Okavango River Basin Technical
Diagnostic Analysis:
Environmental Flow Module
Specialist Report
Country: Namibia
Discipline: Fish Life
Ben C. W. Van Der Waal
February 2009
EFA Namibia Fish Life
Okavango River Basin Technical
Diagnostic Analysis:
Environmental Flow Module
Specialist Report
Country: NAMIBIA
Discipline: FISH LIFE
Author: BEN C W VAN DER WAAL
Date: 13 FEBRUARY 2009
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EFA Namibia Fish Life
EXECUTIVE SUMMARY
The fish life of the Kavango River is better known in the Botswana and Namibian
reaches and the about 80 known species were divided for this exercise into the
following seven indicators: Resident in river [including tigerfish and larger cichlids]
Migrating to floodplains small , represented by small species such as the churchill,
Migrating to floodplains large, represented by redbreast tilapia, Rock dwellers,
example Okavango suckermouth, Sandbank dwellers, example the Chobe sand
catlet, Marginal vegetation dweller, example Zambezi happy and Backwater dweller,
represented by the Okavango tilapia.
More groups could be identified in the Namibian section, eg nesting fish species, that
could again be divided into two types, substrate and floating nesters but this
approach was abandoned after consulting with the Angolan and Botswana fish
biologist colleagues as it would complicate the exercise without adding much value.
.
Three visits were brought with the Namibian team to the two selected sites, Kapako,
upstream of the Cuito confluence with the Kavango, representing a floodplain type of
habitat, and Popa Falls, below the Cuito confluence and representing a rocky type of
environment. Actual fish collections were conducted during low water conditions,
during the early first peak and a month later, when the river had actually dropped a
bit before the record flood peak reached later. Gear used included a set of 11
different mesh gillnets, a small mesh seine net, large scoop net in collaboration with
a AC fish shocker that made it possible to investigate the fish life of rocky habitats
with flowing water. Apart from the fish collections, reference could also be made to
an extensive series of fish collections with a set of gill nets over the period 1995 to
2007. The predicted response of each indicator was drawn up from the existing
information in literature, and personal experience with these indicator groups as well
as their presence in the samples collected during this study. These predictions could
then be used as guidelines for the subsequent response curves drawn for each
indicator group and the ultimate joint scenario exercise.
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EFA Namibia Fish Life
TABLE OF CONTENTS
EXECUTIVE SUMMARY .......................................................................................................... 3
LIST OF TABLES ..................................................................................................................... 6
LIST OF FIGURES ................................................................................................................... 7
ACKNOWLEDGEMENTS ........................................................................................................ 8
1.INTRODUCTION ................................................................................................................... 9
1.1 Background ................................................................................................... 9
1.2 Okavango River Basin EFA Objectives and Workplan .................................. 9
1.2.1 Project objectives .................................................................................... 9
1.3 Layout of this report ..................................................................................... 10
2.STUDY AREA ..................................................................................................................... 11
2.1 Description of the Okavango Basin ........................................................... 11
2. 2
Delineation of the Okavango Basin into Integrated Units of Analysis ....... 12
2.3 Overview of sites ......................................................................................... 13
2.4 Discipline-specific description of Namibia sites ........................................... 13
2.4.1 Site 4: Okavango River at Kapako............................................................ 13
2.4.2 Site 5: Okavango River at Popa Falls ....................................................... 13
2.5 Habitat integrity of the sites ......................................................................... 14
3.IDENTIFICATION OF INDICATORS AND FLOW CATEGORIES ...................................... 15
3.1 Indicators ..................................................................................................... 15
3.1.1 Introduction ........................................................................................... 15
3.2 Indicator list for fish species ................................................................... 15
3.3 Description and location of indicators .......................................................... 16
3.4 Flow categories river sites ........................................................................ 19
3.5 Inundation categories delta sites .............................................................. 22
4.LITERATURE REVIEW ....................................................................................................... 24
4.1 Introduction .................................................................................................. 24
4.2 Review of fish Indicators ...................................................................... 24
4.2.1 Indicator 1 Resident in river ................................................................ 24
Main characteristics of Indicator 1 - resident in river ............................................ 24
4.2.2 Indicator 2 Migrating to floodplains small fish..................................... 26
Main characteristics of Indicator 2 ..................................................................... 26
Life cycle attributes of Indicator 2 ...................................................................... 26
Links to flow ....................................................................................................... 27
4.2.3 Indicator 3 Migrating to floodplains large fish .................................. 27
Main characteristics of Indicator 3 ..................................................................... 27
Life cycle attributes of Indicator 3 ...................................................................... 28
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EFA Namibia Fish Life
Links to flow ....................................................................................................... 28
4.2.4 Indicator 4 Rock dwellers ...................................................................... 28
Main characteristics of Indicator 4 ..................................................................... 28
Life cycle attributes of Indicator 4 ...................................................................... 29
Links to flow ....................................................................................................... 29
4.2.5 Indicator 5 Marginal vegetation dwellers ............................................. 29
Main characteristics of Indicator 5 ..................................................................... 29
Life cycle attributes of Indicator 5 ...................................................................... 30
Links to flow ....................................................................................................... 30
4.2.6 Indicator 6 Sandbank dwellers ............................................................. 30
Main characteristics of Indicator ........................................................................ 30
Life cycle attributes of Indicator 6 ...................................................................... 31
Links to flow ....................................................................................................... 31
4.2.7 Indicator 7 Backwater dwellers ............................................................ 31
Main characteristics of Indicator 7 ..................................................................... 31
Life cycle attributes of Indicator 7 ...................................................................... 32
Links to flow ....................................................................................................... 32
4.3 Summary ..................................................................................................... 33
5.DATA COLLECTION AND ANALYSIS ................................................................................ 34
5.1 Methods for data collection and analysis ..................................................... 34
5.2 Results ........................................................................................................ 34
5.3 A summary of present understanding of the predicted responses of all fish
indicators to potential changes in the flow regime ................................................. 39
5.3.1 Fish Indicator 1 - Resident in river .................................................. 40
5.3.2 Fish Indicator 2 - Migrating to floodplains small fish ....................... 42
5.3.3
Fish Indicator 3 - Migrating to floodplains large fish ................... 43
5.3.4 Fish Indicator 4 - Rock dwellers ....................................................... 45
5.3.5 Fish Indicator 5 - Sandbank dwellers ................................................. 46
5.3.6 Fish Indicator 6 - Marginal vegetation dwellers ................................... 47
5.3.7 Fish Indicator 7 - Backwater dwellers ................................................ 47
5.4 Conclusion ................................................................................................... 49
6.REFERENCES .................................................................................................................... 50
6.1 Relevant Own Work ........................................................................................ 50
6.2 Other References ............................................................................................ 50
APPENDIX A: RAW DATA ..................................................................................................... 53
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EFA Namibia Fish Life
LIST OF TABLES
Table 1
Location of the eight EFA sites ................................................................... 13
Table 2: List of indicators for fish and those chosen to represent each site .................. 15
Table 3: Questions to be addressed at the Knowledge Capture Workshop, per indicator
per site. In all cases, `natural' embraces the full range of natural
variability .................................................................................. 22
Table 4: Inundation categories for the Okavango Delta as recognised by the HOORC
inundation model ...................................................................... 22
Table 5: Status of fish indicators at sites in Namibia during low water conditions at the two
Namibian sites. ......................................................................... 38
Table 6: Status of fish indicators at sites in Namibia during high water flood conditions at
the two Namibian sites. ............................................................ 39
Table 7: Predicted response to possible changes in the flow regime of fish resident in
river in the Okavango River ecosystem - Indicator 1 .............. 40
Table 8: Predicted response to possible changes in the flow regime of fish Migrating to
floodplains small fish in the Okavango River ecosystem -
Indicator 2 ................................................................................ 42
Table 9: Predicted response to possible changes in the flow regime of fish Migrating to
floodplains large fish in the Okavango River ecosystem -
Indicator 3. ............................................................................... 43
Table 10: Predicted response to possible changes in the flow regime of fish Rock
dwellers in the Okavango River ecosystem Indicator 4 ........ 45
Table 11: Predicted response to possible changes in the flow regime of fish Sandbank
dwellers in the Okavango River ecosystem Indicator 5 ......... 46
Table 12: Predicted response to possible changes in the flow regime of fish Marginal
vegetation dwellers in the Okavango River ecosystem Indicator
6 ............................................................................................... 47
Table 13: Predicted response to possible changes in the flow regime of fish Backwater
dwellers in the Okavango River ecosystem Indicator 7 ......... 47
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EFA Namibia Fish Life
LIST OF FIGURES
Figure 1
Upper Okavango River Basin from sources to the northern end of the Delta11
Figure 2
The Okavango River Basin, showing drainage into the Okavango Delta and
the Makgadikgadi Pans ............................................................ 12
Figure 3. 1 :Three representative years for Site 1: Cuebe River @ Capico, illustrating the
approximate division of the flow regime into four flow seasons 20
Figure 3. 2: Three representative years for Site 2: Cubango River @ Mucindi, illustrating
the approximate division of the flow regime into four flow seasons
................................................................................................. 20
Figure 3. 3: Three representative years for Site 3 Cuito River @ Cuito Cuanavale,
illustrating the approximate division of the flow regime into four
flow seasons ............................................................................ 21
Figure 3. 4: Three representative years for Site 4: Okavango River @ Kapako
(hydrological data from Rundu), illustrating the approximate
division of the flow regime into four flow seasons .................... 21
Figure 3. 5: Three representative years for Site 5: Okavango River @ Popa (hydrological
data from Mukwe), illustrating the approximate division of the flow
regime into four flow seasons ................................................... 21
Figure 4. 1: Fish collection sites with two sets of gill nets [red arrows] and seine net
[yellow stars] at the Kapako site in November 2008 ................ 35
Figure 4. 2: Fish collection sites with two sets of gill nets [red arrows] and seine net
[yellow stars] at the Kapako site in February 2009. .................. 36
Figure 4. 3: Fish collection sites with two sets of gill nets [red arrows] and electrofisher
and D-net [yellow stars] at the Popa Falls site in November 2008.
................................................................................................. 37
Figure 4. 4: Fish collection sites with two sets of gill nets [red arrows] and electrofisher
and D-net [yellow stars] at the Popa Falls site in February 2009.38
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EFA Namibia Fish Life
ABBREVIATIONS
ABBREVIATION
MEANING
DTM
Digital Terrain Model
EFA
Environmental Flow Assessment
EPSMO
Environmental Protection and Sustainable Management of the Okavango River
Basin
OBSC
Okavango Basin Steering Committee
OKACOM
of the Okavango River Basin Water Commission
TDA
transboundary diagnostic assessment
HOORC
Harry Oppenheimer Okavango Research Centre
ACKNOWLEDGEMENTS
All the team members got their hands wet and fishy when close to the fishing team but the
following colleagues of the Kavango EFA team are due my sincere thanks as they helped
setting nets, collecting fish under sometimes trying and hot conditions : Mark Paxton, Kevin
Roberts, as well as David Roberts, volunteer student and staff of the Kamutjonga Inland
Fisheries Institute, including Dr Ekkehard Klingelhoeffer and Dominic, Peter and students
Elisa and Linda. Celeste Espach gave much information on maps and GIS and is thanked for
the preparation of the maps. The report is a product of frank discussions with all team
members and especially Jackie King and Angolan [Miguel] and Botswana [Keta]
counterparts.
