A decade of monitoring and management of freshwater algae, in particular Cyanobacteria, in England and Wales

Although the toxicity of cyanobacteria has been known for many years, cyanobacteria-related problems in the UK were generally limited in frequency. However, this all changed and became of national concern following the exceptional environmental conditions in the autumn of 1989, when widespread cyanobacterial blooms and scums developed in fresh waters. This paper summarises the Environment Agency's monitoring programme for freshwater algae since 1991 and describes the actions the Environment Agency has taken as a result of the monitoring data.

The regulators and the regulated: fisheries management, options and dynamics in Kenya's Lake Victoria fishery

The study divides the history of the fishery into five 'regulatory periods': the pre-colonial fishery (pre-1901), the colonial fishery (1901-1963), the post indipendence fishery (1963-1980), the Nile perch 'boom' years (1980-1989), and finally the fishery in the 1990's. Within each of these periods, the nature of and the relationship between, formal and informal regulations differs and changes with time. In the pre-colonial period, the outcome of formal and informal regulations largely sustained the fishery in a productive and species diverse state. However, at no time since then have formal regulations worked, with the result that the nature of production from the fishery changes over time and is dependent on a number of factors, amongst which the most important are effort level increases, technological introductions, species introductions, changes in regional and national job markets, the change from community-based controls to state-based controls within the fishery, and finally, considerable changes to the fish markets.

Management of Biesboch reservoirs for quality control with special reference to eutrophication

The three Biesbosch Reservoirs are pumped storage reservoirs, fed with rather polluted and highly eutrophic water from the River Meuse. Air injection at the bottom of the reservoirs prevents thermal stratification, which would otherwise result in serious water quality deterioration. Reservoir mixing also serves as an economic algal control measure; mixing over sufficient depth causes light to play the role of limiting factor and this, combined with zooplankton grazing, keeps the biomass of phytoplankton at acceptable levels. Special problems are caused by benthic, geosmin-producing Oscillatoria species growing on the inner embankment. Rooting up the bottom with a harrow is used as the method of control, based on underwater observations by biological staff trained as SCUBA-divers. With regard to pollutant behaviour the three reservoirs act as a series of fully mixed reactors. This enables the application of kinetic models to describe their behaviour and allows the use of a selective intake policy, e.g. for suspended solids with associated contaminants, ammonia and polynuclear aromatic hydrocarbons. A combination of selective intake and self- purification processes - enhanced by the compartmentalisation of the storage volume in three reservoirs - leads to a striking improvement for many water-quality parameters.

Economic exploitation in the Philippine small pelagic fishery and implications for management

Causes and impact of the Philippine small pelagic fishery sector problems are presented together with the proposed solutions from fisheries and external sectors. The results of the biological and economic analysis of the small pelagic fishery in the Philippines lead to two conclusions: First, small pelagic fish stocks are subjected to levels of fishing effort far beyond that necessary to generate Maximum Sustainable Yield (MSY) let alone Maximum Economic Yield (MEY). Second, and as a result, both sectors are sustaining economic losses (negative economic rents) implying inefficiencies in the use of labor and capital in the small pelagic fishery. Solutions to the problems of overexploitation will rest not only within the fishery sector, but, more importantly, in sectors outside its traditional realm. The underlying causes of fisheries resource over exploitation are also discussed.

A process for community-based fisheries co-management

There are many similarities, and some differences, between community-based coastal resource management (CBCRM) and co-management. When CBCRM is considered an integral part of co-management, there is a new category of co-management which can be called community-based co-management. Community-based co-management is people-centered, community-oriented, resources-based and partnership-based. The implementation of community-based co-management has four components: resources management, community and economic development, capability building, and institutional support.

Conservation and management of marine fishery resources of Kerala State, India

The highly productive fisheries of Kerala, India, are suffering from overexploitation. Use of unsuitable fishing gears that result in a high level of wasteful bycatch and destruction of egg bearing and juvenile fish should be controlled. This paper makes some suggestions for monitoring and conservation of the fisheries in Kerala.

