THE STATUS OF FISHERIES AND FISHING ACTIVITIES OF THE SONDU-MIRIU RIVER DRAFT REPORT 2

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THE STATUS OF FISHERIES AND FISHING
ACTIVITIES OF THE SONDU-MIRIU RIVER
DRAFT REPORT 2
1. Dr. Raphael K. Kapiyo, Ph.D. (Natural Resource Management)-Team Leader
Maseno University
Department of Environmental Studies
P.O. Box 333
Maseno, Kenya
e-mail: kapiyo@pasage.africaonline.com
Tel: 0722-343984
2. Dr. Jacob K. Kibwage, PhD. (Environmental Planning and Management)
Maseno University
Department of Environmental Studies
P.O. Box 333
Maseno, Kenya.
e-mail: jkkibwage@hotmail.com
Tel: Tel: 0733-793604
3. Dr. Richard O. Abila, Ph.D. (Natural Resource Economics)
Kenya Marine and Fisheries Research Institute (KMFRI)
P. O. Box 1881
Kisumu, Kenya
e-mail: abilarichard@hotmail.com
Tel: 0733-922643
February 2003

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TABLE OF CONTENTS
TABLE OF CONTENTS .......................................................................................... 2
List of Tables ............................................................................................................ 3
List of Figures........................................................................................................... 3
EXECUTIVE SUMMARY ....................................................................................... 4
Physical Description of the River Sondu-Miriu.......................................................... 7
The Study Area ......................................................................................................... 7
Background to the Study ........................................................................................... 8
LITERATURE REVIEW ON THE FISHERIES OF SONDU-MIRIU RIVER........ 10
Fish species diversity............................................................................................... 10
The lower river........................................................................................................ 10
Fish catches in the Lower Sondu-Miriu ................................................................... 13
Fish migration ......................................................................................................... 13
Fishing methods in the Sondu-Miriu........................................................................ 15
Breeding and feeding of Sondu-Miriu fishes............................................................ 16
Potential threats to the Sondu-Miriu fisheries .......................................................... 17
Socio-economic Aspects of Sondu-Miriu Fisheries and Ecology ............................. 19
RESEARCH METHODOLOGY............................................................................. 20
Pilot Survey............................................................................................................. 20
Data requirements ................................................................................................... 21
Field Data Collection Methods ................................................................................ 21
Sample Selection Strategy....................................................................................... 22
Data Analysis, Interpretation and Presentation......................................................... 24
RESULTS AND DISCUSSION .............................................................................. 25
FISH SPECIES STATUS AND DIVERSITY ......................................................... 25
Fish diversity along the zones.................................................................................. 25
Species.................................................................................................................... 27
Perceptions of changing species composition over time........................................... 28
FISHING METHODS AND GEARS...................................................................... 30
Fishing gears........................................................................................................... 30
Expenditure on fishing gear..................................................................................... 33
Seasonality in fishing .............................................................................................. 35
FISH MARKETING AND PROCESSING ACTIVITIES ....................................... 37
Fish marketing ........................................................................................................ 37
Fish processing........................................................................................................ 40
IMPORTANCE OF FISH AND FISHING TO LOCAL COMMUNITY ................. 41
SUMMARY AND CONCLUSIONS....................................................................... 46
THE IMPACTS OF RIVER SONDU-MIRIU FLOW REGIMES............................ 48
REFERENCE.......................................................................................................... 55
APPENDIX............................................................................................................. 58
(a) Glossary............................................................................................................. 58
(b) Fish Species of the Sondu-Miriu ........................................................................ 59

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List of Tables
Table 1: Lower River Sondu-Miriu fish species....................................................... 14
Table 2. Fishing methods on the Sondu-Miriu ......................................................... 16
Table 3 Sampling Frame.......................................................................................... 24
Table 4: The status of fish species in the three zones of R. Sondu-Miriu.................. 27
Responses on presence status .................................................................................. 27
Table 4 Perceptions of status of fish stocks in R. Sondu-miriu................................. 28
Table 5 Perceptions of causes of stock declines ....................................................... 29
Table 6 Perception of relative importance of various fishing gears........................... 31
Table 7 Gear distribution among families ................................................................ 32
Table 8 Estimates of total amount of fishing gear owned......................................... 33
Table 9 Expenditure on fishing gear by families per zones (Ksh)............................. 34
Table 10 Expenditure on fishing gear by importance of fishing (Ksh)...................... 34
Table 11 Gears targeting various fish species in each river zone.............................. 36
Table 12 Local community’s fish market................................................................. 39
Table 13 Fishing groups/ co-operative..................................................................... 39
Table 14 Status of fish processing by respondents ................................................... 40
Table 15 Comparing costs of fresh and processed fish............................................. 41
Table 16 Reason for fishing..................................................................................... 43
Table 17 What happens to the catch......................................................................... 43
Table 18 Seasonality of fish supply ......................................................................... 44
Table 19 Importance of fishing to families............................................................... 45
Table 20 (a – c) Effects of flood regimes: Current status.......................................... 49
Table 21 Possible effects flow regimes Under KENGEN management.................... 52
List of Figures.
Figure 1 Sondu Miriu location map …………………………………………………..9
Figure 2 Local community’s source of fish.............................................................. 38
Figure 3 Fishing and Non Fishing Families in the three Zones................................. 42
Figure 4 Main sources of employment in Sondu-Miriu............................................ 44

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EXECUTIVE SUMMARY
This study was undertaken to determine the status of fisheries and fishing activities in
the River Sondu-Miriu, and to predict the impacts that operation of the Sondu-Miriu
Hydropower Project (SMHPP) might have on fisheries, fishing activities and other
socio-economic variables.
The study was implement through a series of activities, including a reconnaissance
survey, a pilot study and the field survey. The main field survey involved personal
interviews using questionnaires, key informant interview and participant observation
and photography. A stratified random sampling approach was used to select
respondents from each of the six river banks (of the upstream, depleted and lower
stream zones). In total 96 respondents were interviewed using a standard
questionnaire. In-depth interviews and follow-up visits were made to 7 key informants
in the three zones of the study area.
Quantitative data were processed using the SPSS and Microsoft-Excel computer
packages, while qualitative methods were employed to outline various intangible and
non-quantifiable issues.
The results obtained show that;
(i) Fish species diversity was highest in the lower stream zone followed by the
depleted zone (because of the section below Odino Falls) then the upstream
zone. Due to annual migration of riverine fish, the species composition changed
seasonally, especially in the lower stream and the depleted zone below Odino
Falls, with higher diversity during the flooded seasons.
(ii) Small Barbus spp (adel) and Small clarias (ndhira) were the main species
present in the upstream and depleted zone (above Odino Falls), both species
being of low commercial importance. The lower stream had nearly all the
common riverine species, although in varying quantities. The dominant species
were Small Clarias spp (ndhira), Schilbe spp (sire),Synodontis spp ( okoko),
Oreochromis leucosticus (ngege/ opat), Labeo spp. (ningu) and small Barbus

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spp (adel). The abundance of these species changed seasonally especially in the
lower stream and depleted zone below Odino Falls.
(iii) There has been notable decrease in fish stocks in the lower stream zone and the
depleted zone below Odino Falls, however, no significant change in stocks has
been observed in the upstream and the depleted zone above Odino Falls.
(iv) At least seven fish species were thought to have disappeared; in particular
,Alestes spp. (osoga), has certainly disappeared in the lower stream. Other
species thought to have disappeared were Labeo spp. (ningu) and large Barbus
spp (fuani). Possible reasons for fish stock decline included too many gears, bad
fishing methods, poor state of river water and predation by Lates niloticus
(mbuta).
(v) A variety of fishing gear was used to catch fish in the river, the most important
in all zones being hooks and traps. The use of gillnets and fish fences increased
during floods in the lower stream zone while fish-stunning herbs were
seasonally applied in the upstream and depleted zones during the low floods.
(vi) There was seasonality in fishing activity and the use of certain gears, especially
due to the fluctuations in fish abundance in the high flood and low flood
seasons. In the flooded period fishing intensity increased in the lower stream,
where it was done in the river and the flooded plains. In the upstream and the
depleted zones it was difficult to fish during floods due to steep banks and high
water speed.
(vii) The average expenditure on fishing gear varied through two orders of magnitude
with the zones and the importance that families attached to fishing. On average,
families in the lower stream zone spent the highest on fishing gear annually
(Ksh 4,130), followed by the depleted zone (Ksh 202) and the upstream zone
(Ksh 39).
(viii) River Sondu-Miriu was not an important source of fish for the community living
alongside it in the upstream and the depleted zones. Instead Lake Victoria was

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the first source of fish for nearly all families in these zones. Comparatively,
families in the lower stream zone depended more on the river [45% of
respondents in the lower stream said fishing was of major importance, while
86% in the upstream said fishing was of no importance]. However, most of the
respondents in the lower stream still regarded the lake as their main source of
fish.
(ix) More fish was eaten during the flood seasons in all zones, though, this was
largely due to increased abundance of fish in the lower stream rather than in the
upstream and the depleted zones. In any case hardly any fishing took place in
the upstream and depleted zones during floods.
(x) There was very little fish processing activity along the Sondu-Miriu. The
upstream and depleted zones, in particular, had relatively insignificant
processing activity. A little fish processing, mainly by sun-drying and frying
fish, was carried out in the lower stream zone especially during floods.
(xi) Even though many families indicated that one or more of their members carried
out fishing in the river, the overall results suggest that it was not an important
activity in the upstream and the depleted zone above Odino Falls. Fishing was
only important in the lower stream and the depleted zone below Odino Falls,
where fishermen fished both for subsistence and for profits.
(xii) The effect of water diversion (reduced water flow) will mainly be in the
depleted zone. Fishing is not an important activity in most of the depleted zone
due to its topography and its upper section is blocked by Odino Falls. Hence, the
water diversion is unlikely to have much impact on fishing activity.

