THE BIOLOGY AND EXPLOITATION OF SMALL PELAGIC FISHES IN ZAMBIA

by

Raphael Mubamba
Department of Fisheries
P.O. Box 350100
Chilanga
Zambia

1. INTRODUCTION

1.1. Emergence of commercial fishing

In Zambia, small pelagic fish species contribute about 25% of the total fish production from capture fisheries and they are ranked second, after the breams. From the geographical view point, there are three groups of small pelagics in this country. The first group is what may be referred to as the Tanganyika pelagics which have been commercially fished since about 1950. Capital intensive fishing of these pelagics started in 1959. The second group are the Lake Kariba pelagics which developed after the introduction of Limnothrissa miodon from Tanganyika in 1967/68. Commercial exploitation started in 1981 (Zambia). The third group consists of the Mweru-Bangweulu complex where both the pelagic clupeids and cyprinids became commercially important from the 1970's. To be specific, artisanal exploitation of the pelagics started in 1975 at Lake Mweru-Luapula, in 1985 at Lake Mweru-Wantipa and in 1988 at Lake Bangweulu. The location of these lakes is shown in Fig.1.

1.2 Characteristics of the lakes

Small pelagics are a very interesting group of fish in that, they are found in diverse habitats. As seen in Table 1, they are found in shallow and deep lakes with altitudes ranging from 773–1160m above sea level. The range of water temperature is from 17–29°C. The group does not seem to prefer any particular lake productivity and is therefore found in waters with conductivities ranging from 20–860 microsiemens per centimetre.

1.3 Composition, distribution and abundance

1.3.1 Composition

In Zambia, small pelagics are known or identified by their latin/scientific names, English names, common Zambian names or local names. The common Zambian names are names which are used country-wide and especially in urban centres. Local names are used at the lakes by the indigenous ethnic or tribal groups of people.

As shown in Table 2, the scientific names of the most important pelagics in Zambia are Stolothrissa tanganicae, Limnothrissa miodon, Poecilothrissa moeruensis, Microthrissa acutirostris, Microthrissa stappersi, Engraulicypris moeruensis and Barbus trimaculatus (Jackson, 1961). Except for the barbs occurring in the lakes under consideration in this review, all the other pelagics are called sardines in English. In addition, the genera Stolothrissa, Limnothrissa, Poecilothrissa and Microthrissa are all called clupeids, whereas the genera Engraulicypris and Barbus are known as cyprinids. The English name for Engraulicypris moeruensis is whitebait (Mortimer, 1965). The common Zambian name for the species S. tanganicae and L. miodon is

Kapenta and the rest of the species reflected in Table 2 are known as Chisense. However, the local names for Stolothrissa and Limnothrissa are Chilwe/Nsembe and Chisamba/Nsembe respectively. The local names for Poecilothrissa and Microthrissa are Chisense/Kasepa. Engraulicypris moeruensis is also locally known as Chisense. On the other hand, B. trimaculatus is called Imishipa or Chisense at Lake Mweru-Wantipa.

It is also worthwhile nothing here that the clupeids fall under the family name CLUPEIDAE and the cyprinids under the family name CYPRINIDAE.

1.3.2 Distribution and abundance

Both Stolothrissa and Limnothrissa are endemic to Lake Tanganyika where they occur in abundance. However, the geographical range of Limnothrissa has changed, following its introduction into Lake Kariba and Lake Itezhi-tezhi. L. miodon is now very abundant in Lake Kariba and it supports a large industrial fleet.

In Zambia, P. moeruensis has been recorded in Lake Mweru-Luapula only where it has become very abundant. But it is also found elsewhere (Jackson, 1961). Microthrissa acutirostris is found in Lake Mweru-Luapula and Lake Mweru-Wantipa and it is predominant in the latter. Microthrissa stappersi is recorded from Lake Mweru-Luapula but its state in abundance is presently not known. Among the cyprinids, Engraulicypris moeruensis is probably more important and it is found both in Lake Mweru-Luapula and Lake Bangweulu and it is probably more dominant in the latter than the former lake. Barbus trimaculatus is the most widespread of the Zambian pelagics and it has been recorded in Lakes Mweru-Wantipa, Mweru-Luapula, Bangweulu and Kariba (Mortimer, 1965). It has not yet been reported in Lakes Tanganyika and Itezhi-tezhi. As shown in Table 3, B. trimaculatus is now very abundant in Lake Mweru-Wantipa where it is ranked second after Microthrissa acutirostris.

