Research
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The insiders on the background and work of the LAMPI foundation know that the Sábalo (Prochilodus lineatus) is both
economically and ecologically the most important fish in the Pilcomayo river. The many millions of specimens of the Sábalo
that swim up the river every year provide employment, income and an important source of food for the inhabitants of the
communities along the River. In addition the Sábalo also plays a key role in the carbon cycle of the River. Despite the
importance of this fish there is still relatively little knowledge about the ecology of this species in the Pilcomayo. It is known that
individuals of this species during the dry period (May to October) migrate up the river to spawn, but where exactly they come
obstructions are created in the migration route, have consequences for the population in the upper regions? To protect the
population in the upper regiosn what growing areas are important? To get answers to these questions it is necessary to know
more about the migration behavior of these species.
There are different methods to research the migration routes of animals. One of the ways is to put a transmitter on some
animals in the population that emits signals that can be captured for example by a satellite. This method is particularly suitable
for studying larger animals because the transmitters often require rather large (and heavy) batteries. In the case of research on
the migration behavior of fish this happened to be very difficult. In the Netherlands, research on fish is done with smaller
transmitters that send a signal only at the time they pass a socalled detection line. Unfortunatly, working in the Pilcomayo also
makes this very diffecult. This because the Pilcomayo river, in contrast to the beautiful straightened and set rivers in the
Netherlands, changes location each year, is sometimes several kilometers wide, transports large quantities of sand, twigs and
trees. There are also barely any places along the river with the needed power and suitable locations for the computer that picks
up the signals. However, in order to gather information on the migration behaviour of Sábalo, we used a little less high-tech
method. A large number of fish where provide with a small mark. This mark consists of a small plastic tube that uses a nylon
thread to attach to the fish. Through posters, radio and TV publicity knowledge of these marks is given to this work and
fishermen who catch a tagged fish. They are asked to report catches, the number of the mark, fishing location, dat and method
of fishing. In return they receive a small compensation in the form of a fillet.
economically and ecologically the most important fish in the Pilcomayo river. The many millions of specimens of the Sábalo
that swim up the river every year provide employment, income and an important source of food for the inhabitants of the
communities along the River. In addition the Sábalo also plays a key role in the carbon cycle of the River. Despite the
importance of this fish there is still relatively little knowledge about the ecology of this species in the Pilcomayo. It is known that
individuals of this species during the dry period (May to October) migrate up the river to spawn, but where exactly they come
obstructions are created in the migration route, have consequences for the population in the upper regions? To protect the
population in the upper regiosn what growing areas are important? To get answers to these questions it is necessary to know
more about the migration behavior of these species.
There are different methods to research the migration routes of animals. One of the ways is to put a transmitter on some
animals in the population that emits signals that can be captured for example by a satellite. This method is particularly suitable
for studying larger animals because the transmitters often require rather large (and heavy) batteries. In the case of research on
the migration behavior of fish this happened to be very difficult. In the Netherlands, research on fish is done with smaller
transmitters that send a signal only at the time they pass a socalled detection line. Unfortunatly, working in the Pilcomayo also
makes this very diffecult. This because the Pilcomayo river, in contrast to the beautiful straightened and set rivers in the
Netherlands, changes location each year, is sometimes several kilometers wide, transports large quantities of sand, twigs and
trees. There are also barely any places along the river with the needed power and suitable locations for the computer that picks
up the signals. However, in order to gather information on the migration behaviour of Sábalo, we used a little less high-tech
method. A large number of fish where provide with a small mark. This mark consists of a small plastic tube that uses a nylon
thread to attach to the fish. Through posters, radio and TV publicity knowledge of these marks is given to this work and
fishermen who catch a tagged fish. They are asked to report catches, the number of the mark, fishing location, dat and method
of fishing. In return they receive a small compensation in the form of a fillet.
Migration routes of the Sabalo
Last July, the LAMPI team was approached by Proyecto Pilcomayo with to ask
whether there was any interest to participate in a project involving the marking of a
total of 10,000 Sábalo's. The decision was taken quickly and with a team of three
people being Roberto Salazar, Cesar Pizarro and Max van de Ven, the preparations
for this project were made. The biggest handicap was the fact that the marking of
the fish should preferably take place at a spot where the fishing pressure was as
low as possible. This in order to ensure that all marked fish would not directly
swim back into the nets of other fishermen.
A location about 50 km upstream of Villa Montes was chosen for the marking of the
fish. One week long the the team was lead by a half-dozen local fishermen in their
rowing boats, and moved from place to place, determined to catch 1,000 fish
needed for this project to become a success. When the team ran out of provisions
about three days into the trip, from then on the menu was largely limited to fish and
river water. The presence of many panther tracks in the sand along the river made
staying along the river even at night exciting.
After five days, working of our behinds, the team returned back home tired but
happy. In total, 812 fish received a little mark. Slightly less than the target figure of
1000 but given the circumstances a very good result. Now, almost a month after the
marking of the fish, there are now 12 reports of fish caught, returned to the office.
Half of this catch was reported back during the first week after marking. Of the fish
that were recovered 80% were found downstream from the marker location and
20% upstream. The greatest distance so far traveled by a female that was caught
exactly 1 week after being highlighted, she travele about 60 km upstream from the
marker location. The marking of these nearly 1000 Sábalos was the first step to
increase knowledge about the migratory behavior of Sábalo. Because of the
relatively low percentage of fish being caught back it will be necessary to continue
this kind of markers in the future. Hopefully the team LAMPI will be invited again to
participate with this investigation.
whether there was any interest to participate in a project involving the marking of a
total of 10,000 Sábalo's. The decision was taken quickly and with a team of three
people being Roberto Salazar, Cesar Pizarro and Max van de Ven, the preparations
for this project were made. The biggest handicap was the fact that the marking of
the fish should preferably take place at a spot where the fishing pressure was as
low as possible. This in order to ensure that all marked fish would not directly
swim back into the nets of other fishermen.
A location about 50 km upstream of Villa Montes was chosen for the marking of the
fish. One week long the the team was lead by a half-dozen local fishermen in their
rowing boats, and moved from place to place, determined to catch 1,000 fish
needed for this project to become a success. When the team ran out of provisions
about three days into the trip, from then on the menu was largely limited to fish and
river water. The presence of many panther tracks in the sand along the river made
staying along the river even at night exciting.
After five days, working of our behinds, the team returned back home tired but
happy. In total, 812 fish received a little mark. Slightly less than the target figure of
1000 but given the circumstances a very good result. Now, almost a month after the
marking of the fish, there are now 12 reports of fish caught, returned to the office.
Half of this catch was reported back during the first week after marking. Of the fish
that were recovered 80% were found downstream from the marker location and
20% upstream. The greatest distance so far traveled by a female that was caught
exactly 1 week after being highlighted, she travele about 60 km upstream from the
marker location. The marking of these nearly 1000 Sábalos was the first step to
increase knowledge about the migratory behavior of Sábalo. Because of the
relatively low percentage of fish being caught back it will be necessary to continue
this kind of markers in the future. Hopefully the team LAMPI will be invited again to
participate with this investigation.