5. DESCRIPTION OF THE FISHING ACTIVITIES AND A COMPARISON OF THE FISHERIES OF THE SOUTH-EAST ARM OF LAKE MALAWI AND LAKE MALOMBE

There are six minor statistical sampling strata in the south east arm of Lake Malawi and two in Lake Malombe. The Upper Shire river is considered as a single statistical unit, (see map).

The south-east arm covers an area of approximately 2,000 km². Lake Malombe, which is an enlargement of the Upper Shire river outlet from Lake Malawi, has an area of about 390 km².

In Lake Malombe and the Upper Shire river the fish stocks are exploited only by the artisanal sector which employs gillnets, chambo seines, kambuzi seines/chalira and nkacha nets. In Lake Malawi, in addition to the artisanal sector, the stocks of the south-east arm are exploited by the semi-industrial and the industrial fisheries. The semi-industrial fishery mainly uses pair trawls, the industrial fishery bottom trawls, mid-water trawls and ringnets.

5.1 DESCRIPTION OF ARTISANAL GEARS USED

5.1.1 Kambuzi seine net (KS)

This is a beach seine common in all the three major strata in the project region. It has a mesh size ranging from a few mm to 25mm at the bunt and a headline length from 50 to 700m. The depth of the nets can vary from 2 to 12m (Table 5.1 and Figures 5.1c, d and e).

The kambuzi seine is normally cast from the beach in a semi-circle using a single, planked boat. Both sides are pulled to the beach simultaneously by two sets of people. It normally requires 6 to 20 assistants depending on the headline length. When operated behind a chambo seine or another kambuzi seine of longer headline and possibly bigger mesh size, it is locally called a chalira, and is used to catch the fish that escape the first net (Figure 5.1a).

Figure 5. 1a Kambuzi seine net (A) and its use as chalira (B).

Figure 5.1c SE.Arm. Kambuzi seine headline length distribution.

Figure 5.1d Up.Shire. Kambuzi seine headline length distribution.

Figure 5.1e Malombe. Kambuzi seine headline length distribution.

Figure 5.2a Chambo seine net: shape (A) and operation (B-C).

5.1.2 Chambo seine net (CS)

The chambo seine is a beach seine normally operated using a single planked boat. The bunt mesh size can vary from 76 to 90mm and the headline length from 100 to 1800m. The depth can vary from 5 to 20m (Table 5.2 and Figure 5.2b and c).

The chambo seine is operated in the same way as kambuzi seine but requires the use of 10 to 30 helpers for its operation (Figure 5.2a). This gear is commonly in use in the south-east arm of Lake Malawi and the Upper Shire river but very few are now in use in Lake Malombe due to the collapse of the chambo stocks.

Figure 5.2b SE.Arm. Chambo seine headline length distribution.

Figure 5.2c Upper Shire. Chambo seine headline length distribution.

Figure 5.3a Nkacha net: shape (A) and operation (B-F).

5.1.3 Nkacha net (NK)

The nkacha net is a rectangular gear like the kambuzi seine with a similar gradation of mesh size from bunt to wing. The nets are very common in Lake Malombe and less so in the south east arm of Lake Malawi and the Upper Shire river. (Table 5.3 and Figure 5.3b and c)

The nkacha net is an open-water seine net with a footrope that is weighted to the bottom when in operation. It is operated using two planked boats and seven crew members. It is cast in a circular manner and a crew member dives down to tie the foot rope together, effectively forming a bag in which the fish are trapped (Figure 5.3a).

Figure 5.3b Upper Shire. Nkacha net headline length distribution.

Figure 5.3c Malombe. Nkacha net headline length distribution.

Figure 5.4a Gillnet. Bottom set in SE. Arm of Lake Malawi (A) and its use as open-water seine in Lake Malombe (B-E).

5.1.4 Gillnet (GN)

The gillnet is a rectangular gear usually made from 4 or 6 ply twine. In general there is only one mesh size used in a gillnet fleet. The commonest mesh size in Lake Malawi is 90mm, with a range from 64 to 102mm. The headline length can vary from 100 to 3200m and the depth from 5 to 25m (Table 5.4 and Figure 5.4b and c).

