Prehistoric fishing

Amerindians caught sharks and whitemouth croakers, possibly in excess, 5,000 years ago along the coast of Rio de Janeiro State

Sambaqui_247The Brazilian coastline features more than 2,000 known sambaquis, or shellmounds, a kind of archeological vestige that harkens back to the funerary practices and diet of the first coastal inhabitants. In the Tupi language, sambaqui means “pile of shells.” Prehistoric fisher-gatherers who occupied the shores of the Atlantic buried their dead in shallow pits, covered by shells and remains of fish, along with artifacts made of stone and bone. Over time, the most commonly used burial sites accumulated a large quantity of materials that formed mounds, some as high as 30 meters, as can be seen at archeological sites in the southern state of Santa Catarina. According to a study conducted by researchers from the states of Rio de Janeiro, São Paulo and Rio Grande do Sul, fishing by Amerindians along sections of the Rio de Janeiro coastline—from which vestiges can be found in the shellmounds—may have posed the first significant threat to natural stocks of certain types of fish, such as whitemouth croakers (also known as corvina) and sharks.

The authors of the study examined more than 6,000 fragments of bone, teeth and otoliths—calcareous structures of the inner ear—of fish found in 13 shellmounds on the coast of Rio de Janeiro. The sites, between 5,600 and 700 years old, are located between the bays of Ilha Grande Island in Angra dos Reis and Cabo Frio Island in Arraial do Cabo (see map). Analysis of this material, which belongs to the archeological collection of the National Museum of the Federal University of Rio de Janeiro (MN-UFRJ), gave them an approximate idea of the number and size of the specimens caught over the course of thousands of years. It also became the basis on which they would conclude that catching fish was a very well-developed and diversified activity before Europeans arrived in Brazil. Of the museum’s collection, 97 fish species were identified. “That number represents 37% of all fish species recorded so far along that stretch of the Rio de Janeiro coastline,” says marine paleontologist Orangel Aguilera of the Universidade Federal Fluminense (UFF) in Niterói, principal author of the paper, which was published on July 29, 2016 in the journal PLOS One. “The shell people really mastered the art of fishing.”

Great white shark: one of the more than 20 fish species that the shell people caught

Imagem: Elias Levy/Flickr Great white shark: one of the more than 20 fish species that the shell people caughtImagem: Elias Levy/Flickr

The characteristics of the archeological record of some marine species commonly found in shellmounds indicate that certain types of fish were caught in excess or as neonates, sometimes in nursery areas. This practice likely initiated a process that left them vulnerable, or even reduced the coastal populations of some fish. According to Aguilera, the shell people, or sambaquieiros, fished in diverse marine environments, both shallow and deeper, from sandy plains along the coast to the rocky ocean floor where fish were abundant. Despite archeological records showing that man has been fishing for at least 40,000 years, there are few studies of any environmental impact from that prehistoric activity. One rare study, conducted in 2010 by the Fisheries Research Center in Cuba, even suggests that the Amerindians did not have the technology to explore most of the stocks of marine creatures of the Caribbean—a conclusion that has now been refuted by Aguilera.

The marine vestiges recovered in the Rio de Janeiro shellmounds attest that fishing was a dominant activity in the region. The species with the largest number of records, probably the one most frequently caught by the fisher-gatherers along the Rio de Janeiro coast, is the whitemouth croaker (Micropogonias furnieri). The researchers studied 5,532 otoliths of the species, which inhabits muddy, sandy bottoms of coastal waters or estuaries and can grow to 70 centimeters (cm) in length. “Whitemouth croaker is presently the second most widely fished species on the Brazilian coast, second only to sardines,” says oceanographer Acácio Tomás, a researcher at the Fisheries Institute in Santos and coauthor of the paper. “The ancestral peoples also probably fished for sardines, but unfortunately, we have no records of that species in the material collected at the shellmounds in Rio de Janeiro,” Tomás notes. Eleven of the 13 archeological sites studied contained vestiges of M. furnieri. The species’ ubiquity in the shellmounds has enabled researchers to estimate the impact of fishing on croaker stocks over the past 5,000 years. According to their calculations, there has been a 28% reduction in the average size of these fish between then and now, due to continued exploitation of the species.

Sambaqui_Mapa_247The notable presence of vestiges of adult and young sharks, especially from some oceanic species that occur far from the coast, also drew the attention of Aguilera and his colleagues. They examined 660 fossilized vertebrae, in addition to teeth and skull bones, from over 20 different species of this fish, including the great white shark (Carcharodon carcharias), the sand tiger shark (Carcharias taurus), the tiger shark (Galeocerdo cuvier) and the scalloped hammerhead shark (Sphyrna lewini). The abundance of records has been interpreted by the study’s authors as an indication that the shell people had extensive fishing capability.

