Artist’s impression of fish being corralled into watercourts. Image : Florida Museum/Merald Clark

Despite having no agriculture, the Calusa managed to dominate southwest Florida for centuries. New research suggests this inventive Native American civilization built “watercourts” to capture and store live fish, resulting in a bountiful surplus of food that facilitated sociopolitical complexity and ambitious construction projects.


Appearing around 2,000 years ago, the expansive Calusa kingdom of Florida stretched from what is now Tampa Bay to Ten Thousand Islands and as far east as Lake Okeechobee. Their capital city, called Calos, was located near Fort Myers in a place now known as Mound Key Archaeological State Park.

Archaeologists have studied the Calusa for decades, analyzing artificial islands made from discarded shells, the remnants of former dwellings, and their impressive dredging canals. The Calusa are unique in that, unlike the Maya, Aztecs, and Inca, they never jumped onto the agriculture bandwagon. These Native Americans were strict fisher-hunter-gatherers who relied almost exclusively on resources pulled from the sea.


Yet somehow the Calusa managed to fund ambitious construction projects, exert tremendous military power, and collect tributes along a network that spread out for hundreds of miles. These efforts would have required an abundance of readily available food, leading archaeologists to wonder how these fisher-gatherers were able to amass so much seafood and then prevent it all from rotting in the tropical Florida heat.

The two watercourts analyzed in the new study, which are located near two prominent mounds. Image : Florida Museum

New research published in Proceedings of National Academy of Sciences provides some much-needed answers, showing how the Calusa built seaside structures, called watercourts, which they used to capture and store fish.



“What makes the Calusa different is that most other societies that achieve this level of complexity and power are principally farming cultures,” explained William Marquardt, a co-author of the study and a researcher at the Florida Museum of Natural History, in a press release. “For a long time, societies that relied on fishing, hunting and gathering were assumed to be less advanced. But our work over the past 35 years has shown the Calusa developed a politically complex society with sophisticated architecture, religion, a military, specialists, long-distance trade and social ranking—all without being farmers.”


Previous research argued that the watercourts were used to hold fish, but the new paper is the first to provide a comprehensive and systematic analysis of these structures. For the new study, Marquardt and his colleagues sought to find out when the watercourts were constructed, how they were built, how they worked, and how their appearance coincided with other developments in the Calusa kingdom, such as the construction of enormous buildings.

Two watercourts at Mound Key were analyzed in the study, both of which flank a canal measuring around 30 meters wide (100 feet) and around 600 meters long (2,000 feet). Core samples containing sediments were pulled from the site, while remote sensors provided a bird’s eye view of the mounds. Other evidence, such as bits of discarded shells and fish bones, were also collected and analyzed.


As the new research shows, the watercourts were built atop a foundation of oyster shells. They were roughly rectangular in shape, occupying a space of around 3,345 square meters (36,000 square feet) , which is about 62 percent the size of an American football field.

To make the watercourts, the Calusa walled off portions of estuaries, creating holding pens for fish. These walls, which stood 1 meter (3 feet) tall , were made from shells and sediment. Nets or gates were likely used to prevent the fish from escaping. As the new evidence shows, the watercourts were not haphazardly built from middens (i.e. piles of waste), but were instead carefully designed structures . Construction and maintenance of the watercourts was no easy task, requiring “knowledge of tidal systems, hydrology, and the biology of species,” according to the paper.


Trapped in large quantities, the fish could be held in the watercourts and then extracted for processing, such as smoking and drying. Evidence collected at the site show traces of mullet, pinfish, and herring, which are all schooling species of fish.

That said, the watercourts didn’t allow for long-term storage of live fish. Core samples taken from the site exhibited dark gray splotches consistent with the accumulation of organic material. This suggests fresh ocean water wasn’t getting into the enclosures, aside from some splashings during high tide.


“We can’t know exactly how the courts worked, but our gut feeling is that storage would have been short-term—on the order of hours to a few days, not for months at a time,” said Michael Savarese, a co-author of the study and a geologist from Florida Gulf Coast University, in the press release.

Artist’s impression of the “house,” a large structure that served as the political seat of the Calusa kingdom in the 16th century. Image : Merald Clark/Florida Museum


The watercourts were constructed between 1300 CE and 1400 CE, according to radiocarbon dating of the site. This timing coincides with major upgrades to a large dwelling known as the “house,” the presumed home of Caalus, a Calusa king who lived in the mid-16th century. This structure could house as many as 2,000 people and was the likely seat of power for “a long-lived corporate group” that dominated for roughly 500 years, according to the paper.



Ultimately, the researchers associated the construction of these watercourts with a burgeoning Calusa population, which consisted of around 20,000 individuals, and the emergence of complex political systems, as the study describes :

The creation of [food] surpluses required overcoming considerable challenges in terms of storage and distribution of products. Mound Key is located in a subtropical climate, which surely would have caused problems for maintaining the surplus stability and freshness, particularly with animal products. We suggest that the Calusa of Mound Key were able to solve this unique problem in a highly sophisticated manner, which partly involved keeping live fish in watercourt storage areas. The construction of these facilities would have likely required coordinated effort and collective buy-in from larger segments of society.


Equipped with an abundance of food, the Calusa were able to support large-scale labor projects, generous feasts, and the rise of other important institutions which “lead to greater investments in complex social and political formations,” according to the paper.

But it wouldn’t last. This civilization was at its peak when the first Europeans began to arrive in the New World, a development that upturned the Calusa and many other Native American groups.


Yet, the Calusa remain a rare example of a civilization attaining a high degree of sociopolitical complexity in the absence of agriculture. When done correctly, and as the Calusa demonstrated, fish can power an entire kingdom.