Jim, there are new byelaws to be introduced very shortly that will state that no eels can be taken for the table through anglers catch. The 'eelers' licences in fresh water (plus the Golden Mile) will be reduced and then Defra will have to push for a cessation on the eel catch within the EU's fishing fleets.
In General:
Do not buy eels to eat! You will have to live without them, in short. Catch & Release until such a time that their numbers are healthy again (if ever?), as this will be within the new byelaws anyway.
Eels are diminishing through a number of reasons;
Over fishing by commercial operators in the worlds oceans, notably surrounding the Sargasso Sea (their only proven breeding area) that is throttled by commercial expoitation. also by Euro operations netting elvers and mature silver eels enroute to the Sargasso Sea... near the Bermuda Triangle!
The resorces available in Britain and the EU, for the european eel to migrate from freshwater sites (Eels will only return to the sea when they are heading off to breed as mature adult fish, they never return, as they die once having bred), with such deminished populations - like eel ladders in rivers etc. aren't enough to assist the few remaing eels to successfully reach their breeding grounds.
European eels (Anguilla anguilla), are also affected by a nematode parasite (Anguillicola crassus, click the following link:
http://en.wikipedia.org/wiki/Anguillicola_crassus) that effects the swim bladder.
There are possibly many other issues surrounding the decline and no doubt others will contribute as this debate develops. I will also post some more info on the eel and hopefully others (experts in the field!), will do likewise.
Richard