Estimates of standing biomass for the Tanganyika pelagics have been presented by Chapman (1976) and Coulter (1981). According to Lindem (1988), the preliminary results from the hydro acoustic survey in Lake Kariba have shown that the biomass of Limnothrissa miodon, varies from 16–120kg/ha with an average of 37 kg/ha for the whole lake. Biomass estimates for the pelagics in Lakes Mweru-Wantipa, Mweru-Luapula and Bangweulu are not yet available.

2. THE BIOLOGY OF CLUPEIDS

2.1 Stolothrissa tanganicae

This is a small silvery fish with a streamlined body. It has a distinct silver stripe on its sides and the tail is highly forked (Fig 2). The species is known to undertake both diel vertical migration and horizontal migration. It is usually abundant during the cold season (Pearce, 1985). The maximum size recorded in the Zambian waters is 100mm fork length and the maximum age is 2 years. It is a pelagic spawner and breeding takes place during the cold season and rainy season (Ellis, 1971). An average sized fish can spawn up to 35,000 eggs (Matthes, 1968). Adult Stolothrissa feeds on shrimps and copepods while the young are mainly phytoplankton feeders. The most predominant algae eaten are the diatoms (e.g. Stephanodiscus) and the CHLOROPHYCAE as well as blue-greens. The most important predators of Stolothrissa are Lates stappersii, Lates microlepis, large Limnothrissa miodon and some Bathybates spp (Coulter, 1991). Matthes (1968) has found two parasites on Stolothrissa and these are the Lernaeid copepod and an Isopod. The most dominant bacteria on the skin of Stolothrissa are the Micrococci and Streptococci (Watanabe, 1971).

2.2 Limnothrissa miodon

Limnothrissa is a very close relative of Stolothrissa and to the layman, the two species are difficult to distinguish. Limnothrissa has got some silver appearance as well but it is a larger fish. The tail end of Limnothrissa is highly forked and the body is deeper than in Stolothrissa. The silver lining on the sides of Limnothrissa is easily discernible, both in preserved and fresh specimens (Fig. 3). This is also a shoaling species and it undertakes diel vertical migration (Begg, 1974b). In both Lakes Tanganyika and Kariba the species exhibits a bimodal seasonal abundance. Its biomass increases during the cold and rainy seasons (Marshall, 1982). Limnothrissa has been reported to be a littoral spawner, preferring sandy bottoms (Matthes, 1968; Pearce, 1985; Mubamba, pers. observation). Both in Tanganyika and Kariba, breeding takes place during the cold and rainy seasons (Ellis, 1971; Begg, 1974a). A mature individual in Tanganyika can spawn up to 55,000 eggs (Matthes, 1968).

In Lake Tanganyika (Zambia) the maximum size of Limnothrissa stands at 162mm fork length and maximum age is 3–4 years. In that lake the young feed on diatoms and green algae. The species is an omnivore and adult fish are known to feed on algae as well as shrimps insects and Stolothrissa. In Lake Tanganyika the most predominant food items taken by Limnothrissa ranging from 45–58mm fork length are Anabaena, Trachelomonas, Surirella, Scenedesmus and Sphaerocystis. Cannibalism has been reported both in Lake Tanganyika and Lake Kariba. The most important predators of Limnothrissa in Lake Tanganyika include L. stappersi, L. microlepis, Alestes spp and Boulengerochromis microlepis. The only parasite and microbes reported on Limnothrissa are an Isopod and Streptococci respectively (Watanabe, 1971; Matthes, 1968).

