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It is important to emphasise that the south-east arm of Lake Malawi is the last major chambo fishing ground remaining in Malawi. The chambo stocks of the south-west arm of Lake Malawi, Lake Malombe and the Upper Shire river have all effectively collapsed.

Since 1976, data of varying reliability, have been available on chambo catches and fishing effort for each gear-type operating in the south-east arm (CAS). These data are for chambo in general: separate data for each of the 3 species are only available for one year (1990/91) through MTF.

As each of the gear-types used captures all 3 chambo species, an assessment of the combined effect of all fisheries on the chambo stocks is required. Effort in each of these fisheries is expressed differently, e.g. in units of 100m gillnet, set for one night, or in ringnet pulls, or chambo seine pulls. Effort has here been expressed as standardized gillnet sets or Maldeco ringnet pulls by dividing the catch of other gears by the gillnet CPUE or Maldeco ringnet CPUE.

To minimise the effect of large sampling errors, it was necessary to smooth the available catch and effort data by applying a 3-year running average. The overall annual catch was then plotted against the overall standardized effort (Figure 12.1 and Table 12.1). It appears that the 1982–86 data set is clearly different from the 1976–81 and 1987–91 data sets. Catches and CPUE were much higher during the 5 years 1982 to 1986 than at any time before or after.

The reason for this is not clear, although it might be speculated that high stock levels in Lake Malombe from 1981 till 1985 might have induced migration to the south-east arm, or environmental causes, such as increased upwelling, may have led to a greatly increased recruitment. Whatever the reason, it is a phenomenon that should be discounted when assessing the maximum sustainable yield level, as it is not the normally prevailing situation.

Table 12.1. Lake Malawi, south-east arm. Chambo catch (in tonnes). Gillnet catch, effort (in night sets) and catch (in kg) per unit of effort (CPUE). Total chambo catch made by all artisanal and industrial gears, and total standardized effort expressed in gillnet sets.

YearGillnet catch (t)Gillnet effort (×1000)CPUE (kg/set)Total catch all gears (t)standardized effort in gillnet sets (×1000)

Note: * Effort of gillnets and chambo seines have been adjusted by the (middle) 3-year running average method, (see section 6.2 for reason).

Applying Fox and Schaefer models to determine the relationship between annual catches and effort expressed both in gillnet sets and ringnet pulls for the years excluding 1982–85, in all cases a statistically highly significant correlation was established giving estimates of maximum sustainable yield and corresponding effort levels, as shown in Table 12.2.

Table 12.2 Lake Malawi, south east arm chambo fishery. Maximum sustainable yield and corresponding effort levels, expressed in gillnet sets and ringnet pulls, derived from Schaefer and Fox models.

Effort expressed in:MSY-levels1991
Yield (t)
Effort (×1000)
Yield tEffort ×1000
Gillnet sets4180/40201450/148038001070
Ringnet pulls4170/401024.4/24.8380013.9

Note: The ringnet effort for 1991 is very low and does not reflect the true situation. Ringnet effort is calculated using the CPUE of Maldeco's ringnetters. In 1991 these boats operated at their lowest ever effort level, which was about half the effort in 1990. Moreover they fished nearly exclusively in the January-May period, when catch-rates are highest. The 1990 overall effort expenditure was 20,300 ringnet pulls.

For 11 years - not counting the period 1982–86 - the fisheries appear to have been in a fairly steady state with chambo catches varying between 3,300 and 4,400 tonnes annually.

The data collection of 1990/91 has provided estimates in numbers for each of the 3 species and for each of the chambo catching gear-types. These data have been utilized to perform a cohort analysis on a species basis (Figure 12.2). Using the Thompson and Bell predictive model for each species separately, curves have been established for the predicted yields at effort levels above and below the present effort (100% level). These curves provided estimates of the MSY for each species, as well as the effort expenditure necessary to achieve these yields. The results are given in Table 12.3.

Table 12.3 Lake Malawi, south east arm. For each chambo species maximum sustainable yield is predicted by the Thompson and Bell model, effort levels are expressed as a percentage of the present (1991) effort level.

 MSY (t)Maldeco's share of present catchEffort required for MSY relative to 1991 effort
O. lidole163971%70%
O. squamipinnis120653%60%
O. karongae  66527%70%

This MSY estimate is not directly comparable with the surplus yield model MSY, as a different data collection system (MTF) was used, and the estimates are based on only one year's data and thus on a so-called “pseudo” cohort. However, these estimates strongly suggest that the stocks are overfished. An overall reduction in effort of about 30% is indicated. Together these assessments suggest, that the chambo stocks are fully exploited and that there is therefore no room for further expansion by any of the fisheries exploiting chambo. This is further support for the recommendation made in the context of the Malombe situation, i.e. to close access to these fisheries for newcomers, as soon as possible, and freeze the present lakewide gear holdings.