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Physical Description of the River Sondu-Miriu
Sondu-Miriu is one of five major rivers that drain into the Kenyan part of Lake
Victoria (see Figure 1). The river traverses Kericho, Belgut, Nyando and Rachuonyo
districts, covering a total length of about 170 km. It arises from the western side of
Mau escarpment, flows through Mau hills and the Kericho highlands. From Kericho,
the Sondu-Miriu passes through narrows gorges over the Nyakach Escarpment and
finally across a flood plain (lower Kadianga and Nyakwere), from where it enters the
Osodo Bay of Nyanza Gulf of the Lake Victoria. The catchment of the Sondu-Mirui
river system is approximately 3,400 km² with the elevation ranging 2,750 meters at
the source to 1,145 meters at the mouth.
The basin experiences a bimodal rainfall pattern that steadily decreases from 2,000
mm at the Mau Escarpment region to 1,100 mm per annum on the flood plains. The
rainfall upstream contributes most of the river’s water. The actual annual discharge of
the river varies from year to year; depending largely on the rainfall; for example, in
1969 it discharged about 845 x 106 m3, while in 1970, this doubled to 1961 x 106 m3
(WMO, 1974).
The Study Area
For the purpose of this study the part of the Sondu-Miriu river under consideration
may be categorised into three zones: the upstream, depleted and lower (delta) zones
(Figure 1). The upstream zone (upstream of the intake weir) starts from Sondu town
bridge (0°24’ S, 35°1’ E) down to the project’s intake point at Apoko (0°24’ S,
34°53’ E). The depleted zone is between the intake point down to the where the water
will be released back to the river from the power house i.e. the Sangoro area (0°25’ S,
34°39’ E). This depleted section of the river may experience reduced flow. The lower
zone starts from this water outflow point all the way to the mouth of the river in Lake
Victoria (0°18’ S, 34°46’ E). This lower section may experience sudden fluctuations
in flow as a result of power generation water being returned to the river. The Odino
Falls, half way up the depleted section, is recognised as a crucial feature representing
the transition in fishery ecology and special resource relationship with local residents.

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The three zones of the river differ substantially in terms of natural characteristics
(vegetation, undulation, geology, soil characteristics), demography/ human population
densities and in socio-economic aspects. The upstream zone of the river has the
slowest topographic slope rate of the upper escarpment components of the river
(1:250), compared to the depleted section with slope rates of 1:100 or 1:30. In much
of the depleted zone, the river flows at high speed over a rocky bed and has
predominantly rocky sides, so there is little scope for permanent rooted vegetation.
However, the stretch below the Odino Falls and the Sangoro area of the depleted
zone, experiences moderate sediment deposition in the bed and along the banks. The
rate of the river is at its slowest (with a topographic slope of 1:1000) along most of
the delta. This permits a diversified growth of aquatic vegetation along the riverbanks
due to extensive sediment deposition.
The upstream zone is moderately hilly, more fairly populated and has a wetter climate
than the downstream and depleted zone. The lower zone is flat, with less woody
vegetation and is flood prone and is densely populated mostly by the Luo ethnic
group, who occupy both sides of the river. The river is the boundary between two
districts: Rachuonyo on the left bank of the river and Nyando on the right bank of the
river. There is more agriculture in the upper zone, especially on the left bank, than the
depleted zone, which might reduce the dependency on the river.
Background to the Study
Concerns have been raised over the impacts that operation of the Sondu-Miriu
Hydropower Project (SMHPP) might have on fisheries of the river. Fisheries in the
upper catchment area will not be affected by changes in water level downstream
controlled by the SMHPP. The only possible exception to this is the area immediately
above the Intake point, where a storage pond may affect levels for up to 5 km
upstream. The storage pond is not large and will only hold sufficient water to
maintain full power production for about 8 hours. Depending on how this capacity is
used, the water level in the pond may rise and fall by up to 2 metres on a daily basis
during the dry season as the water is used to generate peak power or simply to provide
enough for the turbines to operate minimally during low flow periods.

Figure 1. Location Map: Sondu-Miriu Hydro-Power Project
Lake
Victoria
Kenya
Project Site
Main Road
R Sondu Miriu
Sondu Town
Intake
Outflow
channel
Lower
Zone
Upper Zone
Depleted
Zone
Odino
Falls

LITERATURE REVIEW ON THE FISHERIES OF SONDU-MIRIU RIVER
For the purpose of this study, information has been sought regarding the existing
knowledge on the fisheries of the Sondu-Miriu River basin and the related socio-
economic aspects. The literature is scanty, even though the earliest studies were
conducted as far back as 1958. There were no immediate follow-up studies until the
1990s, causing information gap of almost three decades. However, there has been
increasing interest on the river in the last 10 years, leading to at least three studies on
the fisheries, fish ecology and socio-economics activities.
All these studies, though, have concentrated on the lower portion of the river and, in
contrast, have hardly discussed the situation above the Odino falls (the project’s
depleted and the upstream zones). Therefore, the species identified in literature largely
refer to the river’s flood plains - from the river mouth and extending up to about 15
km upwards. As a result, the studies are useful in revealing the species diversity in
temporal dimension, but are of little importance in understanding the spatial
dimension of fish species diversity (i.e. diversity in the various zones along the river’s
course). This section presents the literature on the fisheries and fishing practices in the
Sondu-Miriu.
Fish species diversity
There is sufficient evidence in literature that River Sondu-Miriu, especially its lower
flood plains, has supported a multi-species anadromous fishery from time
immemorial. Like the other rivers of Lake Victoria, the riverine fisheries of the
Sondu-Miriu were probably quite important during the first half of the last century,
but their significance gradually waned due to reducing stocks and changing market
preferences in favour of the more available and marketable lake species.
The lower river
The earliest reported study on the Sondu-Miriu was probably that of Whitehead
(1959), which also included all the other river fisheries of Kenya’s colonial Nyanza
Province. That study revealed the presence of at least 14 fish species in the Sondu-

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Miriu and the other rivers in the Nyanza Gulf. Whitehead (1959) observed that the
Sondu-Miriu fisheries were mainly restricted to the lower five miles of the river, since
the ‘large waterfall’ (the likely reference to Odino falls) prevented further ascent by
anadromous fishes.
Among the most important migrant fish to Sondu-Miriu River recorded by Whitehead
(1959) were1; Barbus altianalis radcliffi (large barbus - fuani), Labeo victorianus
(ningu), Schilbe mystus (sire) and Tilapia variabilis (mbiru), the latter being the only
cichlid of importance to the river fisheries, and being one of the most abundant
species caught in the lower part of the river. Other less abundant species were Alestes
nurse, Synodontis species (okoko), many Barbus species, Clarias mossambicus
(mumi), Bagrus dogmac and Protopterus aethiopicus (kamongo).
Whitehead’s (1959) report was perhaps the first documented evidence of fish species
diversity in the Sondu-Miriu, but it is doubtful whether it presented a complete list of
species in the river. Quite possibly, some species might have been ignored due to the
then less developed identification system, or the limited coverage of that survey. To
support this argument, barely a year after the first report, Whitehead (1960) identified
three other ‘new’ species of barbus - Barbus cercops, Barbus yongei and Barbus
nyanzae – as being present in the Sondu-Miriu river. Since there is no evidence that
these species were introduced after the first survey, the only plausible explanation for
their ‘discovery’ was that the earlier identification was not fully achieved. These new
species, though, were of little commercial value, owing to their small sizes, hence,
they attracted relatively little attention.
Little is known about the status of the Sondu-Miriu fishery between 1960 and 1990.
Certainly the fishery was undergoing changes as a result of increased harvesting
pressure and changing conditions of their habitat, but little of that has been recorded.
However, more attention has been focussed on the river’s fisheries after 1990,
revealing that the species diversity of the 1950s was still present.
1 The species’ names in the Luo language are in brackets. See Table 1 for Luo names of other species.

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A survey conducted on the Sondu-Miriu River for two years from April 1986 to
March 1988 by Ochumba and Manyala (1992), recorded 28 fish species. The samples
were fished from 15 sampling stations, all on the lower part of the river, below Odino
falls. The five most important species identified in that study were Clarias gariepinus,
Schilbe mystus, Synodontis afrofischeri, Lates niloticus and Oreochromis variabilis.
In another study, Muli and Ojwang (1998) collected fish samples from the lower
Sondu-Miriu from February to December 1991, from which they identified 16 fish
species. The most abundant species, which were recorded for at least half the months
of the period of study, were Schilbe mystus, Synodontis victoriae, Synodontis
afrofischeri, Lates niloticus and Labeo victorianus. Muli and Ojwang’s (1998)
samples, though, were collected from a relatively small section in the lower part of the
river.
Another study conducted by Gichuki et al (2001) from January 1993 to March 1994
on the wetland of the Sondu-Miriu (the river, the swamp, the side pools and the lake-
swamp interface) identified 28 fish species. Of these, the dominant species were
Clarias gariepinus, Synodontis victoriae, Protopterus aethiopicus, Schilbe
intermedius, Labeo victorianus, Oreochromis niloticus and Xenoclarias eupogon. The
main result of that study agreed with the findings of Ochumba and Manyala (1992)
with respect to the total number of species in the river system and, therefore, put in
doubt Muli and Ojwang’s (1998) findings of a much reduced species diversity.
However, it should be taken into account that, compared to the preceding three
studies, Gichuki et al (2001) collected samples from a much wider ecological zone
which extended beyond the river itself. Table 1 summarises and compares results of
the above four studies with respect to the species present on the river and their
importance.
Whitehead (1959) reportedly documented the earliest catch rates for Sondu-Miriu, as
well as for the other rivers, in the Nyanza Gulf. According to his estimates, River
Sondu-Miriu then had an annual total yield of 668 tons, of which 150 tons were
caught in the river barrier traps (kek)2, 200 tons in the river-placed gillnet of 5” and
2 See Table 2 for description of traditional gears (e.g. Kek and Oloch’wira)