In Lake Kariba, the Limnothrissa is stunted or much smaller than in Tanganyika and the maximum size recorded in Zambia is 104mm fork length. The diet of young fish includes diatoms, green algae, Microcystis and rotifers. In adult fish, the most important prey are cladocerans and copepods particularly Bosmina longirostris and Mesocyclops respectively (Cochrane, 1978). The main predator of Limnothrissa in Lake Kariba is Hydrocynus vittatus.

2.3 Poecilothrissa moeruensis

Although the species is now commercially important in Lake Mweru-Luapula, little is known about the biology of this little fish. The first attempt to investigate the life history of the species has been conducted by Kapasa and Van Zweiten (in press). Poecilothrissa is also a silvery fish with a flat but deep body. It is a shoaling fish which becomes abundant in August-September (Scullion, 1985; Kalonga, 1989). The maximum size in Lake Mweru proper is 45mm standard length and in Luapula River it can grow up to 47mm standard length. The species appears to breed twice in a year, that is, from February-March and from August-September. Fish of standard length 26–42mm can produce up to 1140 eggs. The egg diameter varies from 0.11–0.33mm. According to Scullion (1985), Poecilothrissa is a zooplankton feeder. However, Kapasa and Van Zwieten (op. cit.) found that the most important food item of the species are insects, particularly the DIPTERA larvae and adult EPHEMEROPTERA. The major predators of Poecilothrissa are Serranochromis macrocephala, Alestes macropthalmus, Schilbe mystus and Hydrocynus vittatus.

2.4 Microthrissa acutirostris

This is another small silvery fish which is very similar to P. moeruensis and it is now abundant in Lake Mweru-Wantipa. M. acutirostris has a short body but laterally depressed with a short forked tail (Fig. 4b). In Lake Mweru-Wantipa the largest specimen caught in 1989 is 60mm total length. In this lake the species feeds mainly on zooplankton; CLADOCERA (daphnids), CYCLOPOIDA and rotifers; and phytoplankton i.e. Sphaerocystis and Asterionella. Because of the mixed diet, it can be considered to be an omnivore. Its main predators are the Serranochromis spp. In Lake Mweru-Luapula M. acutirostris is known to grow up to 50mm standard length (Jackson, 1961).

2.5 Microthrissa stappersi

This is probably the least known of all the clupeids occurring in Zambia. It is a shoaling species which can grow up to 28mm standard length.

3. THE BIOLOGY OF CYPRINIDS

3.1 Engraulicypris moeruensis

The species has a transparent streamlined body which is laterally depressed (Figs. 5 and 6). The sides of the body are marked with a stripe and the tail is long and forked. The belly is covered with a bright silvery skin. Both the eye and mouth are large. The maximum size in Lake Bangweulu is 57mm total length. In Lake Mweru-Luapula the maximum size is 45mm standard length (Jackson, 1961). Engraulicypris is a shoaling pelagic spawner and breeding takes place during the rainy season, especially in December.

In Lake Bangweulu, the proportion of female fish by number has been found to be 63% and male fish 37% (Chaika, 1984) and this is approximately a 2:1 sex ratio. Engraulicypris is a planktivore and it feeds mainly on the algae Trachelomonas, Microcystis, Sphaerocystis, Volvox and diatoms. Some animal matter include cladocerans, copepods and rotifers. Its main predator is Alestes macropthalmus. A flat worm has been recorded as one of the parasites found in the alimentary canal. In this same lake Engraulicypris becomes abundant during the rainy season.

The food of Engraulicypris in Lake Mweru-Luapula is similar to that of the Engraulicypris in Lake Bangweulu and it consists of the algae Trachelomonas, Microcystis, Sphaerocystis and diatoms. The only animal found is Bosmina. Kapasa and Van Zwieten (op. cit.) have found that the food of Engraulicypris moeruensis in Lake Mweru-Luapula consists of chitinous remains indicating that the species probably feeds exclusively on insects.

Chaika (1985) studied the size of Engraulicypris moeruensis and found that the various lakes which make the Bangweulu complex have different sizes of the species. The largest fish were found in Lake Sune (40mm standard length (SL) followed by Lake Kampolombo (35mm SL), Lake Bangweulu (30mm SL) and Lake Chifunauli (30mm SL).