The chirimila fishery in the south-east arm has a by-catch of mostly sub-adult chambo, contributing less than 8% of the total chambo caught. More than 90% of the catch consists of utaka, kambuzi and usipa. However, little information is available about the catches of this gear and considering that more than 300 nets presently operate in the south-east arm, it is recommended that the composition of these catches is closely monitored.

The prohibition on the use of chambo seines in the south-east arm from November to December each year should be lifted for the reasons already outlined in the discussion of the same issue for Lake Malombe. As this regulation has been generally ignored in the south-east arm (see Table 5.2), in effect there has been no closed season. As it is thought that the south-east arm chambo stocks are presently not overfished, there is no specific need for such a closed season.


Chambo comprises around 30% of the total weight of fish landed from of the south-east arm of Lake Malawi. Most of the rest of the catch consists of smaller fishes: haplochromine cichlids and usipa. Of the four principal chambo-catching gears, only the mid-water trawl makes a substantial catch of other species (Table 12.4). Thus, management recommendations for ringnets, gillnets and chambo seines may be made without considering the catches of other species.

Table 12.4 South-east arm. Interactions between chambo and other fisheries. Total catches 1991.

 ChamboHaplochromine CichlidsUsipaOthersPercentage Chambo
Midwater Trawl95261503459
Chambo Seine54550299
Chirimila Seine1751556625247
Pair Trawl661091006
Demersal Trawl459050624
Kambuzi Seine34565388163
Nkacha Seine11772091

Table 12.5 S-E. Arm. Mean weights of chambo caught in different gears.

GearMesh size
Mean weight of chambo caught in grams.
Midwater Trawl38320
Chambo Seine70–90280
Chirimila Seine6–25130
Pair Trawl22200
Demersal Trawl38220
Kambuzi Seine2–25  80
Nkacha Seine13–25  80

The mean weight of chambo caught is less than the weight at maturity (320–405g, dependent on species), in all gears except for the 102mm ringnet (Table 12.5). Despite their small mesh sizes, trawls generally catch relatively large chambo. Adherence to the legal minimum mesh sizes for chambo seines and gillnets would reduce the catch of immature fish, without a significant loss of by-catch.

Kambuzi and nkacha seines, on the other hand, catch much smaller chambo and are a cause for concern. It should also be noted that the majority of the haplochromines (kambuzi, chisawasawa, utaka, ncheni) caught by these gears are juveniles of species which are exploited as adults by other fisheries (Table 12.6). Since usipa can also be exploited by chirimila nets, only 29% of the catch consists of species which are not exploited by other gears. Only a few stocks (ndunduma, large catfish & deep-water chisawasawa) are free from the potentially damaging effects of exploitation of their juveniles by seines.

Despite the relatively large mean size of fish caught, the high catch rates of the 38mm midwater trawl mean that large numbers of immature fish are caught: it is estimated that immature fish account for 2.2 million of the 3.2 million chambo caught annually by this gear. In previous years, a 102mm net was frequently used. This gear had a significantly higher CPUE for chambo than the 38mm net, and therefore justification for the continued use of the smaller-meshed gear must lie entirely in terms of the haplochromine catch. If these species are also exploited by other gears, then it would be possible to recommend management measures based on the chambo fishery alone.

Table 12.6 Catch composition of kambuzi/nkacha seines relative to other fisheries in the S-E. Arm of Lake Malawi.

Fish Species GroupMostly ImmatureOther Exploiting Gear% Wt in KS+NK
ChamboyesTrawl/Ringnet etc.16.1
UtakayesChirimila/Trawl  1.6
Chisawasawa IyesPair trawl/Gillnet31.6
NcheniyesTrawl/Chirimila/Handline  4.5
Chisawasawa II-Deep-water bottom trawl  -
Ndunduma-Midwater trawl  -
Mlamba/Kampango-Longline/Gillnet/Trawl  -

Note: Data from 2,800 fish, identified to species, November 1991 to April 1992.

12.2.1 Haplochromine trawl fisheries - current assessment and management practises.

Haplochromine cichlids are exploited by three trawling techniques: mid-water trawling, pair trawling and deep-water bottom trawling. At present, the south-east arm is divided into three management areas: A - South of Boadzulu Island, B - South of Monkey Bay, North of Boadzulu Island, C - North of Monkey Bay. Allocation of trawling units to these areas has been based on biomass estimates resulting from experimental trawling by FAO (1976), where the maximum sustainable yield was calculated as 45% of virgin stock biomass. These estimates were clearly stated to be tentative (FAO 1976). No differentiation between trawling techniques was made in the allocation of units, except insofar as different techniques require vessels of different fishing power. On this basis, total catch and effort statistics indicate that Area A is fully exploited, Area B can accommodate an additional pair trawler and Area C a further 10 pair trawl units or 5 single-boat bottom trawlers similar to those already in use (Table 12.7). In the following analysis it will be shown that these estimates are highly misleading.

