Fish and microchips to track shoal movement

It gives a whole new meaning to fish and chips. British scientists are to insert microchips with movement sensors normally found in video games into wild fish to monitor how they roam about the oceans.

Sensitive "three-axis" motion indicators used in handsets to show how people move about for consoles such as Nintendo's Wii will be implanted into Atlantic cod and salmon in an attempt to halt their long-term decline.

A team of 17 at the Centre for Environment, Fisheries and Aquaculture Science (Cefas) in Lowestoft, Suffolk, has spent six years developing the technology at a cost of £559,000.

During the first five years of their six-year research project, they developed basic microchips with magnets that can be stitched into the fish's bodies to record when they open their mouths and whether they are breathing, yawning, coughing, or – of most interest – feeding.

Engineers then hit on the idea of adding "three-axis accelerometers" in video-game technology to electronic tags to enable analysis of the movement of fish in three planes.

This will reveal how much energy they are expending, which can be used to piece together the feeding and movement of large predatory fish. Marine scientists say that the ensuing information about how cod and salmon react to changes in water temperature due to climate change or changes in the abundance of prey will improve computer models used to set fishing quotas.

Each lozenge-shaped chip, which measures 3.6cm long and 1.3cm deep, costs about £800.

The electronic tags will be fitted to between 50 and 100 wild fish. Each caught at sea will be anaesthetised before the tag is stitched into the body cavity next to the guts in an operation lasting about two minutes. The sensors will then emit data 30 times a second, 100 times quicker than existing fisheries tags.

Cefas said that laboratory trials showed the fish did not suffer from having the chips inserted. "Results show that cod recover well from the surgery and, a year after implantation, the tag wounds are healed and the tags (coated in silicon rubber) are well tolerated," it said in a report.

Dr Julian Metcalfe, a senior scientist at Cefas, said the use of motion sensors would give scientists important clues about the behaviour of wild fish. "The key currency [for wild fish] is energy. They must decide whether to go after a prey animal or whether it is too expensive metabolically." He added: "At the moment, we have no idea how fish in the wild apportion energy to the things they do."

Each chip carries the telephone number of Cefas and details of how to claim a £25 reward for its safe return. Given that some of the fish will be eaten by other predators and the chip has a flotation device, some are likely to be washed ashore, giving beachcombers enough money for a different kind of fish and chips.