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EFA Namibia Fish Life
1. INTRODUCTION
1.1
Background
An Environmental Protection and Sustainable Management of the Okavango River Basin
(EPSMO) Project is being implemented under the auspices of the Food and Agriculture
Organization of the United Nations (UN-FAO). One of the activities is to complete a
transboundary diagnostic assessment (TDA) for the purpose of developing a Strategic Action
Plan for the basin. The TDA is an analysis of current and future possible causes of
transboundary issues between the three countries of the basin: Angola, Namibia and
Botswana. The Okavango Basin Steering Committee (OBSC) of the Okavango River Basin
Water Commission (OKACOM) noted during a March 2008 meeting in Windhoek, Namibia,
that future transboundary issues within the Okavango River basin are likely to occur due to
developments that would modify flow regimes. The OBSC also noted that there was
inadequate information about the physico-chemical, ecological and socio-economic effects of
such possible developments. OBSC recommended at this meeting that a preliminary
Environmental Flow Assessment (EFA) be carried out to predict possible development-driven
changes in the flow regime of the Okavango River system, the related ecosystem changes,
and the consequent impacts on people using the river's resources.
This preliminary EFA is a joint project of EPSMO and the Biokavango Project. One
component of the preliminary EFA is a series of country-specific specialist studies, of which
this is the Fish Report for Namibia.
1.2
Okavango River Basin EFA Objectives and Workplan
1.2.1
Project objectives
The goals of the preliminary EFA are:
To summarise all relevant information on the Okavango River system and its users, and
collect new data as appropriate within the constraints of this preliminary EFA
to use these to provide scenarios of possible development pathways into the future for
consideration by decision makers, enabling them to discuss and negotiate on sustainable
development of the Okavango River Basin;
to include in each scenario the major positive and negative ecological, resource-economic
and social impacts of the relevant developments;
to complete this suite of activities as a preliminary EFA, due to time constraints, as input to
the TDA and to a future comprehensive EFA.
The specific objectives at a preliminary level are:
to ascertain at different points along the Okavango River system, including the Delta, the
existing relationships between the flow regime and the ecological nature and functioning of
the river ecosystem;
to ascertain the existing relationships between the river ecosystem and peoples' livelihoods;
to predict possible development-driven changes to the flow regime and thus to the river
ecosystem;
to predict the impacts of such river ecosystem changes on people's livelihoods.
To use these preliminary EFA outputs to enhance biodiversity management of the Delta.
To develop skills for conducting EFAs in Angola, Botswana, and Namibia.
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EFA Namibia Fish Life
1.3
Layout of this report
Chapter 1 gives a brief introduction, to the background of the project and lists project
objectives. Chapter 2 describes the broad study area of the Okavango River Basin and
gives more detail on the two specific sites chosen for this preliminary EFA within the
Namibian section of the river- Kapako and Popa rapids. In Chapter 3, highlighted the agreed
fish indicators and flow categories. Literature review pertinent to freshwater fishes work in the
Okavango River and other similar systems is given in Chapter 4; full indicators are listed. The
field survey work undertaken for fish diversity investigation within Namibia in both the dry
season (October 2008) and wet season (February 2009); together with data collection,
analysis and results are outlined in Chapter 5. Chapter 6 is a first attempt to link fish
indicators to flow and provide information on the flow-response relationships for use in the
Okavango EF-DSS and will be completed after the Knowledge Capture Workshop in March
2009. . References are found in Chapter 7. Appendix A gives a full description of indicators
and Appendix B contains my raw field data.
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EFA Namibia Fish Life
2. STUDY AREA
2.1 Description of the Okavango Basin
The Okavango River Basin consists of the areas drained by the Cubango, Cutato, Cuchi,
Cuelei, Cuebe, and Cuito rivers in Angola, the Okavango River in Namibia and Botswana,
and the Okavango Delta. This basin topographically includes the inactive drainage are of
the Omatako Omuramba. Although this ephemeral river still regularly floods along its
southern portion, it has not contributed any flow to the Okavango River. Outflows from the
Okavango Delta are drained through the Thamalakane and then Boteti Rivers, the latter
eventually joining the Makgadikgadi Pans. The Nata River, which drains the western part of
Zimbabwe, also joins the Makgadikgadi Pans from the east. On the basis of topography, the
Okavango River Basin thus includes the Makgadikgadi Pans and Nata River Basin. This
study, however, focuses on the active drainage parts of the basin in Angola and Namibia,
and the Okavango delta in Botswana. The Omatako Omuramba, Makgadikgadi Pans and
Nata River are not included.
Upper Okavango River Basin
N
W
E
S
Cu
t
Cu
a
#
t
o
c
h
i
#
C
C
u
u
#
it
a
o
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Cu
#
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Menongue
ba
u
n
c
g
h
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Major settlement
o
i
# Cuito Cuanavale
River
C
#
ue
Fossil river
be
C
Panhandle
ANGOLA
uiri
Permanent swamps
ri
#
Seasonal swamps
Cubango
Cuito
NAMIBIA
Okavango
#
Rundu
#
#
#
0
300 Kilometers
#
Figure 1
Upper Okavango River Basin from sources to the northern end of the Delta
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EFA Namibia Fish Life
Okavango River Basin
N
W
E
S
C
u
ta
Cu
#
to
c
h
i#
C
C
ui
ua
#
t
o
nava
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ub
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g
h
o
i
# Cuito Cuanavale
# Cuebe
C
ANGOLA
uirir
#
i
Cubango
Cuito
NAMIBIA
Okavango
#
Rundu
#
# #
#
##
#
#
#
Maun
#
Makgadikgadi Pans
# Ghanzi
#
Major settlement
River
Fossil river
Panhandle
0
600 Kilometers
Permanent swamps
Seasonal swamps
Figure 2
The Okavango River Basin, showing drainage into the Okavango Delta and the
Makgadikgadi Pans
2. 2 Delineation of the Okavango Basin into Integrated Units of
Analysis
Within the Okavango River Basin, no study could address every kilometre stretch of the river,
or every person living within the area, particularly a pilot study such as this one. These
representative areas that are reasonably homogeneous in their ecological characteristics and
can be delineated and used to choose several sites in which focus for data-collection and
monitoring can be done. The results from each representative site can then be extrapolated
over the respective wider areas.
Using this approach, the Basin was delineated into Integrated Units of Analysis
(EPSMO/Biokavango Report Number 2; Delineation Report) by:
dividing the river into relatively homogeneous longitudinal zones in terms of:
· hydrology;
· geomorphology;
· water
chemistry;
· fish;
· aquatic
macroinvertebrates;
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EFA Namibia Fish Life
· vegetation;
· wildlife
harmonising the results from each discipline into one set of biophysical river zones;
dividing the basin into relatively homogeneous areas in terms of social systems;
harmonising the biophysical river zones and the social areas into one set of Integrated Units
of Analysis (IUAs). See delineation report for details
The 19 recognised IUAs were then considered by each national team as candidates for the
location of the allocated number of study sites:
· Angola:
three
sites
· Namibia:
two
sites
· Botswana:
three
sites.
The sites chosen by the national teams are given in Table 1
Table 1
Location of the eight EFA sites
EFA Site No
Country
River
Location
1 Angola
Cuebe
Capico
2 Angola
Cubango
Mucundi
3 Angola
Cuito Cuito
Cuanavale
4 Namibia
Okavango
Kapako
5 Namibia
Okavango
Popa
Rapids
Upper Panhandle
6 Botswana
Okavango
around Shakawe
Xakanaka lagoon
7 Botswana
Xakanaka in Delta
and Khwai River
8
Botswana
Boteti Rivers
Maun and Chanoga
2.3 Overview of sites
2.4 Discipline-specific
description of Namibia sites
2.4.1 Site 4: Okavango River at Kapako
Fish habitat types available at Kapako include main stream with sand banks and steep clay
banks, reed beds, back waters, side channels, some rocky fast flowing sites, large
floodplains with pools and grass covered plains. Back waters and pools in the floodplain
contain typical assemblages of submerged vegetation and the floodplains various
hydrophilous grasses, some trees and other vegetation. Fish assemblages expected in these
habitats would include main channel, backwater, vegetated banks and sand banks.
2.4.2 Site 5: Okavango River at Popa Falls
Fast flowing main channel with islands and mainly rocky bottom bordered by reed and
papyrus beds. Small floodplains with small pools are limited. Submerged water plants were
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EFA Namibia Fish Life
limited to small areas in bays of the main channel. Fish assemblages expected in these
habitats would include those of the main channel, vegetated banks and rocky substrate.
2.5 Habitat
integrity of the sites
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EFA Namibia Fish Life
3. IDENTIFICATION OF INDICATORS AND FLOW CATEGORIES
3.1 Indicators
3.1.1 Introduction
Biophysical indicators are discipline-specific attributes of the river system that respond to a
change in river flow by changing in their:
· abundance;
· concentration;
or
· extent
(area).
Social indicators are attributes of the social structures linked to the river that respond to
changes in the availability of riverine resources (as described by the biophysical indicators).
The indicators are used to characterise the current situation and changes that could occur
with development-driven flow changes.
Within any one biophysical discipline, key attributes can be grouped if they are expected to
respond in the same way to the flow regime of the river. By example, fish species that all
move on to floodplains at about the same time and for the same kinds of breeding or feeding
reasons could be grouped as Fish Guild Migrating to floodplains .
Biophysical indicators are discipline-specific attributes of the river system that respond to a
change in river flow by changing in their:
abundance;
concentration; or
extent (area).
3.2 Indicator list for fish species
In order to cover the major characteristics of the river system and its users many indicators
may be deemed necessary. For any one EF site, however, the number of indicators is
limited to ten (or fewer) in order to make the process manageable. The full list of indicators
was developed collaboratively by the country representatives for the discipline Keta
Mosepele of Botswana, Miguel Morais of Angola and Ben van der Waal of Namibia - and is
provided in Error! Reference source not found. 2. Further details of each indicator,
including the representative species of each biological one, are given in Appendix A and
discussed fully in Chapter 4.
Table 2: List of indicators for fish and those chosen to represent each site
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EFA Namibia Fish Life
Indicato
Sites represented no more than ten
r
Indicator name
indicators per site
Number
1 2 3 4 5 6 7 8
1
Resident in river
X X
X X
2
Migrating to floodplains - small
fish
X X
3
Migrating to floodplains large
fish
4
Rock dwellers
X
5
Sandbank dweller
X
6
Marginal vegetation dwellers
X X
7
Backwater dwellers
X X
3.3 Description and location of indicators
FISH Indicator 1
Name:
Resident in river
Description:
fish species living mainly in the deeper channel and associated
backwaters during adult stages. Some important species
undertake longitudinal migrations related to breeding and
feeding.
Representative species:
Hydrocynus vittatus, Serranochromis spp, Oreochromis spp,
Sargochromis spp. Labeo lunatus,
Other characteristic species: Brycinus lateralis,
Flow-related location:
flowing channels and deep backwaters enabling migrations up
and down the river during certain seasons or water levels for
breeding and feeding purposes
Known water needs1:
require deep water where fish are safe and flow requirements to
stimulate migratory response and enable movement. There
may be secondary flow requirements to maintain habitat and
provide flow and drift of food organisms.
