Maybe I've watched too many sci-fi and horror films, but this seems like an obvious recipe for disaster. The only thing more risky than unleashing giant robot fish into the seas (where they could get up to anything) is to do it near contaminated sites, so that these mechanised piscines can join forces with the mutant crabs and outraged dolphins. Detect pollution? They're more likely to use the pollution to create exploding starfish, or octopi that can use flame-throwers.
It won't be long before they rise from the depths to overthrow humanity. Although from the look of it, they'll start with Spain, so I guess we'd at least get to laugh at that for a while before the frenzied mecha-sharks start knocking at our doors.