3.2 Barbus trimaculatus

As seen in Fig. 4a, B. trimaculatus is a beautiful silvery fish with 3 black spots on the sides of the body. Two of the spots are on the actual body and one is on the tail. The body is laterally depressed and deep. The tail is short and well forked. It has a large head with a very short mouth. The species breeds during the rainy season (Bell-Cross, 1976) and its preferred habitat is a weedy edge with well oxygenated water. In Lake Mweru-Wantipa the species can grow up to 75 mm total length. It is an omnivore and in that lake its food consists of diatoms (especially Cymbella), Sphaerocystis, vascular plant matter, daphnids and CYCLOPOIDA. A few nematode parasites have been encountered in its intestines. It is a shoaling species and large quantities may be caught along with Microthrissa acutirostris in Lake Mweru-Wantipa.

4. OTHER SMALL PELAGICS

There are several other small pelagic fishes that exist in Zambia and some of them have become commercially important in the last few years. With improved management, especially in the area of new product development a few other small pelagics which have the exploitation potential could make significant economic contribution to the fishing industry.

Though not a true pelagic fish, Alestes lateralis, a characid, is one of the species which has become commercially important especially in Lake Itezhi-tezhi and the Kafue River floodplain. The species is also abundant in Lake Kariba and the Lower Zambezi River. Other large populations are known to occur in the Upper Zambezi River (Bell Cross, 1976; Jackson, 1961). A. lateralis is also known as striped robber. Locally, it is called Ncenga or Chitaka (Kafue) and Mbale (Upper Zambezi). It is a shoaling fish associated with submerged aquatic plants and can grow up to 140mm standard length. Breeding takes place during the rainy season and an average size female fish can lay up to 12,000 eggs (Bell-Cross, 1976). In Itezhi-tezhi, its food consists of plankton, mainly Bosmina longirostris (cladoceran) and Microcystis spp (algae). In other strains insects are also major food items. The species can be caught in large numbers using 25 or 37mm gill nets.

Another widely distributed small pelagic fish is Barbus paludinosus commonly known as African top minnow. In Lakes Mweru and Bangweulu it is called Kasepa and Kasenga respectively, whereas in the Kafue it is known as Ncenga. The species is abundant in most farm dams or reservoirs and in fish ponds but its exploitation in these man-made water bodies is not significant. B. paludinosus is a shoaling fish which feeds on zooplankton and some plant material like the diatoms. Breeding occurs during November and December and a female fish can produce up to 5,000 eggs. The largest size known is 130mm standard length.

In the Kafue River floodplain and Lake Itezhi-tezhi, another important small pelagic is Barbus poechii known as dashtail barb in English or Ncenga in local languages. The species is also found in the Upper Zambezi. It has a silver body and can grow up to 110mm standard length. Breeding takes place during the rainy season.

Another small pelagic fish which is worth mentioning is Alestes imberi. It is also known as stop-tail robber or as Imberi, a name used by many Zambians. This is a widespread fish but it is believed to be quite abundant in Lake Kariba. The gill net catches of the species there, are low because of mesh size restrictions. In Lake Kariba, the species is an exclusive insect feeder and its body is extremely fat. It is a shoaling fish, and is known to breed during the rains. Its maximum size is 180mm standard length.

Micralestes acutidens commonly known as silver robber is another small fish which could be considered under the small pelagics of Zambia. The species occurs in abundance in Lake Kariba, Upper Zambezi and probably other water bodies but it is not exploited commercially. It is a shoaling fish found in deep water of the edges of rivers and lakes. It feeds on a variety of organisms including insect larvae, crustaceans and fry of other fish. Its maximum size is about 80mm standard length. Preliminary observations have shown that this little fish can be attracted to light at night.

