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The various layings are worked by three companies, and in addition, the Fisheries Laboratory
of the Ministry of Agriculture, Fish and Food at Burnham on Crouch has an interest in various
layings in the area, for research purposes.
In the early part of the year one producer requested 'Certificates of Purity' to be issued as
required by the French Authorities to cover export consignments Routine sampling was carried
out and the samples submitted to the Public Health Laboratory, Chelmsford for examination.
Two such consignments were dealt with in this way and on each occasion the oysters were
reported as 'Satisfying the standards laid down by the Worshipful Company of Fishmongers'.
In recent years there has been a large increase in the population in this part of Essex, and
this increase has created problems with sewage disposal in the areas adjacent to the River
Roach and its tributaries.
Whilst there has, to date, been no report of any person suffering from infection, or other
disease attributable to shellfish consumption, this particular hazard will have to be closely
watched and action taken under the Public Health (Shellfish) Regulations, 1934 if considered necessary.
The towns adjacent to the waters used by the oyster industry, namely Rochford and Rayleigh,
are conscious of the problems associated with over-loading the various sewage systems which
eventually outfall into the River Roach, and schemes are underway to improve the various effluents.
Rochford Rural District Council covers an area virtually enclosing all the waters of the
Roach and has recently carried out works of improvement to various purification plants. A detailed
survey is proposed early in 1970.
Cockle Industry
The cockle industry at Leigh on Sea produced no problems during the year. The eight
approved establishments continue to operate and visits were made from time to time to ensure
that the requirements of the 1936 Shellfish Order were being complied with.
The experimental suction type dredge used for gathering cockles reported previously as
being used by one of the cockle firms, proved successful and its use has now spread to most of
the firms engaged in this trade.
No report of sickness following the consumption of cockles originating from the Leigh Sheds
was received during the year.
Mussels
At the request of the Ministry of Agriculture, Fisheries and Food, Fisheries Laboratory, at
Burnham on Crouch, the Authority assisted a shellfish survey into the presence of algal toxin.
Samples of mussels were collected from the foreshore at Southend between the 8th April
and the 29th September at two weekly intervals and these were sent by post to the Fisheries
Laboratory for examination.
Duringthe course of the survey thirteen samples were submitted, and none contained toxin.
The following is an extract from a paper entitled 'Mussel Toxicity in Great Britain 1969'
prepared by P.C. Wood, Esq., of the Ministry of Agriculture, Fisheries and Food Laboratory at.
Burnham-on-Crouch, Mr. Wood has kindly agreed that this extract may be printed:—
'During 1968 an outbreak of paralytic shellfish poisoning affected 85 persons in north-east
England (McCollum et al. 1968, Wood and Mason 1968, Wood 1968). As a result of this incident it
was decided that during 1969 the levels of toxicity should be determined in (a) shellfish from
the same general area, and (b) shellfish taken from the principal areas in England and Wales
where bivalves were being exploited commercially.
(a) Toxicity in the north-east. During the winter of 1968 arrangements were made to support the
toxicity determinations with field observations which biological laboratories situated in the
north-east would make if unusual biological events again became evident. The staff of these
laboratories (Department of Agriculture and Fisheries for Scotland, Marine Laboratory, Aberdeen;
Dove Marine Laboratory, Cullercoats; Welcome Marine Laboratory, Robin Hood's Bay) and also
fishery officers and fishermen were asked to report unusual conditions, such as dis-coloured or
highly phosphorescent water, and Mr. G. Robinson of the Scottish Marine Biological Association,
Oceanographic Laboratory, Edinburgh, agreed to give special attention to Continuous Plankton
Recorder samples taken from the area.
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