Commercial Fishing of Arapaima gigas (Paiche) in the Bolivian Amazon

The introduction of species outside their natural habitat is a phenomenon that has occurred on different scales. This phenomenon is an important part of the global environmental change caused by humans. A notable example of this is the commercial fishing of Arapaima in Bolivia. Although this activity can bring some benefits, it also disrupts the natural isolation between populations. These populations have evolved separately over time. In many cases, the introduction of species outside their natural range alters the structure of native communities. This can generate negative effects, which are sometimes irreversible.

Ecosystems in lakes and rivers have been particularly affected by invasive species, especially fish. This has occurred due to initiatives such as promoting sport fishing, aquaculture, and consumer fishing. Creating a new fish resource involves introducing species into existing water bodies. This can alter the receiving ecosystems to adapt to the new inhabitants. Introduced species, such as Arapaima gigas in Bolivia, compete with native species for food, shelter, or breeding sites. Additionally, they can bring diseases and parasites that affect local fauna. Hybridization with local species can reduce genetic diversity in these ecosystems.

A species is considered invasive when it has a significant ecological or economic impact in its new environment. However, measuring these impacts can be complex. In some cases, the negative ecological effects may be accompanied by economic benefits. This has been observed with the commercial fishing of Arapaima in Bolivia.

Introduction of Fish in South America

In South America, the introduction of fish has occurred on different scales and in various countries. Numerous studies document the introduction of species from other continents. Introductions have also been made between different basins and within the same basin. These actions, as in many other regions of the world, were primarily motivated by aquaculture. Sport fishing and the use of ornamental fish were also significant reasons. In many cases, these introductions were promoted by governments and development organizations.

In Bolivia, there is little information about introduced fish. However, it is known that at least eight species have established themselves in natural ecosystems. Examples of these species include Ochorynchus mykiss, Odontesthes bonariensis, Cyprinus carpio, and Gambusia affinis in the Andean region. In the lowlands, Arapaima gigas, Semaprochilodus insignis, Oreochromis niloticus, and Poecilia cf. reticulata have been introduced. These species have adapted well and, in many cases, negatively impacted native species populations. In particular, the commercial fishing of Arapaima in Bolivia has led to significant reconfiguration of the local fishing industry.

The case of Arapaima gigas in the lowlands of Bolivia is especially notable. Although little is known about its impact on local ecosystems, this species has significantly influenced fishing and fish production in northern Bolivia. Before 1994, Arapaima did not appear in the country’s commercial fishing records. However, within a few years, it has become a key species. Currently, it represents more than 50% of the total catch in the Amazon region. In less than a decade, it has assumed an important role in commercial fishing, solidifying itself as an invasive species in Bolivia.

Methods

Knowledge about the species was primarily gathered from the available literature from Brazil, Colombia, and Peru. The current distribution of the species in the Bolivian Amazon was established through records and field observations. These were conducted in the main systems of the country between 2002-2003 and 2006-2008.

To analyze the fish production chain in northern Bolivian Amazonia, a flow diagram was created. This was based on information obtained from interviews and workshops held in Riberalta in 2006 and 2008. The information also served to evaluate the composition and volume of the catches. It came from comments by fishermen, leaders, traders, and others involved in the marketing of fish. The described chain focuses on fish captured in the commercial fishing area of Riberalta. This area includes territories of several indigenous and peasant communities that are part of the production process (Van Damme, 2006).

Synthesis of Knowledge About the Species

1. Identification and Natural Distribution

Arapaima gigas (Schinz in Cuvier, 1822) is the only recognized member of the family Arapaimatidae. This family belongs to the primitive order of Osteoglossiformes (known as “bony-tongue” fish) in South America (Ferraris, 2003; Berra, 2004; Lavoué & Sullivan, 2004; Nelson, 2006). This fish is one of the largest in freshwater environments. It can reach sizes of 3 to 4 meters and weigh over 200 kg (Ferraris, 2003; Berra, 2004; Nelson, 2006).

2. Ecology

Studies in captivity and natural environments have shown that Arapaima gigas has a primarily carnivorous diet. It feeds on fish, decapods, and other small aquatic animals. The introduction of this species in Bolivia has modified local food chains. This has generated controversy regarding its long-term impact, particularly on the commercial fishing of Arapaima in Bolivia.

3. Life Traits

The reproduction of Arapaima gigas can occur throughout the year. However, it intensifies when water levels rise. During these times, suitable areas for building nests become accessible in the forests (Fernandes, 2005; Saavedra et al., 2005b).

The commercial fishing of Arapaima in Bolivia has generated significant economic opportunities. However, it also poses ecological challenges. These challenges must be monitored to ensure the sustainability of local ecosystems.

4. Conservation genetics

Arapaima gigas has a karyotype with 28 submetacentric/metacentric chromosomes and 28 subtelocentric/acrocentric chromosomes. No visible differences between sexes are observed at the chromosomal level. This species presents simple nucleolar organizer regions (NORs) with structural polymorphism in terms of size (Marques, 2003).

Population studies based on nuclear DNA microsatellites (Farias et al., 2003; Hrbek et al., 2007) have shown high genetic flow between various populations. This flow has been observed along the main axis of the Amazon River. Similar results were found using RAPDs in the Araguaia River (Marques, 2003).

Studies with microsatellites revealed high genetic variability among populations. Additionally, a correlation was found between genetic and geographic distances, indicating isolation by distance. Significant differences were observed between populations separated by 2,500 to 3,000 km. Mitochondrial DNA analyses showed important haplotypic variability. However, little historical divergence was detected between localities and no clear relationship between genetic and geographic distances.

Reserve today and contact us to schedule your eco-educational trip about Arapaima in Bolivia! Dive into the fascinating story of Arapaima gigas in the Amazonian ecosystems of Bolivia. This unique trip offers: