Millions of Fish Dead in Bolivian Rivers
Authorities Explain What Really Happened

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ESPAÑOL In mid July millions of fish and other water life were found dead, floating down four major rivers in the Eastern department of Santa Cruz, Bolivia. Our original article on this ecological disaster garnered international attention and news forums across the globe filled with questions, doubts and even accusations of possible water pollution cover-ups. interviewed the Departmental Secretary of Sustainable Development and the Environment, Manlio Roca Zamora, of the Santa Cruz State Government, on Monday 09 August 2010 for more information.

This is the office directly charged with handling the response to this event.

Answers to the questions you posted in our forums

Q: The media initially announced that about 1 million fish had died, then raised that number to about 6 million several days later. Obviously no one can actually count the exact number of dead fish and wildlife, so how do you calculate how many truly died?

A: It’s an estimate, an average. A team of investigators was sent to visit the affected areas. They counted the number of fish dead in numerous sample sections of terrain, arriving at an average of 100 dead fish every 10 meters. This number includes only fish, and only those fish that washed up along the river banks. It does not include the possibly millions more that were being carried by currents in the water. Local villagers indicated the currents were sweeping large amounts of fish down the centers of the rivers, and that these masses of dead fish were “several fish deep”.

Q: That’s 10 fish per meter. Along how many kilometers of riverbanks have dead fish been found?

A: About 300 kilometers total. Four rivers were affected, the Grande River, the Piraí River, the Yapacaní River, and to a lesser extent the Ichilo River, all in the northwestern area of the department of Santa Cruz. This is the total of the lengths of affected areas of all four rivers. Most of the dead fish have washed up along curved areas where the rivers meander. Access is very difficult. It’s the jungle, there aren’t many roads. The affected area covers hundreds of kilometers. Along the river banks there is nothing but deep mud and rotting fish.

Q: That’s approximately 3 million fish.

A: Yes, but this calculation does not include any of the dead fish floating in the water and doesn’t include any other wildife. There are also huge numbers of dead river turtles , lagartos (alligators, caiman), capybara (the world’s largest rodent), and numerous types of birds, such as storks and “batos” (the tallest bird in South America), reptiles and other animals. Tens of thousands of fish also died in enclosed ponds in local fisheries. (Read our Bolivian wildlife page and the section on Bolivian wildlife by WWF Bolivia.)

Q: What species of fish were most affected?

A: We’ve found 27 species of dead fish so far. However, 4 species stand out as having been the most affected. What we’re seeing is that fish that do not have scales, such as the surubí, were more widely affected that fish that do have scales. We’re not yet sure why that is.

Q: You haven’t mentioned Bolivia's pink river dolphins (Inia boliviensis and Inia geoffrensis). News reporters stated river dolphins had died too.

A: We now believe the pink river dolphins were not affected. We haven’t found evidence of a single dead dolphin. Fortunately, our river dolphins inhabit an area that is enclosed and cut off from other sections of rivers. Because of this they appear to have been sheltered. The water in their section of the river was still 3.5 meters deep – deep enough for them to hover near the bottom where waters were just warm enough to keep them from experiencing hypothermia.

Q: In our forums numerous people allege that it’s not true all these millions of fish and other river life were killed by the cold. Some went as far as to say the rivers must have been polluted by industrial waste or poisonous chemicals “dumped” by clandestine cocaine factories. How can you be certain the cold weather caused these millions of fish to die and not something else?

A: Bolivia experienced the coldest winter in over 47 years in mid-July. Although it’s winter here and normal for us to experience sudden cold spells, this was the coldest winter on record in nearly half a century. Temperatures dipped to 0 degrees Celsius outside the water, and inside the water temperatures dropped to about 6 degrees Celcius. That’s about 10 degrees Celcius below our normal lows. The water along the river banks actually turned to frost, something that is virtually unheard of in the tropics. Bolivia’s tropical fish can withstand a dip in water temperatures to about 15 degrees Celcius before the cold adversely affects them. Below that they begin to experience hypothermia.

Q: But couldn’t the fish have swum to deeper waters where it’s warmer?

A: Normally the rivers are deeper than they are now. This area of Bolivia has been experiencing a drought. Although not as severe as the ongoing drought in the Chiquitania to the East or the Chaco to the South of the Department of Santa Cruz, the rivers are very shallow. Too shallow. This extreme cold spell lasted for 7 or 8 days, and the water was too shallow to stay warm enough at greater depths. For example, in the area inhabited by the river dolphins, the waters were only about 3.5 meters deep, at their deepest point.

