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Ecology

Fish and taboos on the Negro river

The position of species in the food chain determines their likelihood for consumption or their prohibition

RENATO SILVANO / UNICAMPFishing close to Manaus: the consumption of a large variety of fish minimizes the impact of exploration of a speciesRENATO SILVANO / UNICAMP

For a period of two years, between 1850 and 1852, the English naturalist Alfred Russell Wallace traveled up and down the Negro river, one of the main tributaries of the Amazon river. It was one of the first scientific expeditions to the region and resulted in the description – by way of drawings and annotations – of 212 species of fish, only now represented in a book. Through the same coffee colored waters, a century and a half later, cruised a team from the State University of Campinas (Unicamp), who interviewed the riverside populations – on the stretches between Ponta Negra, close to the city of Manaus, and the Jaú river, on the right hand side margin – and verified the eating taboos that regulate the consumption of fish.

For example, menstruating women and sick people should not eat certain carnivorous fish, probably because, in the evaluation of the researchers, they are at the top of the food chain and have the highest probability of accumulating toxins. There are also fish that are prohibited for normal consumption as they have a priority for medical use. The ray, for example, is not a carnivore, and has a strong taboo for eating: its fat is used to counteract asthma, coughing and pneumonia.

“Diet if a form of dealing with illnesses”, comments Alpina Begossi, responsible for the project, which has resulted also in the book Peixes do Alto Rio Juruá [Fish of the Upper Juruá River] (co-edition Official Press, Edusp and FAPESP). “There are species of fish recommended for the consumption by sick people and others explicitly with medical problems.” According to her, the banning of the foods – also found among the native population of the São Paulo Atlantic Rainforest, interviewed during research financed by FAPESP during 1992 – could be the result of the influence of Portuguese colonization: by way of the colonization, these populations may have assimilated ancient sanitary preconceptions derived from Hippocratic medicine and even from the rules of purity that the Bible established in the Book of Leviticus.

Carnivores and fruit eaters
In the region of the river Rio Negro, among the carnivorous fish that are taboo for eating by sick people is included the tiger shovel-nosed catfish (surubim in Portuguese – Pseudoplatystoma fasciatum), whilst the red hooked silver dollar (pacu in Portuguese –Mylosssoma rubripinnis) and the Oscar (Astronotus ocellatus) are of the opposite extreme: they eat invertebrates or fruit and are highly recommended. Other fish dishes to be avoided – seen as a burden or oppressive for human consumption – are the piranha (Serrasalmus spp), the white-stripped pimelodus (mandi in Portuguese, Pimelodus albofasciatus), the catfish (filhote in Portuguese – Brachyplatystoma filamentosum) and the pirara (Phractocephalus hemeliopterus).

The discoveries about the Negro river reinforce data obtained in other regions of the Amazon basin, such as on the Araguaia, Juruá and Tocantins rivers, which the Unicamp researchers had covered focusing on the relationship of the riverside population with the aquatic resources and the vegetation in two approaches. The first is ethnobiology, which deals with the perception and classification of the fauna, and the second, human ecology, which defines the use of space, the tactics for obtaining resources and the models of subsistence of the riverside communities.

The Unicamp team intends to use the information that it obtained to give guidance to projects of sustainable development, in a region already threatened: according to the local inhabitants, the region of the Negro river above the town of Barcelos, in the state of Amazonas, is disputed by companies for the exploration of ecotourism in closed areas, without giving access to the local fishermen. On this point, the survey reinforced observations carried out in other fishing regions. “In areas skirting the river the Araguaia river, sports fishing, supported by government environmental agencies, is contributing to the destruction of local fishing, a source of subsistence and of local income, with the sustained management possibilities and integration of the ecosystem”, comments Alpina. One of the goals of the survey that she coordinated is exactly about legal demarcation zones of fishing areas, just as Japan did some years ago.

The recipe for management was already there – it only was recognized by the researchers. The know-how of the river dwellers contains a series of guide lines that serve perfectly as a recipe for sustained management. One of them is the resource of having the greatest possible diversity of medicinal plants, a manner of minimizing the impact of the collection of a single species. In agriculture, the river populations of the Negro river give value to the diversification and genetic improvements in cultivated products – the case of the cassava (Manihot esculenta) is the best example. Nivaldo Peroni, a researcher with the group, verified the existence in the region of nothing less than eighty eight varieties of cassava, all of them resulting from management carried out by the local populations, probably through a passing on of Indian know-how.

In the case of plants, it was sought to estimate with what intensity the forest is used – a parameter for the eventual creation of an extraction reserve. It was discovered in that location a very high vegetal diversity was being made use of: the seventy three interviewees, corresponding to half of the population at the mouth of the channels on the right hand margin of the Negro river, cited 99 species that they knew of and that they eventually explore for diverse ends. A similar survey taken in the middle section of the river Araguaia by the same Unicamp team revealed an even greater diversity: 151 species were cited by 96 people interviewed – certainly due to the greater environmental richness of the region, which includes types of Cerrado (wooded savanna).

