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Anglers fear killer algae repeat

PUBLISHED: 10:11 15 January 2010 | UPDATED: 16:18 30 June 2010

Roy Webster on Fishing



THERE is nothing that fuels a chill of apprehension in the hearts and minds of Broads' anglers than a possible threat of a serious outbreak of the fish killer algae Prymnesium.

Roy Webster on Fishing

THERE is nothing that fuels a chill of apprehension in the hearts and minds of Broads' anglers than a possible threat of a serious outbreak of the fish killer algae Prymnesium.

This deadly organism that was responsible for the slaughter of many tons of coarse fish and eels in the River Thurne catchment area during the late 1960s and early 1970s has been almost dormant for a number of years.

Fish populations, while not completely recovering to the early post-war standards for pike anglers, have been remarkably buoyant in the Thurne Valley waters for more than a quarter century.

But now anglers, especially pike enthusiasts, are concerned that the proposed dredging operation designed to deepen and widen the navigation channel in Heigham Sounds could spark another explosion of the Prymnesium peril.

Will the killer bug be released from the sediment to bloom again and spread its deadly toxins to wipe out the present Thurne valley fish stocks including John Goble's 45lb 8oz record breaking pike?

Those of us that witnessed the carnage never want a repeat of that catastrophe.

Investigations into the cause of this ecological disaster concluded that the excessive bloom of the algae was caused by a lethal combination of warm weather, high phosphate content in the water plus the essential condiment of saline without which the algae cannot bloom to lethal levels.

The phosphate source was established as the Hickling Broad roost of gulls that foraged on the Martham domestic waste tip. The official verdict on the high salinity declared the source was a deep drainage scheme along the coastal strip that divides the Broads form the North Sea.

However, local people knew it was impossible to sink a bore into the upper Thurne flood plain without tapping salt water, and they pointed to a deep dredging on Hickling Broad as the main source of the saline.

In his book covering his life as a river bailiff Tom Cable devoted a whole chapter to the serious Prymnesium outbreak. He noted that his first discovery of dead and dying fish was the end of June, 1969 in an area where he suspected salt water was contaminating the habitat.

At the time of the trouble, infected bream fed voraciously and a league match on the Thurne produced enormous catches headed by 76lbs from Candle Dyke.

The next day, keep nets were banned on the Thurne and anglers were requested not to fish the affected waters.

Further outbreaks of the killer algae were noted in the early 1970s and the trouble reappeared at low levels for the remainder of that decade, until the Martham tip was closed.

To this very day, anglers old enough to remember the carnage believe it was the dredging of Hickling that was the fundamental cause.

It is known that live Prymnesium cells are ever present in the River Thurne head waters. But the chemical cocktail that nourished the massive blooms and released the deadly toxin when they died off has not been evident for a number of years.

The proposal to dredge the Sounds raises two vital issues. Will this operation release any residual phosphate from the silt? Will the clay sub soil that seals the bed of the channel from the salt water aquifer be breached?

The Broads Authority and the Environment Agency monitoring this operation need to produce copper-bottom guarantees to satisfy members of the Pike Anglers' Club and many others Broads men and women.


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