Table 12.7 Total catch and effort of the trawl fisheries in the S-E. Arm of Lake Malawi.

YearArea AArea BArea C
1976510150910062366    49    97
1977340  47813313438    76  126
1978491  97710652891  109  186
1979594153011523129  140  313
1980435121411272617  171  373
1981402109611062899  232  465
1982268  58610832990  309  587
1983437102010062185  286  802
1984479  99410641754  4961059
1985449  87910502458  482  834
1986443105711282208  287  503
1987511132411772608  275  567
1988506107112412067  347  701
1989420121812452059  323  815
1990578132210991938  267  557
1991425102212392170  308  482
(FAO 1976)

12.2.2 Biological investigations

The total catch figures given above include chambo catches, which are now known to be the same stocks as are exploited by artisanal fishing techniques (see section 4): chambo stocks must therefore be assessed separately from haplochromine stocks, which are less influenced by artisanal fishing. Additionally, there is ample evidence that most demersal cichlid species have relatively restricted depth preferences (see section 4, also Eccles & Trewavas 1989), and thus different trawling techniques could be exploiting different stocks. To investigate the interactions between haplochromine trawl fisheries, 54 commercial trawl catches were examined and the numbers and weights of each species caught determined. The percentage contribution of the 20 most important species or species groups (taxa) is given on Table 12.8.

Table 12.8 Species composition of trawl catches in the S-E. Arm (percentage weights, excluding chambo & large catfish)

RankTaxonTrawling Technique
1Diplotaxodon ‘elongate’61.9  18.3  5.5
2Rhamphochromis spp.10.6  8.315.1  
3Lethrinops microdon2.827.5   
4Lethrinops ‘blue/orange’* 14.5  
5Lethrinops ‘dark’*4.87.9
6Otopharynx ‘argyrosoma b’1.2*11.0  
7Placidochromis cf. longimanus* 10.8  
8Aulonocara ‘orange’1.1*7.7
9Lethrinops longipinnis1.54.81.9
10Copadichromis cf. virginalis3.8*3.6
11Lethrinops ‘oliveri’*4.71.3
12Lethrinops alta*4.8*
13Lethrinops gossei*5.0 
14Diplotaxodon argenteus3.11.5 
15Lethrinops stridei* 3.5
16Pseudotropheus livingstonii* 3.4
17Aulonocara brevirostris?*2.51.0
18Pseudotropheus elegans* 2.7
19Sciaenochromis ‘lacustris’*1.4*
20Ctenopharynx intermedius**1.2

Note: *= less than 1%, blank= not recorded

There is clearly very little overlap between the species exploited by the three fishing techniques. In fact, subsequent studies have indicated that these data over-estimate the interaction between the fisheries: nine of the taxa distinguished (2,7, 9–14 & 17) consist of two or more species, in most cases with different habitat preferences and likely to be exploited in different proportions by the three techniques. Thus, there is justification for assessing each of these fisheries separately.

Considering the topography of the south-east arm, there is no reason to regard Areas B & C as separate: the boundary between the areas is wide and cuts across all depths, except for the extreme deep waters, below 70m, which are not presently exploited, and where the fish biomass is low. Since landing & refuelling facilities for all vessels are in Areas A and B, it is not surprising that most fishing in Area C takes place near the boundary with Area B. The species composition of trawl catches in Areas B and C are very similar.

The pair trawl fishery in Area A operates over a large area of shallow gently-shelving bottom, less than 40m deep. Waters of this depth are restricted to narrow bands along the edges of Areas B & C, and thus Area A can be considered as a limnological and biological unit.

12.2.3 Assessment of the haplochromine stocks

The mid-water trawl fishery in Areas B and C is exploited at around the optimum level of 340 boat days, using Maldeco's Crystal Lake as the standard unit (Figure 12.3). There is no room for further expansion of this fishery, which should be expected to yield around 650 tonnes per year.

Further expansion of mid-water trawling, if permitted, should not employ nets with a cod-end mesh of less than 102mm, since this provides optimum selectivity for chambo and avoids overexploitation of the haplochromine stocks.

