into an opening where they could be trapped in nets or
baskets. Most were ebb-weirs, catching fish on a falling
tide, and were typically V-shaped stone or wooden
structures with post-and-wattle fences and baskets of
varying size and construction. Local and regional dif-
ferences in size, location, building materials, and trap-
ping mechanisms indicate the role of local tradition and
practice in the work of fishing communities.
On the Shannon estuary, intertidal archaeological
surveys have revealed evidence for several medieval
wooden fishtraps, dated to between the fifth and the
thirteenth century A.D (O’Sullivan 2001). The Shannon
estuary fish weirs tended to be small structures, hidden
away within the narrow, deep creeks that dissect the
estuary’s vast expanses of soft, impenetrable muds.
Despite being relatively small, they could have literally
sieved the water of all fish moving around with the
tides. They were oriented to catch fish on either the
flooding or ebbing tide and could in season have taken
large catches of salmon, sea trout, lampreys, shad,
flounder, and eels (the latter in October through
November).
The earliest known fish weir is a small post-and-
wattle fence (c. 8 meters in length) on the Fergus
estuary, County Clare (a tributary of the Shannon estu-
ary), dated to 447− 630 A.D (O’Sullivan 1993−1994).
Early medieval fish weirs have also been located on
the mudflats of the Deel estuary, County Limerick,
which flows into the upper Shannon estuary. These
weirs provide intriguing evidence for local continuity
of size, form, and location and appear to have essen-
tially replaced each other between the eleventh and the
late twelfth century A.D. Medieval fish weirs are also
known from the Shannon estuary mudflats at Bunratty,
County Clare, dating to between the eleventh and
the thirteenth century A.D. At Bunratty 4, a complex
V- shaped structure had at least three phases of use at
the site, with several post-and-wattle fences repaired
over a period of time, probably 20−30 years. It has
been radiocarbon dated to A.D 1018 −1159, indicating
its possible use by a Gaelic Irish community at Bunratty
prior to Anglo-Norman colonization. Probably the
most spectacularly preserved medieval fish weir in
Ireland is the site of Bunratty 6. This had two converg-
ing post-and-wattle fences (22 meters in length) of
hazel, ash, and willow braced against the ebbing tide by
diagonally placed poles. These fences led to a rectan-
gular wooden structure on which was placed a massive
woven basket trap (4.2 meters in length, 80 centimeters
in diameter) dated to A.D 1164 −1279. The Bunratty 6
fish weir was probably used by the population of the
Anglo-Norman borough at Bunratty, one of the most
important medieval settlements and ports in the region.
Intriguingly, there is a strong continuity in fish-weir
style and construction across time, indicating perhaps
that Gaelic Irish betaghs were supplying the Anglo-
Norman borough with fish for its domestic tables, fairs
and markets (O’Sullivan 2003).
Archaeological surveys on Strangford Lough,
County Down, have also revealed evidence for medi-
eval fish weirs, mostly concentrated in Grey Abbey
Bay in the northeast end of the Lough. At least fifteen
wooden and stone-built structures have been recorded
and the wooden traps in particular have been radiocar-
bon dated to between the eighth and thirteenth centuries
A.D. (MacErlean and O’Sullivan 2002). Strangford
Lough probably had a range of fish species, including
salmon, sea trout, plaice, flounder, mackerel, cod, grey
mullet, and skate, with large numbers of eels in the
abundant kelp growth.
The Strangford Lough wooden fish weir fences
measure between 40 meters and 200 meters in length.
At the “eye” of the converging post-and-wattle
fences, baskets or nets were probably hung on rect-
angular structures. The earliest fish weir at Chapel
Island, radiocarbon dated to A.D. 711−889, may have
been owned by the early medieval monastery of
Nendrum, County Down, across the lough. In Grey
Abbey Bay, 1.5 kilometers to the east, three wooden
traps and four stone traps have been recorded. At
South Island, a large V-shaped wooden trap has pro-
vided two separate radiocarbon dates of 1023− 1161
A.D. and 1250− 1273 A.D. Similar V-shaped wooden
traps found elsewhere in the bay have produced radio-
carbon dates of 1037− 1188 A.D. and 1046− 1218 A.D.
The Strangford Lough stone-built fish weirs are
broadly similar in size, form, and orientation. They
typically measure between 50 meters and 300 meters
in length, 1.1 meter in width, and they probably stood
between 0.5 meter to 1 meter in height. The stone
fish weirs are variously V-shaped, sickle-shaped, and
tick-shaped in plan, mainly depending on the nature
of the local foreshore.
The massive physical scale and form of the Strangford
Lough weirs probably indicate a local response to
the broad, sandy beaches of the lough, although it
is also clear that these were intended to literally
harvest all of the fish out of this part of the lough.
The Strangford Lough structures were clearly in use in
the bay throughout the Middle Ages. Some of the large
wooden and stone weirs may have been the property
of the Cistercian community of Grey Abbey, founded
in 1193 A.D.
The later Middle Ages see an expansion in Ireland’s
offshore fisheries. By the early thirteenth century,
Irish fleets from ports along the east and south coast
(e.g., Ardglass, Drogheda, Dublin, Wicklow, Arklow, and
Waterford) were operating in the herring fisheries of the
Irish Sea and were exporting fresh, salted, and smoked
fish (particularly herring and hake) in large amounts toFISHING