5. FISHING TECHNIQUES

The Lake Tanganyika pelagics are caught by light attraction at night. The source of light in the industrial sector includes paraffin powered lamps and generators which use mercury vapour lamps. Artisanal fishermen use small lamps and are powered by paraffin. The fishing gears used by industrial fishermen are ring nets, purse seine nets and Chiromila nets whereas artisanal fishermen use beach draw nets, lift nets and scoop nets. However, the latter net is now defunct in Zambia. Industrial companies use nets of mesh sizes ranging from 8–12mm. In the small-scale fishing sector the main size used is 6mm.

Fishing of Chisense in Lake Mweru-Wantipa is carried out during the day using beach draw nets made of materials ranging from meshless cloth, mosquito nets and 6mm mesh nets. There is no light attraction on this lake. At present there are 724 fishers of Chisense and 724 Chisense nets.

On Lake Mweru-Luapula the fishing of Chisense is conducted during the day and at night with light attraction. The main types of gear used are the beach draw net, mid-water seine net, lift net and scoop net. All these nets are used at night but the draw net is also used during the day. Some materials of nets used include meshless cloth, mosquito net and 6mm net. In 1990 it is estimated that there were 300 artisanal fishermen involved in Chisense fishing. The Chisense fishery attracted about 1624 traders in 1991. The number of Chisense nets is about 1402 at present.

The Chisense in Lake Bangweulu is fished both during the day and at night. In 1991, there were about 35 Chisense artisanal fishermen and 35 Chisense nets on the complex. The only type of gear available for fishing Chisense on this lake is the beach draw net made from mainly meshless cloth and mosquito net.

There are 56 companies operating 220 Kapenta dip nets on the Zambian side of Lake Kariba. The fishing is done at night using underwater light. The lights used are powered by generators. The average mesh size of nets used here is 8–10mm.

6. THE CATCH

6.1 Annual catches

In the last five years, catches of the clupeids in Lake Tanganyika have varied from 4400–6000 tonnes per annum. In Lake Mweru-Wantipa, catches of Microthrissa and Barbus have shown an average production of about 4000 tonnes per annum since 1989. In 1990 the estimated catch of small pelagics on the Zambian sector of Lake Mweru-Luapula was 7,000 tonnes. During 1992 catches of Engraulicypris in Lake Bangweulu have been estimated to be about 300 tonnes. The catches of Limnothrissa on the Zambian sector of Lake Kariba have varied from 5800–7500 tonnes per annum since 1987.

6.2 Composition of catch

The catch of small pelagics on Lake Tanganyika consists of 60% Stolothrissa and 40% Limnothrissa by weight. At Mweru-Wantipa the Chisense catch consists of mainly two species as well. There, Microthrissa acutirostris accounts for about 60% and Barbus trimaculatus accounts for 40% by weight. At Lake Kariba, Limnothrissa miodon accounts for 98% and only 2% for Hydrocyrus vittatus by weight.

The data of a sample which was collected in 1986 at Lake Mweru-Luapula show that the composition of Chisense by number consists of 58% Poecilothrissa, 35% Microthrissa and 7% Engraulicypris. In Lake Bangweulu, the catch of Chisense is dominated by Engraulicypris followed by the Barbus spp and Alestes spp.

6.3 The by-catch issue

The main by-catch of the small pelagics in Lake Tanganyika are the juveniles of Lates stappersii which swim together with the clupeids. Young L. stappersii started appearing in the clupeid catch from 1985. The second most important by-catch in this lake are the prawns (locally known as KALAKALA) and these are caught at sizes ranging from 30–50 mm long. The local people do not eat the prawns but they are used as stock feed from time to time. At certain times of the year, there are several benthic cichlids which are caught along with the clupeids.

On Lake Mweru-Wantipa, the Chisense is caught along with the fry and fingerlings of a commercially important bream Oreochromis macrochir and this phenomenon is regarded as being detrimental to the bream. Instead of being returned to the water, the juveniles of Oreochromis are dried and later used as mosquito repellant by burning them. Juveniles of some catfish especially Chryschthys mabusi are another by-catch of the pelagics in Mweru-Wantipa.

