A Preliminary survey of 21 Ceylon lakes. 1. Fisheries of two lakes, Parakrama Samudra and Minneriya Wewa

Fourteen species of indigenous fish and three species of introduced fish commonly used for food are present in Parakrama Samudra and Minneriya Wewa. Commercial fishing is done throughout the year in these two lakes by gill nets, shore-seines ("Ma-del" nets) and cast nets. From records of fish landings maintained from 1957 it is seen that the production of fish at Parakrama Samudra has increased from 41 pounds per acre per annum in 1957 to 117 pounds per acre per annum in 1962 and at Minneriya Wewa from 11 pounds per acre per annum in 1957 to 118 pounds per acre per annum in 1962. Tilapia mossambica formed the chief constituent of the catch at both these lakes and it was due to this fish that the commercial fisheries at both these places were successful. It is recommended that fishing effort be further increased in both these lakes and records be kept to note any tendency towards over-exploitation.

Wadge Bank trawl fishery studies. Pt. 1. The effect of the 1928 to 1935 commercial trawling on the demersal stock

The demersal fish stock of Wadge Bank is one of the important fish resources for both Sri Lanka and India. Sivalingam and Medcof (1957) have given an account of its history, general features and relative productivity. According to records the total fishing effort on the bank had been fluctuating and very recently the number of boats operating on the bank has suddenly increased, and there is a possibility that still more will begin operating on the bank in the near future (Mendis, 1965). The increased fishing effort with the possibility of still further increase calls for proper management practices by those concerned, in order to obtain the maximum sustained yield from the demersal stock. For this purpose a detailed study of the past performance of the fishery is essential. With this in view all records of commercial operations up to 1960 are being analysed by the present author and are to be published in a series. This is the first paper in the series and gives a detailed analysis of the first commercial trawling operations from 1928 to 1935. Since there had been a major break of about 10 years between this and the present fishery this data is being analysed separately.

Wadge Bank trawl fishery studies. Pt. 4. An analysis of the length frequency measurements of the sea bream (Lethrinus nebulosus) made in 1949 and 1953 to 1958

Length frequency distributions of the sea bream collected during the period 1953 to 1958 have been analysed. The increase in average sizes of the sea bream with depth suggests a movement to deeper waters with increase in size. By numbers, the sea bream is more abundant between 21 and 30 fathoms than in deeper areas. The recruitment was continuous and regular. There is no sign of entry or progression of a dominant brood throughout the period under study. Length frequency distribution shows three distinct modes. The first mode occurs regularly but does not progress beyond 40cm, recruitment being balanced by natural and fishing mortality. The other two which are not regular are probably the result of fishing outside regular areas. Short sections of “growth” lines which fit into one another when extrapolated, are evident. The larger lines obtained by extrapolation are parallel to one another. These tentative "growth lines" indicate that this species which enters the fishing grounds, when 15 cm or larger in length are exploited by the trawl fishery for a period of three to four years. This species appears to be six months old when it enters the fishing grounds and increases in length by about 37.5 cm in the next 30 months. Later growth slows down. The average size of the specimens sampled continued to get smaller from 1953 till 1957. It is shown that this reduction in size is due to increased fishing effort.

Seasonal variation in the distribution and availability of Carangids ("Paraw" and "Parati") in the Wadge Bank

The Wadge Bank has been exploited regularly by Ceylon based trawlers since 1955 (Sivalingam & Medcof 1957). The bank is about 4,000 sq. miles in extent (Malpas 1926) and is located south of Cape Comorin within the Continental Shelf of India (Fig. 1). Carangids are taken in large numbers during the months of the south west monsoon (Sivalingam 1966). The quantity, in which the Carangids are captured as shown by the fishing records, is large enough to influence the total catch from the bank during these months (Fig. 2). Carangids are held in high esteem as excellent quality food fishes and accordingly constitute a commercially important group. This paper records the results of a detailed examination of the past fishing records in respect of this group, based on the analysis of the catch and fishing effort for the years 1957 to 1962. The distribution pattern of this group of fish in the Wadge Bank is discussed.

Some considerations on methodology for catch assessment in Lake Niassa (Mozambique)

Lake Niassa fisheries are artisanal and are carried out by numerous fishing boats using various types of gear and operating from numerous fish landing places scattered along the shoreline. A frame survey was conducted in 1983 to get information on the size and structure of the fisheries in Lake Niassa. The methodology to be applied for a catch assessment survey is explained. The primary objective of the survey is to obtain reliable current estimates, for the Mozambican side of Lake Niassa, of the total quantity of fish harvested by the fishermen at the lake (in terms of live weight in tons). Secondary objectives include the species composition of the catch and the fishing effort involved in obtaining the catch.

