| dc.description.abstract | The quality of landed Nile perch (fates niloticus) in Lake Victoria was investigated within
two months of a preliminary survey and five months of the main study. The main
objective was to establish the extent of contamination as raised by members of the
public and the European Union (EU), which led to import bans between 1996 and 1999
and to provide evidence-based information to enable remedial measures that would
assist in reviving confidence of the fish market. The study utilized bacterial counts and
organochlorine pesticide residue concentrations in fish and the environment as
parameters of pollution. The preliminary survey between September and November
2000 included interviews with stakeholders of the industry, observation visits to the
landing beaches and sampling of fish and the environment for chemical and
microbiological analysis using standard laboratory methods. Sampling sites included
three beaches along the Kenyan shore line, Dunga, Uhanya and Usenge, and river
Nyando. Observations indicated poor sanitary conditions at the landing facilities, low
hygiene standards and uncontrolled human activity. Results of analysis showed high
levels of bacterial contamination in both fish and environment and organoclorine
pesticides residues were detected. Public awareness on environment destruction and the
implications of the fish ban was established during interviews with both fishermen and
processors, and was highly highlighted by the mass media. Based on the findings of the
preliminary survey, the main study carried out between February and June 2001
investigated four landing beaches which included, Dunga, Usenge, Kaloka and Osieko,
and one river, Yala.
A total of 120 fish samples were analyzed for microbial counts and 118 for
organochlorine pesticide residues. Total viable bacteria count ranged between 104-107/
cm2 on fish skin surface and total coliform count for the same was 101-104 MPN/cm2•
Total viable count in beach sediment ranged between 104-106/g and total coliform count
for the same was 101-104 MPN/g. Coliform bacteria counts in water ranged between 103104
MPN/100 ml. Both fish and environment were contaminated with coliforms of faecal
origin in all study locations except Kaloka beach. Although the levels of bacterial counts
in fish were higher than the FAD threshold levels, the microorganisms are destroyed
during cooking, and should therefore pose no serious health hazard to the consumer.
However, some pathogenic bacteria are known to produce heat stable toxins which can
pose hazards to the consumer. The presence of faecal coliforms in fresh fish is not
acceptable according to FAO standards. Poor handling could be instrumental to the high
levels of bacterial contamination detected in most of the sampling sites. The study also
looked at the monthly trends in bacterial contamination and the interaction between
location and month. Accumulated analysis of variance showed a highly significant month
and location effect (p<O.OOl) with respect to beach environment contamination by
faecal coliform, and interaction between month and location was also highly significant
at 5.0% confidence level. Fish surface contamination with faecal coliform was
independent of season and the location effect was not significant. The study concluded
that the beaches investigated were not significantly different with respect to sanitary
status and hygiene attitudes, as reflected in fish surface contamination.
Organochlorine pesticide residue levels ranged between 2.0 - 6280 I-lg/kg wet weight in
fish liver and 1.0 - 517 I-lg/kg, wet weight in muscle. In total, 11 out of a spectrum of 13
pesticide residues were detected in fish, which included those banned for use in the
Kenyan environment, i.e. Heptachlor, Endrin, HCH (BHC), Aldrin and Dieldrin. Pesticide
residue concentrations ranged between 2.0 - 248 !-l9/kg wet weight in sediment, and
between 1.0 - 312 I-lg/ml in beach waters. These findings identify the landing beaches
as critical control points for hazards associated with fish contamination. According to
FAa/WHO standards, fish and its growing environment should be completely free from
any pesticide contamination. Lake Victoria environment did not meet these standards.
The overall conclusion was that public concerns over the pollution of the lake
environment have a basis and are paramount in that the level of contamination has a
direct bearing on the market value of the lake's fish and fishery products.
The study also concluded that the concerns of the EU market and import bans were
justified and that the negative perception of the industry could only be reversed through
deliberate efforts by all the stakeholders of the industry to control pollution.
The study recommendations include a well-defined and sustainable monitoring system
of the lake environment for fish and water quality. Based on the results of this study, a
more comprehensive survey of the lake will be put to place, addressing other pollutants
such as heavy metals and polychlorinated biphenyl's. | en |
