TED Case Studies

Nile Perch, Trade and Environment

     CASE NUMBER:   206
     CASE MNEMONIC: PERCH
     CASE NAME:     Nile Perch, Trade and Environment

A.   Identification

1.   The Issue

    In forty years or less, virtually all of the natural, 
biological "wealth" unique to Lake Victoria has been 
destroyed.  At one time the lake contained over 400 
endemic species of haplochromines whose extraordinary 
diversity and speed of evolution were inspiring to 
scientists concerned with "the forces that create and 
maintain the richness of life everywhere."1  Today, a mere 
handful of species exists, threatened on one hand by a 
fearsome enemy - the Nile perch (Lates niloticus) - and on 
the other by the lake's changing conditions.

2.   The Description

    Due to the presence of the Nile perch, the natural 
balance of the Lake Victoria ecosystem has been disrupted.  
The food chain is being altered and in some cases, broken, 
by the indiscriminate eating habits of the Nile perch.  
The subsequent decrease in the number of algae-eating fish 
allows the algae to grow at an alarming rate, theregby 
"choking" the lake.  The increasing amounts of algae, in 
turn, increase the amount of detritis (dead plant 
material) that falls to the deeper portions of the lake 
before decomposing.  As a byproduct of this decompostion, 
the oxygen levels in the deeper layers of water are being 
depleted.  Without oxygen, any aerobic life (such as fish) 
cannot exist in the deeper portions of the lake, forcing 
all life to exist within a narrow range of depth.  In this 
way, the Nile perch has degraded the diverse and thriving 
ecosystem that was once Lake Victoria.

    The abundance of aquatic life are not the only 
dependents of Lake Victoria.  More than thirty million 
people in Kenya, Uganda, and Tanzania rely on the lake for 
its natural resources.  The fishing industry, in 
particular, is suffering.  With traditional food sources 
all but extinct, and nets continuously damaged from the 
sheer force of the Nile perch, local fisheries have had to 
abandon their work.  The costs of scarce wood that is 
burned to dry the Nile perch and of large processing 
plants that are built to prepare the fish for market 
preclude many fisheries from entering the Nile perch 
market.  Only fisheries with large financial resources 
have been able to switch to catching the Nile perch.  
Given time, however, the supply of Nile perch will 
diminish as its food supply dwindles, making these 
fisheries unsustainable.

    The following is the story of Lake Victoria and the 
results of an historic meeting in which scientists, 
resource managers, and policy makers came together to 
create an agenda to rehabilitate it.

    Lake Victoria's ecology and natural resource base has 
been dramatically altered through the introduction of the 
Nile perch (Lates niloticus).  In the 1950s, a proposal to 
increase fish catches in the lake by introducing the Nile 
perch was adamantly opposed by scientists who feared that 
the lack of a natural predator for the fish would result 
in the imminent destruction of the lake's bountiful 
ecosystem.  Despite the controversy, a colonial fisheries 
officer was ordered to clandestinely put the Nile perch 
into the portion of the lake that is in Uganda.2  
Thereafter it was introduced intentionally in both 1962 
and 1963.  By 1964 the Nile perch was recorded in 
Tanzania, by 1970 it was well established in Kenya, and by 
the early 1980s it was abundant throughout Uganda, 
Tanzania, and Kenya, the three countries surrounding Lake 
Victoria.

    Having no natural predators in the lake and a plethora 
of food, the Nile perch flourished, often reaching up to 
250 kgs., forcing it to eat constantly to sustain itself.  
Such eating habits are no longer sustainable.  The Nile 
perch has caused mass extinctions among haplochromine 
populations.  With little available food sources 
remaining, the Nile perch has taken to cannabalism with 
the larger fish feasting on the smaller ones.

    Hundreds of endemic species that evolved under the 
special conditions offered by the protection of Lake 
Victoria have been lost due to extinction, and several 
more are still threatened.  Their loss is devastating for 
Lake Victoria; the fields of ecology, genetics, and 
evolutionary biology; and more evidently, for the local 
fisheries.

    Local fisheries once depended on catching the 
tilapias, catfishes, carps, and lungfishes that comprise 
the local diet.  Today, the compositions and yields of 
such fish catches are virtually negligible.  Extensive 
fish kills, Nile perch, loss of habitat, and overfishing 
have caused many fisheries to collapse and many protein 
sources to be unavailable at the market for local 
consumption.

    Few fisheries have been able to make the switch to 
catching the Nile perch which requires a significant 
amount of capital resources.  Unlike traditional fish 
catches, the Nile perch must be dried over a fire; relying 
on large amounts of scarce wood for fuel has led to an 
increasing rate of deforestation.  After drying, the fish 
is either transported to the local markets or prepared for 
export.  Selling Nile perch at the local markets is not 
the most profitable option for the fisheries.  One 
explanation is that its unpopularity has kept it from 
being fully integrated into the local diet.  A second 
explanation is that there are few fisheries with the 
technology, capital, and infrastructure to move the fish 
further than local markets, let alone export them, so 
local market prices are kept relatively low by the surplus 
of supply over demand.

    A small number of processing plants have been 
established to filet, freeze, and prepare the Nile perch 
for export to Europe and Israel where it will receive a 
higher market value.  In Kenya, Israelis were snuck in to 
assist with the building of processing plants.  54.9% of 
their export volume went to Israel and 22.8% to Spain in 
1987.3  General lack of control over the processors and 
exporters is resulting in the heavy exploitation of the 
Nile perch without any concern to the sustainability of 
the fisheries.

    An important off-shoot of this problem is that the 
socio-economic characteristics of the fisheries 
populations are changing as the inequalities of economic 
opportunities increases, creating a widening gap between 
those with access to capital resources and those without.

    Researchers, conservationists, and policy makers met 
in Jinja, Uganda in 1992 to discuss options to 
rehabilitate Lake Victoria.  Several groups were convened 
to prioritize research needs and develop recommendations.  
The following is a comprehensive list of issues the groups 
concerned themselves with during this period:

    a. riparian wetland ecotones
    b. fish biology, management, and conservation
    c. fisheries management
    d. biodiversity and conservation
    e. socioeconomics
    f. fishery policy, management, and socio-economics
    g. commodity systems and the dynamics of capital
    h. fisheries management and extension
    i. immobility and persons at risk
    j. nutrition and fisheries
    k. fisheries regulation and development
    l. limnology and environment

    At the conclusion of the meeting a long and detailed 
list of resolutions was compiled.  Resolutions important 
to this case include:

a. captive propagation of native species of food fish;
b. restoration and rehabilitation of indigenous stocks;
c. overfishing of Nile perch in specified areas; and
d. expansion of aquaculture to help meet basic needs.

    More importantly, the decision was made to combine 
research, disseminate information, enforce regulations, 
and coordinate fisheries development and management among 
the three riparian states.

3. Related cases

TILAPIA Case