FISH Indicator 2
Name:
Migrating to floodplains small fish
Description:
Smaller [<25 cm] fish species living in the channel and
associated backwaters during low water conditions but
migrating into the floodplains when water covers them. On the
1 food items of species may be even more reliant on water flow characteristics
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EFA Namibia Fish Life
floodplains they breed and feed. Mass migrations back to the
river occur with receding water.
Representative species:
Marcusenius macrolepidotus, Petrocephalus catostoma,
Schilbe intermedius, Barbus paludinosus
Other characteristic species: Synodontis spp
Flow-related location:
stay in main channel and permanent pools during low water
flow, migrating out to floodplain during floods. Migrate back to
permanent waters as soon as flood water reaches a certain
critical depth.
Known water needs
require deep water where fish are safe during low water in main
channel and backwaters but move to flooded floodplains during
flood season for feeding and breeding. Rate of flooding and
especially receding are critical to survival.
FISH Indicator 3
Name:
Migrating to floodplains large fish
Description:
larger [>20 cm] fish species living in the channel and associated
deeper backwaters during low water conditions but migrating
into the floodplains when water covers them. On the floodplains
they breed and feed. Migrations back to the river as soon as
water levels drop occur with receding water.
Representative species:
Clarias gariepinus, Schilbe intermedius. Tilapia rendalli,
Other characteristic species: Clarias ngamensis
Flow-related location:
stay in main channel and permanent pools during low water
flow, migrating out to floodplain during floods. Migrate back to
permanent waters as soon as flood water reaches a certain
critical depth.
Known water needs
require deep water where fish are safe during low water in main
channel and backwaters but move to flooded floodplains during
flood season for feeding and breeding. Rate of flooding and
especially receding are critical to survival.
FISH Indicator 4
Name:
Rock dwellers
Description:
fish species living amongst rocks and in crevices in strongly
flowing water.
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EFA Namibia Fish Life
Representative species:
Labeo cylindricus, Amphilius uranoscopus, Barbus codringtonii,
Synodontis macrostoma, Hippopotamyrus ansorgii, Opsaridium
zambezense, Clariallabes platyprosopos, Chiloglanis fasciatus,
Other characteristic species: Barbus eutaenia, Nannocharax macropterus,
Flow-related location:
strongly flowing water covering rocky bed and bedrock in main
channels
Known water needs:
require constant flow of water with little sediments to prevent
smothering of crevices.
FISH Indicator 5
Name:
Marginal vegetation dwellers
Description:
fish species living mainly amongst vegetation on margin of river
and may move into floodplains during flood conditions.
Representative species:
Pharynchochromis acuticeps, Tilapia sparrmanii, Petrocephalus
catostoma, Barbus poechii, B. multilineatus, B.
thamalakanensis, Aplocheilichthys johnstoni,
Other characteristic species: Pseudocrenilabrus philander
Flow-related location:
stable flow patterns to maintain adapted vegetation on bank of
river and associated backwaters and channels.
Known water needs:
require emergent and submerged vegetation for protection.
There may be some flow and sedimentation/erosion
requirements to maintain vegetation and habitat.
FISH Indicator 6
Name:
Sandbank dwellers
Description:
fish species living mainly on the actively moving sandbanks or a
sandy bottom.
Representative species:
Leptoglanis cf. dorae, Leptoglanis sp, Opsaridium zambezense
Barbus unitaeniatus,
Other characteristic species: Micralestes acutidens
Flow-related location:
flowing water over sandbanks with active erosion/deposition.
Known water needs:
flowing water, absence of high loads of suspended sediments. .
Flow requirements to maintain habitat and provide drift of food.
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EFA Namibia Fish Life
FISH Indicator 7
Name:
Backwater dwellers
Description:
fish species living mainly amongst vegetation on margin of river
and associated backwaters during low water level conditions.
May move into floodplains during flood conditions.
Representative species:
Tilapia ruweti, Clarias theodorae, Pollimyrus castelnaui, Barbus
bifrenatus, B. barotseensis, B. fasciolatus, B. haasianus, B.
lineomaculatus, B. multilineatus, B. thamalakanensis,
Coptostomabarbus wittei, Aplocheilichthys A. katangae, A.
hutereaui.
Other characteristic species: Pharyngochromis acuticeps
Flow-related location:
isolated backwaters during low flow conditions and densely
vegetated parts of floodplains during flood conditions.
Known water needs:
stable flood patterns [flood and dry cycle] to maintain isolated
pools during dry season on the floodplains require emergent
and submerged vegetation for protection.
3.4 Flow categories river sites
One of the main assumptions underlying the EF process to be used in the TDA is that it is
possible to identify parts of the flow regime that are ecologically relevant in different ways
and to describe their nature using the historical hydrological record. Thus, one of the first
steps in the EFA process, for any river, is to consult with local river ecologists to identify
these ecologically most important flow categories. This process was followed at the
Preparation Workshop in September 2008 and four flow categories were agreed on for the
Okavango Basin river sites:
· Dry
season
· Transitional
Season
1
· Flood
Season
· Transitional
Season
2.
Tentative seasonal divisions for river Sites 1-5 are shown in Error! Reference source not
found. to Error! Reference source not found. 7. These seasonal divisions will be
formalised by the project hydrological team in the form of hydrological rules in the
hydrological model. In the interim they provide useful insights into the flow regime of the
river system suggesting a higher within-year flow variability of the Cuebe River and a higher
year-on-year variability of the Cubango River.
It is planned to use similar flow seasons for the remaining river sites: 6 and 8.
19
EFA Namibia Fish Life
120
Wet
100
Trans
n 1
Trans
n 2
Dry
80
Year
Y
2
ear
60
Year
Y
1
ear
Year
Y
3
ear
40
20
0
O
N
D
J
D
F
M
A
M
J
J
M
J
A
S
Figure 3. 1 :Three representative years for Site 1: Cuebe River @ Capico, illustrating the
approximate division of the flow regime into four flow seasons
1200
Wet
1000
Trans 1
Trans 2
Dry
800
Year 1
600
Year 2
Year 3
400
200
0
O
N
D
J
D
F
M
A
M
J
J
M
J
A
S
Figure 3. 2: Three representative years for Site 2: Cubango River @ Mucindi, illustrating the
approximate division of the flow regime into four flow seasons
20
EFA Namibia Fish Life
250
Wet
Dry
200
ns 1
ns 2
Tra
Tra
150
Year 1
ear
Year 2
ear
100
Year 3
ear
50
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 3. 3: Three representative years for Site 3 Cuito River @ Cuito Cuanavale, illustrating the
approximate division of the flow regime into four flow seasons
1000
900
Wet
We
800
Dry
Dr
Tra
Tr n
a s
n 1
s
Tra
Tr n
a s
n 2
s
Dry
Dr
700
600
Year 1
500
Year 2
400
Year 3
300
200
100
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 3. 4: Three representative years for Site 4: Okavango River @ Kapako (hydrological data
from Rundu), illustrating the approximate division of the flow regime into four flow
seasons
1800
1600
Wet
1400
Dry
Trans 1
Trans 2
Dry
1200
1000
Year 3
00
Year 2
800
Year 1
600
400
200
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 3. 5: Three representative years for Site 5: Okavango River @ Popa (hydrological data
from Mukwe), illustrating the approximate division of the flow regime into four flow
seasons
21
EFA Namibia Fish Life
The literature review (Chapter 4) and data collection and analysis exercises (Chapter 5) are
focused on addressing what is initially expected to be nine main questions related to these
flow seasons (Error! Reference source not found. 3).
Table 3: Questions to be addressed at the Knowledge Capture Workshop, per indicator per
site. In all cases, `natural' embraces the full range of natural variability
Question
Season
Response of indicator if:
number
1
Onset is earlier or later than natural median/average
2
Dry Season
Water levels are higher or lower than natural median/average
3
Extends longer than natural median/average
4
Duration is longer or shorter than natural median/average - i.e. hydrograph
Transition 1
is steeper or shallower
5
Flows are more or less variable than natural median/average and range
6
Onset is earlier or later than natural median/average synchronisation with
Flood season
rain may be changed
7
Natural proportion of different types of flood year changed
8
Onset is earlier or later than natural median/average
Transition 2
9
Duration is longer or shorter than natural median/average i.e. hydrograph
is steeper or shallower
3.5 Inundation categories delta sites
The recognised river flow categories are not relevant in the Delta, where inundation is the
major driver of ecosystem form and functioning. The main inundation categories recognised
by the inundation model developed by the Harry Oppenheimer Okavango Research Centre
(HOORC) are shown here (Error! Reference source not found.).
Table 4: Inundation categories for the Okavango Delta as recognised by the HOORC inundation
model
Inundation Inundation category name
Description
category
number
Delta 1
Channel in permanent
swamp
Delta 2
Lagoons in permanent
swamp
Delta 3
Backswamp in permanent
swamp
Delta 4
Seasonal pools in seasonally
flooded zones
Delta 5
Seasonal sedgelands in
seasonally flooded zones
Delta 6
Seasonal grasslands in
seasonally flooded zones
Delta 7
Savannah dried floodplain
22
EFA Namibia Fish Life
in seasonally flooded zones
Boteti 1
Wet connected
Boteti 2
Disconnected pools
Boteti 3
Dry
23
EFA Namibia Fish Life
4. LITERATURE REVIEW
Quite some literature exists on the fish life of the lower portion of the Okavango River basin.
Basic work on fish species present includes work by Skelton [2001] and Hay and Van Zyl
who worked on the fish life of the Kavango River itself. A considerable amount of information
has been gathered on changes in the fish community composition and size over 12 years by
Hay and MFMR but this data has not yet been analysed or reported on. Preliminary analysis
by Van der Waal and Hay [2008] indicate however that the fish populations outside the
Muhango National Park [now part of Bwabwata National Park] have less larger cichlids as
result of selective gillnetting by the local fishing community. This was confirmed during the
experimental gillnetting during the survey [see Appendix B] The conclusion is thus reached
that the fish community in the Kavango River outside the national park in Namibia is not
pristine anymore but altered as result of fishing pressure. Modern tourist angling practised by
lodges and the annual Crockango Bonanza angling competition, are thought to have minimal
impact on the fish community as catch-and-release is practised.
Although a considerable amount has been published on the fish biology of the Kavango and
Zambezi rivers, relevant information on the actual habitat requirements of fish species is
vague. A considerable portion of the argumentation on indicators is therefore based on
personal experience and information from colleagues that worked in the area. Apart from
consulting with the EFA colleagues in Botswana and Angola, knowledgeable persons like Dr
Clinton Hay were also approached for opinion on indicator groups.
4.1 Introduction
All accessible literature was consulted. There is not much specifically on the effect of floods
or changes in flow on groups of fish or their behaviour. Being isolated [stationed in Katima
Mulilo] without access to a library is a great disadvantage. I will try to get some literature at
Kamutjonga Inland Fisheries Institute but time is also limiting. Internet access is very slow
with the available landline telephone connections.