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280 tonnes in the lake-placed gillnets of 5”. The trap-basket units (oloch’wira)
produced 30 tons, while the baskets and gillnets of 2 ½ yielded just about 8 tons each.
This data was based on the total number of each of the various gears in the river, and
their catch rates, which were then projected to give the total yield for the river.
Fish catches in the Lower Sondu-Miriu
By 1992, the annual yield of fish in the Sondu-Miriu had dropped to 81.5 - 108 tons
(Ochumba and Manyala, 1992). This, though, was not strange since catches of
riverine fisheries in the entire Nyanza Gulf have been declining since 1940 (Kibaara,
1981). The main causes of the decline in the catches of riverine species could include
overfishing by destructive fishing methods, papyrus encroachment, habitat
destruction, predation by Nile perch, poor management and pollution (Whitehead,
1959; Ochumba and Manyala, 1992, Ogutu-Ohwayo, 1990; Muli, 1998). The
potential threats are discussed
Fish migration
The river fisheries and those of the lake are complementary and very closely linked.
Many of the river fishes spend the greater part of their time in the lake, but ascend
rivers to spawn. The river fisheries actually depend on this active migration of
anadromous, and mainly non-cichlid, fishes up rivers to spawn. As pointed out by
Whitehead (1958 p275), ‘…purely riverine fishes are rare in Nyanza’. The river and
lake fisheries are intimately connected through complex ecological relationships. Any
biological disturbance on the main lake could, therefore, have direct effect on the river
fishes.
It is thought that fish migrate upwards to breed in response to certain physical and
chemical properties of river floodwater, most probably, water height, velocity,
turbidity, concentration of dissolved salts, temperature, pH etc. Normal, moderately
high, floods would possess all the conditions required to stimulate migration by the
various anadromous species.

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Table 1: Lower River Sondu-Miriu fish species
Relative species abundance in Sondu-Miriu Species
Scientific name Local
Luo name
Species
identified in the
lower part of
the river in
1955-57 by
Whitehead
(1959); (1960).
[Most abundant
(XXX); Least
important (X)]
Mean monthly
fish species
counts
recorded from
1986-88 by
Ochumba and
Manyala
(1992) in the
15 km zone
below Odino
Falls
Mean monthly
fish species
counts
recorded in
1991 by Muli
and Ojwang
(1998) in the
lower part of
the river
% fish
species
abundance
recorded in
1993-94 by
Gichuki et
al (2001) in
the river
wetland
Alestes nurse XX - - -
Alestes sadleri Osoga - - <1 -
Aplocheilichthys
bukobanus**
- 1 - -
Bagrus dogmac Seu X 5 <1 -
Barbus altianalis Fuani XXX 24 2 -
Barbus cercops Adel X - - -
Barbus neglectus Adel - 61 1 -
Barbus nyanzae Adel X - - -
Barbus yongei Adel X - - -
Brycinus jacksonii - 17 - -
Brycinus sadleri - 7 - -
Clarias gariepinus Mumi - 73 <1 16.7%
Clarias mossambicus Mumi X - - -
Clenopoma muriei - 2 - -
Gnathonemus
longiberbis
Odhore - 1 - -
Haplochromis spp. Fulu - 94 - -
Labeo victorianus Ningu XXX 32 4 10.5%
Lates niloticus Mbuta - 135 4 -
Marcusenius grahami - 3 - -
Mastacembalus frenatus Okunga - <1 - -
Micropterus salmoides - <1 - -
Mormyrus Kannume Suma - 1 <1 -
Oreochromis leucosticus Opat - 31 1 -
Oreochromis niloticus Nyamami - 164 1 7.4%
Oreochromis variabilis Mbiru XXX 233 <1 -
Petrecephalus cutostoma Obu - 1 - -
Protopterus aethiopicus Kamongo X 3 - 11.8%
Schilbe intermedius* Sire - - - 11.6%
Schilbe mystus* Sire XXX 402 214 -
Synodontis afrofischeri Okoko
rateng
19 7 13.1%
Synodontis victoriae Okoko
rachar
92 86 13.9%
Tilapia zilli Silli - 25 - 1.3%
Xenoclarias spp. Ndhira - 4 - 9.2%
• * Reclassified
• ** Previously recorded as Aplocheilichthys edwardis
s

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According to Ochumba and Manyala (1992), the upstream migration of fish extends
for up to 10 km from the river mouth. Whitehead (1959) reported that some species,
for example, Barbus altianalis, could migrate to as far as 70 miles up a river (but this
is unlikely in the Sondu Miriu due to the physical barrier). Labeo spp and Schilbe spp
are also active migrants.
In the Sondu-Miriu River, migration would be expected to happen during its two
peak rainfall seasons. Since there will be no change in the normal flooding regimes,
any migrants will be unaffected by the project.
Fishing methods in the Sondu-Miriu
Fishing in rivers is carried out using a number of fishing methods. As early as the
mid-1950s, Whitehead (1958b) observed a number of fishing methods in use,
including; gillnets (2½ - 5 inches), river barrier traps (kek), lines and clasp nets. There
were also oloch’wira traps and baskets. Table 2 summarises the features of the
traditional fishing methods in the Sondu-Miriu.
While not specifically referring to the Sondu-Miriu, it is common knowledge that
most of the traditional fishing methods in the rivers entering Lake Victoria have been
abandoned, or are very sparingly used nowadays. It is, therefore, quite likely that only
a few of the traditional fishing methods still persist in Sondu-Miriu.

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Table 2. Fishing methods on the Sondu-Miriu
Method Details Importance in
Lower Sondu-Miriu
based on survey
results obtained by
Whitehead (1959)
Kek A barrier of sticks, often reinforced with
stones, built entirely across a river, and with a
series of non-return fishing devices.
150 tons a year
Oloch’wira Circular maze-like enclosures with funnel
entrances (trap baskets), built on the flood
plains.
30 tons a year
Baskets (ounga) a large variety used for scooping or trapping 8 tons a year
Gillnet of 5” placed
in the river initially made of flax material, but later
changed to nylon type which persists today 200 tons a year
Gillnet of 2 ½ placed
in the river
As above 8 tons a year
Long lines (and
rods) used with hooks
Unrecorded
Clasp nets used particularly near waterfalls.
Unrecorded
Breeding and feeding of Sondu-Miriu fishes
Ochumba and Manyala (1992) have described, in considerable detail, the breeding
and feeding patterns of the Sondu-Miriu fishes. This includes a description of the
sexual maturity stages of the eight major species in the Sondu-Miriu. The report
shows that there is a large variation in size at first maturity among the species in the
river.
The breeding seasons also vary for different fish species. In general, most species
breed during the long rainy season (March – May), with a repeat in the short rainy
season (September – October). There is evidence that Schilbe mystus, C. gariepinus,
S. afrofischeri, S. victoriae and L. victorianus have long peak breeding seasons that
extend beyond the rainy seasons. B. altianalis, though, breeds strictly during the rainy
season. It is, however, noteworthy that the actual breeding seasons may change
depending on the rainfall pattern and other climatic variables.

17
The top ranking food items of the Sondu-Miriu river fishes identified by Ochumba
and Manyala (1992) are terrestial and aquatic insects, vegetable matter, detritus,
crustaceans, molluscs, zooplankton and phytoplankton. The importance of each food
item depends on the feeding grounds, substratum type and season. Most fish species
observed by Ochumba and Manyala (1992) were opportunistic and omnivorous
feeders.
Potential threats to the Sondu-Miriu fisheries
As early as the mid 1950s there were already reports of threats to the river fisheries in
the Nyanza gulf in Kenya, which also included the Sondu-Miriu fisheries. The main
threat, according to Whitehead (1959) was overfishing; as evidence, he cited the high
levels of catches of unspawned fishes in the rivers and the increased usage of small-
meshed gillnets. There was, though, insufficient trend data to prove that the fish
catches were already declining at that time.
The possibilities for further development of the river systems, through irrigation and
hydro-electric schemes could also pose another threat, since this would affect fish
movement and both the flood water quality and quantity, as well as conditions in the
fishing grounds. According to Ochumba and Manyala (1992) the effects which could
arise from dam construction on rivers are: (i) interruption of migration pathways by
dam walls, (ii) disruption of spawning pattern through unnatural short-term flow, (iii)
loss of area available for spawning, growth and habitat diversity, (iv) changes in
species abundance and diversity, and (v) lack of nutrients down stream, leading to
changes in nutrient cycle. [For hydro-electric schemes, the barrier problem could be
minimised by creating fish ladders or passes to allow the ascent of anadromous fish.
Such ladders, ideally, should be installed as part of the main dam rather than as a later
addition]. However, in the case of the Sondu-Miriu hydropower project, no dam has
been constructed, hence, Ochumba and Manyala’s recommendation would not apply.
Another potential threat to river fisheries is pollution. Fortunately, a number of studies
have been carried which have revealed much information on indicators of pollution of
the Sondu-Miriu, in relation to other rivers in the Nyanza Gulf. There is, thus, a basis

18
to judge and compare the likely contribution of pollution to the state of fisheries in the
Sondu-Miriu.
One of such studies by Lung’ayia (1994) involved the use of diatom analysis on water
samples taken from Lake Victoria and on the main inflowing rivers3, Sondu-Miriu
included, between March and July 1994. Diatoms and phytoplankton generally
respond to different organic and inorganic substances very markedly and, therefore,
could be used to develop indices of pollution of the aquatic system.
The results of the diatom composition in the rivers showed that Sondu –Miriu had the
highest diatom diversity, recording 10 species out of the 29 species of diatoms found
in all the rivers. Similarly, Sondu-Miriu had the highest density of diatoms. According
to Lung’ayia (1994), the richer diversity and density of diatoms in Sondu-Miriu,
compared to the other rivers, indicated that this river had little pollution. This, in any
case, would be supported by the fact that Sondu-Miriu had a large water volume, low
turbidity and drainage area, with relatively little factory and municipal effluents.
Another study conducted by Mwamburi and Oloo (1995) from March 1994 to March
1995 determined the chemical and physical parameters and the metal concentration in
the surface water and in the sediments of the main rivers flowing into the Kenyan part
of Lake Victoria. Sondu-Miriu had the lowest values of both the mean conductivity
(40.7µScm3) and total suspended solids (40.6 mg/l), but the highest mean dissolved
oxygen levels (7.2 mg/l), indicating that the river was the least polluted. Furthermore,
Sondu-Miriu recorded the lowest values of turbidity (47.3 N.T.U), total alkalinity
(22.9 mg/l CaCO3), total hardness (9.8 mg/l CaCO3) and mean temperature (21.6°C),
all which reaffirm the low pollution status of the river.
Another study by Kirugara and Nevejan (1996) revealed that Sondu-Miriu had a
mean suspended load of 66 mg/l and an annual suspended load of 107 160 tons/ year,
which placed it among the least ‘loaded’ rivers in the Nyanza gulf. The two authors
further identified the main pollutant sources in the Gulf rivers as, agricultural
3 They included Awach, Nyando, Kibos, Kasat, Yala, Nzoia and Sondu-Miriu.