The U.S. Gulf of Mexico Party Boat Industry: Activity Centers, Species Targeted, and Fisheries Management Opinions

In addition to providing an overview of the party boat fishery in the U.S. Gulf of Mexico, a management-oriented methodology is presented that can be used elsewhere to assess regulatory impacts. Party boat operators were interviewed to determine species targeted, percent time committed to targeting each species, and opinions on current catch restrictions. Over two-thirds of the fieet was located on the west coast of Florida. Overall, most boats targeted <5 species. Four species accounted for 90 percent of the estimated effort by party boats in the U.S. Gulf of Mexico: Snapper; Lutjanus sp.; grouper, Epinephelus sp. and Mycteroperca sp.; amberjack, Seriola dumerili; and king mackerel, Scomberomorus cavalla. Party boat effort in Texas was devoted primarily to snapper, whereas in Florida most effort was devoted to snapper and grouper collectively. Party boat operators were diverse in their opinions of management regulations in force when interviewed. Results revealed why major opposition would he expected from Texas party boat operators for red snapper bag limits and other restrictions proposed by the Gulf of Mexico Fishery Management Council.

Biological Analysis of Two Management Options for the Atlantic Menhaden Fishery

Biological implications of two managment options (the closed corridor and the recommended shortened season (Option 7) options) for the Atlantic menhaden, Brevoortia tyrannus, fishery are reported based on purse-seine landings and port sampling data from 1970 to 1984 and captain's daily fishing reports from 1978 to 1982. Large catches of age-O menhaden raise concern for growth overfishing. Area-specific yield-per-recruit analyses are used to investigate the biological consequences of these management options. The closed corridor option indicates coastwide gains in yield-per-recruit ranging from 0.3 to 7.2% depending on changes in fishing activity with most areas showing gains. The shortened fishing season indicates coastwide gains in yield per recruit ranging from O. 4 to 10.2% depending onf ishing year with most geographic areas showing gains. The shortened fishing season option offers the greatest gains when large numbers ofy oung menhaden would be caught late in the fishing year, while gains from the closed corridor option depend on how the fishing fleet responds to that management plan. The shortened season offers greater potential coastwide gains to the fishery, but also may result in greater losses to the North Carolina fall fishery. The analytical approach is applicable to the management of other coastal migratory fish stocks that fall under the Atlantic States Marine Fisheries Commission or other interstate management groups.

Restricted Access vs. Open Access Methods of Management: Toward More Effective Regulation of Fishing Effort

This paper gives an overview of the economic rationale for limited entry as a method of fishery management and discusses general advantages and disadvantages of license limitation and catch rights as the two primary methods of restricting access to marine fisheries. Traditional open-access methods of regulation (e.g., gear restrictions, size limits, trip limits, quotas, and closures) can be temporarily effective in protecting fish populations, but they generally fail to provide lasting biological or economic benefits to fishermen because they do not restrict access to the fishery. The general result of regulation with unrestricted access to a fishery is additional and more costly and complex regulations as competition increases for dwindling fishery resources. Regulation that restricts access to a fishery in conjunction with selected traditional methods of regulation would encourage efficient resource usage and minimize the need for future regulatory adjustments, provided that enforcement and monitoring costs are not too great. In theory, catch rights are superior to license limitation as a means of restricting access to a fishery.

Methodologies and mechanisms for management of cumulative coastal environmental impacts. Part I: Synthesis, with annotated bibliography; Part II: Development and application of a cumulative impacts assessment protocol

What Are ~umulat iveE ffects? Coastal managers now recognize that many of the most serious resource degradation problems have built up gradually as the combined outcome of numerous actions and choices which alone may have had relatively minor impacts. For example, alteration of essential habitat through wetland loss, degradation of water quality from nonpoint source pollution, and changes in salinity of estuarine waters from water diversion projects can be attributed to numerous small actions and choices. These incremental losses have broad spatial and temporal dimensions, resulting in the gradual alteration of structure and functioning of biophysical systems. In the environmental management field, the term "cumulative effects" is generally used to describe this phenomenon of changes in the environment that result from numerous, small-scale alterations.

