In the Middle Ages, fishing was an important source of food, livelihood, and income in Irish coastal and estuarine landscapes and the ownership, regulation, and use of fisheries was often a significant aspect of social and economic relationships. Fish was of great importance in the medieval diet, as religious custom forbade meat consumption during Lent, Advent, and after Pentecost as well as on holy days and the eves of Christian celebrations. Moreover, in aristocratic and ecclesiastical households, some species of fish were regarded as delicacies and were often maintained in fishponds. Through the medieval period, both sea fish and freshwater fish were caught by boats, nets, and traps for local consumption or were preserved or transported in barrels to settlements elsewhere, occasionally across large distances.
In the early Middle Ages, it is likely that fishing was a small-scale, subsistence activity intended primarily to produce food for the domestic table, with the surplus distributed in local markets. Early Irish laws, dating to the seventh and eighth century a.d., regulated the use of fishweirs for catching salmon, trout, and eels (the range of Irish native species being quite limited). Sea fishing was probably less important at the time (Kelly 1997). By the tenth and the eleventh century a.d, the growth of urban populations, improved methods of salting and smoking preservation, and the development of Atlantic sea fisheries would have led to fishing becoming a much more significant source of wealth and power. It is likely that by the twelfth century and thirteenth century (if not earlier in many locations) most estuarine and riverine fish weirs would have been taken into the hands of monastic houses, bishops, and manorial lords (Hutchinson 1994; O’Neill 1987; Childs and Kowaleski 2000). Irish salmon and eels were particularly valuable sources of income from these freshwater fishweirs.
Recent coastal archaeological surveys have identified spectacular evidence for medieval fish weirs on the Shannon estuary, County Clare and County Limerick (O’Sullivan 2001), and on Strangford Lough, County Down (McErlean and O’Sullivan 2002). These were artificial barriers of stone or wood built to deflect fish 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 differences in size, location, building materials, and trapping 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 estuary), 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 essentially 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 converging 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 rectangular 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 medieval 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 radiocarbon 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 rectangular 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 provided 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 radiocarbon 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 to Bristol, Chester, and the west coast of England. The herring fisheries off Ardglass and Carlingford were also attracting hundreds of ships from Wales, southwest England, and Spain. During the fourteenth and fifteenth centuries, the rich fishing grounds off the south and west coasts, warmed by climatic change, were being harvested by foreign fishing fleets, particularly those of England, Wales, Scotland, Brittany, Gascony, and Iberia. Among these saltwater fish, herring was the most important export, along with cod, hake, pollock, whiting, and ling.
Although the Gaelic Irish population may not have fished these grounds themselves, they used them as an important source of income. Foreign fishing fleets operated out of sheltering havens under the control of Gaelic Irish lords (e.g., the O’Driscolls and O’Sullivan Beares of west Cork), who profited by victualing the fleets, by issuing licenses for fishing, and by charging for the use of their harbors and foreshores (Breen 2001). By the mid-fifteenth century, the English government, concerned at loss of customs revenue through illegal exports, attempted to restrict foreign fisheries off Baltimore, to little initial effect. In the early sixteenth century, foreign fishing fleets operating off Ireland were required to land a portion of their catch in Ireland. Nevertheless, by the late sixteenth century, reputedly 600 Spanish ships were fishing off Ireland.
