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.