According to the researchers’ estimates, the bones they studied belonged to specimens whose length varied from 30 centimeters in the case of young fish, to 2.5 meters for mature specimens. The sharks caught by the sambaquieiros were nearly always smaller than the current average estimated size for those same species, which today are considered vulnerable or endangered. This was probably the consequence of overfishing in nursery areas, which are important for maintaining the animals’ reproductive capacity. Among the remains of ray found in the shellmounds, the most abundant were from the spotted eagle ray (Aetobatus narinari).

Whitemouth croaker: the species most widely fished by the shell people of Rio de Janeiro

Imagem: Cláudio D. Timm/Wikipedia Whitemouth croaker: the species most widely fished by the shell people of Rio de JaneiroImagem: Cláudio D. Timm/Wikipedia

Canoes and fishing nets?
The location of the archeological sites is an indication that the Amerindians did not settle in these latitudes by chance. The 13 shellmounds are scattered along a 270-kilometer strip of the Rio de Janeiro coastline known to be a zone of resurgence, characterized by an upwelling of deeper, more nutrient-rich waters. There tend to be higher concentrations of fish at the points along the coastline where this phenomenon occurs. “The shell people were major gatherers of shellfish, but it was an insufficient diet for them. It was fish that basically sustained them,” says archeologist Tania Andrade Lima of MN-UFRJ, another coauthor of the paper. “They were well-acquainted with the marine environment and fished both along the coast and near the high seas.” In addition to serving as the main staple of the shell people’s diet, the sea creatures they caught could also be used in funerary rituals, such as the burial of whole shells with the dead, or for making decorative objects. Shark’s teeth were perforated and used as necklace pieces, a type of adornment typically found in shellmounds.

Although all of the shellmounds analyzed in the study are under the influence of a zone of resurgence, the sites may be grouped according to a number of characteristic geographic features. The Acaiá shellmound is located on the island of Ilha Grande. The Algodão, Major, Bigode, Caieira and Peri sites are on islets or in rocky coastal areas of Ribeira Bay, in Angra dos Reis. Camboinhas is found on a sandy coastal plain dominated by lagoons in the oceanic region of Niterói. The shellmounds at Saquarema, Beirada, Manitiba and Ponte do Girau occupy a portion of sandy plain that is also dotted with coastal lagoons, in the area of Saquarema. And lastly, Cabo Frio Island, in the municipality of Arraial do Cabo, contains two sites: Usiminas, on a rocky bottom, and Ilha do Cabo Frio, located in a dune area.

Shark’s teeth: used as a necklace adornment

Imagem: Lopes, et al. 2016. PLOS One Shark’s teeth: used as a necklace adornmentImagem: Lopes, et al. 2016. PLOS One

The researchers support the theory that, in order to explore these diverse marine environments, the ancient peoples developed strategies and tools for fishing. To catch sea creatures, they probably employed lines and gillnets made of plant fibers, and fishhooks and harpoons made of animal bones. The search for species that lived far off the coast or for islands strategically situated for fishing on the open sea required the use of some type of boat. “We have no archeological records of canoes or nets, which were made of wood and plant fibers that are not preserved over time,” explains Aguilera, who was assisted in production of the article by Mariana Lopes and Thayse Bertucci, both graduate students at UFF. There is, however, indirect evidence that the Amerindians were good fishermen: projectiles made of bone, found in shellmounds, appear to have been used to deliver the final blow to large specimens; and stone artifacts, also found at some sites, may have been used to make canoes.

Archeologist Paulo DeBlasis of USP’s Museum of Archeology and Ethnology (MAE-USP), an expert on the shellmounds of the Brazilian coast, praises the work of Aguilera and his colleagues. “The article uses a very interesting approach to the shell people’s relationship with marine fishing,” he comments. According to DeBlasis, even today some very traditionalist researchers believe that, due to the abundance of shells in the sambaquis, seafood was the dietary staple of the prehistoric coastal inhabitants. “There are some island-based archeological sites in Santa Catarina as well. For some time now, we’ve had the perception that they were great fishermen, in addition to hunting marine and terrestrial mammals.”

Remains of other fish caught by the Rio de Janeiro shell people: over 6,000 fragments were analyzed

Imagem: Lopes, et al. 2016. PLOS One Remains of other fish caught by the Rio de Janeiro shell people: over 6,000 fragments were analyzedImagem: Lopes, et al. 2016. PLOS One

No one knows to what extent plants and agricultural crops also played a role in the diet of the coastal Amerindians. Five years ago, bioanthropologist Sabine Eggers of the USP Biosciences Institute (IB-USP) reconstructed the diet of Luzio, an Amerindian who lived about 10,000 years ago on a river shellmound in Vale do Ribeira, São Paulo, about 100 kilometers from the present-day coastline. The study yielded a surprising finding: Luzio ate game meat, tubers, fruits and almost no fish or crustaceans, either freshwater or saltwater. Judging from the new study of material from the Rio de Janeiro shellmounds, however, the ancient peoples along that coast really enjoyed a good catch.

Scientific article
LOPES, M. S. et al. The path towards endangered species: Prehistoric fisheries in Southeastern Brazil. PLOS One. June 29, 2016.