The Chisense in Lake Mweru-Luapula, is caught along with various sizes but mainly juveniles of some fish species. The most dominant by-catch include Alestes macropthalmus, Schilbe mystus and Eutropius sp (Scullion, 1985). The effects of Chisense fishing on other non-target species are not clearly known but some investigations are required.

The only by-catch known in the catches of Chisense on Lake Bangweulu is Alestes but little is known on the effects the commercially important species. The Limnothrissa in Lake Kariba is also caught along with Hydrocynus vittatus but it appears, there are no threats to the other important stocks because they are not significant in the by-catch.

7. METHODS OF PROCESSING

Most of the small pelagics caught in Zambian water bodies are processed by sun-drying and this is the only method used by artisanal fishermen. The actual drying process takes 1–2 days. However, smaller proportions of the pelagics are also frozen mainly by the industrial fishermen. The canning of clupeids from Lake Tanganyika is also conducted by two companies on the Copperbelt Province of Zambia. At Lake Tanganyika, most of the clupeids are sun-dried on earthen slabs and on beach draw nets. Blast freezing goes to about -20°C. Because of this, the quality of the product is good. The Chisense at Lake Mweru-Wantipa is dried either on sandy beaches or on net but the quality of the fish is rather poor. On Lake Mweru-Luapula, the Chisense is dried on earthen or concrete slabs, on canvas sheets or on sandy beaches (Scullion, 1985). All the Chisense caught in Lake Bangweulu is dried on sandy beaches and it is of poor quality. The clupeids in Lake Kariba are probably the best dried and the fish are dried on racks and concrete slabs. Small proportions of the Kapenta are deep frozen on this lake.

The finished product of the pelagics is also subjected to spoilage or damage mainly due to a number of pests. The most important pests include insects (e.g. Dermestes), rats, terns and chickens.

8. MARKETING

The net work of roads leading to most fishery areas in Zambia is very good and the roads are used all year. However, there are many transport problems in swamps.

Transportation of the small pelagics from the fishery areas to the markets is carried out by use of public buses and private lorries or trucks, some of which are refrigerated. Most of the fish is sold in markets along the line of rail, particularly in Lusaka, Central and Copperbelt Provinces.

In as far as international trade is concerned, one would find that, Zambia imports reasonable quantities of the clupeids from Tanzania through Mpulungu. However, some of the Chisense from Lake Mweru-Luapula is unofticially exported to Zaire where it is not fished. The Limnothrissa in Lake Kariba is also exported to a number of countries including Zimbabwe, Botswana, Namibia and South Africa.

Prices of small pelagics vary according to region and season. For example, the clupeids from Lake Tanganyika are more expensive than all other pelagics from other lakes. Additionally, the prices of pelagics are higher during the rainy season than the dry season. In Zambia prices of all fish are currently decontrolled.

9. GENDER

The fishing and trading of small pelagics in Zambia are highly dependent on gender. At Lake Tanganyika all the fishers of Kapenta are men while women are processors and traders. At Lakes Mweru-Wantipa, Mweru-Luapula and Bangweulu both men and women are engaged in fishing for Chisense but more of the women are processors and traders. Since the fishing is also conducted during the day, one will find that both boys and girls are active participants in activities related to the Chisense industry in these lakes.

10. CONCLUSION

Zambia is one of the countries which is endowed with numerous pelagic fisheries and it appears that there is a significant potential for the development of these fisheries. However, there is need for increased understanding of the population dynamics and stock sizes of the pelagics. The full life histories of these small fishes need to be determined before the establishment of programmes on utilization.

11. REFERENCES

Begg, G.W. 1974a. Investigations into the biology and status of the Tanganyika sardine, Limnothrissa miodon Boulenger, in Lake Kariba, Rhodesia LKFRI Project Report No. 17.

Begg, G.W. 1974b. The relationship between the diurnal movements of some zooplankton components and the sardine, Limnothrissa miodon in Lake Kariba, Rhodesia. LKFRI Report No. 20.

Bell-Cross, G. 1976. The Fishes of Rhodesia. Trustee of the National Museums and Monuments of Rhodesia, Salisbury. Rhodesia. 268p.

