Pesticide Residues in Fish - Pesticides: Evaluation of Environmental Pollution - page 379

OCP residues were analyzed in samples of fish taken from four different locations along
the Indian Ocean coast of Kenya. Considering all the four sampling sites in the two sam-
pling seasons, the ranges of concentrations of residues detected in the fish samples (in mg/
kg ww) were as follows: lindane 16.1 (in sample from Mombasa)—1445 (Sabaki), aldrin 1.55
(Kilifi)—323 (Kilifi), dieldrin 4.81 (Ramisi)—109 (Sabaki), endosulfan 5.91 (Mombasa)—54.6
(Sabaki), p,p0-DDT 9.11 (Mombasa)—29.3 (Kilifi), p,p0-DDE 1.94 (Kilifi)—97.5 (Sabaki), and
p,p′-DDD 1.68 (Mombasa)—98.9 (Kilifi). The concentration ranges obtained in fish in this
study indicate that Mombasa Old Town was the least contaminated by organochlorine
residues as higher residues were detected near Malindi, at Funzi Lazy lagoon and at Kilifi
creek, which were near the confluences of Rivers Sabaki, Ramisi, and Goshi at the Indian
Ocean coast, indicating that the sources of the residues in fish of the Indian Ocean coast
were through discharge from the rivers. Seasonal variation in the concentration of residues
detected in fish samples was clear, with higher residue levels being recorded in the rainy
season in May compared with those detected in the dry season in January. This seasonal
variation was particularly observable in p,p′-DDT residues, which were only detected in
samples taken in the rainy season but not in those taken in the dry season in all the sam-
pling sites. The high DDT/DDE and aldrin/dieldrin concentration ratios also indicated
that the sources of these residues were recent. This conclusion was also supported by high
BCF values of lindane in fish sampled in Sabaki and of aldrin sampled from Kilifi and
Ramisi. Overall, the concentration ranges of some of the residues such as DDT, DDE, and
DDD were comparable with those reported earlier for fish samples from Lake Kariba in
Zimbabwe, but concentration ranges of lindane and aldrin were much higher than those
reported in fish from Lake Kariba. The concentration ranges of the residues of dieldrin,
lindane, and DDE were comparable with those obtained in fish from Tana River in Kenya
but the other residues of aldrin, endosulfan, DDD, and DDT were much higher than those
detected in fish from River Tana (Barasa et al. 2008).
The natural gifts of aquatic resources, fish, and other fishery items have played an
important role in the culture and lifestyle of the people of Bangladesh. Fisheries and
aquatic resources are economically, ecologically, culturally, and aesthetically important
to the nation. In Bangladesh, at present, there are 260 freshwater fish species, 12 species
of exotic fish, 475 species of marine fish, and 60 species of prawn and shrimp available
(Chandra 2006). Fisheries sector contributes to 5.24% of GDP (Gross Domestic Product),
63% of animal protein supply, and 4.76% of foreign exchange earnings for the nation
(Chandra 2006). During the winter season when the natural depression attains shallow
water and even dry up, there is huge amount of fish catches from freshwater and marine
water. During this time, the Bay of Bengal, the coastal crisscross channels, and other
depressions remain calm and quiet and are strengthened as a result fishing activities,
and huge fish are harvested during this period than the other seasons.
Long-term preservation of fish by drying is common practice in Bangladesh. This prac-
tice is usually carried out in the remote coastal isolated islands and inland depressions,
where chilling and freezing facilities are lacking. The finally dried fish products are gen-
erally stored in a dump warehouse near coastal towns. In addition to this, the weather is
humid, particularly during the monsoon period, and the dry fish absorb moisture rapidly
and become suitable for infestation by beetles and mites. The most unexpected cause of
infestation is improper drying of the fish by fishermen to prevent a large reduction in their
weight, as the fishermen earn more profit selling the dry fish having more weight. For the
protection of dry fish from infestation, they use a mixture of OC (DDT and heptachlor)
insecticides (Bhuiyan et al. 2008). Some analyses in Bangladesh show alarming pollut-
ants in fish like DDT and heptachlor (BCAS 1990). In Kuakata (a fish-processing zone in