Apparently the River Thames' eel population has fallen by a massive 98% over the past five years, and to combat this new legislation will require eel passes and screens to be installed to allow free passage to eels up down English and Welsh rivers.

The Guardian and The Telegraph have similar articles about the new laws, but the Telegraph wins for having an actual picture of an eel pass, which turns out to be a fibreglass chute filled with plastic bristles and only a little water that the eels can slither through. Be sure to click the next link for their close up picture including a baby eel.

I'm still not sure what an eel screen is. After an admittedly quick search the best definition I could find was from the Office of Public Sector Information's page on the new laws: "eel screen" means any device, moving or stationary, that is designed to impede the passage of eels through a diversion structure. I'm not that much the wiser to be honest, as it's rather lacking in context or examples of why impeding their passage is a good thing.