Chaika J.J. 1984. Quarterly Report for Lake Bangweulu, October-December 1983. Department of Fisheries, Samfya. 7p.

Chaika J.J. 1985. Annual Report for Lake Bangweulu, 1984. Department of Fisheries, Samfya. 7p.

Chapman, D.W. 1976. Acoustic Estimates of Pelagic Ichthyomass in Lake Tanganyika with an inexpensive Echosounder. Trans.of the Am. Fish. Soc., 105 (5): 581–587.

Cochrane, K.L. 1978. Seasonal fluctuations in the catches of Limnothrissa miodon (Boulenger) in Lake Kariba. M.Sc Thesis, University of Rhodesia.

Coulter, G.W. 1981. Biomass, Production and Potential Yield of the Lake Tanganyika pelagic fish community. Trans. of the Am. Fish. Soc, 110: 325–335.

Coulter, G.W. 1991. Lake Tanganyika and its life. Natural History Museum, Oxford University Press. London, Oxford and New York. 354p.

Ellis C.H.A. 1971. The size at maturity and breeding seasons of sardines in Southern Lake Tanganyika. Afr. J. Trop. Hydrobiol. and Fish. 1 (1): 59–66.

Jackson, P.B.N. 1961. The Fisheries of Northern Rhodesia: A Checklist of Indigenous Species. Govt. Printer, Lusaka. 140p.

Kalonga, M.K. 1989. Report on the frame survey of Poecilothrissa moeruensis on Lake Mweru-Luapula. Department of Fisheries, Nchelenge.

Kapasa C.K. and P.A.M. Van Zweiten. in press. Preliminary report on the fishery and biology of the Chisense complex (Poecilothrissa moeruensis, Neobola moeruensis) of Lake Mweru-Luapula (Zambia) including notes on the feeding biology of the main species of the by-catch. Department of Fisheries, Nchelenge, Zambia.

Lindem, T. 1988. Results from the Hydro Acoustic Survey Lake Kariba, September 1988. A report prepared for the Zambia/Zimbabwe SADCC Fisheries Project. University of Oslo, Norway. 7p.

Matthes, H. 1968. Preliminary investigations into the biology of Lake Tanganyika CLUPEIDAE. Fish. Res. Bull. Zambia, 4:39–45.

Marshall, B.E. 1982. The influence of river flow on sardine catches in Lake Kariba. J. Fish. Biol., 20:465–470.

Mortimer, M.A.E. 1965. The Fish and Fisheries of Zambia,. The Game and Fisheries Department, Ndola, Zambia. 98p.

Pearce, M.J. 1985. A description and stock assessment of the pelagic fisheries in the south east of the Zambian waters of Lake Tanganyika. Department of Fisheries, Chilanga. 74p.

Scullion, J. 1985. Development of the artisanal fishery based on the xploitation of Poecilothrissa moeruensis (CLUPEIDAE) on Lake Mweru-Luapula, Zambia. Department of Fisheries, Chilanga.

Watanabe, K. 1971. Bacteria from fresh water fish at landing on Lakes Kariba and Tanganyika Fish. Res. Bull. Zambia 5: 187–198.

Table 1. Characteristics of the lakes.

Table 2. Names of common pelagic fish species in Zambia.

Table 3. Distribution and abundance of pelagic fishes in Zambia

x     PRESENT
xx   ABUNDANT

Fig. 1 Location of the lakes where pelagics occur in Zambia.

Fig. 2 Stolothrissa tanganicae in Lake Tanganyika.

Fig. 3 Limnothrissa miodon, caught in Village Reservoir, Chilanga.

Fig. 4a Barbus trimaculatus in Lake Mweru-Wantipa, caught on 21 December 1989.

Fig. 4b Microthrissa acutirostris in Lake Mweru-Wantipa, caught 21 December 1989

Fig. 5 Engraulicypris moeruensis in Lake Mweru-Luapula, caught on 14 April 1986 near Kenani Island.

Fig. 6 Engraulicypris moeruensis in Lake Kampolombo of the Bangweulu complex, caught on 21 July 1982.