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’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.
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!
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!
It’s been a hectic month and I’ve not had the time I’d like to update the blog. November saw the release of another 40 PSAT tagged eels and 50 archival tagged eels. The wait is now on to receive the data back- it’s going to be a nervous year!
With the bulk of this year’s tagging out of the way, I’ll now be able to turn my attention to the next few months of work- and the arrival of the glass eels. The more I think about it, the more I realise that eels are more like 4 species in one. Each life stage has its own challenges and mysteries. I have the nagging feeling that our project, while solving some mysteries, will only raise more!
11:01 (Universal time): the first 10 PSAT tagged eels of the eeliad project are released
11:55 (Universal time): the second batch of 10 PSAT tagged eels of the project are released.
Good luck girls!
Well, here I am in Ireland in time to see the first satellite tagged eels released. It’s been a huge effort from the capture and tagging teams and a job done really really well. So congratulations to them!
It is amazing to see these big silver eels ready to head out to the unknown, and even more amazing to see them be tagged (think ‘eel hospital’). They’re all in good health, so good luck to them. We’ll be checking the satellites every minute from now on!
The PSAT tagged eels are accompanied by some archival tagged eels too, so with a bit of luck we might get some recoveries of those tags for some high-resolution data. The tagging team travel to France for another release at the end of the week, before returning to Ireland for another round of tagging in December.
I’m a bit late with this post…the first tags of the eeliad project were deployed a week or so ago, on the east coast of Sweden. The tags were the buoyant type that, if the eels are not caught, will float to the surface of the ocean and, in some proportion, get picked up by beachcombers.
Well done to the team in Sweden…now we have to wait for the tags to start coming back through the fishery or by recovery from beaches. It’s an exciting time.