I once attended a seminar and one of the speakers was an expert in ocean currents/sea temperatures...the main man.
He likened the gulf stream to the m25 where only 5% of the cars on it are heading to Scotland..same with the gulf current. He said only a very small percentage of the gulf stream actually hits our western shores.

He went on to explain that we also have what is known as the continental slope current which occurs as deep water to the North draws water up from the Bay of Biscay. This apparently is prominent. The discovery of eel leptocephali at various stages found in the Atlantic first occurred over a hundred years ago, a line was simply drawn at all these points making the estimated spawning grounds the Sargasso. I asked him therefore where he thought our eels spawn....he replied Bay of Biscay. He went to say he has a bet on with the leading scientist of the eeliad project that this is where eels spawn....food for thought. Should also add that the American eel also spawns in the same area of the sargasso and these are found in iceland...if euro eels spawn in the same are perhaps there is also hybridisation.

It is thought that eels are panmictic in their spawning habits, ie one mass random spawning rather than pairing off as in say salmon. This makes genetic analysis difficult, and it is doubtful that they " home" again like salmon. One thing that i feel needs further research is linked to this...head shape. It is thought that there two types of head shape found in eels broadheads - predatory and narrowheads - invertebrate feeders with a possible intermediate shape too. Now, does the head shape change when they reach there host water, dictated by the prey available???? or is it predetermined and therefore genetic. If its the latter then some form of choice when mating must occurr and therefore panmixia doesnt occurr. If its the former then its evolutionary but as you know these things take a long time so making the eel unique. Back to the genetic theory....do eels from certain waters ie where prey fish are abundant ( making them broadheads) therefore mate with fish from the same area??? So many questions and very few answers.

Ocean currents and eel genetics: my God, it all takes me back 30 years plus to when I was actually studying both oceanography and genetics within a degree course. Much of it of course now either forgotten, or completely overtaken by more recent scientific knowledge.
I think I am going to ignore hybridisation for the moment at least. Don't want to throw yet another ingredient into the pot.
The American eel choice of similar spawning areas is interesting. If the eel larvae are merely carried by the oceanic currents, rather than actively swimming, it seems surprising that Europe appears to have no American eels, and vice versa.
For, at this stage they are so damn small that one cannot really imagine them to have much more mobility than does plankton.
As for spawning grounds, as previously, some Anguilla anguilla MUST spawn in the Sargasso area. However your gambling scientist could also be right. Do we have any reason at all to suppose that all adult eels spawn in just the one place? If indeed the Bay of Biscay is another spawning ground, have any eel fry been captured along that route?
It is a subject that is so much debated by anglers, the general public and fishery scientists that I am astonished that more research has not been put into the matter. There is a PhD at least for someone there.

The broad/narrow heads debate has also been around a hell of a long time. If I had to guess, then I would go for a non genetic cause here. I can't remember too much about the difference after all this time: Are there two quite distinct ranges of head widths, or is there a "wide" overlap, a continuous range?
Has it actually been established that wide individuals show any marked food preferences? The narrow snout eels might of course have rather less choice in the matter. Put simply, if there is a range of snout widths resulting from normal genetic variability, then wide mouthed fish would simply be more successful in taking large food items. There is a difference between preferring a large food item and the ability to actually be able get it in the mouth. But then, once you find that you do like ice cream, and that you can yawn widely enough to ingest the whole cornet, you may well want more of the same.
This discussion continues to be of great interest, but apologies to those of you in here who are very barbel centric.

PS Love the name "Eeliad Project".

Yes must apologise for going off on a tangent. I agree with what you say JayZ there are more questions than answers concerning the species. More research needed.