4.2 Review of fish Indicators
4.2.1
Indicator 1 Resident in river
Main characteristics of Indicator 1 - resident in river
The fishes migrating in the river stay in the main channels for most of their lives. They require
normal flow patterns, including normal seasonal level changes, water quality and quantity
within normal ranges. As these fish live in the river, food has to come downstream from
shallower, more productive sites, including phytoplankton, detritus and associated diatoms,
unicellular organisms and small fish. Upstream and [sometimes] downstream migrations of
small fish species when floods recede, may be important to the survival of large resident
predators [including largemouths [Serranochromis spp] tigerfish and catfish].
Many species undertake longitudinal migrations during specific seasons or part of the flood
cycle, such as tigerfish to breed, catfish breeding and feeding, mormyrids and some
small species to repopulate part of the system.
This indicator is characterised by large growing species living in the main stream that are not
predated on by tigerfish. Lateral migrations by juveniles of these species into the floodplain
take place.
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EFA Namibia Fish Life
Importance of indicator: fish need river with deep holes and backwaters in which they can
stay. Maintenance of the flow characteristics during the whole annual flood cycle is
important. Habitats in the river must provide the food required. Other requirements for the
nesting cichlids are shallower sand banks to nest on [discussed under Indicator 5].
species
Habitat requirements
Chosen
representative
species
Oreochromis andersonii
Deep slower flowing water, supply of detritus
X
in current, shallower sandy sandbanks in
side channels and backwater with slow flow
in early spring to early summer
O. macrochir
Deep slower flowing water, supply of detritus
x
in current, shallower sandy sandbanks in
side channels and backwater with slow flow
in early spring to early summer
Serranochromis robustus
Steep banks with hiding spots or aquatic
x
vegetation along strongly flowing deep
water. Also suitable nesting places in 1-2m
deep still water on edge of vegetation during
early spring for spawning and incubation
S. altus
Hiding places amongst vegetation on edge
of fast flowing channels. Clean water with
good visibility and nesting sites amongst
aquatic and emergent vegetation in
shallower areas during spring
Sargochromis giardi
Deep water holes and backwash with
detritus and mollusc life [food]] in deep
channels. Breeds in shallower water on
\sandbanks in slow flowing side channels
and backwaters
Hydrocynus vittatus
Open and running water of river channel and
x
open backwaters and channels. Require
deep water and clear water conditions.
Migrate after food and undertake longitudinal
breeding migrations
Labeo lunatus
Deep water in mainstream and backwaters,
feed on detritus and algae. Undertake
longitudinal breeding migrations
Life cycle attributes of Indicator 1 resident in river
This guild stays in deep pools and eddies in the main stream and backwaters during low
water levels and partly also during the flood season. They find their food there [detritus plays
an important role as food for vegetarian cichlids] Predatory fish rely on small fish species
migrating into the channel during draw down phase. Longitudinal migrations during early
summer for breeding [tigerfish] and feeding [tigerfish and catfish during late summer occur.
Longitudinal migrations of young of many species take place during the draw down phase.
Barbs and robbers move mainly upstream but some fish [mormyrids in Zambezi] move
downstream and form basis of a traditional fishery
Links to flow
25
EFA Namibia Fish Life
· Fish require deep holes [more than 3m during low level] to feel at ease [else get
spooked too often and will move away]. Such holes and pools must be maintained by
the current and large floods are needed to shape the channel.
· Fish find their food mainly visually; murky water would impact seriously
· Cichlids breed on communal shallow sandbanks or backwaters, 1-2m deep during the
early spring. Water temperature must be around 20o and flow rate slow. Very muddy
environments will be detrimental.
· Tigerfish and others undertake spawning migrations and move also during certain
seasons.
· Emergent and submerged aquatic vegetation is important for the survival of young
fish. Some lateral movement by young fish into floodplains or vegetated areas occurs
in summer, so some flooding would also be a necessity.
4.2.2
Indicator 2
Migrating to floodplains small fish
Main characteristics of Indicator 2
Small fish [smaller than 25cm max length] living in the main channel but migrating into the
floodplains are characterised by migrations associated with water levels, breeding activities
and feeding requirements. Breeding is stimulated by rising water levels and prespawning
migration and concentrations may occur [in bulldogs and barbs].
species
Habitat requirements
Chosen
representative
species
Marcusenius
Amongst vegetation in deep channels.
x
macrolepidotus
Moves onto floodplain to feed and breed late
with the peak of the flood. Mass migrations
back to the river take place with receding
water levels
Schilbe intermedius
Lives in deep pools on side of channels.
Moves into channels in floodplain and moves
onto floodplain to hunt. Spawning is late with
peak flood.
Barbus paludinosus
Lives in marginal vegetation in river but
moves with first floodwater onto floodplain to
colonise new deeper water bodies on
floodplain. Breeds on floodplain, more than
one generations per year.
Synodontis spp
Lives in deeper pools in the main river and
amongst structure [stumps , roots etc] but
migrates out onto the floodplain later in the
season to feed and breed. Stays in pools in
the floodplain and migrates back when
floods recede.
Life cycle attributes of Indicator 2
Fish of this guild live in the main river and deeper pools during the low phase of the
hydrological cycle but migrate laterally into the floodplain when floods start. Reasons for this
migration are feeding or breeding. It must be remembered that many juveniles of many
26
EFA Namibia Fish Life
species from other indicators all migrate out of the main channels into the floodplain for
protection and feeding purposes and only return to the deeper channels when the flood
recedes.
Links to flow
·
Migration onto floodplain takes place at different stages of flood by different species
[eg B. paludinosus and other Barbus spp are early migrators and Marcusenius and
Schilbe and Serranochromis move later]. Timing of flood is thus very important to all
these species as a late flood may depress successful spawning. A very early flood
similarly affects spawning cycles negatively. This explains the absence of upstream
migrations in the main channel of small fish during certain years when floods are
small or out of phase.
·
The rate of filling of the floodplain may be very important for the stimulation of
spawning of the different species.
·
Feeding success depends on continued fertility of the floodplain, again depending on
sediment deposition and maintenance of the floodplain vegetation and cycling of
nutrients.
·
Any disruption in the erosion and sedimentation in and onto the floodplain [including
removal of certain particle size by trapping in dams built higher up in the river], would
have a serious cascading effect on this indicator.
4.2.3
Indicator 3
Migrating to floodplains large fish
Main characteristics of Indicator 3
Larger growing fish living in the main channel but migrating into the floodplains are
characterised by migrations associated with water levels, breeding activities and feeding
requirements. Breeding is stimulated by rising water levels and prespawning migration and
concentrations may occur [in tigerfish and catfish].
species
Habitat requirements
Chosen
representative
species
Clarias gariepinus
Deep water pools in river, but moves into
x
shallow water for feeding purposes. Migrates
into floodplain with first rise of flood to spawn
on freshly inundated vegetation. Stays in
deeper pools of floodplain to feed
Clarias ngamensis
Deep backwater pools and lakes. Feeds on
molluscs and seeds, migrates onto floodplain
for early breeding and feeding
Tilapia rendalli
Moves from side of channels onto floodplain
x
with first floodwater. Constructs nest in water
shallower than 60cm amongst vegetation.
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EFA Namibia Fish Life
Vulnerable to draw down asit is a nest
brooder
Life cycle attributes of Indicator 3
Fish of this guild live in the main river and deeper pools during the low phase of the
hydrological cycle but migrate laterally into the floodplain when floods start. Reasons for this
migration are feeding or breeding. It must be remembered that many juveniles of many
species from other indicators also migrate out of the main channels into the floodplain for
protection and feeding purposes and only return to the deeper channels when the flood
recedes.
Links to flow
·
Migration onto floodplain takes place at different stages of flood by different species
[eg Clarias and T. rendalli are early migrators and Oreochromis and Serranochromis
move later]. Timing of flood is thus very important to all these species as a late flood
may depress successful spawning. A very early flood similarly affects spawning
cycles negatively. This explains the absence of upstream migrations in the main
channel of small fish during certain years when floods are small or out of phase.
·
The rate of filling of the floodplain may be very important for the stimulation of
spawning of the different species.
·
Feeding success depends on continued fertility of the floodplain, again depending on
sediment deposition and maintenance of the floodplain vegetation and cycling of
nutrients.
·
Any disruption in the erosion and sedimentation in and onto the floodplain [including
removal of certain particle size by trapping in dams], would have a serious cascading
effect on this indicator.
4.2.4
Indicator 4
Rock dwellers
Main characteristics of Indicator 4
Species all associated with rocky areas with strong flow where no sedimentation takes place.
Many species are only known from such habitats and may be the most sensitive fish
indicators. The whole life cycle is completed in this habitat. Feeding is dependent on drift
from other areas with exception of algal feeders such as Labeo cylindricus and Chiloglanis
spp.
species
Habitat requirements
Chosen
representative
species
R= rheophilic
Amphilius uranoscopus
Crevices in rocks, nocturnal insectivore
X R
Labeo cylindricus
Around rocks, feeding on aufwuchs
X
Barbus codringtonii
Deeper channels amongst rocks, feeding
28
EFA Namibia Fish Life
on pebble beds
Synodontis macrostoma
Crepuscular in crevices
Hippopotamyrus ansorgii,
Crepuscular associated with rocks
Clariallabes platyprosopos
Found only in crevices next to fast running
X R
water
Opsaridium zambezense
Over sand in cascade environments
Aethiomastacembelus
Crepuscular in crevices in rocks in fast
X R
vanderwaali
flowing water
Nannocharax macropterus
Deeper water and runs next to rocks
Chiloglanis fasciatus,
In crevices and on rocks, can move in open X R
sucking aufwuchs from rocks
Barbus eutaenia
Deeper runs associated with cascades
Life cycle attributes of Indicator 4
All fish of this indicator prefer clear, fast flowing water with very little transported or deposited
sediment. The rocks and bedrock must be kept open and no sedimentation take place or
crevices filled with sediment.
All food items have to be derived from other systems in the river and exported for
consumption.
Links to flow
·
Real rheophilic species [marked in table with R] live in crevices in the bedrock in
flowing water conditions only and are reliant on these conditions. Any change in flow
rate including lowering of water level, decrease in flow rate below normal ranges,
increase in sediment load, change in water quality, including water temperature,
dissolved oxygen end conductivity, will affect this groups seriously.
·
Associated species rely on fast flowing water over rocks providing microhabitats
including course sand beds, pebbles, sparse aquatic vegetation, cascades and
protected pools.
·
Rock dwellers can be divided into two feeding groups: a feeding on algal growth on
rocks [labeo and Chiloglanis] and insectivores [most other species] these last are fully
reliant on the provision of food arriving moistly from outside this habitat.
·
Breeding is associated with floods at the normal time. Some species undertake
longitudinal migrations eg Labeo and Barbus.
4.2.5
Indicator 5
Marginal vegetation dwellers
Main characteristics of Indicator 5
Species living in protected environment of emergent and/or submerged vegetation on the
edge of the river during low water conditions and more widely spread on the floodplain during
floods. This groups also includes many young of larger cichlids [Oreochromis, Tilapia,
Sargochromis and Serranochromis as well as Clarias spp, Schilbe, Synodontis and
Mormyrids]. These fish all seek protection from predation mainly from the tigerfish but also
larger Serranochromis species.