Q: Is there any other way you can be completely certain that this disaster is not actually due to chemical dumping or another type of water pollution?

A: This disaster took place in four separate rivers, the Grande, the Piraí, the Yapacani, and the Ichilo, in various different, very separate places. In addition, tens of thousands of fish died in local fisheries where fish are separated by species or size in numerous ponds that are not connected to each other or to any rivers. It would have been virtually impossible for something of this magnitude, and in so many different areas, to be caused by chemical dumping or water pollution of some kind. In addition, Santa Cruz was not the only department affected. Large numbers of fish and water life also died North of Santa Cruz in the department of Beni and to a lesser extent in some areas of the department of Cochabamba. Even so, our investigators took water and soil samples in numerous places along the rivers to rule out that possibility.

Q: What does the government of Santa Cruz have planned in terms of clean-up?

A: We’re talking about hundreds of kilometers of river and river banks, millions of dead fish and other wildlife (thousands of tons of dead wildlife), and tropical jungle that is difficult, if not impossible to access in most places. We don’t have the resources, equipment, machinery or manpower to clean up everything, and even if we did there are no roads into most of these areas. To clean up the area by hand would be an even greater health risk. If someone were to pick up these contaminated fish and get cut by contaminated fish spines, which are full of bacteria, infection could occur. What we can do, is concentrate on the population which is, of course, our first priority.

Q: So what are you doing to inform and educate the population about possible health risks?

A: We’re using the media to get the word out. We’re running radio jingles throughout the affected area. We’ve prohibited any fishing in the area, including sports fishing. Many of these families fish for their own consumption and for sale to urban markets. That is forbidden now. This week the necessary legal decree will be issued to officially back this prohibition, which is already in place.

In urban areas, markets that traditionally sell fish from these rivers will be selling fish from other rivers and river basins, and even other countries such as Argentina. In addition, we’re now working to require fish sellers to provide a certificate of origin, much like the certificates of origin Bolivia requires of lumber companies.

Q: How long will this prohibition last?

A: There is no way to predict that. We’ll be testing the waters and the fish in the area periodically and will lift the prohibition species by species and river by river as time goes by. But regardless, the prohibition must last at least one year. The fish must be left alone for at least one cycle (one year) so they can begin to repopulate.

Q: What about the inhabitants of this area who depend of fishing for their own subsistence and for their livelihoods?

A: Fishing is not the primary source of subsistence for the population of this area. Most are primarily involved in agriculture and in raising livestock and fishing is a secondary source of income, so in that regard, this catastrophe hasn’t had a serious impact on the food supply. However, as an alternative we’re working on a plan to provide families with chicks to raise. The chickens will come from a CIAT farm (Centro de Investigación Agrícola Tropical, or Tropical Agriculture Research Center). Mostly we’ll be supplying them with both egg-laying hens and chickens to be used for food. In addition, for the first three months, while the chickens grow and begin to lay eggs, we’ll also be supplying soy-based foods to ensure the families consume sufficient protein.

Q: What about the water itself? Many of these communities completely depend on the river for fishing, bathing, washing, cooking, and drinking. What will these communities do for water now?

A: (He calls for a large recently printed map of the disaster area, tells me I am the first person to see it, and shows me the locations of numerous water wells). Deep water wells are already in place in many of these areas. Some are 200 to 300 meters deep. There won’t be a water shortage in the area, at least not in terms of drinking water.

Q: Can you be sure the water in the wells has not been contaminated?

A: We’ve tested the well waters and they have not been contaminated. But as an extra precaution, we’re delivering 60,000 water treatment pellets to ensure people are drinking clean water. The availability of drinking water isn’t an immediate problem.

Q: You mentioned the inhabitants of the area are mostly involved in agriculture. Don’t they depend on the river water for irrigation? Could that contaminate crops?

A: No, no one uses river water to irrigate crops. In fact, most farmers don’t practice irrigation at all, they depend completely on the rain because this is a tropical, rainy area. Although this year we’ve had less rain than normal, the drought this particular area has suffered has not been quite that serious.

Q: Do you foresee any other possible health problems?

A: There is the possibility of gastrointestinal problems appearing, but in the three weeks since this occurred, none have been reported in relation to this particular event, that we know of. However, in area health centers and hospitals, medical brigades and health care personnel are on alert for any signs of this.
09 August 2010


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