内陆渔业

Fisheries Monitoring Survey at Sebaboleng Dam, Maseru Town, Lesotho. ALCOM Field Document No. 30.

Managing inland fisheries
01/01/1994

A fisheries monitoring survey was carried out between March 1991 and February 1992, at the Sebaboleng dam, Maseru, Lesotho. It was undertaken by the Fisheries Section of the Ministry of Agriculture, Co-operatives and Marketing, Lesotho, and by the Department of Youth and Women's Affairs, in collaboration with ALCOM.

The purposes of the survey were threefold. First, to collect catch and effort data over a 12-month period from small-scale fisheries at Sebaboleng and Maqalika Dams in Maseru Town, as a complement to fish sampling data. Second, to collect basic socio-economic data on individual fishermen and use it to prepare a profile of the fishermen. Last, but not the least, the method and the survey design were themselves the focus for testing and evaluation, since documented experiences from similar surveys in southern Africa are scarce.

A census survey design covering the fishermen of Sebaboleng and Maqalika dams was chosen, in order to fully cover fishing activities and catches. A questionnaire was used for collecting fisheries data, and a key sheet (identification sheet) for socio-economic data on individuals fishing at the dams. The survey proved difficult to implement successfully, because of the suspicion of respondents about the purpose of the survey, and because of the survey design chosen.

Initially, two reservoirs were included in the survey. However, one of them, Maqalika, had to be excluded after a short time, since fishermen refused to be interviewed there. This was because they were scared of being chased off by the authorities. (Access to the Maqalika dam is restricted since it is an important source of water supply for Maseru town).

Fishing is a part-time activity for all fishermen included in the survey. A total of 240 fishermen were identified at the two reservoirs, of whom five fish exclusively at Maqalika Dam. Of the rest, a vast majority fished at Sebaboleng only. 225 persons (94%) state that they are regular part-time fishermen, i.e. go fishing more than once a month. The rest, 15 persons (6%), are classified as occasional part-time fishermen, who go fishing less often. The proportion of occasional part-time fishermen is likely to be under-estimated, though; a large number of people say they fish more than once a month, but do not appear at the dam site that often.

None of the respondents regards fishing as his main economic activity. 35% of the respondents are employed, 32% unemployed and the rest are students or self-employed. Fishing is more frequent during the warm season (October–March) than during the cold (April–September).

The Catch per Unit Effort (CPUE) at Sebaloleng dam is generally low. Overall CPUE is 40 g/hour and it fluctuates between 10–109 g. over the survey year. CPUE refers only to three types of fishing gear: hook and line, rod and line, rod and reel. Data is too sparse to calculate CPUE for other gear types.

The average number of days fished per week and fisherman is 1.8 days. The average hours per day fished are 7.3. The estimated total fishing effort was 4185 man-hours.

The total catch per week oscillates between 0–8.3 kg over the year and the overall average is 3.2 kg. per week. The total annual harvest by hook fishermen was 167.4 kg, or 9.3 kg per hectare (surface area 18 hectares when full).

The fishing effort and the total catches are not constant over the year, but due to the great variations and the limited number of data, these fluctuations are statistically not significant and there is no clear pattern over the year.

152 respondents (67%) cited household consumption as their only reason for fishing, making it by far the most common reason for fishing. Household consumption in combination with cash is the second most frequent reason for fishing (21%). Very few fishermen fish exclusively for cash income; the amount of fish catch sold is very small. Recreation does not stand out as a common reason for fishing either.

The average age of the fishermen is 29. The persons identified in the survey are all men. Women do not seem to be fishing, but they do take part in processing and marketing activities.

Most respondents (84%) have learned to fish from friends, the others from relatives.

The main fishing gear used are hook and line (61%), which is usually a line with one or two hooks attached to a wire stand; and, rod and line (30%) which usually has a home-made rod of cane or wood stick. Other fishing gear used at the dam, although in small numbers, are rod and reel, small twine nets for seining, and spears. 62% of the respondents indicated that they had bought a part of the gear, or the whole gear, at an average cost of Maloti 23.43 (US$ 7.84). The most common practice is that of using only one gear type. Only 16% of the respondents indicate that they use two or more gear types in combination.

On an average, fishermen live at distances 20 minutes away on foot from Sebaboleng dam. 78% of the respondents live in the neighbourhoods adjacent to Sebaboleng Dam.

The fish species most preferred as catch are, in order of preference: Common carp (Cyprinus carpio), catfish (Clarias gariepinus) and mud mullet (Labeo umbratus). Larger size fish (>31 cm long) are generally preferred, independent of species.

Catches in the Sebaboleng dam comprise four species. Mud mullet (Labeo umbratus) is the most common species, in terms of number of fish, during most part of the year. During the first three survey months (January to early March), as well as during July–August and September–October, common carp (Cyprinus carpio) dominates catches. Catfish (Clarias gariepinus) is caught in very small numbers during five warm season months, but represents almost a third of the catch during February–March. Only one smallmouth yellowfish (Barbus holubi) was reported caught. Bluegill sunfish (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) are present in Sebaboleng dam, but are not reported in the catches.

The sizes of fish most commonly caught are 11–20 cm long for common carp and mud mullet, and 1–10 cm long (juveniles) for catfish. Very few large fish (>31 cm) are caught, regardless of season or species.

Fish was sold in small quantities during seven of the survey months. Fish was sold only on 15 occasions, and the average earning for the fisherman on each such occasion was Maloti 11.62 (US $3.88). Fewer than 15 individuals sell fish.

Fish is mainly sold fresh. Only on one occasion was it sold in dried form. Three species were sold: common carp, mud mullet and catfish.

Costs incurred by the fishery were rarely reported. The highest costs were for replacement of gear apart from hooks (47% of the total), i.e. usually purchase of fishing lines. Earnings from sale of fish exceeded the costs in this fishery. The sums involved, however, were small.