19
activities, leading to pesticide and fertiliser use, in the catchment area, industrial
activities, urban and domestic wastes.
The initial feasibility study for the Sondu-Miriu Hydropower Project conducted by
LBDA/ JICA (1985b) appeared to differ with some of the above reports. Regarding
the water quality of the Sondu-Miriu river, the study described the river as “red brown
colour with high turbidity, and highly saturated with dissolved oxygen and nitrates”,
the latter two respectively measuring 8.0 mg/l and 1.5mg/l at the Sondu Bridge point.
The divergent findings might be explained in terms of time lapse in conducting the
studies, location of sampling points, different analytical tools and probably actual
changes in its water quality. It could also be due to comparing data sets collected over
short periods with annual averages. However, the overriding outcome in most
literature is that Sondu-Miriu river is among the least polluted rivers in the Nyanza
gulf. Thus, the fisheries population in the river may not be influenced very much by
the limited pollution in the river.
Socio-economic Aspects of Sondu-Miriu Fisheries and Ecology
Gichuki et al (2001) surveyed the plants and fishes of the Lower Sondu-Miriu wetland
and described their use by adjacent communities. Using a standard schedule
(structured/ open-ended) in collecting socio-economic information, 300 people were
interviewed supplemented by 50 key informants from the same 300 homes. Their
dependence on the wetland plants for the supply of building material and cooking fuel
is highlighted. The study revealed that from the 300 respondents interviewed, 40 used
macrophytes, 200 mixed macrophytes and firewood, 50 used firewood and 10 used
kerosene for cooking.
According to Gichuki and Odhiambo (1994), some wetland plants in the Lower
Sondu-Miriu are used by the local community for food, fodder and compost, while
some have medicinal value. They also indicated that the swamp serves as the only
source of green pasture for domestic and wild animals during the dry season. The
study recommended the traditional use of wetland plants as opposed to commercial-
scale enterprise and industry since, in their view, subsistence utilization is compatible
with sustainable utilization. They argued that local utilisation should be supported

20
because the wetland is the main source of income to the community, in an area where
poverty is endemic.
According to Balirwa (1995), marginal edges of lakes and flood plains may contribute
important harvests because they form temporary feeding habitats for fish, especially
during periods of floods and also because they are spawning and nursery habitats. For
the people of the Lower Sondu-Miriu, the fishing industry in the swamp provides the
bulk of the protein in their diet (Gichuki, et al (2001). No literature could be found
that specifically focused on the socio-economic aspects of fisheries and the general
ecology on the middle and upper zones of the river.
RESEARCH METHODOLOGY
Keeping in view the nature and scope of the study, the consultants adopted various
methodological procedures and techniques in the collection, processing, analysis and
presentation of the data. An exhaustive reconnaissance survey/pilot study was necessary due
to the lack of adequate statistics on the study area. The fisheries study on River Sondu-Miriu
targeted knowledge on the dependence by the riparian villages on the fish species in the three
sections of the river, that is, the upper, depleted and lower zones. In other words, the study
reflected the objective of identifying all those parties involved with or benefiting from the
fishery industry along the river; to undertake the inventory of their characteristics, practices
and contribution to the rural economy and finally to understand the impeding problems of or
threats to the sector.
Pilot Survey
The study started with a 3-day pilot survey. The main purpose of this survey was to familiarise
the consultants with the current situation on the ground so as to identify the various respondents
to be included in the sampling frame of the main study. All the schedules/ questionnaires, to be
used in the main survey, were tested on 10 respondents from the study area’s 3 zones and were
validated and modified as necessary during this period. This exercise also enabled the study
group to code the questionnaire and determine how long it would take to complete each type of
questionnaire. This also contributed to the understanding of the respondents’ ability and
willingness to answer questions and thus its effects on the response rate.

21
Data requirements
Both primary and secondary data collection techniques were used in order to gain an
understanding of the following aspects:
• The human demographic characteristics and trends along the River Sondu Mirui and
their implications on fishery resources;
• Socio-economic importance of fish and fishing to local communities in terms of
employment, income-generation and food security.
• Cultural importance of fish among the local community
 Past and present fishing methods;
 Marketing of fish and its by-products
 Organisation of the fishing industry in the area
• Fish species diversity;
• Breeding migrations
• Fish stock/ catch / seasonal variations;
The above aspects were identified as being necessary in the formulation of a future plan
for the management of fishery resources in the Sondu-Miriu River.
Field Data Collection Methods
The following data collection instruments were applied to acquire relevant data to the
study:-
(a) Standard Questionnaires (see appendix)
This was the major research instrument in the survey. Structured standard questionnaires
(schedules), with both open-ended and closed questions, were utilised at all levels of data
collection. The questionnaires not only helped to maintain a focus on the main topics of
relevance, but also allowed the interviewee to elaborate on points of interest. All questionnaires
were self-administered to avoid misunderstanding of questions by the respondents.

22
(b) Key-Informant Interviewing
This method was used on people who are particularly knowledgeable about the fishing
activities and were recognised as village opinion leaders, for example, the District Fisheries
Staff, the area Chiefs and Sub-chiefs, community-based group leaders, NGO representatives,
etc. Through this method, we were able to reconstruct previous practices and activities
associated with fishing along the river.
(c) Participant Observation and Photography
To understand fully the fishing operations, site visits, direct observations, participation and
taking of photographs were also used in the study. Observation and recording of the activities
and events of daily life related to fishing was undertaken to help understand the general
lifestyles of the various actors involved in the local fishing industry, their living and working
conditions, and modes of transporting/marketing fish.
Direct observation on fishing activities was a good way to cross-check the respondents'
answers. Digital photographs were taken to represent some salient features relevant to the
study, such as fishing implements and methods of treatment/processing. Some of the digital
photographs proved to be a good stimulus to the respondents.
Sample Selection Strategy
A stratified random sampling approach was used. The zones were pre-selected based on the
unique characteristics to the hydropower project but selection of respondents were done
randomly. As indicated earlier, the study area was first divided into three major zones: the
upstream, depleted and lower (delta) zones. These three zones were further sub-divided into
left and right bank sections of the river when facing downstream. Approximately equal
numbers of people in each area were questioned.
During the pilot survey, the adjacent communities to the river were categorized into three
layers depending on their distance from the river. Therefore, the survey captured respondents
living within a distance up to and not more than 3 km from the river. It was gauged that those
living within this distance envelope on either side of the river would have special relationship

23
with the river either in the form of resources obtained from it (especially fish), or problems from
it (in terms of ravaging floods). Beyond this distance, the communities would barely be
concerned about the river.
The population from which the sample of respondents was selected covered the area from the
Sondu Bridge up to the lake, but within the envelope defined by the first roads on either side,
and parallel to the river at approximately the defined distance. Within each zone, samples of
households were selected randomly on three contours; that is, the first band of homes was
immediately next to the river, then the middle band of homes and lastly the band of homes
next to the roads.. The idea was to cover and capture the most representative set of village
situations, which would reflect the relationship and interaction between the local
communities and the river in terms of fishery resources.
As per the Terms of Reference, an estimated 100 respondents (i.e. at least 30 for every of the
three zones) were targeted in the study. Limiting the respondents to heads of households,
without age or sex discrimination, 96 respondents were obtained from these six sub-sections
as detailed in Table 3. Between one home and the other, time taken and distance covered was
used as a guide. This was to ensure that the study was spread uniformly over the area of
study.
Formal interviews were carried out in the months of November and part of December, 2002.
Interviews were conducted using the local languages, Dholuo and Kiswahili, and in some
cases in English. Interviews revolved around the major aspects on fisheries outlined earlier in
this report. In-depth interviews and follow-up visits were made to 7 key informants in the
three zones of the study area. These key informants were selected on the basis of their
experiences and reliance on the fisheries from the river and their willingness to talk to the
researchers and provide explanation on certain issues.
Of the 96 respondents selected for the study, 63 came from families where at least one person
fished regularly or occasionally, while 33 were from non-fishing backgrounds. The mean age
of respondents was 51 years; of which the mean age of respondents in the upstream, depleted
and lower stream zones were 52, 49 and 51 years respectively.

24
Table 3 Sampling Frame
SECTION
ZONE
LEFT BANK RIGHT BANK TOTAL
UPSTREAM ZONE
DEPLETED ZONE
LOWER ZONE
19
17
15
16
13
16
35
30
31
TOTAL 51 45 96
Data Analysis, Interpretation and Presentation
This was the last phase of the study. All questionnaires and field notes were edited on daily
basis to validate the data. Data processing and analysis began as soon as the execution of the
study was complete. Both descriptive and quantitative techniques were utilised in the
processing, analysis and presentation of data. This is because descriptive or qualitative
methods tend to be strong in validity but weak in reliability while quantitative techniques
tend to be strong in reliability but weak in validity. By combining the use of both methods,
modern researchers believe that they can balance the strengths and weaknesses of the two and
achieve a higher degree of reliability and validity, compared with the use of only one method.
Qualitative methods have been employed to outline various intangible and non-quantifiable
issues. Quantitative data were processed using the SPSS and Microsoft-Excel computer
packages. The results of the study have been organised in the next chapter according to the
main sections of the questionnaires used in collection of data with the intention of
highlighting and achieving the objectives of the study.

