For hundreds of years, naturalists have described the extraordinary abundance of river chelonians, especially Podocnemis expansa (Schweigger 1812), which was a very common species at the end of the 19th century (Silva-Coutinho 1868). This species is threatened because of blatant exploration and the lack of conservation measures (Smith 1979). Bates (1863) estimated that, during the 19th century, approximately 48 million P. expansa eggs were removed annually from the middle Solimões and Madeira Rivers. Today, there is scant occurrence of egg deposition by this species on beaches in most Amazonian rivers, although large populations still survive on the Purus River (Smith 1979). Nevertheless, chelonian eggs and adults are still important sources of protein and serve as currency in commerce for the local human population on most of the Amazonian rivers. (Cavalcanti 1999; Pezzuti and Vogt 1999; Soares 2000). A good example of continued abundance can be found on Abufari Beach of the Purus River, considered to be the last large egg-laying refuge for P. expansa in the state of Amazonas, where about 4000 females annually lay their eggs (A. Kemenes, direct obs.). However, the means required to protect this kind of phenomena is a considerable challenge. Because of predacity abetted by the adults and eggs linked to the demand for these items, combined with the poverty of riverside populations only increases the danger of extinction en masse. According to reports from the oldest fishermen, the Purus River has historically been a river of intense and continuous exploration of mainly chelonians and alligators. Its floodplain lakes and immense flooded area form an extended aquatic labyrinth, parallel to the Purus River and the Solimões River, uniting the local centers of commerce with consumers and middlemen in the cities of Manacapuru, Tapauá, and Manaus. The illegal trade of wild fauna species in these cities has become normal. For many riverine families, it is the only means of survival. Various kinds of wild animal meat and live chelonians are commonly available at municipal markets and sometimes even in other public places in these interior cities of Amazonas State.

The Amazonian floodplain is a complex aquatic system that has become one of the main areas of operation of well-organized animal smugglers in Amazonas State. The Abufari Reserve, which was once erroneously considered by the riverside people as an inexhaustible source of hunting and fishing, is systematically losing its natural riches. Therefore, the objective of the present study was to evaluate the traffic activity of Podocnemis in the middle Purus River, with the hope that this research could be useful for environmental officials to aid them in inspection missions during critical periods of year.

METHODS

Study Area

The Abufari Reserve is located at 4°50′–5°30′S and at 63°20′–62°50′W, encompassing a total area of 288,000 ha. It is situated 30 km from the city of Tapauá, between the beaches of Beabá and Camaleão (Fig. 1). This reserve is drained by the Purus River, a right margin tributary of the lower Solimões River, which extends for 200 km (Fig. 2). The Purus River has a series of large white sand beaches of constant, firm, and uniform texture. These beaches are all of a possessing a saliencies that oscillates between gambols and sand banks, including water wells and various water springs that disappear in the middle of October when the river level drops and the beaches become larger.

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Monitoring

In 2000 and 2001, the Brazilian Environmental Institute (IBAMA) base, located in front of Abufari Beach, confiscated animals and trawl nets in the possession of smugglers. The capa-saco (chelonian trawl net) was the principal tool used to capture the chelonians (Fig. 3). Without buoys, and being heavily weighted at the bottom, this trawl net opens up in the form of a sack and is placed across a medium-size stream that has a strong water flux. Consequently, this net is difficult to detect, because it lies well below the water line. When chelonians try to escape, the strong water flow captures them in this net. All of the chelonians confiscated belonged to only 3 registered aquatic species, most of them being Podocnemis sextuberculata (Cornelia 1849), which were as long as 28 cm and weighed more than 4 kg, then P. expansa, which reached 60 kg and 80 cm in length; and finally Podocnemis unifilis (Troschel 1848), which usually weighed about 8 kg and were 40 cm in length.

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RESULTS AND DISCUSSION

The Abufari Reserve is found within the Purus River waterway, which has constant traffic of boats, ships, and canoes. These vessels are routinely detained at the IBAMA base for a mandatory inspection of documents for fishing and equipment. During 2000 and 2001, 550 fishing vessels (iceboats: boats with ice on board to preserve fish), 120 regional transport vessels, and 92 wooden canoes were inspected, of which 6 iceboats, 8 regional boats, and 12 canoes were found transporting chelonians (Table 1). As well, in 2000 and 2001, 122 chelonian trawl nets were seized in Abufari Reserve. About 70% of these were on the Abufari River, and the rest were on the Purus River, its tributaries, and associated water channels. When considering the 3978 chelonians confiscated during these 2 years, 55% were taken from the Abufari River, P. sextuberculata (83.63%), P. expansa (10.41%), and P. unifilis (1.78%). Morphometry data of these same chelonians that were seized in the works are shown in Table 2. The more regular capture of these species occurred during the period when the water level of the Purus River was between 1000 and 1400 cm (Fig. 4A) (number of P. expansa = 91.98–0.038 [water level], n = 10, p < 0.05, R² = 0.36; and number of P. sextuberculata = 496.7–0.18 [water level], n = 14, p < 0.05, R² = 0.3).

Table 1. Most significant seizures apprehended on the Abufari Reserve in 2000 and 2001: the date, period, locale, method of transportation or hideout, Podocnemis species and quantity of animals.

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Table 2. Morphometry of some Podocnemis species confiscated in many locales of Abufari Reserve in 2000 and 2001 with individual number (N).^a

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These confiscates not only demonstrate their relation to the stage water level but also in accordance to the flood pulse of the river system in general. It was during these low phases that the large numbers of chelonians were confiscated. The trawl nets were subsequently seized during a period that coincided with the chelonians (Fig. 4B) (number of trawl nets = 31.57– 0.01 [water level], n =  54, p < 0.05, R² = 0.52). The above values only indicate seizure estimates of chelonians, when, in reality, there are probably large variations in the number of animals taken from smugglers each year. In the single month of August of 1999, 38,000 chelonians were taken from 1 ferry that was used to transport cargo along the Solimões River (Cavalcanti 1999). The large number of seizures registered in this study may possibly represent only a small fraction of the total number of chelonians taken from the Purus River and the rest of Amazonas State. The number of animals apprehended in relation to the number of nets was considered low. This could indicate that the nets were taken away before the offenders made their catch or that they escaped from the reserve with many animals, without being caught by forest agents.

The amount of trawl nets confiscated on the Abufari River indicates the local migration and trajectory of chelonians in the reserve. However, the large number of animals confiscated and clandestine campsites along the margin of interior lakes belonging to the Chapéu Complex indicate that the perpetrators prefer not to remain on the margins of the Abufari River but rather in more protected sites that are removed and isolated (Table 1). Most seizures of chelonians occurred when the water level of the Purus River was between 1000 and 1400 cm. Most confiscates of P. expansa and P. sextuberculata occurred between the end of the dry season, during the months of June, August, October, and November (Fig. 4). However, catches of P. sextuberculata were confiscated over a much longer period than P. expansa, which shows that P. sextuberculata present a migratory behavior less selective than P. expansa in terms of water-level change, this is perhaps because of its smaller size, more solitary behavior, and a larger number of individuals in population.

The difficulty in inspecting vessels, combined with innumerable methods that smugglers have invented to conceal illegal material and elude the inspectors, has made it very challenging to control trafficking. However, without constant and effective policing, perpetrators will continue to take advantage of these prohibitions to make an even greater profit. Unfortunately, in this Amazon paradise the animal hunting is facilitated by the sheer abundance of organisms and a lack of sustainable development resource policies, along with greater backing of solid investments in environmental education.