The single-boat bottom trawl fishery in Areas B & C has been seriously overexploited since 1983, and suffered a major collapse of stocks in 1988–89 (Figure 12.4). Despite reduced effort levels in 1990 and 1991, the stock has yet to recover. The maximum sustainable yield of this fishery is around 1,500 tonnes, at an effort level of 460 boat days (Maldeco's Dennis Sanudi & Liloya and Fatch's trawler have similar fishing power). Thus, the fishery is presently yielding around half of its potential.

Expansion of this fishery in the south-east arm is not possible. If recovery of the stocks is not apparent within the next few years, further reductions in effort, or temporary closure of the fishery will be required.

Catch per unit effort and effort of the pair trawl fishery showed wide fluctuations in the early stages of exploitation, before stabilising in 1978 (Figure 12.5). The accuracy of surplus yield models in fisheries stock assessment is highly sensitive to the assumption that the stocks are in equilibrium (Pitcher & Hart 1982). Even in a single species fishery, stocks cannot be considered to be in equilibrium during the first few years of exploitation: in an unfished population there is a considerable number of old fish. These will be rapidly removed by fishing, and an equilibrium age structure will develop, assuming that exploitation does not reach excessive levels within the first few years. The situation is further complicated when there is a multispecies fishery in which large, slow-maturing fish are replaced by smaller species. Such species changes were documented by FAO (1976) between 1971 and 1975. A change in mesh size from 25 to 38mm was introduced in 1977.

Thus, catch and effort statistics for 1968 to 1977 should not be used for stock assessment. From Figure 12.5, it can be seen that a regression of CPUE on effort is rendered statistically significant only by the inclusion of the year 1968 - the first year of exploitation. Thus, MSY estimates of FAO (1976) and Tweddle & Magasa (1989) should be treated with caution. Leaving aside the years 1968 to 1971, there is no significant correlation between CPUE and effort for this fishery, as the data from 1978 to 1991 appear as a random cloud of points.

Closer inspection of the years 1978 to 1991 (Figure 12.6) indicates that the pair trawl fishery has moved through three phases, each with a different relationship between CPUE and effort. The third phase, lasting from 1987 to the present, suggests a potential for very high yields at reduced effort levels, but also that a collapse of stocks could occur with a relatively small increase in effort.

Figure 12.3 The midwater trawl haplochromine fishery is fully exploited. MSY is 654 tonnes, at an effort of 337 boat days (Schaefer model: r=0.78, 12df)Figure 12.3
Figure 12.4 The deepwater bottom trawl fishery is heavily over-exploited. MSY is 1580 tonnes, at an effort level of 604 standard boat days (Schaefer model, effort standardized to effort of Maldeco's Dennis Sanudi, 1990–91 not included: r=0.78, 10df).Figure 12.4
Figure 12.5 The pair trawl fishery in Area A (south of Boadzulu Island) initially showed large fluctuations in CPUE and effort, before stabilising from 1978 onwards. The initial few years should not be included in calculation of surplus production models because of the large changes in age structure which result from exploitation of a virgin stock.Figure 12.5
Figure 12.6 Since 1979, the pair trawl fishery in Area A has moved through three phases, each characterized by a different relationship between CPUE and effort. The present phase, which began in 1987, shows great instability. This phase has not lasted long enough to justify an attempt to fit a surplus yield model.Figure 12.6

Possible explanations for the phase changes in the pair trawl fishery are:

(a) Decrease in mesh size:

The legal minimum of 38mm is not enforced, instead 22mm meshes are used, and the practice of double-bagging the codend is reported.

(b) Increase in the length of pulls leading to clogging of the net:

Currently pair trawlers in Area A make a single pull of 10–12 hours duration. This keeps the catch fresh, as there are no refrigeration facilities on these open boats. It also prevents the crew from selling part of the catch out of sight of the owner, who does not generally accompany the fishermen during their operations. Previous practices have not been documented.

(c) Change of fishing ground:

At present, trawling within one mile (1.6km) of the shore is legally prohibited, but this is not enforced. During experimental fishing cruises, the majority of pair trawlers observed were fishing close to the shore: this is consistent with the species composition of the catch. Previous practices have not been documented.

(d) Change in species composition of the catch:

Samples taken by experimental trawling (ODA Demersal Fisheries Reassessment Project) indicate that since the FAO report of 1976, changes in the species composition of the demersal cichlid communities have continued. Large cichlid species preferring depths of 30m or deeper had already declined by 1975 - many of these have declined further, or become locally extinct. More recently, populations of large species in shallow waters have also diminished (Table 12.9).

Table 12.9 Change in species composition of cichlid communities in Area A.