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EFA Namibia Fish Life
species
Habitat requirements
Chosen
representative
species
Pharynchochromis
Associated with emergent vegetation on
X
acuticeps
river edge but also in open water
Tilapia sparrmanii
Strongly associated with marginal
X
vegetation, moving to floodplain during
floods
Petrocephalus catostoma
Hiding in marginal vegetation during
X
daytime and moving actively at night
Barbus poechii,
Associated with deeper water amongst
vegetation.
B. multilineatus
Amongst vegetation
B. thamalakanensis
Amongst vegetation
Aplocheilichthys johnstoni
Lives exclusively at the surface of water
X
amongst submerged and emergent aquatic
plants
Hemichromis elongatus
On river margin near aquatic plants.
Nesting species constructing nest in
shallow area
Pseudocrenilabrus
Strongly associated with vegetation and
X
philander
also nesting there
Life cycle attributes of Indicator 5
This group lives mainly on the edge of the main channels and tributaries.
It is comprised of smaller species that are in themselves very vulnerable to predation by top
predators.
Suitable marginal vegetation is important for survival. Any loss of marginal vegetation will
impact negatively on this group.
Links to flow
· During low flow conditions, this group is most susceptible to predation as their
habitat may not have the vegetation needed to protect them.
· Species breed along marginal vegetation and also find their food there,
comprising of detritus and small aquatic organisms.
· The cichlids in this group eat insects and other invertebrates.
· Other species feed on insects and invertebrates and are dependent on the spatial
distribution of these insect pests.
4.2.6
Indicator 6
Sandbank dwellers
Main characteristics of Indicator
Specialist group living on/on fast flow over sandbanks,
Live on lower, actively depositing portion of sandbanks [before drop-off]
Depend on flow rate and particle size of sandbank [course grained, sorted]
30
EFA Namibia Fish Life
species
Habitat requirements
Chosen
representative
species
Leptoglanis cf dorae, L. sp
Lives only in loose graded sand on top of
X
sandbanks in running water. Lives on small
invertebrates caught while buried with eyes
only exposed.
Barbus unitaeniatus
Prefers sandbanks and flowing water, feeds X
on sand bottom, selecting organisms and
detrital particles.
Opsaridium zambezense
Active mini predator preferring clean sandy
X
bottom on sandbanks or below rapids
Micralestes acutidens
Active scavenger on edge of sandbanks
Life cycle attributes of Indicator 6
·
Small fish species adapted to bury in loose sand or swim in current over sand. Some
are confined to this habitat only [Leptoglanis] but others have a more wide
distribution [Micralestes].
·
Fish need active flow of water over sandbanks to created unique required habitat and
to provide inflow of food items from other parts of the river. The sand specialist
Leptoglanis spp require loose graded sand, found only where sandbanks are actively
moving.
Links to flow
·
Sandbanks can only exist where there is a dynamic balance between flow and bed
load and erosion and deposition. Any change in these will bring about a
disappearance of the type of sandbanks found in the Kavango River.
·
Fish species catch food on sight and need clear water.
·
Fish species are all adapted to the white colour of the sand a change in colour may
make these species more visible.
·
They breed on the edge of the river during summer, requiring typical early flood flow
rates.
4.2.7
Indicator 7
Backwater dwellers
Main characteristics of Indicator 7
Species of this group are small species adapted to live in shallow water and dense
vegetation where environmental conditions can become extreme in terms of water
temperature, oxygen levels and conductivity and pH. During the low water phase, they
31
EFA Namibia Fish Life
survive in backwater pools on the floodplain and when floods arrive, they are the first to
migrate with the water to colonize newly inundated areas and harvest the rich food resource.
Most species are insectivores as well as plankton feeders and piscivores. Most breed on the
floodplain and are stimulated by rising floods.
species
Habitat requirements
Chosen
representative
species
Tilapia ruweti
Densely vegetated shallow standing water
X
at edge of floodplain
Clarias theodorae
Dense aquatic vegetation in pools and edge X
of floodplain
Pollimyrus castelnaui
Densely vegetated areas and pools on the
X
floodplain
Barbus haasianus
Densely vegetated shallow edges of pools
X
and edge of floodplain
B. bifrenatus, B fasciolatus, Amongst emergent vegetation on edge of
B. lineomaculatus, B.
streams and pools and edge of floodplain
multilineatus
Aplocheilichthys katangae,
Amongst floating and emergent vegetation
X
A hutereaui
on edge of streams and pools on floodplain
Coptostomabarbus wittei
Densely vegetated margins of pools and
edge of floodplain
Life cycle attributes of Indicator 7
·
This indicator relies on survival of fish in small inocula on the floodplain, non drying
pools on the floodplain during the dry season.
·
During floods they move over the floodplain and require well vegetated areas for
protection and breeding.
·
This group comprises small species that are adapted to live in sometimes harsh
environments and play an important role in nutrient cycling, utilizing the wealth of
terrestrial and later aquatic invertebrates developing on the edge of the floodplain.
·
They themselves play an important role as food for many of the predatory species
[there are more than 20 predators in the system]
·
This group is also important to the Kavango people as they form an important part of
the fish harvested with baskets by women.
Links to flow
·
Indicator species depend on survival in isolated pools on the floodplain during the dry
phase of the flood cycle.
·
Maintenance of the vegetation cover is important during all stages of the flood.
·
floods are essential for feeding and breeding. Pools must maintain their shape, depth
and fertility, all a function of scouring and sedimentation during floods.
·
High and strong floods are needed to maintain the existents of deep pools on the
floodplain.
32
EFA Namibia Fish Life
4.3 Summary
A considerable amount of basic research has been conducted on the fish life of the Kavango
in Namibia by mainly Hay of the Ministry of Fisheries and Marine Resources [MFMR]. This
research was however directed at fisheries management and not at flood and flow
requirements of fish species. A substantial record of the presence and abundance of fish
species at six major sites was collected over a 12 year period that is valuable to monitor any
changes that have taken place or may take place in future. The identification of indicators
was not easy as group 1 for instance, contain some species that warrant a separate indictor
of fish remaining in the channel, like Serranochromis robustus, which does not show any
migratory trends [according to telemetry work by Thorstad et al 2001, 2003, 2005].
33
EFA Namibia Fish Life
5. DATA COLLECTION AND ANALYSIS
5.1 Methods for data collection and analysis
Fish data were collected at the Kapako and Popa Falls sites [and additionally at Kwetze,
Mahangu, Bwabwata National Park] on the following dates:
site
KAPAKO
POPA FALLS
KWETZE
LOW WATER
20-21 October 2008
21-22 October 2008
22-23 October 2008
HIGH WATER
7-8 January 2009
97 January 2009
HIGH WATER
8-9 February 2009
10-11 February 09
and using the following fishing gear:
1. 2 fleets of gillnets each consisting of 11 panels of 10 m length each of the following
stretched mesh size: 12, 16, 22, 28, 35, 45, 57, 73, 93, 118 and 150mm. They were
set overnight in representative habitats suitable for gillnet fishing [with least flow and
at least 1m depth] at each site. The fish caught overnight over a 12h period were
identified and length and sexual condition established.
2. Seine net of 8m by 2 m deep with bag of 2m deep and with 10mm mesh. This was
used to collect fish in pools of up to 100cm depth. All fish collected were identified
and length taken for each fish.
Fish shocker in conjunction with a large D-net [scoop net]. A 900W AC 220V portable
generator was directly connected to two electrodes attached to an inverted V pole keeping
the electrodes 30cm apart. This was used only in the rapids of Popa to collect rock living fish
species. Fish were flushed out by the current introduced with the electrodes and the strong
current then washed them into the D-net held
5.2 Results
The exact localities on the two study sites where fish were collected with a variety of fishing
gear are illustrated in Figures 8 to 12. downstream. This apparatus could only be used in
water 50cm or less deep.
34
EFA Namibia Fish Life
Figure 4. 1: Fish collection sites with two sets of gill nets [red arrows] and seine net [yellow
stars] at the Kapako site in November 2008
35
EFA Namibia Fish Life
Figure 4. 2: Fish collection sites with two sets of gill nets [red arrows] and seine net [yellow
stars] at the Kapako site in February 2009.
36
EFA Namibia Fish Life
Figure 4. 3: Fish collection sites with two sets of gill nets [red arrows] and electrofisher and D-
net [yellow stars] at the Popa Falls site in November 2008.
37
EFA Namibia Fish Life
Figure 4. 4: Fish collection sites with two sets of gill nets [red arrows] and electrofisher and D-
net [yellow stars] at the Popa Falls site in February 2009.
The fish collections during the low and high water levels represent the expected indicators.
For details on the actual fish species, numbers and sizes collected, please refer to Appendix
B. Results on the presence of indicators at the two study sites are summarized in Tables 5
and 6. Apart from data from the two surveys, previously collected data from 1982 to 2008
was also considered.
Table 5: Status of fish indicators at sites in Namibia during low water conditions at the two
Namibian sites.
Indicator
KAPAKO POPA
FALLS
Resident in river
ABUNDANT ABUNDANT
Migrating to floodplains small fish
ABUNDANT RARE
Migrating to floodplains large fish
ABUNDANT RARE
Rock dwellers
ABSENT ABUNDANT
Sandbank dweller
RARE VERY
RARE
Marginal vegetation dwellers
ABUNDANT RARE
Backwater dwellers
ABUNDANT RARE
38
EFA Namibia Fish Life
Table 6: Status of fish indicators at sites in Namibia during high water flood conditions at the
two Namibian sites.
Indicator
KAPAKO POPA
FALLS
Resident in river
ABUNDANT ABUNDANT
Migrating to floodplains small fish
ABUNDANT VERY
RARE
Migrating to floodplains large fish
ABUNDANT RARE
Rock dwellers
VERY RARE
ABUNDANT
Sandbank dweller
RARE VERY
RARE
Marginal vegetation dwellers
ABUNDANT RARE
Backwater dwellers
ABUNDANT RARE
5.3
A summary of present understanding of the predicted
responses of all fish indicators to potential changes in the flow
regime
Tables of expected response of fish indicators to change in flow regime in the Namibian
sector of the Kavango River are presented in the following tables [Table 7 to
39
EFA Namibia Fish Life
5.3.1
Fish Indicator 1 - Resident in river
Table 7: Predicted response to possible changes in the flow regime of fish resident in river in the Okavango River ecosystem - Indicator 1
Predicted response of indicator
Confidence in
Question
prediction (very
number
Season
Possible flow change
low, low, medium,
Site 4 Kapako Site 5 Popa rapids
high)
Negative if earlier
Negative if earlier
Onset is earlier or later than
1
No effect if later unless it interferes with
No effect if later unless it interferes with
medium
natural
breeding season in case of cichlids
breeding season in case of cichlids
Higher = less effect
Higher = less effect
Dry Season
2
Water levels are higher or
Lower = vulnerable, may interfere with
Lower = vulnerable, may interfere with
high
lower than natural
spawning of cichlids
spawning of cichlids
Negative effect vulnerable and spawning
3
Extends longer than natural
Negative effect vulnerable and spawning
delayed of non-cichlids
delayed of non-cichlids
high
Duration is longer or shorter
Steep rise may affect spawning sites of
Steep rise may affect spawning sites of
4
than natural - i.e. hydrograph
nesting species
nesting species
high
Transition 1
is steeper or shallower
Nil - acceptable
Nil - acceptable
Low [but system
5
Flows are more or less
variable than natural
is very robust]
Earlier flood: may be out of synch with
Earlier flood: may be out of synch with
Onset is earlier or later than
spawning season,
spawning season,
6
natural synchronisation with
medium
Late flood : not so much [Delta fish breed
late flood: not so much [Delta fish breed
rain may be changed
later]
later]
Flood
High floods are important for survival of
High floods are important for survival of
season
group direct connection between high
group direct connection between high
flood and good fishery catches two years
flood and good fishery catches two years
7
Natural proportion of different
High have data
types of flood year changed
later.
later
More lower floods has direct depressing
]More lower floods has direct depressing
effect on fish production.
effect on fish production.
