Studies on the seasonal cycle of sea surface temperatures, salinities, oxygen and phytoplankton in Koddiyar Bay, Trincomalee in relation to the shore seine fishery

In Sri Lanka waters, Durairatnam (1963, 1969) had reported on the seasonal variation of plankton at Puttalam lagoon, Dutch Bay, Portugal Bay and in the inshore and off shore waters off Colombo. Similar investigations were carried out at Koddiyar Bay especially in the estuarine waters where the three tributaries of the river Mahaveli empty their waters into the bay. The estuary is perennial. The fishes constituting the estuarine fisheries are mostly shallow water marine species which can tolerate considerable variations of salinities. Prawns and crabs also constitute a very valuable fishery in estuarine waters.

Influence of light on diurnal behaviour of Carangids in the Wadge Bank trawl fishery

Adequate data on the Wadge Bank fishery relating to several groups of fish, including Carangids, taken in bottom trawls are available for study. Analysis of this data indicated that the variation in Carangid catches was related to the time of day. In this paper, the available Wadge Bank fishery data is analysed and discussed to show the diurnal changes in Carangid catches and the probable influence of light in affecting these changes.

The western Indian Ocean tuna fishery from 1980 to 1985: a summary of data collected by coastal states

Longliner and purse-seiner catch/effort statistics for tuna fisheries in the western Indian Ocean collected by Mozambique, Seychelles and Somalia are summarized. Although the data are not considered sufficient to indicate trends for the western Indian Ocean as a whole, an examination of data from the Seychelles EEZ shows that catch rates for yellowfin tuna declined consistently from 1982 to 1985, to about half their former levels. The data were processed by the FAO/Indo Pacific Tuna Development and Management Programme, Colombo, Sri Lanka.

The history and fishery potential of Kisoro Minor Lakes part two: Preliminary survey of Lakes Mutanda and Mulehe fisheries 

The fisheries of Lakes Mutanda and Mulehe during 1998/9 were mainly at subsistence scale and only few fishers operated at irregular intervals. The commercial catch records between 1963 to 1999 showed that Lake Mulehe was landing more fish than Lake Mutanda despite the fact that Lake Mutanda (26.4 km2) was bigger than Lake Mulehe (4.11 cm2). The constant decline of catches was due to irregular restocking and applying low stocking densities of fry. However, restocking should consider using species that withstand low temperature (15-240C) in the district. These include Oreochromis niloticus (Nile tilapia), Macropterus salmoides (Black bass), and Cyprinus carpio (Common carp). Most of these species have either disappeared or declined to very low levels. Due to lack of commercial fish species for harvest, the fishers by 1998/9 resorted to harvesting the haplochromines, Clarias carsoni and edible frogs (Xenopus kigesiensis) as alternative resources. Experimental studies have shown the need and techniques to enhance fish production on these two lakes.

Characterization of the fisheries of the major and minor lakes of Uganda and the socio-economic factors influencing fishery exploitation

There is growing recognition that the performance of the fisheries sector depends on the communities responsible for activities within it. These communities include fishers, processors, fish mongers, traders, local leaders, fishery administrators etc. On the basis of this, characterisation and diagnostic studies were conducted in 1995 focussing on mainly the fishers and opinion leaders on the major and some minor water bodies in Uganda. The study revealed that the desire to earn income is the driving force behind the malfishing practices experienced on Uganda fisheries. The destructive fishing gears and fishing methods as responses advanced by the fishers and opinion leaders were seines and cast nets on lakes Victoria, Kyoga and Albert and to a less extent traps

National Agricultural Research Organisation. Fisheries Resources Research Institute Annual Report 2000/2001

It is now clear that fisheries resources are among the key assets contributing to the national development objective of poverty eradication through providing food, employment, income and export earnings. It was recently reported in the papers that monthly fish exports had increased by 23% and fetched about US$ 10 Million during the month of November 2001 alone. This value may be underestimated as it is based solely on recorded exports from fish processing factories numbering 12. Although fisheries resources are renewable they can be depleted through unsustainable exploitation. It is therefore important to ensure that there is guided development and management of this asset so that it can continue contributing to the livelihood of the people who depend on it. Therefore, FIRRI contributes to the fisheries sub-sector developmental objective of ensuring increased and sustainable fishery production and utilization by providing information to guide sustainable management of capture fisheries resources and development of aquaculture.

National Agricultural Research Organisation. Fisheries Resources Research Institute Annual Report 2003/2004

About 18% of Uganda’s surface area is covered with water from which 300,000 metric tonnes of fish are produced. Fish are currently the second most important export commodity generating approximately US$100 million. Fish provides 50% of protein diet for the 20 million people translating into per capita consumption of 12 kg. Close to the production system, this figure rises to 50 – 100 kg. It is estimated that fishery-related activities employ at least one million people countrywide (i.e. 5% of the population). Fish is an important source of high quality food, employment, and revenue and it is currently the second most important export commodity next to coffee generating approximately US $ 80 million annually. Fish exports to regional markets are worth at least US $ 20 million annually. Fish flesh is rich in proteins, which are superior to those of beef and poultry. Fish flesh contains an anticholesterol which assists in reducing heart diseases. Some fishes are of medicinal value e.g. haplochromines (Nkejje) are used to treat measles. Most of the fish in Uganda is got from lakes Victoria, Kyoga, Albert and Albert Nile, Edward and George production systems as well as from the 160 minor lakes and rivers and the associated wetland systems. Capture fisheries based in these systems contribute up to 99% of the fish production in Uganda but aquaculture is also picking up. The fishing industry employs up to one million Ugandans.