SpeciesPreferred DepthTotal Length1971197219751991
(% Sample Weight.)
Lethrinops mylodon50–60m25cm1.6 *0.2  <0.1  ABSENT
Lethrinops macracanthus40–80m24cm2.7  3.6*0.1  ABSENT
Lethrinops longimanus40–80m20cm1.1  1.9*0.4  <0.1
Lethrinops stridei30–50m19cm11.5  8.2*1.4  0.4
Taeniolethrinops furcicauda20–40m25cm0.8  1.8  3.1*<0.1
Taeniolethrinops praeorbitalis20–40m30cm3.3  4.0  2.1*0.5
Otopharynx cf. argyrosoma20–50m12cm7.0*13.1  13.9  19.9
Pseudotropheus elegans20–40m15cm<0.1*2.5  4.2  9.6
Pseudotropheus livingstonii20–40m12cm2.5  3.6*22.0  19.2

Notes: * indicates period of greatest change in relative abundance (Data from Turner et al. 1992).

The pair trawl fishery in Area A is in a dangerously unstable state. As it is not possible to determine the maximum sustainable yield or optimum fishing effort for this fishery, future developments need to be monitored closely, and corrective action taken swiftly, through limitation of fishing effort or temporary closure of the fishery.

Before any increase or redistribution of fishing units is performed, potential trawling grounds in Areas B & C should be resurveyed, taking into account (i) that pair trawl units generally operate in waters of less than 40m depth, (ii) that single-boat bottom trawlers operate between 50 and 70m depth - deeper areas can be excluded, (iii) that units licensed to fish in these areas will continue to fish as far south as possible for economic reasons, (iv) that much of the coast near Makanjila is rocky and cannot be trawled, and (v) that many species now extinct in Area A are confined to the south-east arm and would probably become entirely extinct if pair trawl operations were to reach a similar intensity in Areas B & C.


All three sectors of the fishing industry operate in the south-east arm of Lake Malawi. The socio-economic conditions are here considered from the aspect of the economic importance of the different minor strata and the different artisanal fishing techniques employed.

Price data for earning calculations (catch value) were derived from MTF, all cost data were obtained in separate studies on costs and earnings in the artisanal sector of the fishery, as described in section 8.4.

12.3.1 Economic importance of the artisanal fishery in the south-east arm of Lake Malawi.

The artisanal fishery of the south-east arm of Lake Malawi accounts for 40% of the total economic output from the artisanal fisheries in the project area, with chambo being the most valuable fish (Figure 12.7). Chambo and kambuzi beach prices have increased, but not much more than the inflation rate would suggest (Figure 12.8).

The chirimila fishery is the dominant fishery in the south-east arm in terms of economic output and employment. Chirimila fisherman-entrepreneurs produce 34% of the artisanal fisheries output in the south-east arm and employ almost 40% of all crew members (Figure 12.9).

Minor stratum 2.1 produces almost 40% of the output of the south-east arm. Chambo, kambuzi and usipa are the main “income earners”. Fishing activities in MS 2.3 appear to be rather unsuccessful. This minor stratum contributes only a little more than 3% to the overall earnings and all fisheries operate at a very low level of profitability (Figure 12.10).

12.3.2 Comparison of the profitability of the different fisheries

(a) Chirimila fishery

The profitability of the chirimila fishery is generally low (Figure 12.11). In MS 2.1, where most fisherman use an outboard engine (72%), the annual profit does not reach MK 1,500. Figures for MS 2.3 indicate, that fishermen do not make any profit at all. The chirimila fishery in MS 2.3 is very seasonal. The mean number of fishing days per year is low (26) as is the number of pulls per fishing day (2.7). The operational costs are very high due to the use of outboard engines. In MS 2.4 several factors contribute to the success of the fishermen. The mean CPUE is high and stable throughout the year, fishermen are able to operate almost 100 days per year with up to 11 pulls per fishing day.

Figure 12.7 Contribution of the different types of fish to the overall economic output of the south-east arm of Lake malawi.

Figure 12.7

Figure 12.8 Beach prices, south-east arm of Lake Malawi, 1991

a. Chambo

Figure 12.8a

b. Kambuzi

Figure 12.8b

Figure 12.9 Economic importance of the different artisanal fisheries in the south-east arm of Lake Malawi.

Figure 12.9

Figure 12.10 Earnings composition in the south-east arm of Lake Malawi.

Figure 12.10

Figure 12.11 Annual gross income of chirimila net owners: comparison between minor strata.

Figure 12.11

Figure 12.12 Annual gross income of gillnet owners: comparison between minor strata.

Figure 12.12

Figure 12.13 Annual gross income of chambo seine owners: comparison between minor strata. Note: No chambo seines were found in minor stratum 2.5.

