Burbot – Its Extinction and Return


Although the burbot, also known as the eelpout and the lingcod, was once quite common in Britain, no confirmed specimen has been captured since 1969 in Britain.

A freshwater cod, the burbot thrived in rivers in Britain and worldwide. However, no burbot has been sighted in Britain since 1969. However, the British government will start a program to re-introduce the burbot.

A secretive fish, active mainly at night, it is possible that some still lurk, undiscovered somewhere in Britain’s network of lakes and rivers.

The burbot is a member of the cod (Gadidae) family, which is widely distributed in the temperate seas of the world, although most common in the North Atlantic. Worldwide, there are 22 species in the family, and all but one of them are sea fishes. The one exception is the burbot, which lives exclusively in freshwater.

Its geographical distribution is also amazing, for it is found right across the northern hemisphere. In North America, it ranges from the Atlantic coast across Canada and the United States into Alaska, then from Siberia to Sweden, France, and England. Its distribution was restricted to eastern England, from Yorkshire southwards to Suffolk.

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Description

The burbot has a slender body with a broad head, two dorsal fins, and a single anal fin. Its similarities to the cod are seen in its long chin barbel and the structure of the dorsal fins.

It hunts using its keen sense of smell, using its long tubular front nostrils to find the source of the smell.

The burbot also has a pattern of sense cells in the lateral line extension on the head.

Ancient Fish

The explanation for the limited distribution of the burbot is believed to lie in the history of the British Isles, just after the last Ice Age. Then, the North Sea was spanned by a land bridge over which many animals crossed to colonize our islands.

Although described as a land bridge, it must have been as much water as land, but it was fresh water from the rivers of what is now northern Europe, such as the Rhine and Elbe, as well as from melting ice.

Conditions probably consisted mainly of swamps, with patches of dry, high ground surrounded by an interconnected mass of freshwater channels.

Many of the fishes that make up Britain’s fauna moved through these channels to colonize the rivers, which, during the ice cover, had been stripped of much of their life. Some species were well-adapted to life in fast-flowing water and spread through the eastern river system into other rivers.

Other species, such as the burbot, ruffe, silver bream, and spined loach, preferred still or slow-flowing water and never spread widely. They tended to be confined to the eastern counties of England.

USFWS

Going Extinct

Historical records of the burbot show that it was once common in the River Trent and other rivers that flow into the Humber estuary. It was also abundant in the Fens, the Great Ouse, the Broads, and as far south as the Suffolk Stour.

By the 1880s, it became obvious that it was much scarcer than it had been half a century earlier. In The ‘Fishes of Great Britain and Ireland’, Francis Day wrote that ‘the species is decreasing in numbers and perhaps doomed to extinction. Records over the next century have shown that his prediction was accurate.

The capture of a burbot by an angler in the Old West River in Cambridgeshire in September 1969 is the last record of the species in Britain. This capture led to a great deal of interest in the species. One angling newspaper later offered a substantial reward for a specimen’s capture, verification, and return alive but has never had to pay out.

Surveys conducted by local water authorities in areas where the burbot used to occur have failed to find any. Although it is difficult to be certain, the British burbot is extinct.

Reason For Extinction

The reasons for its decline and probable extinction are not easy to pinpoint because while the British burbot has died out, those in Sweden, Germany, and North America have shown no sign of diminishing numbers.

An important factor is that British populations were at the extreme western limit of the species’ range. They were cut off by the North Sea from European populations and isolated into sub-populations that lacked genetic diversity within each river.

Such small sub-populations are generally more vulnerable to local problems such as drought or pollution. The River Trent, for example, was badly polluted in the 19th and early 20th centuries, although it is much cleaner now.

Lifestyle

In Sweden, where the species has been studied, spawning occurs in mid-February, when the lakes are ice-covered, and the temperature on the lake bottom is below 4 C (39 F). The burbot spawns over clear sandy or rocky bottoms, and the eggs sink to the lake bottom in about 24 hours. 35 days later, they hatch.

Outside the spawning season, the burbot spends most of the day hidden under rocks, among roots, and in holes in the river or lake bed. Studies of captive burbot in Scandinavia have shown that they are most active early in the evening and around dawn when they hunt for food but are not very active during the night.

Return To British Waters

The British Government has started a program to reintroduce the burbot to British waters. They are sponsoring a project to reintroduce the burbot.

Burbot eggs will be brought in from Europe and hatched. They will be raised in hatcheries until they are ready to be released into the wild.

The burbot has already been reintroduced in this manner in Belgium and Germany.

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