Attempts to reintroduce a species of fish to British rivers have received a setback from the Department for Environment, Food and Rural Affairs.

The Times can reveal that there has been so much concern about allowing the import of 60 burbot, the only fresh-water member of the cod family, that 37 fish destined for scientific trials have now died. The remaining 23 may have to be humanely destroyed.

Academics at the University of Southampton are frustrated that their efforts to conduct a study for a reintroduction of the burbot to its native habitat in rivers in the east of England are being thwarted. Burbot were last seen in Britain almost 40 years ago.

The research team had originally hoped that 60 fish would be in the country for trials at London Zoo. Scientists do not wish to introduce the burbot to rivers if the waters are too warm. Paul Kemp, a fisheries lecturer, applied for a licence to import live fish from Denmark in August last year. He did not expect any problems as burbot have previously been allowed into Britain. However, officials at Defra raised concerns that the burbot must be clear of a parasite that can cause widespread disease and which, if introduced into Britain, would wipe out river stocks and fish farms. The most effective treatment to kill the infectious bug,Gyrodactylus salaris, is for the fish to be bathed in salt water for 24 hours, Defra said. Dr Kemp argued that such a concentration of salt water would kill the fish but may not kill the parasite. He suggested some alternatives.

So confident was Dr Kemp that the matter would be resolved that, in December, he ordered 60 fish. They were housed in tanks at a research laboratory awaiting dispatch to Britain. Two weeks ago, nine months after his first inquiry, Defra told him that it could not promise an early resolution. By then most of the burbot had died. Dr Kemp said: “All we can do now is wait for Defra to review the position. But we certainly cannot organise the capture of any more burbot and then wait for them to die.” He hopes now that Defra will approve a procedure to allow the import in time for January.

A Defra spokesman said: “We will consider any reasonable possible remedy, but this parasite is very serious for the country’s fish.”

Ugly but good for the table

— The last confirmed sighting of a burbot was on September 14, 1969, in the Old West river, Aldreth, Cambridgeshire

— It is believed to be the only freshwater fish to have died out in the past century

— They were found in the Trent, the Tame, Dove, Derwent, Neme, Great Ouse, Little Ouse, Cam, Thet, Waveney, Skerne, Esk, and Foss

— An 1844 record noted: “An ugly fish, but excellent for the table”

— Burbot, Lota lota, can grow to 14kg (31lb) and can live for 20 years

— Anton Chekhov wrote a comic story, The Burbot, about two Russian peasants trying to dislodge a stubborn burbot from submerged tree roots

Source: Times archives, Southampton University research

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