Figure 12.13

(b) Gillnet fishery

Although the gillnet fishery contributes substantially to the overall production of the south-east arm, for the individual fisherman this technique does not appear to be profitable (Figure 12.12). The highest profits are made in MS 2.1. where the fishermen own large gillnets and work almost 260 days per year to compensate for the low mean CPUE. In MS 2.5 many fisherman-entrepreneurs operate their units without an assistant, which keeps the costs of operation low.

(c) Chambo seine fishery

A comparison between minor strata shows large variations in the profitability of chambo seining. Chambo seine fishermen in MS 2.1 and 2.2 are the most successful artisanal fishermen in the whole project area (Figure 12.13). High chambo catches per pull, high chambo prices and the opportunity to fish more than 100 days a year make this fishery extremely lucrative.

(d) Kambuzi seine fishery

Although kambuzi seine fishermen use increasingly smaller mesh sizes (mean 15mm) and the headline length of their nets is far greater than the maximum legal length, the profitability of kambuzi seining remains low. Increasing the mesh sizes to 25mm, which is proposed as a management option, would leave most kambuzi seine fishermen without any profit. (Figure 12.14).

(e) Nkacha net fishery

Apart from chambo seining, all fishing techniques discussed above, including the nkacha seines, appear to be much less profitable in the south-east arm than in Lake Malombe. Nkacha fishermen are highly mobile and move, especially during closed seasons, which are different in Lake Malombe and in the south-east arm, from one lake to the other. The project's frame survey, carried out in Jan. 1990 (closed season for nkacha net in Lake Malombe) counted 38 nkacha nets in the south-east arm, while in a frame survey, carried out by the Department of Fisheries in August 1990, no nkacha net was found. This suggests that the nkacha units are not resident in the south-east arm of Lake Malawi.


  1. Adoption of the principle of limiting access to Malawi's fisheries and implementing it for the south-east arm of Lake Malawi (and the Upper Shire river and Lake Malombe), as soon as possible.

  2. The current total gear holdings of fisherman-entrepreneurs should not be allowed to increase in numbers or size.

  3. The minimum mesh size of gillnet and chambo beach-seines should be raised to 95mm throughout Lake Malawi (and the Upper Shire river and Lake Malombe).

  4. The use of fine-meshed seines, such as kambuzi/chalira seines and the nkacha seine should be completely banned in Lake Malawi.

  5. The current ban on chambo seine operations in Lake Malawi during November and December should be lifted.

  6. The developments, particularly in the chirimila fishery should be monitored closely and catch composition determined.


As a result of experimental trawling surveys (FAO 1976), demersal fish stocks in Lake Malawi were thought to be underexploited. A decline in catch rates was attributed to deterioration of the condition of the craft, especially the ‘semi-industrial’ pair trawlers (Tweddle & Magasa, 1986). Therefore an expansion of both semi-industrial and industrial sectors was recommended and is currently in progress.

Re-analysis of catch and effort statistics in the light of the biological research reported here indicates that:

  1. The chambo stock in the south-east arm of Lake Malawi is fully exploited.

  2. The mid-water trawl haplochromine fishery is fully exploited.

  3. The deep-water haplochromine trawl fishery is severely overexploited.

  4. The pair trawl fishery in Area A is in an unstable phase and probably overexploited.

  5. Pair trawling in Areas B & C has been irregular, and does not permit an assessment of the stocks to be carried out. The size, productivity and potential yields of the pair trawling grounds in Areas B & C (or elsewhere) have not been adequately surveyed.

Thus there are sufficient grounds for considering that expansion of these fisheries may not bring the previously anticipated increases in catches. The economic consequences of the various scenarios for the development of industrial and semi-industrial fisheries are considered below.

12.5.1 Industrial Fisheries

Bio-economic modelling is used to investigate seven scenarios for the development of the industrial fishery (Maldeco) to predict which one would optimise the joint management of the chambo, chisawasawa, and ndunduma stocks exploited by the industrial, semi-industrial (stern trawl unit Fatch) and artisanal fisheries.

Industrial fisheries are operated by a single company, Maldeco Fisheries. At present the company operates two trawlers (with a third as a reserve) and two ringnet pairs. This fleet and the other competing fisheries are summarised in Table 12.10

Table 12.10 Present fleet of Maldeco Fisheries and competitors

Vessel (length)License AreaStocks ExploitedMain Competitors
Ringnetters (2 pairs)
Crystal Lake
Dennis Sanudi

It is intended that a new multipurpose vessel (MPV, 17.5m) will be operational in 1993. This boat will be capable of mechanised ringnetting and midwater or bottom trawling, although it is unclear how much effort will be expended with each gear. Assuming that the new vessel has a fishing power equivalent to the Crystal Lake, the largest of the current fleet, and that the mechanised ringnet will be capable of the equivalent of 24 pulls per day (as projected), the effect of the introduction of this vessel has been modelled, both in terms of its effect on the three main fish stocks (chambo, chisawasawa and ndunduma) and on the economic performance of the company. Scenarios excluding the new vessel are also simulated (Table 12.11).