História da pescaria de camarāo de águas pouco produndas no Banco de Sofala

This work compiled data and information previously reported on the shrimp fishery and stock, since the beginning of commercial fishery in 1965. It includes a fishery description, the evolution of the fishing effort, landing and catch rates. The main historical management measures implemented in the fishery are also described, which includes the licensing regime, minimum mesh size requirements, closed seasons and total allowable catch. The methodologies used for stock assessment are also presented.

Captura de camarāo de águas pouco profundas e condições ambientais no Banco de Sofala

The present study deals with the performance of shrimp in shallow waters in Sofala Bank presents both seasonal fluctuations as well as fluctuations year to year. These variations may be due to several reasons: abundance of shrimp, fishing effort, fishing techniques and environmental conditions such as the turbidity of the water, tides, temperature and salinity.

Estado actual da pescaria de camarāo no Banco de Sofala

A summary of the shrimp fishery history as well as the most important recommendations for the period 1977-1990 is presented. During the last years the catch rates have decreased. Although many possible causes can be appointed, such as, weather conditions and increase of effort, there is no clear explanation for it. A relationship between catch rates in the main period of recruitment (January to March) and the level of recruitment of the same year was established. Based on this relationship, the total annual catch is predicted for the level of fishing mortality chosen. Fishing mortality is estimated as 2.28 yearˉ¹ and a gradual reduction of fishing effort is recommended until 2.17 yearˉ¹ calculated as F(sub)0.1.

Análise dos efeitos da introduçāo de medidas de gestāo na pescaria de camarāo do Banco de Sofala

Biological effects of management measures introduced in the shrimp fishery from 1985 to 1990 are analysed as well as the results from simulation of different closed seasons. Observed changes in recruitment, total catch, biomass and average individual weight during 1985 to 1990 for Penaeus indicus and Hetapenaeus Monoceros are also analysed. Further studies on a stock-recruitment relationship are important due to decline of recruitment levels in this period. A three-month closed season starting in January is recommended, without increases in the monthly fishing effort. The TAC shall be fixed according to the recruitment level each year.

Avaliaçāo preliminar do estado da exploraçāo de Kapenta (Limnothrissa miodon, Boulenger 1906), em cahora bassa com base em dados históricos de captura e esforço de 1995-2000

The fishing of kapenta (Limnothrissa miodon, Boulenger 1906) on the Cahora Bassa Dam started around 1992, when considerable stocks of this species were discovered in the lake. The species is believed to have successful established in the Dam following a natural introduction through a downstream movement from Kariba dam where it was introduced in 1967/68. Fisheries statistics on the kapenta fishery have been collected since 1993 by the Ministry of Fisheries through the Provincial Offices for Fisheries Administration of Tete (SPAP - Tete) but only data from 1995 onward are available on the database of the Ministry of Fisheries and these are the data that was used for compiling the present report on which trends of fishing effort, catch and CPUE are analyzed. Catch and effort have increased with time, from a minimum of the 4 thousand metric tons for an annual fishing effort of 36 fishing rigs in 1995 to a maximum of 12 tons for a fishing effort of 135 rigs while CPUE followed a decreasing trend during the same period. Correlation analysis between catch and effort suggests that probably environmental factors may have influence on catch variation than the increase on fishing effort. Two models were applied for calculating MSY and FMSY resulting in two pairs of roof leading to two scenario of fisheries management. 10137 tons and a FMSY of 177 fishing rigs were computed using Schaefer model while 11690 tons and a FMSY of 278 were obtained using Fox model. Considering the differences between the two results and considering the fact that the two models have no differences in terms of precision and the fact that their determination coefficient are not different it is suggested, using the precautionary principle that result from Schaefer model be a adopted for fisheries management purpose.

East African Fisheries Research Organization Annual Report 1958

A brief review of work carried out since the laboratory was established ten years ago will put present studies into perspective and show to what extent the aims of this organisation are being fulfilled. These aims can be simply defined under two heads: the maintenance of a watch on the commercial fisheries and original research designed to provide the necessary if these fisheries are to be exploited rationally and managed efficiently. While reference to past results, which cover a wide range of subjects, can best be made in the appropriate sections of this report, a short general statement on the Lake Victoria Fisheries may be useful. From the earliest records contained in Michael Graham's Report it was clear that even before 1929 considerable inroads had been made the stocks of fish in Lake Victoria. Some control measures were subsequently introduced which must have had a moderating effect, but so the Game Department reports continued to express concern regarding the state of the fisheries. During the last war some reduction in fishing effort occurred due to ,a shortage of nets, this afforded some respite to the fisheries, but after this period the fishing effort again increased steadily. At the present time the fishing effort is higher than it has ever been.

