A Preliminary survey of 21 Ceylon lakes. 2. Limnology and fish production potential

Some morphometric, physical and chemical conditions of 21 lakes in Ceylon are described. The values for the organic matter in the plankton and for the dry weight of bottom fauna in the lakes have been calculated. These values have been utilised to evaluate the potential fish production figures for the lakes. Fishing trials were made in each lake. Suggestions regarding mesh sizes and time of fishing are put forward.

A Preliminary survey of 21 Ceylon lakes. 3. Parasites and predators, food of fish, and marginal fauna

Three nematodes, two acanthocephalans and three cestodes were collected by dissecting 15 species of fish. Of these parasites only Hedruris sp. a larval nematode is responsible directly for the death of fish, since it is found in predatory species a reduction of these might prove of considerable consequence to fish, production. Bothriocephalus gowleonensis, a cestode probably introduced from China with Chinese carp, was recorded in an indigenous carp Puntius sarana. This parasite causes heavy mortality in grass carp in China and is a potential danger to local species. A single crustacean parasite was recorded. It is likely that they are widespread. No protozoa were recorded but there can be little doubt that they occur in local freshwater species and may be of considerable importance in fisheries. Several predators (insects, fish and other vertebrates) were recorded and are doubtless of considerable importance. However, the role of parasites and of predators (especially fishes) in relation to the productivity of fisheries can hardly be assessed at present and needs further study. A study of the fauna found at the shallow edges of 21 irrigation reservoirs showed an abundance of fauna in the low-country reservoirs whilst the up-country reservoirs had a poor fauna. The fauna showed insects, crustacea and mollusca in this order of abundance. The presence of insect and molluscs feeding fish in our fauna shows that these rich sources of food are being utilised.

The processing of fish and other marine resources

The preservation of freshness in fish (commonly referred to as fish handling) and the conversion of fresh fish into other products can both be considered as methods of processing. In commercial practice, however, the term "processing" is confined to the conversion of fresh fish into other products.

Spinitectus corti, a fish nematode new to Ceylon

During a study by H.H. Costa of the food habits and the ecology of parasites of the fish Ophiocephalus gachua kelaarti Gunther in the Peradeniya district a few specimens of Spinitectus (both males and females) were found. These specimens were later identified to be Spinitectus corti Moorthy.

Evaluation of stern trawler operation in the Wadge Bank for economic exploitation of its demersal fish resources

The records of the exploitation of demersal fish resources by trawlers during the past two decades indicated a decline in productivity and uneconomical fishing operations. The possible reasons for the decline can be deduced by analysis of the fishing records of trawlers that have fished in the banks. Such an analysis can also provide a basis for planned management in the exploitation of demersal stocks of fish. This paper attempts to provide such a basis for the Wadge Bank.

Investigations on the bottom conditions and the possibilities for marine prawn and fish trawling on the north and east coast of Ceylon

The execution of this survey was decided upon by Swedevelop in agreement with the Sri Lanka Fisheries Corporation and was a part of the investigations and studies for a fishery project at Trincomalee which was carried out by Scandia Consult. The main purpose was to investigate the following aspects: bottom conditions, especially prawn trawling conditions; size of the potential prawn trawling catches; size and quality of the potential fish trawling catches; suitable sizes and types of boats and trawling gear; duration of trawl fishing season.

Biology, stock size and catch of small pelagic fish along the coast of Mozambique

A compilation of all the available information on the main small pelagic fish resources of Mozambican waters is presented. Resource data on distribution areas, reproduction, age, growth and stock size are described. Actual catch and catch per unit of effort of the commercially exploited stocks are also given. Results of the preliminary assessment of the stocks of scad and mackerel and the problems involving the assessment of Kelee shad stock at Maputo Bay are discussed.

A short note on the available information about demersal fish on the shallow part of Sofala Bank

The present information on the biomass and catch of demersal species which constitute a large part of the by-catch of the shrimp trawlers on the Sofala Bank (Mozambique), and thus seem to be more vulnerable than the pelagic stocks to an increase in effort is described. In addition, preliminary data on growth and mortality of two demersal species, Johnius belengerii and Otolithes ruber , which are frequently found in the by-catch, is presented.

Socio-economic implications of the fish export trade in Uganda

Implications of the fish export trade on the people and the fisheries resource of Lake Victoria, Uganda were examined. Eight fish processing factories and ninety fishers were analyzed in terms of socio-economic characteristics of fishers and the economic characteristics of fish factories. Results indicated that industrial fish processors in Uganda are presently the main link between the artisanal fisher-folk and the overseas export markets. Their entry into the market has stabilized and expanded the fisher-folk market and average earnings. Fishers attributed improvement in incomes and living standards (76%) to positive changes in the fish market (78%) in the last 5 years (1994-1999). Ugandan fisher-folk communities are not seriously affected by the Nile perch exports (73%) because they normally have easy access to cheap fish at prices much less than urban prices and; depend mainly on alternative fish species of less export value. The price of Nile perch influences positively the price of Tilapia