Early decrease may affect breeding in late Early decrease may affect breeding in late
8
Transition 2
Onset is earlier or later than
spawners
spawners
low
natural
Late decrease no effect
Late decrease no effect
40
EFA Namibia Fish Life
Duration is longer or shorter
Steep hydrograph slope may affect survival
Steep hydrograph slope may affect survival
9
than natural i.e. hydrograph
of young fish negatively.
of young fish negatively.
low
is steeper or shallower
Longer duration no effect
Longer duration no effect
41
EFA Namibia Fish Life
5.3.2 Fish Indicator 2 - Migrating to floodplains small fish
Table 8: Predicted response to possible changes in the flow regime of fish Migrating to floodplains small fish in the Okavango River ecosystem -
Indicator 2
Predicted response of indicator
Confidence in
Question
prediction (very
number
Season
Possible flow change
low, low, medium,
Site 4 Kapako Site 5 Popa rapids
high)
Onset is earlier or later than
Negative for non-cichlids if later
Effects not prominent
1
medium
natural
Negative for cichlids if earlier than normal
Higher is OK
Affected if water levels are lower, not if
Dry Season
2
Water levels are higher or
If low, fish are affected during most
higher
high
lower than natural
sensitive stage
3
Extends longer than natural
Negative for all fish
Effects not prominent
medium
Duration is longer or shorter
Longer = no effedct, shorter means no
Negative on migration if shorter
4
than natural - i.e. hydrograph
opportunity to migrate, strong currents on
high
Transition 1
floodplain, loss by predation
is steeper or shallower
Higher variability is detrimental
Higher variability is detrimental
5
Flows are more or less
high
variable than natural
Earlier flood season may have
Earlier flood season may have
Onset is earlier or later than
devastating effect no migration, no
devastating effect no migration, no
6
natural synchronisation with
successful breeding. Late flood may affect breeding. Late flood may affect fish but
low
Flood
rain may be changed
fish but not sure as Delta fish are adapted
not sure as Delta fish are adapted same
season
same species
species
Negative long term effect
Negative long term effect
7
Natural proportion of different
medium
types of flood year changed
Onset is earlier or later than
Earlier = short production cycle on flood
Earlier = short production cycle on flood
8
natural
plain. Later no effect
plain. Later no effect
medium
Transition 2
Duration is longer or shorter
Shorter transition negative to fish.
Shorter season negative to fish.
9
than natural i.e. hydrograph
Extended season = beneficial for fish life.
Extended season = beneficial for fish life.
medium
is steeper or shallower
42
EFA Namibia Fish Life
5.3.3 Fish Indicator 3 - Migrating to floodplains large fish
Table 9: Predicted response to possible changes in the flow regime of fish Migrating to floodplains large fish in the Okavango River ecosystem -
Indicator 3.
Confidence in
Predicted response of indicator
Question
prediction (very
number
Season Possible
flow
change
low, low,
Site 4 Kapako Site 5 Popa rapids
medium, high)
Onset is earlier or later than Negative for non-cichlids if later
Effects not prominent
1
Negative for cichlids if earlier than
medium
natural
normal
Dry Season
Higher is OK
Affected if water levels are lower, not if
Water levels are higher or
2
If low, fish are affected during most
higher
high
lower than natural
sensitive stage
3
Extends longer than natural Negative for all fish
Effects not prominent
medium
Duration is longer or shorter Longer = no effedct, shorter means no
Negative on migration if shorter
4
than natural - i.e.
opportunity to migrate, strong currents
high
hydrograph is steeper or
on floodplain, loss by predation
Transition 1 shallower
Flows are more or less
Higher variability is detrimental
Higher variability is detrimental
5
high
variable than natural
Earlier flood season may have
Earlier flood season may have
Onset is earlier or later than devastating effect no migration, no
devastating effect no migration, no
6
natural synchronisation
successful breeding. Late flood may
breeding. Late flood may affect fish
low
Flood
with rain may be changed
affect fish but not sure as Delta fish are
but not sure as Delta fish are adapted
season
adapted same species
same species
Natural proportion of
Negative long term effect
Negative long term effect
7
different types of flood year
medium
changed
Onset is earlier or later than Earlier = short production cycle on flood Earlier = short production cycle on flood
8 Transition
2
medium
natural
plain. Later no effect
plain. Later no effect
43
EFA Namibia Fish Life
Duration is longer or shorter Shorter transition negative to fish.
Shorter season negative to fish.
than natural i.e.
Extended season = beneficial for fish
Extended season = beneficial for fish
9
medium
hydrograph is steeper or
life.
life.
shallower
44
EFA Namibia Fish Life
5.3.4
Fish Indicator 4 - Rock dwellers
Table 10: Predicted response to possible changes in the flow regime of fish Rock dwellers in the Okavango River ecosystem Indicator 4
Predicted response of indicator
Confidence in
Question
prediction (very
number
Season
Possible flow change
low, low, medium,
Site 4 Kapako Site 5 Popa rapids
high)
Onset is earlier or later than
No effect
Both have negative effect
1
medium
natural
Higher no effect
2
Water levels are higher or
Dry Season
Lower level serious effect, shrinking of
medium
lower than natural
already small habitat type
3
Extends longer than natural
Negative effect breeding may be
depressed
low
Duration is longer or shorter
Longer little effect
Shorter sudden changes in flow and
4
than natural - i.e. hydrograph
low
conditions may affect feeding and breeding
Transition 1
is steeper or shallower
preparation
5
Flows are more or less
Extremes both detrimental
medium
variable than natural
Onset is earlier or later than
Early flood out of synch with natural
6
natural synchronisation with
spawning cycle
low
Flood
rain may be changed
Late flood again affect breeding
season
7
Natural proportion of different
Extremes, especially low flows are
types of flood year changed
detrimental for these fish
medium
Onset is earlier or later than
Earlier drop may affect habitat food supply
8
and breeding for late spawners
medium
natural
Later no effect
Transition 2
Duration is longer or shorter
Extremes may have serious effect on
9
than natural i.e. hydrograph
survival
medium
is steeper or shallower
45
EFA Namibia Fish Life
5.3.5
Fish Indicator 5 - Sandbank dwellers
Table 11: Predicted response to possible changes in the flow regime of fish Sandbank dwellers in the Okavango River ecosystem Indicator 5
Predicted response of indicator
Confidence in
Question
prediction (very
number
Season
Possible flow change
low, low, medium,
Site 4 Kapako Site 5 Popa rapids
high)
Onset is earlier or later than
Negative effect if earlier.
Negative effect if earlier.
1
natural
Later little effect
Later little effect
medium
Lower than normal serious effect
Lower than normal serious effect
Dry Season
2
Water levels are higher or
Higher may affect shape and quality of
Higher may affect shape and quality of
high
lower than natural
sand banks directly, and thus the fish
sand banks directly, and thus the fish
3
Extends longer than natural
Negative impact
Negative impact
high
Duration is longer or shorter
Both may have effect on physical structure
Both may have effect on physical structure
4
than natural - i.e. hydrograph
of sand bans. Food shortages develop with
of sand bans. Food shortages develop with
medium
Transition 1
is steeper or shallower
extended period
extended period
Extreme flows detrimental
Extreme flows detrimental
5
Flows are more or less
medium
variable than natural
Onset is earlier or later than
Breeding season of fish species may be
Breeding season of fish species may be
6
natural synchronisation with
affected.
affected.
medium
Flood
rain may be changed
season
Extremes may affect sandbank
Extremes may affect sandbank
7
Natural proportion of different
types of flood year changed
development, feeding and breeding
development, feeding and breeding
high
Onset is earlier or later than
Early drop may affect growth and breeding
Early drop may affect growth and breeding
8
natural
of late season spawners
of late season spawners
medium
Transition 2
Duration is longer or shorter
Extremes may affect populations seriously
Extremes may affect populations seriously
9
than natural i.e. hydrograph
medium
is steeper or shallower
46
EFA Namibia Fish Life
5.3.6
Fish Indicator 6 - Marginal vegetation dwellers
Table 12: Predicted response to possible changes in the flow regime of fish Marginal vegetation dwellers in the Okavango River ecosystem
Indicator 6
Predicted response of indicator
Confidence in
Question
prediction (very
number
Season
Possible flow change
low, low, medium,
Site 4 Kapako Site 5 Popa rapids
high)
Onset is earlier or later than
Negative effect with earlier low water
Negative effect with earlier low water
1
natural
Later no effect
Later no effect
medium
Dry Season
Water levels lower may be negative
Water levels lower may be negative
2
Water levels are higher or
lower than natural
Higher water levels little effect
Higher water levels little effect
medium
3
Extends longer than natural
Serious effect if longer vegetation affected Serious effect if longer vegetation affected medium
Longer transition little effect
Longer transition little effect
Duration is longer or shorter
Shorter transition more serious, may
Shorter transition more serious, may
4
than natural - i.e. hydrograph
medium
affect vegetation that takes time to adapt to
affect vegetation that takes time to adapt to
Transition 1
is steeper or shallower
new water level
new water level
Extremes detrimental
Extremes detrimental
5
Flows are more or less
medium
variable than natural
Onset is earlier or later than
Earlier flood may affect breeding success
Earlier flood may affect breeding success
6
natural synchronisation with
negatively
negatively
medium
Flood
rain may be changed
Late flood may affect growth and breeding
Late flood may affect growth and breeding
season
Extremes negative effect
Extremes negative effect
7
Natural proportion of different
medium
types of flood year changed
Onset is earlier or later than
Early drop negative effect.
Early drop negative effect.
8
natural
Late drop - little effect
Late drop - little effect
medium
Transition 2
Duration is longer or shorter
Extremes negative effect
Extremes negative effect
9
than natural i.e. hydrograph
medium
is steeper or shallower
5.3.7
Fish Indicator 7 - Backwater dwellers
Table 13: Predicted response to possible changes in the flow regime of fish Backwater dwellers in the Okavango River ecosystem Indicator 7
47
EFA Namibia Fish Life
Predicted response of indicator
Confidence in
Question
prediction (very
number
Season
Possible flow change
low, low, medium,
Site 4 Kapako Site 5 Popa rapids
high)
Onset is earlier or later than
Early dry season will affect vegetation ,
1
medium
natural
habitat availability and fish survival
Dry Season
Higher no effect
2
Water levels are higher or
medium
lower than natural
Lower desiccation, fish population crash
3
Extends longer than natural
Desiccation, fish die
medium
Duration is longer or shorter
Longer negative effect
4
than natural - i.e. hydrograph
Shorter, little effect
low
Transition 1
is steeper or shallower
Extremes negative effect
5
Flows are more or less
medium
variable than natural
Early flood may retard spawning of fish
Onset is earlier or later than
species
6
natural synchronisation with
Late flood season may be out of synch for
medium
Flood
rain may be changed
breeding [but see adaptation in Delta to late
season
floods?