In the same manner, the knowledge and the consumption of a large variety of fish minimize the impact of the exploration of a particular species. The occurrence of eating taboos, exactly to impose restrictions, diminishes the predatory pressure. Finally, two practices with implications for administration: the exploration of the environmental diversity with technologies of different types of fishing, according to the area and the species, and the informal division of fishing territories between groups of fishing communities, which impedes the superimposition of fishing grounds.

In an evaluation of the fish being landed at the town of Barcelos, the focal point of the survey, where Andréa Leme developed her thesis for her doctorate degree, it was verified that the tactic for fishing most widely used (92%) is the zagaia, a type of wooden spear. Practiced at night, it requires a detailed knowledge of the habitat and of the behavior of the fish. Upholding the low population density of the region, the zagaia is a non-predatory practice: the fisherman captures only the catch that he desires. The fish most sought after for consumption, without taboos, are the tucunaré (Cychla monoculus), aracu (Leporinus spp), (Brycon cephalus), pacu and the oscar, known collectively as the white meat fish.

To evaluate the knowledge of the riverside population about their fish, the researchers fell back on a simple procedure: they mounted a group of some twenty four photographs of species, presented to each interviewee in a random manner. They were shown to the fisherman who was then asked for the name of the fish, what it ate, where it lived and what family members (in the local language) it had. “The knowledge demonstrated in relation to the ecology of the different fish was spectacular”, comments Renato Silvano, a member of the team. “The fishermen’s replies were as exact and to the point to what scientific literature says, that they could serve as a basis for biological research.”

The researchers were surprised for another reason. “We use morphology for the classification of the species”, stated Alpina, “and the riverside fishermen also use ecology.” For example, for the scientists, piranha and pacu make up part of the same family, the Serrasalmidae. This is not the case Negro river population, who separate these two species taking into account their diet: the pacus feed on invertebrates and fruit – for this reason they are recommended to be eaten by sick people -, whilst the piranha are carnivores.

The information collected indicates to what point external impacts are modifying the diet of the riverside populations. In this case, the balance swings in favor of the populations on the Negro, when compared to those on the Araguaia. While in the region of the Negro 75% of animal protein is obtained locally, via fishing, in the Araguaia region local fishing has almost stopped, substituted by that of sports fishing. Alpina underlines: “Any policy of administration must take into account the accumulated knowledge of these populations and the rules of use already in existence about natural resources”. However, this is not what is happening. From her point of view, the country’s environmental policy is still inclined to go from the general to the particular in search of solutions, but she believes that things could be different.

A 150-year wait

Finally carrying out the dream of the British naturalist Alfred Russell Wallace (1823-1913), who divided with his fellow countryman Charles Darwin (1809-1882) the discovery of the mechanisms of the evolution of species. The book Peixes do Rio Negro [Fish of the River Rio Negro], organized by Mônica de Toledo-Piza Ragazzo, from the Biosciences Institute of the University of São Paulo (USP), and recently published by Edusp and by the Official Press, brings together 212 illustrations and annotations done by Wallace during his journey from 1850 until 1852 along the Negro and Uaupés rivers.

There are beautiful pencil drawings, very often done under adverse conditions, above all for a European. On his return to England, Wallace lost all of the specimens collected in a shipwreck. He only managed to save one metal box in which there were the drawings of the fish and the palm trees, which he kept with him for some fifty years, without managing to have them published. In 1905 he donated the drawings and manuscripts to the Natural History Museum, in the hope that they would be edited. Almost ninety years afterwards, Mônica rescued the forgotten material (see Pesquisa FAPESP nº. 55).

“For now, all of the illustrated species can still be found in the Negro river”, says the researcher. Among them are varieties of large size and commercial importance, such as the laulao catfish (Brachyplatystoma vaillantii), the catfish (filhote), the silver croaker (pescada in Portuguese (Plagioscion squamosissimus) and the surubim). But Wallace also attended to the smaller species, such as the transparent candiru (Paravandellia) and another that the Indians call rain fish (Rivulus tecminae), since it was supposed that they fell from the sky with the rain.

Fascinated by the richness of the ichthyological Amazon fauna, Wallace was also accompanied on his journey by locals of that period, who brought to him each day new species of fish, conserved in local white rum. From the indigenous tribes of the Rio Uaupés, the English explorer obtained artifacts, which were also lost in the shipwreck.

The project
Use of resources in the Negro river: Ethnoichthyology and Ethnobotany ofRiverside Populations (nº 98/16160-5); Modality Regular line of research assistance; Coordinator Alpina Begossi – University of Campinas; Investment R$ 67,603.98

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