They have similar, but simpler ones on the Thames. I was surprised this was not mentioned. It might have been in the  link about trash. Basically they have cages with an open end that are fixed at certain point son the river. The pick up any of the larger debris as it goes down river.<p>Here you go - found an article: <a href="http:&#x2F;&#x2F;www.digitaljournal.com&#x2F;article&#x2F;88158" rel="nofollow">http:&#x2F;&#x2F;www.digitaljournal.com&#x2F;article&#x2F;88158</a>