site at http://www.turtles.org/glossary.htm#teds, in their turtle dictionary.
Anyway, as I know, the federal law in May 1st 1997 became effective. This law doesn't allow to buy shrimps from
countries where fishers must not have TED.