eeliad blog

I haven’t updated the site in a while- things have been super-busy with fieldwork and following up.  This year’s tagging has been a great success in Ireland, Sweden and Spain (thanks to all involved).  There were many highlights, from perching in the middle of the Corrib river being interviewed for the Discovery Channel, meeting Japanese eel expert Katsumi Tsukamoto to talk about our respective work programmes, the quality of the facilities in every location.  Most of all though, meeting up to work again with friends and colleagues- it never gets tiring.

The eel quality sampling programme has also been underway and is almost complete.  This has been a fantastic team effort across Europe, and although the results will take a little while to emerge, the scale and quality of the sampling work is a great achievement and a testament to the commitment of all involved.

Meanwhile, in labs in Denmark, Sweden and France, we’re inching closer to understanding population structure through the analysis of genetic and otolith signatures of glass and adult eels.  These techniques are complicated at the best of times, but the eel life-cycle makes it more challenging than most species. 

Well, if you want to find out about what eels do all day, click this link: http://www.sciencemag.org/cgi/content/abstract/325/5948/1660

I hope you enjoy it.  Remember, you can get in touch with eeliad@cefas.co.uk for more information.

We heard today that our paper on eel behaviour in the ocean will be published in Science very soon.  It’s been a long journey from first looking at the data to it actually getting published, but then again, our findings are something that scientists have been trying to find out for decades.  We shouldn’t have thought it would be easy!

As soon as it’s published, I’ll link it here.  

We’re now finalising our plans for eel sampling for this coming autumn.  It’s going to be quite an effort, with institutes in at least seven countries going out and collecting silver eels in sufficient quantities that we can assess their vital statistics: length, weight, sex, fat content, pollutant load, diseases carried, how ’silver’ they are etc.  All of these factors will affect how likely they are to achieve a successful migration to the Sargasso.

Of course, it is not quality of the eels alone that will determine their migratory success.   There are lots of other things that might get in their way: barriers to migration, such as dams or hydropower stations, predation, by marine mammals, birds, or sharks, or maybe failure to find the way.  The relative importance of these problems is something that we will aim to quantify, as well as the quality of individual eels themselves.

It’s tough being an eel.

At the moment, the eeliad team is meeting to discuss the progress we’ve made in the project so far.  We’re one year into our four year mission to uncover some of the fundamental mysteries that surround eel biology.

The last 12 months seem to have gone really quickly, but we’ve also done a lot.  Maybe those facts are related!  Our first publications in science journals will be published soon, and we are almost ready to start telling the world a bit more about what we’ve found out and why it is significant.

It is certainly an exciting time in the project, and it’s really inspiring to think about what we hope to achieve over the next few years. 

It’s been a few months since we released eels with tags attached or implanted.  According to perceived wisdom, they should be arriving at the Sargasso Sea and spawning right about now.  So are they?

So far, we’ve heard from a significant proportion of the pop-off tags we deployed, and only a couple of the implanted tags.  These are the tags from eels that didn’t make it all the way to the Sargasso and from eels that only made a short journey before the tags were released. 

We’re still waiting for a lot of data to be returned.  It is frustrating because we want to know what is happening, but these kinds of studies take a long time to come to fruition.  Often, the most important data are the data that are returned at the very end of the data collection period.  We won’t be able to assess the success of our tagging, at least in a preliminary way, until the start of the 2009 tagging season in October.  Keep checking back for updates!

Some of you may have seen the article published in the Times on Saturday (http://www.timesonline.co.uk/tol/news/environment/article6163961.ece).  It’s well worth a read and I’d like to thank Frank Pope, the author of the article, for his interest in the project and the eel story, and his obvious enthusiasm in discussing the finer points of eel ecology.

The starting point of the story was obviously the recovery of one of our archival drift tags- the details of which I’ll save for another post- which confirms how useful this kind of method will be, but also revealed just how hazardous the eels’ journey to the Sargasso Sea is. It’s not easy being an eel!

We recently held a meeting to review the information we’ve received from satellite tagged eels.  It’s very exciting to get data back from eels that we last saw many months ago.  We get all sorts of information from the satellite tags- direction of migration, migration speed, the depths and temperatures chosen by the eels as they swim through the ocean and, by comparing the information we have on tings like eel lenght or fat content, whether some types of eels are more successful at swimming towards their spawning grounds.

It’s still early days yet, and there are ups and downs yet to come, but we’ve already tracked eels farther than they’ve ever been tracked before and discovered a few more secrets about eel behaviour.  The coming weeks and months will provide even more data, and uncover a few more mysteries I am sure!

I spent today at the World Conservation Monitoring Centre (http://www.unep-wcmc.org/) in Cambridge.  The WCMC does what it says in the name- and the variety and scope of their work is very impressive.  Especially exciting is the way that they are developing new mapping techniques that can display and communicate complex data in simple ways. 

It was a very thought provoking meeting, so much so that I was too busy thinking about future opportunities to take the right turning off the motorway on the way home!

Eels are mysterious creatures.  They are other worldly too…you can understand why Aristotle thought that they came from ‘the guts of the earth’.  But how old can an eel get?  Sometimes, I hear reports that European eels can live to 90 years old or more.  For a long-finned eel, found in New Zealand, female eels are 85 years old on average…that’s just incredible. 

Ageing of fish is a really important.  It helps us to estimate growth rates, understand population structure and, over time, helps us understand how these things may be changing.  Cemagref in Bordeaux, France, is hosting a four-day eel ageing workshop in April. The aim is to standardise techniques across Europe, and to develop techniques to age eels.  It’s not yet an exact science, and there are still many debates about how best to do it.  Better estimates of the age of glass eels and elvers will help us find out how long it takes for larval eels to reach Europe from the spawning grounds.  Good luck to all those taking part next month!