25
RESULTS AND DISCUSSION
FISH SPECIES STATUS AND DIVERSITY
This study has analysed the fish species status and diversity in two dimensions; first is
the spatial dimension, in which variations are investigated along the three zones of the
river. Second is the temporal dimension in which changes due to passage of time are
assessed in each of the river zones.
Fish diversity along the zones
The survey revealed changing fish species diversity along River Sondu-Miriu. The
species diversity was markedly higher in the lower stream than in the upstream and
the depleted zones (particularly above the Odino Falls). As may be expected, the
species composition in the upstream zone and the depleted zone above Odino Falls
were quite similar. Due to annual migration patterns, fish species composition
changed seasonally especially in the lower stream and the depleted zone below Odino
Falls, with higher diversity during floods.
Table 4 presents the status of the various fish species in the three zones of the river,
indicating the number of times each was reported as ‘common’ or ‘present’. A
species was described as ‘common’ if it was frequently seen or caught in that part of
the river. In contrast ‘present’ meant that the community knew the fish species existed
in their part of river, but was infrequently seen.
The results show that in the upstream zone and in the depleted zone above Odino
Falls, the small Barbus spp (adel) and Clarius spp (cat fish - mumi or ndhira) were
most common, followed by Oreochromis leucosticus (tilapia - opat or small ngege).
Other major species thought to be present in the upstream zone in lesser quantities
were Haplochromis spp (fulu), Lates niloticus (Nile perch – mbuta) and Labeo spp
(ningu). (In subsequent discussions of these results with fisheries biologists, most
doubted the accuracy of fish identification by respondents, arguing that he Odino
barrier could not allow ascent of Nile perch. They suggested that Nile perch and
Haplochromis spp, in particular, might have been misidentified in the upstream zone

26
and depleted zone above the falls. However, another hypothesis was that some fish
species might have been deliberately transferred into upstream ponds by private pond
owners).
The depleted zone below Odino Falls had greater species diversity, which included
the species mentioned above, plus Gnathonemus spp (odhore), Synodontis spp
(okoko), the large Barbus spp (fuani), Mastacembalus spp (okunga),Oreochromis
variabilis (tilapia - mbiru), Schilbe spp (sire) and Mormyrus spp (suma).
The lower stream had nearly all the species in Table 1 except Rastrineobola argentea
(dagaa or omena), Tilapia zilli (silli) and the small Clarius spp (Nyapus). The most
common species were Clarius spp (cat fish - mumi or ndhira), Schilbe spp
(sire),Synodontis spp (okoko), Oreochromis leucosticus (opat or small ngege), Labeo
spp (ningu), small Barbus spp (adel), Mastacembalus spp (okunga) and Lates
niloticus (Nile perch - mbuta), while Protopterus spp (mud fish - kamongo),
Gnathonemus spp (odhore), and Oreochromis niloticus (tilapia - nyamami) were less
common. The large Barbus spp (fuani), Haplochromis spp (fulu), Oreochromis
variabilis (tilapia - mbiru), Bagrus spp (seu) and Mormyrus spp (suma) were thought
to be present but rare. Most respondents thought that Alestes spp (osoga), which was
very common in earlier years (the 1970s and earlier), had totally disappeared.

27
Table 4: The status of fish species in the three zones of R. Sondu-Miriu
Species Responses on presence status
Upstream Depleted Lower
Common Present Common Present Common Present
Barbus spp (Adel) 30 0 26 2 16 13
Barbus spp (Fuani) 4 3 5 6 1 14
Haplochromis spp (Fulu) 6 9 8 7 4 19
Protopterus spp (Kamongo) 0 1 3 1 8 15
Oreochromis variabilis
(Mbiru)
0 4 6 2 3 11
Lates niloticus (Mbuta) 3 6 6 7 12 15
Clarias spp (Mumi/ ndhira) 27 2 21 7 26 7
Oreochromis
leucosticus(Opat)
13 15 19 7 23 8
Labeo spp (Ningu) 5 6 17 4 16 14
Gnathonemus spp (Odhore) 0 0 2 2 10 17
Synodontis spp (Okoko) 0 2 5 0 26 5
Mastacembalus spp
(Okunga)
0 2 8 2 13 15
Rastrineobola argentea
(Dagaa)
0 0 1 0 1 4
Alestes spp. (Osoga) 0 3 4 2 0 9
Bagrus dogmac (Seu) 0 0 4 3 5 18
Tilapia zilli (Silli) 0 0 0 0 2 0
Schilbe spp (Sire) 0 0 7 4 27 4
Mormyrus spp (Suma) 0 0 5 4 4 16
Xenoclarias spp (nyapus) 0 0 0 0 0 1
Oreochromis spp (Nyamami 0 0 2 2 8 17
Total responses per zone 141 213 436
Number of respondents 35 30 31

28
Perceptions of changing species composition over time
The second dimension of change was mainly related to the disappearance of certain
species, or decrease in overall stocks, over time. Decreasing fish stocks was most
certain in the lower stream, having been reported by about 61% of respondents in that
zone (Table 4). In the depleted zone, the largest block of respondents (47%) similarly
indicated that their stocks were decreasing while 37% reported no change. Nearly all
the respondents in the depleted zone who reported no change were from the part
above Odino Falls. The situation in the upstream zone was also not clear-cut, with
about 51% of respondents perceiving no change in stock sizes while 26% thought the
stocks were decreasing, and another 17% suggesting an increase.
Thus, in general the results suggested that there has been notable decrease in fish
stocks in the lower stream zone and the depleted zone below Odino Falls, however, no
significant change in stocks has been observed in the upstream and the depleted zone
above Odino Falls. [However, this may be viewed in the context that the amount of
fish in the upstream and the depleted zone above the falls is already too low, and
perhaps has been low for such a long time that that any changes are not easily noticed,
or is of little interest to the community].
Table 4 Perceptions of status of fish stocks in R. Sondu-miriu
Count
6 2 6 14
9 14 19 42
18 11 5 34
2 3 1 6
35 30 31 96
increasing
decreasing
no change
not sure
Perception on
the amount of
fish in the river
Total count
upstream
zone depleted zone lower zone
Respondents by zones of river
Total
Seven fish species were mentioned as having disappeared faster, namely; Labeo spp.
(ningu), the large Barbus spp. (fuani), Alestes spp. (osoga),Lates niloticus (mbuta),

29
Synodontis spp. (okoko), and Haplochromis spp. (fulu). Of these, respondents were
most certain about the disappearance of ), Alestes spp (osoga), particularly in the
lower stream. It is noteworthy that about 63% of respondents in the upstream zone
thought that no species had disappeared, or were not sure of any, which concurred
with the general perception above, that stocks had not significantly declined in that
zone (or possibly that fish stocks have remained low for a very long time).
A number of reasons were given that could cause a decrease in fish stocks (Table 5).
The more prominent reasons were high fishing pressure, due to too many gears and
bad fishing methods, as well as the bad (polluted) state of the river. [This seems
inconsistent with the earlier discussion that River Sondu-Miriu is among the least
polluted]. Some respondents in the upstream zone thought that their fish was washed
away during high floods, while in the lower stream zone some respondents blamed
predation by Nile perch.
Table 5 Perceptions of causes of stock declines
Count
2 - 2 4
1 - 1 2
2 - - 2
- 1 - 1
11 16 14 41
19 11 5 35
- 2 3 5
- - 4 4
- - 2 2
35 30 31 96
poor state of river
prevented by odino falls
washed down stream by floods
change of climate
not sure
not changing
High demand
Bad fishing methods
Predation by Nile perch
why
amount of
fish in river
is changing
Total
upstream
zone
depleted
zone
lower
zone
No. of respondents by river
zones
Total

30
FISHING METHODS AND GEARS
Fishing gears
There were 9 types of fishing gear in River Sondu-Miriu (Table 6). As indicated by
the number of positive responses in Table 6 (also confirmed in Table 8), the lower
stream had the most types of gears while the depleted zone had the least, both
presently and in the past. Hooks have been the most common gear in all three zones,
followed by traps. Gillnets have also been important in the lower stream and the
depleted zones, the latter mainly in the section below Odino Falls. Fish fences were
only found in the lower stream zone, especially in the flood plains. The seine nets and
mosquito seines were rare, although a few of the latter were present in the upstream
and depleted zones. Fish-stunning herbs (poisons) were occasionally used in the
upstream and the depleted zone (above Odino Falls).
Comparing the present and the past (more than 10 years ago), Table 6 suggests that
the number of hooks have increased slightly in the upstream while they have remained
nearly the same in both the depleted zone and the lower stream. Traps have been
constant in nearly all the zones, while the use of herbs has completely disappeared in
the lower stream. Fish fences have disappeared in both the upstream and depleted
zones, while they have remained nearly the same in the lower stream. Seine nets,
spears and baskets are still only important in the lower stream, just as it was in the
past.

