Author Topic: European eels - anguilla anguilla  (Read 4569 times)

Wowbagger

  • Stout dipper
    • Stuff mostly about weather
European eels - anguilla anguilla
« on: 09 March, 2022, 11:25:18 pm »
Probably at least once a week I wander down to the park after the hours of darkness and take a torch with me to shine into the lake and the various pools. I almost invariably see lots of small roach, and occasionally, the large (up to 30lb or so) common carp that inhabit the lake. I also occasionally see eels. I did see some tench last summer, but nothing since. I haven't seen a pike for ages, nor have I ever seen the one example of the wels (European catfish) which anglers tell me is in the lake and probably weighs in excess of 50lb now.

Eels, or so we were told in our primary school days, use the gulf stream to travel between their breeding grounds in the Sargasso sea and Europe/Africa/wherever they happen to turn up. However, reading a little around the subject, it seems that no-one has ever witnessed eels breeding in the Sargasso sea, or anywhere else for that matter.

It has crossed my mind for quite a while that it's a very odd trait for a species: why restrict yourself to one specific area of the world to breed? Other migratory species - most of which fly quite fast, which the eel manifestly doesn't - breed at either end of their migratory journey, and that makes a lot of sense. Why would an eel, or even two eels - not take advantage of any odd nook or cranny for a bit of hanky-panky as long as all other conditions remained satisfactory?

I had a hunt around the internet for anything that anyone might have written about eels, and there are indeed a few academic papers. Most of these, sadly, are behind paywalls and my interest, at this stage, doesn't extend to paying good money for something obscure which may well not answer my question. It seems that the panmixia hypothesis is documented in a 1925 paper from one J. Schmidt, and a 1977 book "The Eel" by F. W. Tesch.

However, the paper that interested me, and seems to undermine the panmixia hypothesis, is from 2001 by Thierry Wirth and Louis Bernatchez. Their research suggests that, from the different testing locations that they used, that if there were a single breeding population, there would be no genetic differences between eels caught anywhere east of the Atlantic. However:

Quote
Analysis of seven microsatellite loci among 13 samples from the north Atlantic, the Baltic Sea and the Mediterranean Sea basins reveals that there is global genetic differentiation. Moreover, pairwise Cavalli-Sforza and Edwards' chord distances correlate significantly with coastal geographical distance. This pattern of genetic structure implies non-random mating and restricted gene flow among eels from different sampled locations, which therefore refute the hypothesis of panmixia. Consequently, the reproductive biology of European eel must be reconsidered.

Which is jolly interesting.

Does anyone else ever meet any eels on their perambulations?

PS Tesch's book can be had from Amazon, a snip at £207 for a new one.
Quote from: Dez
It doesn’t matter where you start. Just start.

Re: European eels - anguilla anguilla
« Reply #1 on: 10 March, 2022, 10:00:09 am »
Intriguing - I have had an interest in eels from an early age, not caused by that scene in the Tin Drum but rather as a result of growing up near the Severn and witnessing the harvesting of elvers, and then fishing for adult eels. I even delivered a short lecture on the life cycle of the European Eel in about 1999 which I have on VHS somewhere (and which is probably very wrong). 

I did hear about doubts being cast on the Sargasso Sea theory quite recently but didn’t get round to exploring the subject.  Thank you for raising this important issue and providing me with more things to distract me from work!

Re: European eels - anguilla anguilla
« Reply #2 on: 10 March, 2022, 11:31:37 am »
A character in Graham Swift's Waterland:

Quote
Now there is much the eel can tell us about curiosity—rather more indeed than curiosity can inform us of the eel.

Cudzoziemiec

  • Ride adventurously and stop for a brew.
Re: European eels - anguilla anguilla
« Reply #3 on: 10 March, 2022, 08:50:46 pm »
Apparently the island of Anguilla is named for its eel-like shape, not because the creatures are found there.
Riding a concrete path through the nebulous and chaotic future.

Salvatore

  • Джон Спунър
    • Pics
Re: European eels - anguilla anguilla
« Reply #4 on: 10 March, 2022, 09:44:47 pm »
Follow Surprised Eel Historian, PhD on twitter for all sorts of interesting eel facts.
Quote
et avec John, excellent lecteur de road-book, on s'en est sortis sans erreur

Re: European eels - anguilla anguilla
« Reply #5 on: 11 March, 2022, 03:28:38 am »
Grilled eel is also extremely tasty.

rogerzilla

  • When n+1 gets out of hand
Re: European eels - anguilla anguilla
« Reply #6 on: 11 March, 2022, 08:02:56 am »
They can cross land in wet weather (wriggling like snakes for up to 400m) which is how they get into lakes where they were never deliberately introduced.  Supposedly even the model boating pond in Newbury had them.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

T42

  • Apprentice geezer
Re: European eels - anguilla anguilla
« Reply #7 on: 11 March, 2022, 09:41:58 am »
I saw a wels the other week, in a casserole at our favourite Thai restaurant.  Very agreeable fish.
I've dusted off all those old bottles and set them up straight

Wowbagger

  • Stout dipper
    • Stuff mostly about weather
Re: European eels - anguilla anguilla
« Reply #8 on: 11 March, 2022, 10:18:27 am »
I saw a wels the other week, in a casserole at our favourite Thai restaurant.  Very agreeable fish.

I suppose it was most welscoming?
Quote from: Dez
It doesn’t matter where you start. Just start.

Wowbagger

  • Stout dipper
    • Stuff mostly about weather
Re: European eels - anguilla anguilla
« Reply #9 on: 23 August, 2023, 02:31:59 pm »
https://www.theguardian.com/environment/2023/aug/23/no-evidence-eel-dna-somerset-levels-analysis-water-shows

The Somerset Levels are not full of eels.

Last summer, during the drought, there were plenty of eels in the park lakes of Southend, even though quite a few of them died through lack of water or pollution. I haven't looked for any this summer. The best bet is usually to go to the park in darkness and shine a strong torch into the water.
Quote from: Dez
It doesn’t matter where you start. Just start.

Re: European eels - anguilla anguilla
« Reply #10 on: 23 August, 2023, 04:38:51 pm »


The Somerset Levels are not full of eels.



But my hovercraft is
They laughed when I said I was going to be a stand-up comedian. They're not laughing now.

Regulator

  • That's Councillor Regulator to you...
Re: European eels - anguilla anguilla
« Reply #11 on: 23 August, 2023, 05:03:37 pm »
They can cross land in wet weather (wriggling like snakes for up to 400m) which is how they get into lakes where they were never deliberately introduced.  Supposedly even the model boating pond in Newbury had them.

I can remember them crossing the lawn from the river at the bottom of the garden to the pond... (this was in NZ where we had lots of eels in the local rivers.  We used to catch them quite regularly.  Lovely on the barbie or in a hāngī).
Quote from: clarion
I completely agree with Reg.

Green Party Councillor

Wowbagger

  • Stout dipper
    • Stuff mostly about weather
Re: European eels - anguilla anguilla
« Reply #12 on: 23 August, 2023, 05:16:08 pm »


The Somerset Levels are not full of eels.



But my hovercraft is

I must admit, I expected Mr. Larrington to be the first to bite... ;)
Quote from: Dez
It doesn’t matter where you start. Just start.