Extreme low floods will affect fish survival
7
Natural proportion of different
medium
types of flood year changed
Early lower water diminishes survival of this
Onset is earlier or later than
8
indicator
low
natural
Late - no effect
Transition 2
Duration is longer or shorter
Extremes will affect fishj
9
than natural i.e. hydrograph
loiw
is steeper or shallower
48
5.4 Conclusion
It was possible to divide the fish species of the Kavango into seven indicator groups
that would help to describe the response of fish groups to changes in the hydrology
of the river. Three fish collections were made during the study period to collect fish
species at the two study sites. A third site in the Muhango conservation area was
included for comparison during low water conditions. This information was blended
with the previously collected data by earlier surveys by MFMR to obtain a larger
picture.
There are many missing data that render this exercise inconclusive and a bit of an
experimental one:
· The division of the fish species into the proposed indicators is preliminary and
should be reviewed.
· Specific information on the actual habitat needs of many fish species is
lacking and many fish could not easily be grouped into the proposed indicator
groups or can be fitted into more than one group.
· Another factor is that the Kavango fish species are generally adaptable with
few species that could be described as real habitat specialists.
· The exact environmental requirements of many species are not known at all
despite the considerable amount of literature available and general literature
had to be used.
Future research should look at the link between habitat requirements, water
conditions and migration of fish in the system in order to better predict the effect of
changed flow patterns on fish life.
FLOW-RESPONSE RELATIONSHIPS FOR USE IN THE OKAVANGO EF-DSS
Response Curves were drawn by the fish team during the Windhoek workshop in
March 2009 and these curves will be included in a CD of data that accompanies the
project Final Report.
49
EFA Namibia Fish Life
6. REFERENCES
6.1 Relevant Own Work
Van der Waal, B C W 1980. Aspects of the fisheries of Lake Liambezi, Caprivi. J.
Limnol. Soc. sth. Afr. 6(1): 19-31.
Van der Waal, B C W and P H Skelton 1984a. Check list of fishes of Caprivi.
Madoqua 13(4): 303-320.
Van der Waal, B C W 1985a. Aspects of the biology of larger fish species of Lake
Liambezi, Caprivi, South West Africa. Madoqua 14(2): 101-144.
Skelton, P H, M N Bruton, G S Merron and B C W van der Waal 1986b. The fishes of
the Okavango Drainage System in Angola, South West Africa and Botswana:
Taxonomy and distribution. Ichthyological Bulletin of the J L B Smith Institute of
Ichthyology 50:21 pp.
Van der Waal, B C W 1990. Aspects of the fishery of the Eastern Caprivi, Namibia.
Madoqua 17(1): 1-16.
Van der Waal, B C W 1991a. Fish life of the oshana delta in Owambo, Namibia and
the translocation of Cunene species. Madoqua 17(2): 201-209.
Van der Waal, B C W 1991b. A survey of the fisheries in Kavango, Namibia
. Madoqua 17(2): 113-122.
Van der Waal, B C W 1996a. Some observations on fish migrations in Caprivi,
Namibia. Sth. Afr. J.aquat. Sci. 22(1/2): 62-80.
Van der Waal, B C W 1997b. Some observations on the fish life in a seasonal sand
river. Sth. Afr. J. aquat. Sci. 23(1):95-102.
Van der Waal, B C W 1998. Survival strategies of sharptooth catfish Clarias
gariepinus in desiccating pans in the northern Kruger National Park. Koedoe 41
(2):131-138.
Tweddle, D, Skelton, P H, Van der Waal, B C W, Bills, I R, Chilala, A and Lekoto, O
T. 2004. Aquatic Biodiversity survey for the "Four Corners" Transboundary Natural
Resources Management Area. Final Report July 2004. African Wildlife Foundation,
Kasane.
Van der Waal, B C W 1993. Fish invasion of the impoverished oshanas of Owambo,
Namibia. Symposium International sur la Diversite Biologique des Poissons d'eaux
douces et saumatres d'Afrique.Dakar, Senegal.
6.2 Other References
Abbott, J., Hay, C., Kapirika, S., Næsje, T.F. and Purvis, J. 2003. Shared Resource
Management on the Zambezi/Chobe Systems in Northeast Namibia: Current
Practices and Future Opportunities: Report of the Ngweze/Katima Mulilo Fish Market
Survey April 2002 to January 2003. 20 Pages
Curtis, Barbara, Kevin S. Roberts, Michael Griffin, Shirley Bethune, Clinton J. Hay
and Holger Kolberg. 1998. Species richness and conservation of Namibian
freshwater macro-invertebrates, fish and amphibians. Biodiversity and Conservation
7, 447-466.
Hay, C.J., B.J. van Zyl & G.J. Steyn. 1996. A quantitative assessment of the biotic
integrity of the Okavango river, Namibia, based on fish. Water SA. Vol. 22 (3): 263-
284.
Hay, C.J., Næsje, T.F., Breistein, J., Hårsaker, K., Kolding, J. Sandlund, O.T. &van
Zyl, B.J. (2000). Fish populations, gill net selectivity, and artisanal fisheries in the
50
EFA Namibia Fish Life
Okavango River, Namibia. Recommendations for a sustainable fishery. NINA.NIKU
Project Report no.10. 105 pages.
Hay, C.J., Van Zyl, B.J., and Steyn, G.J., 1996. A quantitative assessment of the
biotic integrity of the Okavango River, Namibia, based on fish. Water SA Vol. 22 No.
3 : 263-284.
Hay, C.J., van Zyl, B.J., van der Bank, F.H., Ferreira, J.T. and Steyn, G.J. 1999. The
distribution of freshwater fish in Namibia. Cimbebasia: 15: 41-63.
Hay, C.J.; van Zyl, B.J. and Steyn, G.J., 1997. Ecology of Synodontis nigromaculatus
from the Okavango River. Journal of African Zoology. 111(5): 355-363
Hocutt, C.H., Johnson, P.N., Hay, C.J. and Van Zyl, B.J.,1994. Biological basis of
water quality assessment : Kavango River, Namibia. Rev. Hydrobiol. trop. 27 (4) :
361-384.
Jubb, R.A. & I.G. Gaigher. 1971. Checklist of the fishes of Botswana. Arnoldia 7(5):
1-22.
Merron, G.S. 1991. The ecology and management of the fishes of the Okavango
Delta, Botswana, with particular reference to the role of seasonal floods. PhD Thesis,
Rhodes.
Økland, F, E.B. Thorstad C.J. Hay, T.F. Næsje & B. Chanda 2005. Patterns of
movement and habitat use by tigerfish (Hydrocynus vittatus) in the Upper Zambezi
River (Namibia). Ecology of Freshwater Fish. 2005. 14: 79-86.
Økland, F., Hay, C.J., Næsje, T.F. & Thorstad, E.B. 2000. Movement and habitat
utilisation of cichlids in the Zambezi River, Namibia. A radio telemetry study in 1999-
2000. NINA.NIKU Project Report no. 11. 18 pages.
Økland, F., Hay, C.J., Næsje, T.F., Chanda, B. & Thorstad, E.B. 2007. Movements
of, and habitat utilisation by threespot tilapia Oreochromis andersonii (Teleostei:
Cichlidae) in the Upper Zambezi River, Namibia. - African Journal of Aquatic Science
32(1): 35-38.
Økland, F., Hay, C.J., Næsje, T.F., Chanda, B. & Thorstad, E.B. 2002. Movements
and habitat utilisation of nembwe (Serranochromis robustus) in the Upper Zambezi
River. Implications for fisheries management. NINA.NIKU Project Report no. 20. 25
pages.
Purvis, J., Abbott, J., Næsje, T.F. and Hay, C. 2003. Shared Resource Management
on the Zambezi/Chobe Systems in Northeast Namibia: Current Practices and Future
Opportunities: Existing fishery management systems and implications for future
management. 30 Pages.
Skelton, P.H. 1993. A complete Guide to the freshwater fishes of Southern Africa.
Southern Book Publishers, Zimbabwe: 388 pgs.
Thorstad, E.B., Hay, C.J. Næsje, T.F & Økland, F. 2001. Movements and habitat
utilisation of three cichlid species in the Zambezi River, Namibia. Ecology of
Freshwater Fish. 10: 238-246.
Thorstad, E.B., Hay, C.J. Næsje, T.F., Chanda, B. & Økland, F. 2004. Effects of
catch-and-release angling on large cichlids in the subtropical Zambezi River.
Fisheries Research. 69: 141-144.
Thorstad, E.B., Hay, C.J., Næsje, T.F., Chanda, B. & Økland, F. 2002. Movements
and habitat utilisation of tigerfish (Hydrocynus vittatus) in the Upper Zambezi River.
Implications for fisheries management. NINA.NIKU Project Report no. 19. 28 pages.
Thorstad, E.B., Hay, C.J., Næsje, T.F., Chanda, B. & Økland, F. 2003a. Movements
and habitat utilisation of threespot tilapia in the Upper Zambezi River. Implications for
fisheries management. NINA.NIKU Project Report no. 23. 22 pages.
Thorstad, E.B., Hay, C.J., Næsje, T.F., Chanda, B. & Økland, F. 2003b. Space use
and habitat utilisation of tigerfish and the two cichlid species nembwe and threespot
tilapia in the Upper Zambezi River. Implications for fisheries management.
NINA.NIKU Project Report no. 24. 22 pages.
51
EFA Namibia Fish Life
Thorstad, E.B., Hay, C.J., Økland, F., Nickanor, N. and Næsje, T.F. 2007. Spatial
behaviour and management of greenhead tilapia (Oreochromis macrochir) in the
Zambezi River, Namibia. NINA Project Report no. 287.30 pages.
Thorstad, Eva B., Clinton J. Hay, Tor F. Næsje, Ben Chanda & Finn Økland. 2005.
Movements and habitat utilization of nembwe, Serranochromis robustus (Günther,
1864), in the Upper Zambezi River. African Zoology. Vol. 40(2): 253-259.
University, South Africa. 159pp.
52
EFA Namibia Fish Life
APPENDIX A: RAW DATA
Table 14 Summary of numbers of each fish species caught with all collecting gear at
Kapako, Popa Falls and at Kwetche [additional collection site in Muhango
[part of Bwabwata National Park] in the Kavango River during November
2008 and February 2009.