East African Freshwater Fisheries Research Organization Annual Report 1965

Throughout the year the Fisheries Departments of Tanzania and Uganda continued to forward to EAFFRO data on the commercial fisheries of Lake Victoria, particularly statistics of fishing-effort and fish-landings. The Kenya Fisheries Department was re-established at Kisumu towards the end of 1964 and has expanded its activities during 1965; whilst regular records of commercial fishing activity have not been despatched to Jinja, appropriate information has been made available on request from the Chief Fisheries Officer. None of the existing research officers at EAFFRO have been assigned to a detailed survey of the statistical data available, although several officers have taken the opportunity of analysing the data regarding the species considered under their own research programmes. As recorded in the last Annual Report, one important function of the UNDP Lake Victoria Fisheries Research Project will be to undertake the relevant statistical surveys essential to the proper management of the commercial fisheries of Lake Victoria. The level of the lake remained abnormally high but fluctuated somewhat during the year, reaching a maximum in May, but falling to a minimum in October before beginning to rise again with the rains at the end of the twelve-month period. The maximum figure for the year recorded at Jinja: 12.92 ft. above datum did not reach the peak recorded in 1964: 13.33 ft. above datum, which was the maximum reading taken since records were begun in 1899. Scientific work carried out by the organization during the year 1965 included work on the following: Commercial fisheries of Lake Victoria Nile Perch investigations Fisheries surveys in Kenya and Tanzania Studies on anadromous fishes Studies on mormyrid fishes Studies on Tilapia species Studies on Alestes Studies on Haplochromis species

East African Freshwater Fisheries Research Organization Annual Report 1972

Feeding habits of many animals have been used widely in animal classifications. This is so, because the type of diet an organism requires demands structural specialisation which will utilise the available resource. Many animals may however have many structural modifications to enable them to be described as omnivourous or generalised feeders such as H. empodisma and H. riponianus (GREENWOOD 1960) which may show varying degrees of structural and adaptational intermediacy between two trophic groups. Generally, however, the diet of many animals including fish changes as the animal grow larger. The change in structural modifications is usually correlated with changes in the diet. In fishes the change may involve change from tricuspid to biscuspid and finally to unicuspid type of teeth. The degree of modification in the structure depends on the diet, thus Haplochromis that feeds on soft tissues of snails only requires modifications in oral dentition while Haplochromis that feeds on both soft tissues and shells of snails require modification in the lower pharyngeal bone for grinding purposes. Other modifications connected with food utilisation may be located in the alimentary canal. (I) The fish species that are commercially exploited are Protopterus aethiopicus, Clarias mossambicus, Tilapia esculenta, Tilapia amphimelas and Tilapia hybrids. The other fish species present in the lake but not commercially exploited are: Gnathonemus sp. Alestes sp. Labeo sp., Barbus paludinoses, Barbus jacksoni, Barbus lineomaculatus, Barbus regersi, Leptogrlanis sp., Schilbe sp., Haplochromis spp. and Hemihaplochromis sp. (2) Protopterus sp. and Clarias sp. are mostly caught with hooks on long lines. There has been a steady increase in number of hooks on the lake. Since the stocks of Protopterus and C/arias in the lake have a limit, we should control the number of hooks used by each of the fishermen in order to avoid overharvesting. (3) All the previous studies on Lake Kitangiri fisheries suggested the use of gill nets with mesh size greater than 88.9 mm in order to avoid the capture of immature Ti/apia spp. But if the fishermen are to obtain economic gains from the fishery, the optimum mesh size for use is 88.9 -101.6 mm. (4) The gillnet is a passive gear with very beneficial selective characteristics. Unfortunately the drive-in fishery which exists on Lake Kitangiri more or less destroys the gillnet selectivity characteristics. It is therefore recommended that the beating of water with poles be discouraged and stopped. (5) There is need for provision of stable fishing canoes to replace the unstable bottle palm dug-out canoes which are currently being used and which are very risky to operate. (6) The fish processing facilities on Lake Kitangiri are still inadequate. Most of the fish is sun dried, Since sun drying is very difficult during the rainy season, most fishermen carry out intensive fishing during the dry season, Concentrating most of the fishing effort in anyone season instead of spreading evenly this effort over the whole year could damage the age structure of the exploitable stocks. (7) There are considerable fluctuations in the volume of water of the lake. The feasibility of regulating the water loss through the effluent Sibiti river should be investigated by the Water Development Department. (8) Damming the Sibiti river is an expensive undertaking and therefore, the Rural Development Bank of Tanzania should be asked to assess the economic feasibility of such a project.