National Agricultural Research Organisation. Fisheries Resources Research Institute Annual Report 2004/2005

About 18% of Uganda’s surface area is covered with water from which about 300,000 metric tonnes of fish are produced. Fish are currently the second most important export commodity generating approximately US$100 million annually. Fish provides 50% of protein diet for the 20 million people translating into per capita consumption of 12 kg. Close to the production system, this figure rises to 50 – 100 kg. It is estimated that fishery-related activities employ at least one million people countrywide (i.e. 5% of the population). Fish exports to regional markets are worth at least US $ 20 million annually. Fish flesh contains an anticholesterol which assists in reducing heart diseases. Some fishes are of medicinal value e.g. haplochromines (Nkejje) are used to treat measles. Most of the fish in Uganda is got from lakes Victoria, Kyoga, Albert and Albert Nile, Edward and George production systems as well as from the 160 minor lakes and rivers and the associated wetland systems. Capture fisheries based in these systems contribute up to 99% of the fish production in Uganda but aquaculture is also picking up. The fishing industry employs up to one million Ugandans

East African Freshwater Fishery Research Organization Annual Report 1961

The Annual report presents Scientific work carried out during the report year 1961 under the following: Scientific Work of the Organization Fisheries of Lake Victoria Commercial records Population analysis Rational exploitation Other species of Tilapia Small mesh gill net fisheries Bagrus docmac Investigation Lates Investigation Breeding studies on T. zillii & T. nigra The culture of Tilapia in ponds Migration of River Fish Hydrology and Algology Gear Research Buoy releases Vertical gill nets and lastly publications.

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.

Reproduction, age and growth of the kelee shad, Hilsa kelee (Cuvier, 1829) (pisces: fam. Clupeidae) with informations on its fishery in Maputo Bay, Mozambique

Age, growth and reproduction of H. kelee were studied, and a brief description of its fishery in Maputo Bay (Mozambique) is given. Most material was collected from gill net fisheries during 1977-1980, but some was taken from shrimp trawlers operating in the same area during 1980-1981. Main spawning takes place during October-January with a peak in December. There is also some evidence that spawning takes place during June-July. The size at first maturity was approximately equals 14-15 cm. Ageing was carried out using primary growth rings in the otoliths and length-frequency analysis of fish caught by shrimp trawlers. Von Bertalanffy's growth equation parameters were determined. Males and females grew in similar fashion. There are seasonal trends in the catch composition of the gill net fishery, showing high values during April to September and low during October to December.

Limnology and fishery biology of the streams at Horton Plains, Sri Lanka (Ceylon)

The present study deals with the chemical, algal and faunal characteristics of the stream system at Horton Plains, the highest plains in Ceylon (altitude 2'225 m). The cultivation of seed potatoes and subsequent use of fertilizers have caused extensive silting and severe eutrophication of the stream systems. Since there are no indigenous fish, the trout Salmo gairdnerii has been introduced and it is the only fish found in these streams. The commonest fauna in the streams are crabs (Paratelphusa sp.), shrimps (Caridimr sp.), Simulium sp. and Chironomus sp. Their increase in number is probably correlated with increase in organic and detritus matter. The most important food items of the trout are the crabs living abundantly in the stream, insect larvae and terrestrial insects were also commonly found in the guts. Records of stocking and taking of trout in the Horton plains streams have shown that now less trout are taken relatively to the numbers stocked. This decrease may be possibly due to the eutrophication of the stream and also due to the possible use of pollutants in connection with the cultivation of seed potatoes.

Social and economic implications of the fishery distribution patterns on Lake Victoria, Uganda

The fisheries of Lake Victoria have undergonea dramatic transformation during the last two decades. From being a locally based fishery with little intervention and capital investment from outside,the present fishery is dominated by national and international capital penetrating the industry. It is explosion in the growth of nile perch and the strong demand devloped for this fishin the global markets, which have transformed the fisheries of the Lake victoria. This report presents the results of a survey carried out between October 2001 and February 2002 about the fishery distribution patterns and their impacts on fisher communities of Lake Victoria. The fisheries distribution pattern of the lake is described as well as the flows and benefits from the fisheries resource and the resource constraints and sustainability options. A major part of the paper discusses some of the socio-economic impacts of the rapid changes that are responsible for the present fisheries. It particularly focuses on the effect of the Nile perch boom, its globalization and the development of the fish industry in Uganda, on food security and employment for the local population.

A preliminary study on the cuttlefish catches from the Wadge Bank trawler fishery

Although much work has been done on the evaluation of the Wadge Bank fishery data, no detailed study has been made in the past on the analysis of cuttlefish catches. In this paper an attempt has been made to analyse this data in order to gather a preliminary knowledge of seasonal and annual variation in the availability, distribution by depth and catches in relation to the time of the day.