Kapako
Popa falls Kwetche
Site in Kavango River
Species
NO % NO
NO % NO NO
% NO
Marcusenius macrolepidotus
144
20.7 112 15.2
Barbus paludinosus
124
17.9 100 13.6
Synodontis nigromaculatus
3
1.4
185
25.2
Brycinus lateralis
80 11.5 6 2.9 43 5.9
Petrocephalus catostoma
96 13.8 1 0.5 16 2.2
Synodontis sp
70 10.1 1 0.5 31 4.2
Schilbe intermedius
21 3 5 2.4 49 6.7
Barbus poechii
19 2.7 9 4.3 34 4.6
Pollimyrus castelnaui
1 0.1 50 6.8
Labeo cylindricus
38
18.4
Opsaridium zambezense
34
16.4
Hydrocynus vittatus
8 1.2 11
5.3 15 2
Tilapia sparrmanii
13 1.9 4 1.9 14 1.9
Barbus eutaenia
1 0.1 17
8.2 12 1.6
Clarias ngamensis
28 4 1 0.1
Pseudocrenilabrus philander
14 2 8 3.9 6 0.8
Oreochromis andersonii
26 3.7
Aplocheilichthys johnstoni
2 0.3 1 0.5 20 2.7
Micralestes acutidens
1 0.1 19
9.2
Barbus radiatus
7 1 10 1.4
Pharyngochromis acuticeps
6 0.9 1 0.5 8 1.1
Clarias gariepinus
12 1.7 2 0.3
Barbus codringtonii
12
5.8
Tilapia rendalli
5 0.7 2 1 3 0.4
Ctenopoma multispine
6 0.9 3 1.4
Chiloglanis fasciatus
9
4.3
Serranochromis macrocephalus
8
1.1
Barbus multilineatus
6 0.9
Serranochromis robustus
4
1.9
Barbus fasciolatus
4
0.5
Amphilius uranoscopus
4
1.9
Cyphomyrus discorhynchus
4
1.9
Serranochromis altus
3
0.4
Sargochromis sp
3
0.4
Barbus bifrenatus
3
0.4
Hemigrammocharax multifasciatus
3
1.4
Barbus unitaeniatus
1 0.1 1 0.5
Tilapia sp.
2
1
53
EFA Namibia Fish Life
Labeo lunatus
2
1
Oreochromis sp.
1
0.5
Barbus thamalakanensis
1 0.1
Barbus kerstenii
1 0.1
Leptoglanis sp.
1
0.5
Clarias stappersii
1 0.1
Sargochromis giardi
1
0.1
Mormyrus lacerda
1
0.1
Hemichromis elongatus
1
0.5
Aplocheilichthys katangae
1
0.1
Total 694
100
207
100
735
100
54
EFA Namibia Fish Life
The Okavango River Basin Transboundary Diagnostic Analysis Technical Reports
I
Diagnostic Analysis to establish a base of available
n 1994, the three riparian countries of the Okavango
scientific evidence to guide future decision making.
River Basin Angola, Botswana and Namibia agreed
The study, created from inputs from multi-disciplinary
to plan for collaborative management of the natural
teams in each country, with specialists in hydrology,
resources of the Okavango, forming the Permanent
hydraulics, channel form, water quality, vegetation,
Okavango River Basin Water Commission (OKACOM).
aquatic invertebrates, fish, birds, river-dependent
In 2003, with funding from the Global Environment
terrestrial wildlife, resource economics and socio-
Facility, OKACOM launched the Environmental
cultural issues, was coordinated and managed by a
Protection and Sustainable Management of the
group of specialists from the southern African region
Okavango River Basin (EPSMO) Project to coordinate
in 2008 and 2009.
development and to anticipate and address threats to
the river and the associated communities and
The following specialist technical reports were
environment. Implemented by the United Nations
produced as part of this process and form
Development Program and executed by the United
substantive background content for the Okavango
Nations Food and Agriculture Organization, the project
River Basin Trans-boundary Diagnostic Analysis
produced the Transboundary.
Final Study
Reports integrating findings from all country and background reports, and covering the entire
Reports
basin.
Aylward, B.
Economic Valuation of Basin Resources: Final Report to
EPSMO Project of the UN Food & Agriculture Organization as
an Input to the Okavango River Basin Transboundary
Diagnostic Analysis
Barnes, J. et al.
Okavango River Basin Transboundary Diagnostic Analysis:
Socio-Economic Assessment Final Report
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment Project
C.A.
Initiation Report (Report No: 01/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment EFA
C.A.
Process Report (Report No: 02/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Guidelines for Data Collection, Analysis and Scenario Creation
(Report No: 03/2009)
Bethune,
S.
Mazvimavi,
Okavango River Basin Environmental Flow Assessment
D. and Quintino, M.
Delineation Report (Report No: 04/2009)
Beuster, H.
Okavango River Basin Environmental Flow Assessment
Hydrology Report: Data And Models(Report No: 05/2009)
Beuster,
H. Okavango River Basin Environmental Flow Assessment
Scenario Report : Hydrology (Report No: 06/2009)
Jones, M.J.
The Groundwater Hydrology of The Okavango Basin (FAO
Internal Report, April 2010)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions (Volume 1
of 4)(Report No. 07/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions (Volume 2
of 4: Indicator results) (Report No. 07/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions: Climate
Change Scenarios (Volume 3 of 4) (Report No. 07/2009)
King, J., Brown, C.A.,
Okavango River Basin Environmental Flow Assessment
Joubert, A.R. and
Scenario Report: Biophysical Predictions (Volume 4 of 4:
Barnes, J.
Climate Change Indicator Results) (Report No: 07/2009)
King, J., Brown, C.A.
Okavango River Basin Environmental Flow Assessment Project
and Barnes, J.
Final Report (Report No: 08/2009)
Malzbender, D.
Environmental Protection And Sustainable Management Of The
Okavango River Basin (EPSMO): Governance Review
Vanderpost, C. and
Database and GIS design for an expanded Okavango Basin
Dhliwayo, M.
Information System (OBIS)
Veríssimo, Luis
GIS Database for the Environment Protection and Sustainable
Management of the Okavango River Basin Project
Wolski,
P.
Assessment of hydrological effects of climate change in the
Okavango Basin
Country Reports
Angola
Andrade e Sousa,
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Biophysical Series
Helder André de
Okavango: Módulo do Caudal Ambiental: Relatório do
55
EFA Namibia Fish Life
Especialista: País: Angola: Disciplina: Sedimentologia &
Geomorfologia
Gomes, Amândio
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Vegetação
Gomes,
Amândio
Análise Técnica, Biofísica e Socio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango: Relatório
Final:Vegetação da Parte Angolana da Bacia Hidrográfica Do
Rio Cubango
Livramento, Filomena
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina:Macroinvertebrados
Miguel, Gabriel Luís
Análise Técnica, Biofísica E Sócio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango:
Subsídio Para o Conhecimento Hidrogeológico
Relatório de Hidrogeologia
Morais, Miguel
Análise Diagnóstica Transfronteiriça da Bacia do Análise Rio
Cubango (Okavango): Módulo da Avaliação do Caudal
Ambiental: Relatório do Especialista País: Angola Disciplina:
Ictiofauna
Morais,
Miguel
Análise Técnica, Biófisica e Sócio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango: Relatório
Final: Peixes e Pesca Fluvial da Bacia do Okavango em Angola
Pereira, Maria João
Qualidade da Água, no Lado Angolano da Bacia Hidrográfica
do Rio Cubango
Santos,
Carmen
Ivelize
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Van-Dúnem S. N.
Okavango: Módulo do Caudal Ambiental: Relatório de
Especialidade: Angola: Vida Selvagem
Santos, Carmen Ivelize
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Van-Dúnem S.N.
Okavango:Módulo Avaliação do Caudal Ambiental: Relatório de
Especialidade: Angola: Aves
Botswana Bonyongo, M.C.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Wildlife
Hancock, P.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module : Specialist Report: Country:
Botswana: Discipline: Birds
Mosepele,
K. Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Fish
Mosepele, B. and
Okavango River Basin Technical Diagnostic Analysis:
Dallas, Helen
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Aquatic Macro Invertebrates
Namibia
Collin Christian &
Okavango River Basin: Transboundary Diagnostic Analysis
Associates CC
Project: Environmental Flow Assessment Module:
Geomorphology
Curtis, B.A.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report Country:
Namibia Discipline: Vegetation
Bethune, S.
Environmental Protection and Sustainable Management of the
Okavango River Basin (EPSMO): Transboundary Diagnostic
Analysis: Basin Ecosystems Report
Nakanwe, S.N.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia: Discipline: Aquatic Macro Invertebrates
Paxton,
M. Okavango River Basin Transboundary Diagnostic Analysis:
Environmental Flow Module: Specialist
Report:Country:Namibia: Discipline: Birds (Avifauna)
Roberts, K.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia: Discipline: Wildlife
Waal,
B.V. Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia:Discipline: Fish Life
Country Reports
Angola
Gomes, Joaquim
Análise Técnica dos Aspectos Relacionados com o Potencial
Socioeconomic
Duarte
de Irrigação no Lado Angolano da Bacia Hidrográfica do Rio
Series
Cubango: Relatório Final
Mendelsohn,
.J.
Land use in Kavango: Past, Present and Future
Pereira, Maria João
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Qualidade da Água
Saraiva, Rute et al.
Diagnóstico Transfronteiriço Bacia do Okavango: Análise
Socioeconómica Angola
56
EFA Namibia Fish Life
Botswana Chimbari, M. and
Okavango River Basin Trans-Boundary Diagnostic Assessment
Magole, Lapologang
(TDA): Botswana Component: Partial Report: Key Public Health
Issues in the Okavango Basin, Botswana
Magole,
Lapologang
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Land Use Planning
Magole, Lapologang
Transboundary Diagnostic Analysis (TDA) of the Botswana p
Portion of the Okavango River Basin: Stakeholder Involvement
in the ODMP and its Relevance to the TDA Process
Masamba,
W.R.
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Output 4: Water Supply and
Sanitation
Masamba,W.R.
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Irrigation Development
Mbaiwa.J.E. Transboundary Diagnostic Analysis of the Okavango River
Basin: the Status of Tourism Development in the Okavango
Delta: Botswana
Mbaiwa.J.E. &
Assessing the Impact of Climate Change on Tourism Activities
Mmopelwa, G.
and their Economic Benefits in the Okavango Delta
Mmopelwa,
G.
Okavango River Basin Trans-boundary Diagnostic Assessment:
Botswana Component: Output 5: Socio-Economic Profile
Ngwenya, B.N.
Final Report: A Socio-Economic Profile of River Resources and
HIV and AIDS in the Okavango Basin: Botswana
Vanderpost,
C.
Assessment of Existing Social Services and Projected Growth
in the Context of the Transboundary Diagnostic Analysis of the
Botswana Portion of the Okavango River Basin
Namibia
Barnes, J and
Okavango River Basin Technical Diagnostic Analysis:
Wamunyima, D
Environmental Flow Module: Specialist Report:
Country: Namibia: Discipline: Socio-economics
Collin Christian &
Technical Report on Hydro-electric Power Development in the
Associates CC
Namibian Section of the Okavango River Basin
Liebenberg, J.P.
Technical Report on Irrigation Development in the Namibia
Section of the Okavango River Basin
Ortmann, Cynthia L.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module : Specialist Report Country:
Namibia: discipline: Water Quality
Nashipili,
Okavango River Basin Technical Diagnostic Analysis: Specialist
Ndinomwaameni
Report: Country: Namibia: Discipline: Water Supply and
Sanitation
Paxton,
C.
Transboundary Diagnostic Analysis: Specialist Report:
Discipline: Water Quality Requirements For Human Health in
the Okavango River Basin: Country: Namibia
57
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