Table 6 Perception of relative importance of various fishing gears
NOW BEFORE
Upstream zone Depleted zone Lower stream
zone
Upstream zone Depleted zone Lower stream zone
Gear Type
Common Present Common Present Common Present Common Present Common Present Common Present
Gillnets 1 2 7 6 11 15 3 - 5 4 14 10
Seine nets - - - - 2 3 - - - - 4 10
Mosquito seines 4 6 2 2 2 2 5 1 1 1 4 4
Hooks 32 4 23 4 25 8 27 2 24 4 24 2
Traps 11 3 9 4 20 5 12 7 12 5 25 1
Fish fences - - - - 9 8 2 5 1 4 8 10
Poisons/ herbs 7 10 3 8 - - 7 7 5 6 3 5
Baskets 1 2 4 2 3 10 4 6 5 4 17 6
Spears - - 1 2 3 7 - - 2 2 6 9

Of the respondents in this survey, 65% came from families where at least one member
fished regularly or infrequently. About 19% of those who fished had no gear, possibly
depending on borrowed or hired gear or were paid to fish for the gear owner (Table
7). Of the respondents who had gear the majority (46%) owned hooks alone while
another 21% had a combination of hooks and traps (Table 8). In Table 8, the average
number of each type of gear owned per 100 families in each zone has been estimated
based on the actual number of each type of gear owned by respondents’ families. The
results further confirm the importance of hooks and traps in the river.
Table 7 Gear distribution among families
Count
12 33 45
1 - 1
1 - 1
29 - 29
3 - 3
1 - 1
13 - 13
3 - 3
63 33 96
no gear
gill nets
mosquito nets
hooks
traps
herbs
hooks and traps
hooks and gill nets
type of
gear
owned
by family
Total
yes no
respondent family fish
in nearby river?
Total

33
Table 8 Estimates of total amount of fishing gear owned
Number of gears owned (per 100 families)
Upstream Depleted Lower
Gillnets (‘tonde’/ ‘sarif) - - 319
Seine nets (rimba) - - -
Mosquito nets (‘ambega’) 29 7 35
Hooks (‘olou’) 89 153 10,084
Traps (‘osadhi’) 29 40 497
Fish fences - - 42
Poison (‘yadh rech) - 3* -
Baskets (‘ounga’) 3 17 13
Spear (‘bidhi’) - 67 6
Number of respondents 35 30 31
* Represents presence of a bush of fish poison herbs
Expenditure on fishing gear4
Respondents in the lower stream zone had the highest average expenditure on fishing
gear, followed by those in the depleted zone, the latter were probably influenced by
the section below Odino Falls. Table 9 shows that families of respondents in the lower
stream spent an average of Ksh 4,130 per year on fishing gear, compared with Ksh
202 in the depleted zone. The upstream zone had a very low average expenditure of
only Ksh 39 per year. This signifies the relative importance of fishing to the lower
stream as compared to the depleted and the upper stream zones. The expenditure on
fishing gear, though, depended more on the importance that a family attached to
fishing than on their location. Table 10 shows that families where fishing was of
major importance spent nearly 4 times more on fishing gear than where fishing was of
minor importance, and about 400 times more than where fishing was of no
importance.
4 Exchange rate at time of survey: Ksh 78 = US $ 1

34
Table 9 Expenditure on fishing gear by families per zones (Ksh)
Expenditure on fishing gear by family
39 35 0 500
202 30 0 3,000
4,130 31 0 50,000
1,411 96 0 50,000
zones of river
upstream zone
depleted zone
lower zone
Overall mean
Mean
(Ksh) N
Minimum
(Ksh)
Maximum
(Ksh)
Table 10 Expenditure on fishing gear by importance of fishing (Ksh)
Expenditure on fishing gear by family
17 62 0 500
6,556 16 0 50,000
1,636 18 0 15,000
1,410 96 0 50,000
Importance of
fishing to family
No importance
Major importance
Minor importance
Overall mean
Mean
(Ksh) N
Minimum
(Ksh)
Maximum
(Ksh)

35
Most of the fishing gears in the river targeted a wide range of fish species wherever
they were used. Table 11 presents the relative usage of each gear, derived by
aggregating the responses in which a gear was mentioned as able to catch a given fish
species in the river. The adoption of indiscriminate gears was an indication that there
was no fish species sufficiently abundant throughout the year and which commanded
a high commercial value, so that it could be singularly targeted, in the same way the
major commercial fish species in the lake, namely; Nile perch, Rastrineobola
argentea and tilapia.
Seasonality in fishing
The use of a variety of gears also suggests seasonality in the occurrence of different
fish species. It was established that apart from hooks, which were used almost
throughout the year, the other gears were used quite seasonally. In the upstream and
depleted zones, traps tended to be used during high floods while the herbs were
applied during very low floods to avoid diluting their effect. However, seasonality of
fishing was not pronounced in the upstream and depleted zones since fishing itself
was not highly regarded there. In particular, the steep banks and high water speed
made it difficult to fish in the depleted zone.
In the lower stream the effect of seasonality was clearly explained. During high floods
the lower Nyakach plains became completely flooded on both banks of the river,
forcing most residents to migrate temporarily to higher grounds. At this time, the
whole flooded area turns into a fishing ground, where Clarias spp, Synodontis spp.
and a few other species are readily caught using traps, fish fences, baskets and even
by bare hands! To confirm this, table 18 shows that more fish was caught and eaten
during high floods than in the low flood period.

36
Table 11 Gears targeting various fish species in each river zone
Species Responses about gear targeting species
Gillnets
Seine nets Mosquito
seine
Hooks Traps
(osadhi)
Baskets Poison/ herbs Spears
U D L U D L U D
L U D L U D L U D L U D L U D L
Alestes spp. (Osoga) 2 - 6 - - - - - - 15 - 9 4 - 12 1 - - 10 - - - - -
Bagrus dogmac (Seu) - - 7 - - - 1 1 - - 18 16 - 3 13 1 1 1 - 3 - - - -
Barbus spp (Adel) 2 2 7 - - - - 1 - 26 27 9 7 4 14 1 - 3 14 6 - - - -
Barbus spp (Fuani) 2 - 6 - - - 2 1 - 16 19 9 4 3 11 1 2 - 9 3 - - - -
Clarias spp (Mumi 2 3 10 - - - 1 1 - 20 31 24 7 4 19 1 - - 14 3 - - 1 1
Gnathonemus spp (Odhore) - - 7 - - - 1 1 - - 18 10 - 3 12 1 1 2 - 3 - - - -
Haplochromis spp (Fulu) 2 - 8 - - - - 1 1 15 21 10 - 3 12 1 - 2 10 4 - - - -
Labeo spp (Ningu) 2 6 12 - - - 1 1 - 15 17 11 5 3 12 1 1 - 10 3 - - - -
Lates niloticus (Mbuta) 2 - 13 - - 1 1 1 - 15 19 22 4 3 12 1 1 - 10 3 - - 1 -
Mastacembalus spp (Okunga) - - 6 - - - - - - 15 17 12 - 3 12 1 1 - 10 3 - - - -
Mormyrus spp (Suma) - - 6 - - - 1 1 - -- 18 8 - 3 12 1 - 3 - 2 - -- - -
Oreochromis leucosticus(Opat) 2 3 7 - - - - - - 21 25 9 5 3 14 1 2 3 10 5 - - - -
Oreochromis spp (Ngege) 2 2 10 - - - 1 1 1 15 18 13 4 3 21 1 2 2 10 3 - - - -
Oreochromis variabilis (Mbiru) 2 - 6 - - - - 1 -- 15 17 10 4 3 12 1 - 2 10 3 - - - -
Protopterus spp (Kamongo) - - - - - - 2 1 - - - 18 - - 19 1 2 4 - 3 - - 2 2
Rastrineobola argentea (Dagaa) - - - - - -- - - 2 - - - - - - 1 - - - - - - -- -
Schilbe spp (Sire) 18 1 1 21 17 3 12 1 2 2
Synodontis spp (Okoko) 15 21 15 3 12 1 1 3
Tilapia zilli (Silli) 6 9 12 1 2

37
FISH MARKETING AND PROCESSING ACTIVITIES
Fish marketing
Despite the fishing activities previously discussed, River Sondu-Miriu is hardly the
main source of fish for the local community. This was especially true for the upstream
and the depleted zones, where only 17% and 23% of respondents, respectively,
mentioned the river as a source of fish, nearly all of them obtaining fish from Lake
Victoria as well. In fact only 3% of all respondents obtained their fish entirely from
the river. Figures 2 (a – c) display the various sources of fish to the local community
in the three zones of the river.
The place where local families actually buy fish seemingly depends on the distance
from the lake, rather than the river. On both banks of the upstream and the depleted
zones, families overwhelmingly bought their fish from a local market (Table 12).
Most families in the lower stream zone bought their fish from the lakeshore, but a
good number also bought from a local market or the river. This suggests that the river
is only important in the lower stream as a source of fish, the lake being the first source
of fish to communities in all zones of the river.
The fishermen in the upstream and depleted zones usually sold their fish individually,
as there were no co-operatives or marketing associations (Table 13). However, it was
indicated that there were a few groupings in the lower stream zones, whose functions
were mainly welfare and did not assist to market fish. Chuowe Fishing Group
operating in the lower left bank (at Chuowe/ Osodo Beach), though, assisted
fishermen in marketing fish. The absence of organised fishing and marketing
associations was a further pointer to the low level fishing activity along the river.