National report of the frame survey 2006 in the Ugandan part of Lake Victoria

Fisheries Frame surveys have been carried out on Lake Victoria biannually since 2000 to determine· the number of fishers, fish landing sites, facilities at the landing sites. Information on the composition fishing crafts, their mode of propulsion, fishing gears and the fish species they target is also collected. This information is used to guide development and management of the lake's fisheries. The results of the four surveys carried out since 2000 show that the number of landing sites has decreased by 24% from 597 in 2000 to 481 in 2006, mainly as result of reorganisation of landing sites into Beach Management Units (BMUs). The fish landing sites continue to have inadequate facilities to service the fisheries industry e.g. in the 2006 survey only 11.2% of landing sites had fish shades; <0.6% had cold rooms; 3.5% had electricity; and only 35.5% had toilet facilities. Similarly, only 11.4% of landing sites had portable water; 2.5% had jetties, 3.7% had 'fish stores; and 36% were accessible by all weather roads. There is need to improve facilities servicing fisheries at landing sites, with major emphasis on sanitary facilities, especially toilets and portable water. The BMUs should be sensitised to prioritise the construction and utilisation of public toilet facilities at their respective landing sites. The ultimate aim should be to have public toilets at all fish landing sites. The trend of the various indicators of fishing effort has continued upwards: The total number of fishers increased by 43.5% from 37,721 in 2004 to 54,148 in 2006 and the number of fishing crafts increased (43.9%) from 16,775 in 2004 to 24,148 in 2006 over the same period. The total number of gillnets increased by 28.6% from 458,597 in 2004 to 589,777 in 2006 and the number of long line hooks increased by 136% from 968,848 to 2,285,609. The number of fishing crafts using outboard engines also increased from 3,173 in 2004 to 5,047 in 2006 suggesting that more fishers were going far in search of fish. There is still a large number of illegal gears especially beach seines, which increased by 58.8% from 954 in 2004 to 1420 in 2006. Efforts to remove these very destructive gears should be stepped up. There was also larger increase in number of illegal gillnets <5 inch mesh size. These increased by 63% from 56,246 in 2004 to 91,740 in 2006 compared with 23.8% increase of gillnets ~5 inch mesh size. There were also large increases in the numbers of gillnets of 5 and 5% inch mesh size, which increased by 48% and 130% from 2004 to 2006 implying a trend towards use of smaller gillnet mesh sizes. The number of traps which are used in shallow vegetated areas, flood plains and river mouths to target tilapiines and riverine species decreased drastically from 5,361 traps in 2004 to only 499 traps in 2006, a decrease of 974%, a phenomenon attributed to the receding water levels which have left the shallow vegetated areas dry. A total of 17,475 fishing crafts, 72% of all fishing crafts, in the Ugandan part of the lake are still using paddles and the. number of parachute crafts is also still very high, (Le. 5,064) comprising a high proportion (21 %) of the total number of fishing. There is need to promote the use of large fishing crafts with sails or a combination of sail and outboard motor. The Mukene fishery in the Ugandan waters of Lake Victoria has remained underdeveloped with only 9% of all fishing crafts operating in this fishery. Also less than 2% of fishing crafts with sails or motor operate in this fishery which implies that it is limited to near shore waters. Effort should be made to develop this fishery as it appears to have high potential, especially in deep offshore waters which are hardly fished.

A report of the fisheries catch assessment surveys in the Ugandan waters of Lake Victoria for November 2005

The fisheries of Lake Victoria have undergone many changes in the recent past which have been characterized by shifts in abundance of different fish Species and changes in fishing effort. Monitoring of the population dynamics as well as the magnitude, distribution and trends of fishing effort and fish Catches is probably more necessary now than ever before for sound management of the fisheries of the lake. This will enable the formulation of appropriate fisheries policies and legislation to ensure that the fisheries are sustainable. One of the avenues to collect information to support the above process is through conducting regular Catch Assessment Surveys (CASs). The EU funded Implementation of a Fisheries Management Plan (IFMP) project for Lake Victoria through the Lake Victoria Fisheries Organization (LVFO) is supporting the implementation of regionally harmonized CASs in Lake Victoria. The CASs under IFMP are following a statistically design laid down in Standard Operating Procedures (SOPs) agreed around the whole lake. In the Ugandan part of the lake, the CASs are carried out at 54 fish landing sites selected in the eleven districts sharing the lake. They are jointly conducted by the Fisheries Resources Research Institute (FIRRI), Jinja; the Department of Fisheries Resources (DFR), Entebbe; and the Districts of Busia, Bugiri, Mayuge, Jinja, Mukono, Wakiso, Kampala, Mpigi, Masaka, Kalangala and Rakai. The CAS enumerators are recruited from the fishing communities and work under direct supervision of sub county Fisheries Officers. It is planned to involve the recently formed Beach Management Units (BMUs) in fisheries data collection when modalities for their roles have been streamlined.