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Once the Calusa captured fished, they were likely harvested with seine or dip nets or speared, said archaeologist William Marquardt. Source: Florida Museum / Merald Clark

Ingeniously Engineered ‘Watercourts’ Fueled Florida’s Calusa Kingdom

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A research project has finally solved an archaeological mystery in America. Experts believe that they now know how a Native American people, the Calusa who lived in Florida, were able to develop and expand despite not practicing agriculture. They argue that the Calusa built massive ‘watercourts’, where they captured fish in huge quantities to produce a food surplus.

The Calusa dominated South Florida for centuries before the arrival of the Spanish in the 16 th century. They engaged in long-distance trading, built monumental architecture and reduced other groups to the status of tributaries. There is no evidence that they ever engaged in farming and yet they had an informal empire. It has long been assumed that only agricultural societies could produce the food surpluses that were needed for empires and sophisticated political systems.

Mystery of the Ancient Watercourts

A study of an archaeological site with massive structures known as ‘watercourts’ was conducted by Prof. Victor Thompson and his colleagues, from several American universities. They surveyed the structures on Mound Key, an artificial island in Estero Bay off the coast of South Florida.  The archaeological site itself is built on the shells of sea fish and it was the capital of the Calusa.

Left: Mound Key was likely the seat of Calusa power for 500 years. By the 16th century, the Calusa kingdom stretched from the Florida Keys to the southern edge of Tampa Bay. Right: A remote sensing map reveals some of Mound Key’s standout features, including two large shell mounds, the grand canal and two massive watercourts flanking the island’s southwest shoreline. (Victor Thompson / PNAS)

Left: Mound Key was likely the seat of Calusa power for 500 years. By the 16th century, the Calusa kingdom stretched from the Florida Keys to the southern edge of Tampa Bay. Right: A remote sensing map reveals some of Mound Key’s standout features, including two large shell mounds, the grand canal and two massive watercourts flanking the island’s southwest shoreline. (Victor Thompson / PNAS)

According to Haaretz, the site is “about 51 hectares (almost 130 acres) in area, about 1500 years old and contains by volumetric calculation at least 500,000 cubic meters (1,640,000 ft) of oysters shell.” The Calusa also built a canal that divided the island in two.

Some three hundred years after they built the watercourts that flank the canal. These rectangular walled structures were built in an estuary. It appears that “they likely served as short-term holding pens for fish before they were eaten, smoked or dried,” according to Heritage Daily . The largest watercourt is about 100 feet high (32m) and has a bream or shelf of shells about 3 feet (1m) high.  PNAS reports that “these structures were engineered with knowledge of tidal systems, hydrology, and the biology of species to be stored in these courts.”

Massive Fishponds

The Calusa caught the fish in the open sea and brought them to the enclosures for a short time. It appears that they built massive canoes to catch the fish and “they would then bring the wild fish to the pools and keep them until they needed them,” reports Haaretz.

Artist's conception of Calusa people preparing for fishing in the estuary. (Florida Museum / Merald Clark)

Artist's conception of Calusa people preparing for fishing in the estuary. ( Florida Museum / Merald Clark)

Once the fish were in the pool the enclosures would be sealed with a net or a gate. These structures show the “considerable ability of the Calusa, a non-agricultural society, to engineer systems that significantly alter their natural environment,” reports PNAS.

King’s Manor

The experts examined the structures with sensors, carbon-dated them and investigated the core sediments. The remote sensors mapped the location and found that slopes were leading to the watercourts and they may have been built to help in the transportation of the fish. They also found evidence that huts or racks were specially built to smoke the fish, which would have helped them preserve the food in the hot climate of Florida. It appears that they were designed so that the enclosed water pools could be replenished during high tide.

Atop a 30-foot-high shell mound, the Calusa constructed an expansive manor capable of holding 2,000 people, according to Spanish records. Fish stored in Mound Key’s watercourts may have provided the food resources needed to complete the project. (Florida Museum / Merald Clark)

Atop a 30-foot-high shell mound, the Calusa constructed an expansive manor capable of holding 2,000 people, according to Spanish records. Fish stored in Mound Key’s watercourts may have provided the food resources needed to complete the project. ( Florida Museum / Merald Clark)

Organic remains at the watercourse were carbon dated, which indicates that they were constructed around 1300 and 1400 AD.  Based on previous archaeological studies they were built at the same time as the king’s dwelling or manor, a large structure that could hold an estimated 2000 people. The construction of the stone enclosures would seem to have been related to a drop in the water level.

Calusa and Climate Change

Heritage Daily quotes Karen Walker, collections manager with Florida Museum, saying that the construction may be related to change in the environment, which “may have impacted fish populations enough to help inspire some engineering innovation.”

The researchers documented an intensification in fishing over time, especially for mullet. (Florida Museum / Merald Clark)

The researchers documented an intensification in fishing over time, especially for mullet. ( Florida Museum / Merald Clark)

It appears that the Calusa were able to adapt to at least two dramatic changes in the climate, successfully. According to Thompson, “the Calusa adapted to climatic shifts in salinity that were due to global temperature and this affected what fish were available,” reports Haaretz

William Marquardt, who took part in the study, told Gizmodo that “what makes the Calusa different is that most other societies that achieve this level of complexity and power are principally farming cultures.” The orthodoxy had long been that societies that relied on aquaculture and hunter-gathering societies were not sophisticated. However, the Calusa were able to use fishing to create a powerful kingdom, religion and trade networks that endured for centuries.

Fish bone and scales, such as this fragment of a mullet scale found in a watercourt, revealed which species Calusa were capturing. (Florida Museum / Zachary Randall)

Fish bone and scales, such as this fragment of a mullet scale found in a watercourt, revealed which species Calusa were capturing. ( Florida Museum / Zachary Randall)

Non-Agricultural Civilization Rewrites History

These structures were used to capture fish that provided the society with its food surplus. The Calusa elite used this to create “the most politically complex polity in Florida,” according to PNAS.  The fish captured in the structures also decisively shaped the society’s culture and society.

Thompson told Heritage Daily “the fact that the Calusa obtained much of their food from the estuaries structured almost every aspect of their lives.” They were a maritime society and they lived in harmony with the rhythm of the sea.

The Calusa as a people who depended on aquaculture often came into conflict with the Spanish colonists, who found them incomprehensible. They managed to resist the Spanish and even ejected Franciscan missionaries from their territory who tried to turn them into agriculturists. However, the Calusa state came to an end in the mid-eighteenth century as a result of slave raids. The last survivors of the culture fled to Cuba for sanctuary.

Gizmodo reports that the “Calusa remain a rare example of a civilization attaining a high degree of sociopolitical complexity in the absence of agriculture.” This is very important for our understanding of the development and even the nature of civilization. It also demonstrates that those societies that are best adapted to their environment are the most successful.

Top image: Once the Calusa captured fished, they were likely harvested with seine or dip nets or speared, said archaeologist William Marquardt. Source: Florida Museum / Merald Clark

By Ed Whelan

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