It is normally used with a single planked boat (with or without an engine) and a crew of four. In the south east arm of Lake Malawi and the Upper Shire River the gillnet is bottom-set overnight and hauled up in the morning. In Lake Malombe, the gillnet is used as an open-water seine net. One end connected to a lamp on a tray is cast first and the rest of the net is shot from a boat in a circular manner. The operation can be repeated several times a night (Figure 5.4a).

Figure 5.4b SE.Arm. Gillnet headline length distribution.

Figure 5.4c Malombe. Gillnet headline length distribution.

Figure 5.5a Chirimila net, only in use in the SE. Arm of Lake Malawi: shape (A) and operation (B-E).

5.1.5 Chirimila net (CH)

The chirimila net is an open-water seine net which has been recorded only in Lake Malawi. It has a conical appearance. The bunt mesh size ranges from mosquito netting to 25mm and headline length from 20 to 90m. The depth of the net ranges from 5 to 50m. The headrope is almost always twice as long as the footrope (Table 5.5 and Figure 5.5b).

Figure 5.5a. The net is operated from two dugout canoes and one planked boat with a total crew of 9. The planked boat and the larger dugout are actually involved in the casting and hauling operations. At night the headman, located in the smaller dugout canoe equipped with a brightly shining kerosene pressure lamp, directs the actions of the crew in the other craft. When he locates a fish school (usually usipa), he tells the other fishermen when to shoot the net. The net is towed in the opposite direction to the movement of the fish. When the fish are caught, the headman joins in hauling the net into the boat and the larger dugout. During the day the net is used for utaka fishing, as it can quickly be prepared for this by removing the mosquito-net lining, that is needed for catching usipa.

Figure 5.5b SE.Arm. Chirimila headline length distribution.

5.2 SPECIES COMPOSITION

The total fish catch in the artisanal fisheries of the south-east arm of Lake Malawi, Lake Malombe and the Upper Shire river (as estimated from MTF survey of 1991) was 8781t, 5403t and 506t respectively. The contributions of chambo and kasawala (juvenile chambo) to the catches in the various artisanal gears are summarised in Table 5.6.

Table 5.6 Percentage of chambo and kasawala of the catch of the artisanal gears.

5.2.1 Lake Malombe

Kambuzi (small demersal haplochromines) is the target fish for the kambuzi seines and nkacha nets in the south-east arm of Lake Malawi, Lake Malombe and the Upper Shire River. In Lake Malombe kambuzi and mbaba (larger haplochromines) form 95% of the nkacha net and 90% of the kambuzi net catches. Chambo, including Kasawala forms 58% of the catch in the chambo seines and 40% of the catch in the gillnets with nchila, mlamba and other tilapiine species becoming increasingly important in these gears, due to the decline in chambo catches (Figure 5.6).

Nkacha nets contributed 72%, kambuzi seines 16%, gillnets 11% and chambo seines 0.6% to the total 1991 (MTF) fish catch in Lake Malombe.

5.2.2 Upper Shire river

Kambuzi (including mbaba) forms 98% and 45% of the total fish catch in nkacha and kambuzi seine fisheries in the Upper Shire river. Chambo, including Kasawala forms 94% of the total fish catch in chambo seine. The gillnet fishery is carried out at a subsistence level sustained by mlamba and tilapiine species (Figure 5.6).

Nkacha nets contribute 80%, kambuzi seines 0.4%, chambo seines 19% and the gillnets 0.7% to the total fish production in the Upper Shire river.

5.2.3 South-east arm of Lake Malawi

Kambuzi forms 98%, 54% and 26% of the total fish production in the nkacha, kambuzi seine and chirimila net fisheries in the south-east arm of Lake Malawi. Usipa forms 39% and 31% in the kambuzi seine and chirimila net catches. Utaka forms 33% of the total fish production in the chirimila catch. Chambo, including Kasawala forms 99% and 75% of the total fish catch in the chambo seine and gillnets (Figure 5.6).

Chirimila nets contribute 44%, kambuzi seines 19%, nkacha nets 15%, gillnets 12% and chambo seines 10% to the total fish production from the artisanal sector in the south-east arm of Lake Malawi.

Figure 5.6 Catch composition by gear type and species group (in %).