Fish overboard

2 min read

Wilson’s worldDavid Wilson is editor of Engineeringtalk and Electronicstalk, and contributing editor to The Engineer

Hugh Fearnley-Whittingstall has a big problem with the way that fish are currently being caught. And on his latest TV show - Hugh’s Fish Fight - which was broadcast this month as part of Channel 4’s Big Fish Fight, it became pretty clear why.

The Fish Fight programme - and an associated website: - highlighted the astonishing fact that fishermen are discarding loads of unwanted fish that they catch in their nets.

Apparently, the reason behind this terrible waste is that in a mixed fishery where many different fish live together, the fishermen cannot control the species that they catch. So they discard the dead ones that they don’t want.

Because discards are not monitored, Fish Fight campaigners say that it’s difficult to know exactly how many fish are being thrown away. But the EU estimates that in the North Sea, discards are between 40 per cent and 60 per cent of the total catch!

While many of these fish are species that aren’t commonly eaten, others are far from it – these cod, haddock, plaice and other popular fish are simply over-quota.  They have to be thrown overboard before they reach the docks since they can’t be legally landed.

Anyone with an ounce of common sense can see how outrageous this is. Indeed, so many people thought so after the show that over half a million of them signed up to support a campaign to get the EU fisheries policy changed.

Being of a technical bent, however, I couldn’t help think that there must be a technical solution to this thorny issue - a device, for example, that would selectively ward off the species of fish that fishermen were not really interested in catching.

After all, there are plenty of gadgets out there that can scare off squirrels, mice and rats from the home, so surely it goes without saying that there must be some means to repel unwanted fish from fishermens’ nets.

Well, apparently, there is. Already, researchers at Oak Ridge, New Jersey-based SharkDefense Technologies have discovered that shark-repellent metal alloys can be effectively deployed to ward off sharks in a move that might see fishermen who are looking to land tuna and swordfish no longer capture the sharks too.

According to the company, these electropositive metals (EPMs) are a new class of materials that produce a voltage when immersed in seawater and it is believed that this voltage overwhelms the ampullary organ in sharks, producing a repellent action.

Well, if there’s one technology that has been shown to work with sharks, there must be others that could be deployed to put off other fish species too.

So perhaps it is time for those of us in the engineering fraternity to mail off a petition to European commissioner Maria Damanaki asking her to fund a cross-disciplinary research project that could identify some of the key physiological attributes of certain species of fish after which we could develop even more technical means to dissuade them from the fisherman’s nets.

David Wilson

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