38
Figure 2 Local community’s source of fish
Figure 2a
Upstream zone
Lake victoria
Local river
Lake victoria and
local river
Figure 2b
Depleted zone
Lake victoria
Local river
Lake victoria and
local river
Figure 2c
Lower zone
Lake victoria
Local river
Lake victoria and
local river

39
Table 12 Local community’s fish market
Count
33 29 7 69
1 - 16 17
1 1 8 10
35 30 31 96
Local market
Lake shore
Local market and river
Where family
buys fish
Total
upstream
zone
depleted
zone
lower
zone
No. of respondent families
buying fish from various sources
Total
Table 13 Fishing groups/ co-operative
Count
- 2 17 19
34 27 14 75
1 1 - 2
35 30 31 96
yes
no
not sure
do fishing groups/coops
exists here?
Total
upstream
zone
depleted
zone
lower
zone
zones of river
Total

40
Fish processing
There is very little fish processing activity along Sondu-Miriu. Only about 8 of the 96
respondents, most of them from the lower stream zone, carried out any form of fish
processing (Table 14). The upstream and the depleted zones had virtually no
processing activity, a reflection of the low level of fishing activity in these zones. The
amount of fish processing activity increased from the upstream zone to the depleted
and the lower zones in line with increasing fishing activity.
Table 15 further suggests that most respondents perceived the price of processed fish
to be cheaper than that of fresh fish. This was especially evident in the upstream and
the depleted zones. A possible explanation is that it was cheaper to transport and store
processed fish than fresh fish from the lakeshore to the markets on the Nyakach hills.
In the lower stream zone there was no clear indication of differences in the prices of
fresh and processed fish.
In the Kenyan situation, artisanal fish processing is not usually done to improve value,
but mainly to preserve fish. The absence of fish processing, therefore, is an indication
that the fish demand exceeds supply, hence, no surplus to process and store.
Table 14 Status of fish processing by respondents
Count
1 4 9 14
33 22 16 71
1 4 6 11
35 30 31 96
yes
no
not sure
respondent
family process
fish
Total
upstream
zone
depleted
zone
lower
zone
zones of river
Total

41
Table 15 Comparing costs of fresh and processed fish
Count
2 1 1 4
24 22 13 59
3 3 11 17
6 4 6 16
35 30 31 96
same as fresh fish
cheaper than fresh fish
more expensive than fresh fish
not sure
cost of
processed
fish
Total
upstream
zone
depleted
zone
lower
zone
No. of respondents by zones of
river
Total
IMPORTANCE OF FISH AND FISHING TO LOCAL COMMUNITY
River Sondu-Miriu has a role as a source of employment, income and food (fish),
though, the importance of these functions depends on the particular zone. In this
survey most respondents indicated that at least one member of their family fished in
the river, on that basis the number of fishing families along the river was reflected as
more than that which did not fish (Figure 3). The main reason for fishing, however,
seemed to be for subsistence, except in the lower stream where some people also
aimed for profits (Table 16). This is further confirmed in Table 17 presenting what
happened to the fish catch.
A previously explained, the importance of the river as a source of food seemed to be
seasonal. In all three zones, more fish were eaten during high floods (usually in March
to May). Since fishing hardly took place in the upstream and the depleted zones
during floods, the increased fish consumption during floods was largely due to
increased abundance in the lower stream. Table 18 shows that the importance of the
river as a source of food during floods increased from the upstream through the
depleted zone to the lower stream.
The importance of fishing as a source of employment is doubtful, particularly above
Odino Falls. Figure 4 (a – c) show that fishing was not regarded as the main

42
employment in the upstream and the depleted zone. In the upstream zone most
families were engaged in farming-related activities (66%), followed by other informal
employment (29%). In the depleted zone forest exploitation activities (such as selling
charcoal, grass, sisal and baskets) were the main income and employment sources for
half the families, followed by farming-related activities (40%). In the lower stream,
however, fishing was the main employment source (52%), followed by farming-
related activities (32%).
Overall, families in the upstream and the depleted zone (particularly above Odino
Falls) did not regard fishing as an important activity (even though most respondents
indicated that at least one member of their family fished). In Table 19, nearly 86% and
77% of respondents in the upstream and the depleted zone respectively indicated that
fishing was of no importance to them. In comparison, 45% of respondents in the
lower stream zone regarded fishing as of major importance, while 26% indicated that
it was of minor importance to their families.
Figure 3 Fishing and Non Fishing Families in the three Zones
0
5
10
15
20
25
Upstream Depleted Lower
Number of Families
Family Who fish
Family Who do not Fish

43
Table 16 Reason for fishing
Count
2 - 1 3
18 15 4 37
15 10 8 33
- 5 18 23
35 30 31 96
profit
food
does not fish
profit and food
Family
fish
for?
Total
upstream
zone
depleted
zone
lower
zone
No. of respondents by zones of river
Total
Table 17 What happens to the catch
Count
14 10 9 33
19 15 8 42
2 5 14 21
35 30 31 96
Do not fish
all eaten fresh by family
some eaten some sold
what happens
to the catch?
Total
upstream
zone
depleted
zone
lower
zone
No. of respondents by zones of
river
Total

44
Figure 4 Main sources of employment in Sondu-Miriu
a
Upstream zone Fishing related
Farming related
Formal employment
Other informal
employment
Forest exploitation
b
Depleted zone Fishing related
Farming related
Formal employment
Other informal
employment
Forest exploitation
c
Lower zone Fishing related
Farming related
Formal employment
Other informal
employment
Forest exploitation
Table 18 Seasonality of fish supply

45
Count
18 20 28 66
2 2
13 7 1 21
2 3 2 7
35 30 31 96
high floods
low floods
no change
not sure
you eat
more fish
during?
Total
upstream
zone
depleted
zone
lower
zone
No. of respondents by zones of
river
Total
Table 19 Importance of fishing to families
Count
30 23 9 62
2 14 16
5 5 8 18
35 30 31 96
No importance
Major importance
Minor importance
Importance
of fishing to
family
Total
upstream
zone
depleted
zone
lower
zone
No. of respondents by zones of
river
Total

46
SUMMARY AND CONCLUSIONS
• Fish species diversity was highest in the lower stream zone followed by the
depleted zone (because of the section below Odino Falls) then the upstream zone.
Due to annual migration of riverine fish, the species composition changed
seasonally, especially in the lower stream and the depleted zone below Odino
Falls, with higher diversity during the flooded seasons.
• Small Barbus spp (adel) and Small clarias (ndhira) were the main species present
in the upstream and depleted zone (above Odino Falls), both species being of low
commercial importance. The lower stream had nearly all the common riverine
species, although in varying quantities. The dominant species were Small Clarias
spp (ndhira), Schilbe spp (sire),Synodontis spp ( okoko), Oreochromis leucosticus
(ngege/ opat), Labeo spp. (ningu) and small Barbus spp (adel). The abundance of
these species changed seasonally especially in the lower stream and depleted zone
below Odino Falls.
• There has been notable decrease in fish stocks in the lower stream zone and the
depleted zone below Odino Falls, however, no significant change in stocks has
been observed in the upstream and the depleted zone above Odino Falls.
• At least seven fish species were thought to have disappeared; in particular ,Alestes
spp. (osoga), has certainly disappeared in the lower stream. Other species thought
to have disappeared were Labeo spp. (ningu) and large Barbus spp (fuani).
Possible reasons for fish stock decline included too many gears, bad fishing
methods, poor state of river water and predation by Lates niloticus (mbuta).
• A variety of fishing gear was used to catch fish in the river, the most important in
all zones being hooks and traps. The use of gillnets and fish fences increased
during floods in the lower stream zone while fish-stunning herbs were seasonally
applied in the upstream and depleted zones during the low floods.
• There was seasonality in fishing activity and the use of certain gears, especially
due to the fluctuations in fish abundance in the high flood and low flood seasons.

47
In the flooded period fishing intensity increased in the lower stream, where it was
done in the river and the flooded plains. In the upstream and the depleted zones it
was difficult to fish during floods due to steep banks and high water speed.
• The average expenditure on fishing gear varied through two orders of magnitude
with the zones and the importance that families attached to fishing. On average,
families in the lower stream zone spent the highest on fishing gear annually (Ksh
4,130), followed by the depleted zone (Ksh 202) and the upstream zone (Ksh 39).
• River Sondu-Miriu was not an important source of fish for the community living
alongside it in the upstream and the depleted zones. Instead Lake Victoria was the
first source of fish for nearly all families in these zones. Comparatively, families
in the lower stream zone depended more on the river [45% of respondents in the
lower stream said fishing was of major importance, while 86% in the upstream
said fishing was of no importance]. However, most of the respondents in the lower
stream still regarded the lake as their main source of fish.
• More fish was eaten during the flood seasons in all zones, though, this was largely
due to increased abundance of fish in the lower stream rather than in the upstream
and the depleted zones. In any case hardly any fishing took place in the upstream
and depleted zones during floods.
• There was very little fish processing activity along the Sondu-Miriu. The upstream
and depleted zones, in particular, had relatively insignificant processing activity.
A little fish processing, mainly by sun-drying and frying fish, was carried out in
the lower stream zone especially during floods.
• Even though many families indicated that one or more of their members carried
out fishing in the river, the overall results suggest that it was not an important
activity in the upstream and the depleted zone above Odino Falls. Fishing was
only important in the lower stream and the depleted zone below Odino Falls,
where fishermen fished both for subsistence and for profits.

48
THE IMPACTS OF RIVER SONDU-MIRIU FLOW REGIMES
The environmental flow assessment study for the project (SMHPP, 2002) has
provided much detail on the flow patterns of River Sondu-Miriu. The normal flow
pattern of the river is a single high flow season in April – May through to August –
September (sometimes with two peaks), trailing off into a low flow season from
October to March. The high season flows are typically above 40 cumecs, with peak
flows exceeding 100 cumecs, while the low season flows generally drop to below 20
cumecs (flows may sometimes drop to levels that are encountered during drought
years). Within the season, there are also considerable fluctuations in daily flow rates.
Based on the natural flow patterns, four clear seasonal flow regimes may be defined;
Low flow (less than 12 cumecs), medium flow (between 12 and 40 cumecs), high
flow (between 40 and 100 cumecs) and high peaked flow (greater than 40 cumecs and
peaking upto, or above, 150 cumecs).
The regulating pond constructed for SMHPP can only store enough water for eight
hours at full power generating capacity. Power generation will be at full capacity
during the high flow season but will remain below full capacity throughout much of
the low season (the low flow and the medium flow regimes). To meet its water
demand, the project will only divert a maximum flow of 40 cumecs from the depleted
section, which will be channelled back to the river stream at the outlet. Hence, the
project will have no impact on water flow in the upstream zone (possibly only a slight
change in normal flow pattern on the area immediately around the pond due to water
accumulation). The impact of the project on the lower zone will depend on the water
release program, especially the rate and consistency at which water will be released at
the outlet.
In Tables 20 (a – c) the impact that the current water flow regimes have on the local
community are assessed against different ecological and socio-economic parameters,
namely; fish abundance, fish species diversity, fishing activity at household level, fish
processing and marketing activities, fish consumption, types of fishing gear and site
of fishing. The impact of the flow regimes on the same variable under the
management of KENGEN have also been predicted in Tables 21 (a – c).