The effects of changing effort levels on the fish stocks are assumed to follow exponential relationships (Fox model), linear models (Schaefer) give essentially similar results, but indicate rather more dramatic declines in catches at higher effort levels.

The model (Table 12.11) includes the effect of fishing effort by other sectors, held at 1991 levels. This comprises the exploitation of chisawasawa by the stern trawler (Fatch), and the chambo catches of the artisanal fisheries and pair trawlers.

The most recent figures available for the economic performance of Maldeco Fisheries date from 1989, and include projected loan & interest repayments. For this reason, all catch values are given in 1989 prices.

It should be stressed that the predictions of this model should be interpreted as approximate averages of equilibrium conditions, where fishing effort remains constant for a period of several years. They are not predictions of the catch for next year if a particular scenario is followed.

Scenario 1:

With the current fleet and pattern of fishing effort (Table 12.11) it is expected that Maldeco Fisheries will maximise its profits, at least in the short-term. In the longterm the repair and replacement of ageing vessels is likely to increase costs and reduce profits.

Scenario 2:

The addition of the Liloya to the active fleet. This boat is currently not licensed to operate on a full-time basis. It is permitted to operate only as a substitute when one of the other trawlers is under repair. The granting of a license for full-time operation of this vessel is predicted to result in reduced profits for Maldeco, and reduced catches for both Maldeco and Fatch. In 1988 and 1989 the Liloya was operated in addition to the other vessels. The use of Liloya for 6 months in 1988 led to a decline of 47% in the CPUE of Dennis Sanudi and of 24% for Fatch's trawler. This result lends credibility to the predictions of the model.

Scenario 3:

Withdrawal of Maldeco from bottom trawling is likely to lead to a substantial reduction in their profits, but the overall fish catch is only marginally reduced, as reduction in effort will lead to a great increase in Fatch's catch. As Fatch is assumed to fish for 250 days (1991 level) in the model, if this huge increase in catches were to lead to profits being invested in improvement of the boat's mechanical reliability, with an increase of fishing effort to 330–350 days per year, this scenario would probably lead to the greatest overall fish yield from the stocks. Alternatively, with the recovery of the chisawasawa stock, Maldeco might choose to switch the Crystal Lake from mid-water trawling to bottom trawling for part of the year. This would increase the chambo yields of the artisanal sector. This scenario provides the best outcome from the point of view of maximising total yields, and ensuring a wide distribution of profits. It is probably an unrealistic option in view of possible commercial conflicts.

Table 12.11. Predicted consequences of the development of Maldeco Fisheries.

Ringnet Pairs       
102mm Ringnet3753753753753750375
Crystal Lake and/or New Vessel      
102mm Ringnet00000700
38mm MW Trawl350350350700350350700
102mm MW Trawl00003502000
38mm B Trawl00000800
Dennis Sanudi or Liloya       
38mm B Trawl35070003503500700
Catch Value3722369631344266432938094231
Variable Fishing Costs6187674699899895771138
Fixed Vessel Costs (i)206252160562562405609
Total Costs (ii)3512370733174239423936694434
Profit (iii)4422204925932237228
Fatch's stern trawler5832701259583583886270
Chambo (artisanal/pairs)2698268527102086208624742076
Total Chambo4490449044904280428044404280
Total Other Species2057168319171967205721101593
Total Fish Yield6547617364076247633765505873

Notes: (i) for new vessel includes interest repayments and depreciation;
(ii) includes MK 2,688,000 factory/administrative costs etc, & interest on loans for upgrading;
(iii) includes MK 232,000 from other sales.

Scenario 4:

The addition of the MPV to the current fleet using a 38mm mid-water trawl will lead to an overexploitation of the chambo and ndunduma stocks and a consequent decline in catch and profits. Artisanal fisheries will suffer an almost 25% decline in the chambo catch.

Scenario 5:

The addition of the MPV to the current fleet using a 102mm mid-water trawl will lead to the overexploitation of the chambo stocks and a consequent decline in catch and profits.

Scenario 6:

The MPV replaces the ringnetters and the Dennis Sanudi. Maldeco can expect to suffer a small decline in profits, until the loan for purchase of the MPV is repaid. Total catches are likely to remain largely unchanged, but operating costs will be reduced. The exact level of effort which should be allocated to each gear will depend on the efficiency of the MPV's mechanised ringnet. Artisanal fishermen can expect a 6–8% reduction in chambo catches, but Fatch's trawler should have increased yields, leaving total catches unchanged. This is probably the best compromise between Maldeco's requirement to maximise its profitability and the interests of the Department of Fisheries in maximising yields.

