Environmental Engineering Reference
In-Depth Information
powered by three feet hydraulic power plants; the two feet aft side also act as a rudder. This
vessel is also provided by two winches at the bow and one aft, and both bear anchor
mooring. The winch-system has the function to advance or retreat the vessel during
harvesting operations without the aid of the propellers. This system permits the elimination
of sediment resuspension caused by turbulence of propeller on the shallow water. The
studies conducted on this kind of vessel, fully demonstrated that such production system
constitutes the best compromise for environmental sustainability and economic yield
achievement (Zentilin & Orel, 2009).
5.3 Control measures
Regulations (EC) No 853/2004 and No 854/2004 of the European Parliament and of the
Council, establish specific rules for the hygiene of foodstuffs and for the organisation of
official controls on products of animal origin intended for human consumption respectively.
In this way clam farmers may only harvest living bivalve molluscs from production areas
with fixed locations and boundaries that the competent authority has classified. The
competent authority in fact must fix the location and boundaries of production and relaying
areas that it classifies and it may, where appropriate, do so in cooperation with the food
business operators. In addition the competent authority must classify production areas from
which it authorises the harvesting of living bivalve molluscs as being of one of three
categories according to the level of faecal contamination, as following: Class A areas from
which living bivalve molluscs may be collected for direct human consumption; Class B areas
from which living bivalve molluscs may be collected, but placed on the market for human
consumption only after treatment in a purification centre or after relaying so as to meet the
health standards, molluscs from these areas must not exceed the limits of a five-tube, three
dilution Most Probable Number (MPN) test of 4,600
Escherichia coli
per 100 g of flesh and
intervalvular liquid; finally Class C areas from which living bivalve molluscs may be
collected but placed on the market only after relaying over a long period so as to meet the
health standards, molluscs from these areas must not exceed the limits of a five-tube, three
dilution MPN test of 46,000
E. coli
per 100 g of flesh and intervalvular liquid.
If the competent authority decides in principle to classify a production or relaying area, it
must make an inventory of the sources of pollution of human or animal origin likely to be a
source of contamination for the production area; examines the quantities of organic
pollutants which are released during the different periods of the year; determines the
characteristics of the circulation of pollutants by virtue of current patterns, bathymetry and
the tidal cycle in the production area; establishes a sampling programme of bivalve molluscs
in the production area which is based on the examination of established data, and with a
number of samples, a geographical distribution of the sampling points and a sampling
frequency which must ensure that the results of the analysis are as representative as possible
for the area considered. Classified relaying and production areas must be periodically
monitored to check: there is no malpractice with regard to the origin, provenance and
destination of living bivalve molluscs; the microbiological quality of bivalves in relation to
the production and relaying areas; the presence of toxin-producing plankton in production
and relaying waters and biotoxins in living bivalves and for the presence of chemical
contaminants in molluscs. Sampling plans must be drawn up providing for such checks to
take place at regular intervals, or on a case-by-case basis if harvesting periods are irregular.
The geographical distribution of the sampling points and the sampling frequency must
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