Eels are such a fascinating food to look at the history of, because they were so popular for so long, but now, you'd be hard pressed to find many takers for a bowl of Jellied eels. There was a New York times article published in 2017 that had a similar takeaway-- sure, people used to eat eels, but why would you really pick a bowl of eels over a meat pie at one of London's few remaining eel, pie, and mash shops? There's a novelty to eel eating now that really obscures the long and really global history of eel eating.

You reference the long history of eel eating, but to provide a bit more context for it, I've seen it suggested thet eel eating was introduced by the Roman empire. there's lots of documentation on the Roman eel obsession-- look to Juvenal's fifth satire, which explains the letdown of receiving a sickly stringy sewer eel over a lamprey, or Horace's 8th satire of book two, where a lamprey is the center of a feast. When the Romans conquered britain, they brought this love of eels with them-- and eels were consistently available, meaning they were a food source that translated well in this corner of the empire. I've seen it suggested that there is evidence of pre-Roman eel consumption in the Netherlands, but I'm not sure what this evidence is.

After the Roman occupation of Britain, we get some evidence for the continued popularity of eel consumption in Bede's Historia Ecclesiastica, which tells of Britain as a land with "the greatest plenty of eel and fish." IN another, more interesting anecdote, he tells us of a town wracked by famine. Bishop Wilfred " when he came into the province, and found so great misery from famine there, taught them to get their food by fishing; for their sea and rivers abounded in fish, but the people had no skill to take any of them, except eels alone. The bishop's men having gathered eel-nets everywhere, cast them into the sea, and by the blessing of God took three hundred fishes of divers sorts, which being divided into three parts, they gave a hundred to the poor, a hundred to those of whom they had the nets, and kept a hundred for their own use." In the absence of real meaningful fishing knowledge, eel eating and eel fishing was at popular in the 8th century, perhaps as a remnant of the diet the Romans had brought with them.

Eel consumption remained popular well into the victorian era, and it remained so popular that in 1412, London authorities implemented rules that set the price of eels at a fair rate per pound by the mayor, recognizing just how integral eels were to the life of the city. In the early 17th century, the British parliament implemented protectionists laws protecting british eeler interests and banning the importation of Dutch eels, though these rules were later overturned when the supply of eels in Britain was unable to keep up with demand.

I haven't found any evidence that eel eating was thought of particularly negatively. People liked eels-- they were easy to keep alive, easy to cook down and preserve without salt (into jellied eels) easy to cook in pies, and harder to substitute with low quality goods than beef, which could be replaced with vermin, cats, and dogs. One piece of eel related legislation declared eels "esteemed (as in truth they are) most Excellent Food (The Price being set by The Right Honorable the Lord Mayor of London) are bought and sold at very reasonable rates.’ They were readily available, but also could be cooked in manners befitting both the lower classes (in pies by vendors) and the higher classes (just as they had once been enjoyed by the Roman elite classes). Eel pie has a particularly storied history, with references to eel pie dating the 1400s and over 100 eel pie shops existing in London at the turn of the twentieth century.

Eels also had cultural capital which endured across place. For those who ventured to the United States, eels were a food enjoyed by both British colonizers and by native American populations. The two earliest "american" cookbooks contained recipes for eels, which were an importation from their place in the British diet.

The reason for their decline is pretty straightforward-- while eels were once ubiquitous in the Thames and easy to acquire, a combination of overfishing and pollution meant they were increasingly expensive and difficult to find. And once they lost their place of prominence, as other meat options became less expensive and more accessible, there was never any reason to bring eel back. There are still some eel pie shops around today, but you won't find eel pie (just stewed and jellied eels), because it's simply too expensive to make. Now, eel has a bad reputation that's difficult to overcome-- they're slimy, but they are pretty good-- some people describe them as similar to salmon, and they're oily, but some people can't get over the ick factor, especially of jellied eels. You won't find a lot of people mourning the loss of eel eating-- they weren't missed in diet because while they were popular, they were far from the primary protein option. But they-- and the affection for eels-- hasnt dissapeared completely. I'll leave with this 1973 excerpt from Jane Grigson's Fish Book

"I love eel. Sometimes I think it is my favourite fish. It is delicate, but rich; it falls neatly from the bone; grilled to golden brown and flecked with dark crustiness from a charcoal fire, it makes the best of all picnic food; stewed in red wine, cushioned with onions and mushrooms, bordered with triangles of fresh bread, it is the meal for cold nights in autumn; smoked and cut into elegant fillets, it starts a wedding feast or a Christmas Eve dinner with style and confidence."

I'll add my sources when I have a chance in a bit!