Santander, February 19th-22nd 2008 - Aranzadi

A large-scale exploitation of oysters during the Middle Ages at Beauvoir-sur-Mer (France)
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Figure 5. Example of implements potentially used to exploit the oysters (CAD L. Quesnel).
We have already demonstrated that all sizes of
oysters were gathered. But have they all been opened?
The presence of opening scars on shells provides
an answer. Figure 2c shows the frequency of
all the oysters with opening scars in the archaeological
assemblage. Compared to the whole oysters
(Fig. 2a), figure 2c shows that the exclusion of oysters
without scars increases the dimensions of oysters
exploited: 58 mm for the right valves and 62
mm for the left ones. This shows that smaller oysters
were gathered and brought to the site but that
some of them were not opened. These smaller individuals
were transported fixed on larger oysters,
and in the studied sample some are still attached.
3.2. The joined oysters
Twenty eight percent of the MNI of oysters were
found as joined valves at Beauvoir-sur-Mer. This is
undoubtedly an underestimation because of the
conditions of conservation and transport of the
shells after excavation. The presence of joined oysters
is not incompatible with their consumption –
some of these joined oysters had opening scars on
their internal side (Fig. 6).
If, as the many scars observed show, large
numbers of the oysters at Beauvoir-sur-Mer were
opened, why were they found joined in the
deposit?
Two elements help the two valves of oysters to
remain joined. The first is the adductor muscle
and the second is the ligament. Opening the oysters
requires that the muscle be cut. The oyster
can then be half opened and the meat extracted
without separating the valves. The ligament present
at the hinge maintained the oysters half-opened
and this was also true at the time of disposal
of the oysters. The ligament is difficult to observe
in archaeological contexts because it became
detached from the shells. So the way that the oysters
of Beauvoir-sur-Mer were consumed (or processed
for consumption) did not necessitate
separation of the two valves.
3. DISCUSSION
To begin the discussion it can be interesting to
summarize the similarities of the archaeological site
of Beauvoir-sur-Mer with that of Saint-Michel-en-
L’Herm which may be partly contemporaneous.
MUNIBE Suplemento - Gehigarria 31, 2010
S.C. Aranzadi. Z.E. Donostia/San Sebastián