A five foot long (1.5 meter) robo-fish prototype that monitors oxygen levels and salinity is currently being tested in waters north of Spain as part of the EU-funded Shoal Consortium project. If the project proves successful, teams of autonomous robot fish could be patrolling ports, harbors, and estuaries for telltale signs of pollutants in the next few years.

With current monitoring techniques relying on the collection of samples, usually by divers, that then need to be transported to a lab for testing, many harbors limit their pollution monitoring efforts to about once a month. So if harmful chemicals are detected, the culprit may be long gone.

"The idea is that we want to have real-time monitoring of pollution," says Luke Speller, a senior scientist at the BMT Group, a member of the consortium. "So that if someone is dumping chemicals or something is leaking, we can get to it straight away, find out what is causing the problem and put a stop to it."

In addition to its oxygen and salinity monitoring capabilities, the current prototype has an interchangeable sensor unit which can detect a variety of harmful chemicals and heavy metals like copper and lead. The robots can communicate with one another to locate the source of the problem, and regularly report back to a monitoring station.

"Traditional robots use propellers or thrusters for propulsion. What we're trying to do is use the fin of a fish to propel ourselves through the water," explains Ian Dukes, from the University of Essex, another member of the consortium. "The fin does lend itself for a really useful tool in shallow waters, especially where there is a lot of debris. We can work in environments that are very weedy, and would usually snag up propellers."

Biomimetic robot fish aren't new – researchers at MIT developed the RoboTuna back in 1993 – and this year alone has added the BIOSwimmer and this example from NYU-Poly to the mix. Others are attempting to replicate the swimming motion of rays, jellyfish, and octopi, but these and other robots are stymied by limited battery life, which prevents them from becoming truly practical.

The Shoal Consortium's prototypes, which cost US$32,000 each, operate for just eight hours before needing to be charged. However, there's no doubt that if this problem can be overcome (with, perhaps, some sort of underwater charging station) the robo-fish will find homes in coastal waters around the world.

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