49
Table 20 (a – c) Effects of flood regimes: Current status
(a) Upstream zone
HIGH FLOODS MEDIUM
FLOODS
LOW FLOODS
FISH ABUNDANCE No change No change No change
FISH SPECIES
DIVERSITY No change No change No change
FISHING Low fishing
activity More fishing
activity More fishing
activity
FISH MARKETING No effect No effect No effect
FISH PROCESSING No effect No effect No effect
FISH
CONSUMPTION More fish
consumption
resulting from
flooded lower
stream
Average fish
consumption
mainly from lower
stream
Average fish
consumption from
lower stream and
from upstream
FAMILY MEMBER
FISHING Mostly adult
males Mixture of adult
males and young
boys
Mixture of adult
males and young
boys
FISHING GEARS No difference No difference No difference
SITE OF FISHING Fishing at the river
shoreline Fishing in mid-
stream Fishing in small
river lagoons

50
(b) Depleted zone
HIGH FLOODS MEDIUM
FLOODS
LOW FLOODS
FISH ABUNDANCE No change above
Odino Falls, but
greater abundance
below
No change No change above
Odino falls, but
decreased
abundance below
FISH SPECIES
DIVERSITY More diversity
particularly below
Odino Falls
No change Less species
diversity
particularly below
Odino Falls
FISHING ACTIVITY Low fishing
activity More fishing
activity More fishing
activity
FISH MARKETING No effect Isolated fish
marketing below
Odino Falls
No effect
FISH PROCESSING No effect Isolated fish
processing below
Odino Falls
No effect
FISH
CONSUMPTION More fish
consumption
resulting from
flooded lower
stream and below
Odino Falls
More fish
consumption
mainly from lower
stream and below
Odino Falls
Average fish
consumption from
lower stream and
from below Odino
Falls
FAMILY MEMBER
FISHING Mostly adult
males Mixture of adult
males and young
boys
Mixture of adult
males and young
boys
FISHING GEARS No difference More traps and
gillnets especially
below Odino Falls
No difference
SITE OF FISHING Fishing at the river
shoreline above
Odino Falls and
limited fishing
below
Fishing in mid-
stream Fishing in small
river lagoons

51
(c) Low stream zone
HIGH FLOODS MEDIUM
FLOODS
LOW FLOODS
FISH ABUNDANCE Abundant Abundant Decreased fish
stocks
FISH SPECIES
DIVERSITY
Increased diversity
Increased diversity
No change
FISHING More fishing
activity
More fishing
activity
Less fishing
activity
FISH MARKETING Increased fish
marketing
Increased fish
marketing
No effect
FISH PROCESSING More fish
processing
More fish
processing
Limited fish
processing
FISH
CONSUMPTION
More fish
consumption
More fish
consumption
Average fish
consumption
FAMILY MEMBER
FISHING
Mostly adult
males and few
women
Mixture of adult
males, women and
young boys
Mixture of adult
males, women and
young boys
FISHING GEARS Increased use of
traps and gillnets
Increased use of
traps and gillnets
No change
SITE OF FISHING Fishing in the
river and the
flooded plains
Fishing in the
river and floode
plains
Fishing in river
and papyrus
swamps

52
Table 21 Possible effects flow regimes Under KENGEN management
(a) Upstream section
High flow
(60-80
cumecs)
Medium
flow (20-40
cumecs)
Medium flow
peaked (20-40
cumecs)
Low flow (2-
10 cumecs)
FISH
ABUNDANCE No change No change No change
No change
FISH SPECIES
DIVERSITY No change No change No change No change
FISHING Low fishing
activity More fishing
activity
More fishing
activity More fishing
activity
FISH
MARKETING No effect No effect
No effect No effect
FISH
PROCESSING No effect No effect
No effect No effect
FISH
CONSUMPTION No effect No effect
More
consumption More
consumption
FISHING GEARS No
difference No
difference
No difference No difference
SITE OF FISHING Fishing at
the rive
shoreline
Fishing in
mid stream Fishing in
midstream Fishing in
small river
lagoons

53
(b) Depleted section
High flow
(60-80
cumecs)
Medium flow
(40-
60cumecs)
Medium flow
peaked (20-
40 cumecs)
Low flow (2-
10 cumecs)
FISH
ABUNDANCE No change
above Odino
Falls, but
greater
abundance
below
No change
above Odino
Falls, but
greater
abundance
below
No change
above Odino
falls, but
decreased
abundance
below
No change
above Odino
falls, but
decreased
abundance
below
FISH SPECIES
DIVERSITY More
diversity
particularly
below Odino
Falls
More
diversity
particularly
below Odino
Falls
Less species
diversity
particularly
below Odino
Falls
Less species
diversity
particularly
below Odino
Falls
FISHING Low fishing
activity Low fishing
activity
More fishing
activity More fishing
activity
FISH
MARKETING No effect No effect
No effect No effect
FISH
PROCESSING No effect No effect
No effect No effect
FISH
CONSUMPTION No effect
regarding
consumption
of fish from
depleted zone
No effect
regarding
consumption
of fish from
the depleted
zone
More fish
consumption
especially
from below
Odino falls
More fish
consumption
especially
from below
Odino falls
FISHING GEARS No difference More traps
and gillnets
especially
below Odino
Falls
More traps
and gillnets
especially
below Odino
Falls
No difference
SITE OF
FISHING Fishing at the
river shoreline
above Odino
Falls and
limited
fishing below
Fishing at the
river shoreline
above Odino
Falls and
limited
fishing below
Fishing in
mid-stream Fishing in
small river
lagoons

54
(c) Lower stream zone
High flow
(60-80
cumecs)
Medium flow
(20-40
cumecs)
Medium flow
peaked (20-40
cumecs)
Low flow
(2-10
cumecs)
FISH
ABUNDANCE Abundant Abundant
Decreased fish
stocks Decreased
fish stocks
FISH SPECIES
DIVERSITY Increased
diversity Increased
diversity
No change No change
FISHING More fishing
activity More fishing
activity
Less fishing
activity Less fishing
activity
FISH
MARKETING Increased fish
marketing Increased fish
marketing
Less fish
marketing Less fish
marketing
FISH
PROCESSING More fish
processing More fish
processing
Less fish
processing Less fish
processing
FISH
CONSUMPTION More fish
consumption More fish
consumption
Average fish
consumption
FISHING GEARS Increased use
of traps and
gillnets
Increased use
of traps and
gillnets
No change
SITE OF
FISHING Fishing in the
river and the
flooded plains
Fishing in the
river and
papyrus
swamps
Fishing in
river and
papyrus
swamps
Fishing in
river and
papyrus
swamps

55
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58
APPENDIX
(a) Glossary
Anadromous:- marine fish species whose reproduction takes place in freshwaters
(rivers),growing phase is sea e.g. Atlantic salmon (Salmo salar)
Cichlids: (Cichlidae): Family belonging to the sub-order of the perch like fish. Similar to the
perch but for the presence of only one olfactory pit on each side of the head. In Lake
Victoria include tilapine fishes and haplochromis.
Diatom: this is an order belonging to the class algae. These are microscopically small
unicellular plants. The cell walls are permeated with silicon, becoming glassily
transparent and consisting of two like –like inter – gripping halves. The shells are
practicably indestructible.
Fish Migration: is the movement of fish from one location to another. Can be within fresh
waters or between fresh and salty water. Usually for the purpose of feeding or
reproduction.
Omnivorous feeders: refers to animals that ingest both plant and animal materials. In fishery
an example is Clarias.
Opportunistic feeders: refers to organisms (animals) whose feeding habits depend on the
occurrence of the food items in the environment i.e. tends to feed on what is
available.
pH. : this is the concentration of hydrogen ions. In water it shows whether the water is acidic,
neutral or alkali pH value is no quantity in itself and has to be considered in relation
to other factors esp. hardness.
Phytoplankton: are plant plankton , found in fresh waters , consist mainly of algae.
Potamodromous: these are fresh water fish species which move upstream into rivers from
the Lake for breeding purposes. These usually happen in the rainy season. e.g. Schilbe
intermedius, Synodontis victoriae, Labeo victorianous.
Species diversity: It is a characterisation of a community taking into consideration the
numerical structure and the composition.
Turbidity: is the unclearness of water, usually due to suspended materials. Affects light
penetration into the water, hence production (primary)
Zooplankton: plankton is a collection name for all free floating acquatic organisms. There
are either carried or moved by water and its currents this is made possible by fatty
deposits and the development of body extensions. Zooplankton = animals
planton.fresh water zooplankton consist of tiny ,upto 1mm. Organisms. Divided into
3 main groups, Rotifers, copepoda and cladosera.

59
(b) Fish Species of the Sondu-Miriu
Scientific name Local Luo name Common English name
Alestes nurse
Alestes sadleri Osoga
Aplocheilichthys
bukobanus**
Bagrus dogmac Seu
Barbus altianalis Fuani
Barbus cercops Adel
Barbus neglectus Adel
Barbus nyanzae Adel
Barbus yongei Adel
Brycinus jacksonii
Brycinus sadleri
Clarias gariepinus Mumi Cat fish
Clarias mossambicus Mumi Cat fish
Clenopoma muriei
Gnathonemus longiberbis Odhore
Haplochromis spp. Fulu
Labeo victorianus Ningu
Lates niloticus Mbuta Nile perch
Marcusenius grahami
Mastacembalus frenatus Okunga
Micropterus salmoides
Mormyrus Kannume Suma
Oreochromis leucosticus Opat
Oreochromis niloticus Nyamami Tilapia
Oreochromis variabilis Mbiru Tilapia
Petrecephalus cutostoma Obu
Protopterus aethiopicus Kamongo Mud fish
Schilbe intermedius* Sire
Schilbe mystus* Sire
Synodontis afrofischeri Okoko rateng
Synodontis victoriae Okoko rachar
Tilapia zilli Silli
Xenoclarias spp. Ndhira