Scenario 7:

The addition of the MPV using a 38mm mid-water trawl and the Liloya to the active fleet. Based on present levels of the profitability of fishing operations, but neglecting the state of the fish stocks, this is the scenario which would be favoured. However, it is predicted that Maldeco would suffer a sharp decline in profits; the artisanal fishermen would suffer a loss of 25% of their chambo catch and Fatch's catch would fall by 50%. In addition total yields would decline by 10%. There would be no benefit to any sector of the fishery and this scenario must be avoided.

Table 12.12: Operations model for a pair trawl fishing unit

Wages: 2 head fishermen1920  
8 crew members4800  
2 watchmen960  
2 cleaners960  
1 manager3000  
Loan repayment25000 (1)
Interest on loan capital18000 (2)
License + registration76255402 
Crew incentive3900  
Sales of chambo57300 (4)
Sales of chisawasawa156825 (5)
Sales of others14730228855(6)
PROFIT (pre-tax) 105253 

Notes: (1) MK 100,000 over 4 years
(2) 18 % interest
(3) 260 days of fishing per year
(4) MK 2.40/kg
(5) MK .60/kg
(6) MK .60/kg

Figure 12.14 Annual gross income of kambuzi seine owners: comparison between minor strata.

Figure 12.14

Figure 12.15 Annual profit of pair trawl units at different levels of fishing effort, comparison between different fishing grounds in the south-east arm of Lake Malawi.

Figure 12.15

12.5.2 Economic assessment of the semi-industrial sector of the fishery

At present, seven pair-trawl units exploit the chisawasawa and chambo stocks in the south-east arm. Of these, six submitted returns on catch and effort to the Department of Fisheries in 1991.

In total, these units contribute MK 726,000 to the overall economic output of the fisheries of Lake Malawi. Chisawasawa is the most important category of fish caught, both in terms of weight and value. Chambo accounts for 22% of the total value, but only 7% of the total catch. Earnings and profit in the semi-industrial fishery are not evenly distributed. In 1991, only two units were able to operate for more than 250 days, while two managed less than 50 fishing days.

Studies on costs and earnings in the semi-industrial sector of the fishery have been carried out to assess the economic performance of the pair-trawl units and to give a basis for the prediction of the impact of fisheries management strategies. The data have been incorporated into a bio-economic model, which indicates the different levels of profitability of fishing in different areas of Lake Malawi.

Economic data were obtained through interviews with three fishermen, chosen at random from the six who report their catches to the Department of Fisheries. CPUEs for the different areas of Lake Malawi and for the different species were derived from statistics of the Department of Fisheries.

At an effort level of 260 days per boat per year, normally the maximum, Area A of the south-east arm of Lake Malawi appears to be the most profitable fishing ground. Here the CPUE of chisawasawa is reasonably high compared with other areas, while that of chambo is the highest. Semi-industrial fishermen can realize an estimated profit of MK 100,000 per year (Table 12.12).

In Area A, pair trawl units need to fish only 85 days per year to break even. In Areas D & E more than twice as much fishing is required (Figure 12.15). The further north they fish, the less profitable the business becomes. Pair-trawl fishing in Area G appears to be totally unprofitable because of low CPUEs for both chisawasawa and chambo. Experimental trawling (FAO, 1976) has indicated that in all areas to the north of Area G, catch rates are approximately the same as in Area G, and are thus also likely to be unprofitable fishing grounds.

12.5.3 Conclusions

In order to maximise total yields and ensure a wide distribution of profits, Maldeco should retain their present ringnet and mid-water trawl operations, but their bottom trawl license should be withdrawn (Scenario 3). However, this option will not be acceptable.

With the aim of maximising the profit of Maldeco, two options have approximately equal merits: the retention of the current fleet, or the replacement of all vessels except the Crystal Lake by the new multipurpose vessel (Scenarios 1 and 6). The new vessel should operate a mix of bottom trawl, 102mm cod-end mesh mid-water trawl and ringnet.

The maximum expansion of Maldeco's operations by the addition, to the current fleet, of the Liloya and the proposed new vessel (Scenario 7) would be disastrous.

Despite the long history of heavy exploitation in Area A, its pair trawl fishery is still more profitable, than in the other areas. However, for reasons given in sections 12.1 and 12.2.3 further expansion should be discouraged. Farther north (Areas B - E) pair trawling is less profitable, and north of Salima (Area G) not profitable at all. Granting additional licenses for these areas would be unwise - operators will suffer losses and will likely attempt to move to more profitable fishing grounds, which would endanger the sustainability of those stocks.

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