The past, present and projected scenarios in the Lake AIbert and Albert Nile fisheries: implications for sustainable management

Lake Albert is one of the largest lakes in Uganda that still supports a multi-species fishery which as a result of variable adult sizes of the species, causes management challenges especially in relation to gear mesh size enforcement. Prior to the 1980s, commercial species were 17 largesized fishes especially Citharinus citharinus, Distichodus niloticus and Lates spp. that were confmed to inshore habitats of the lake and were thus rapidly over fished. Frame and catch assessment surveys conducted in this study revealed a >80% dominance of small size fish species (Neobola bredoi and Brycinus nurse) and a 40 -60% decrease in the contribution of the large commercial species. Sustainability of small size fish species is uncertain due to seasonal fluctuations and low beach value. At about 150,000 tons of fish recorded from Lake Albert and Albert Nile, the beach value was estimated at 55.3 million USD. Despite the noted decline in catches of the large sized fishes their contribution was more than 50% of total beach value. Therefore, management measures should couple value addition for the small sized species and maintain effort regulation targeting recovery of the large previously important commercial species

Economic viabilty of fishing enterprises on Lake Victoria, Uganda

Fishing in Uganda are largely developed into comericially oriented activity as a result of the fish export trade that started in the late 1980's. Despite this rapid commercialization,poverty level among fishing communities have remained relatively high thus raising concerns about the profitability of fishing. An analysis of the costs, earnings and profitability of the various fishing enterprises in Uganda was undertaken to address this concern.

Health and disease status of Thai pangas, Pangasius hypophthalmus cultured in rural ponds of Mymensingh, Bangladesh

Thai pangas, Pangasius hypophthalmus is one of the important aquaculture species in Bangladesh. Over the last few years spectacular development has been taking place in Thai pangas farming in Mymensingh district. Due to availability of easy breeding and culture techniques as well as quick return, more and more people are converting their rice fields into pangas farms overnight. The present study was carried out to examine health and disease status of Thai pangas mainly through clinical, histopathological and bacteriological techniques. In addition, for collecting primary data on disease and health status of Thai pangas and the resultant socioeconomic impacts on rural households, questionnaire interview and participatory rural appraisal tools were used with selected farming households in three upazilas of Mymensingh district. The most prevalent diseases as reported by the farmers were red spot, followed by anal protrusion, tail and fin rot, pop eye, dropsy and gill rot. Other conditions like cotton wool type lesion, ulceration and white spot were reported but with lower incidence. Four isolates of Aeromonas hydrophila were recovered from kidney and lesion of diseased fish. Hemorrhage over the body especially near mouth and caudal region was noticed in the fishes associated with aeromonad infection. Internally, kidney, liver and spleen became swollen and enlarged. The isolates varied with their pathogenicity. All the four isolates were sensitive to Nitrofurantoin, Cotrimoxazole and Tetracycline but were resistant to Amoxycilline. An attempt was made to treat diseased fish with extracts from neem leaf, garlic and turmeric. Recovery of infection was monitored through mortality and histopathology. General histopathological changes of different organs were also studied. Extract from neem (Azadirachta indica) leaf gave better result. Telangiectasis, lamellar hypertrophy and hyperplasia hemorrhage, lamellar fusion, necrosis of lamellar epithelial cells, presence of parasites and their cysts were the major pathology of gills. Hemorrhagic lesion, pyknotic nuclei and melanomacrophage centers (MMC) were found in the liver of fish. Major pathologies in kidney of fish included presence of MMC, necrotic and ruptured kidney tubules, severe haemopoietic necrosis, and hemorrhage. The economic loss due to disease in Thai pangas farming was estimated from the difference between expected production and actual production. On an average, Thai pangas farmers of Mymensingh incur a loss of Tk. 23,104/ha/cycle due to fish disease (3.6% of expected total production). The loss, however, varied with location and size of farms, type of farmers and management practices. The study also highlighted fish health management related problems and recommended further work for the development of user-friendly farmer-oriented fish health management packages.

Nursery management system of stinging catfish, Heteropneustes fossilis and walking catfish, Clarias batrachus in Bangladesh

A total of four experiments were conducted to develop nursery management system for the two important native catfishes viz. stinging catfish, Heteropneustes fossilis and walking catfish, Clarias batrachus during 2003 and 2004. Two experiments were conducted in on-station condition to determine stocking density efficacy in hapa and in earthen mini ponds for H. fossilis. This was followed by on-farm trial on stocking density in earthen mini ponds. In hapa, the highest survival rate was 60% for H. fosssilis at stocking density of 100/square meter; followed by 54.5 and 50% at stocking densities of 150 and 200/square meter, respectively. Similarly, gain in weight and length was also better in lower stocking densities. Similar survival rate (45 to 55%) was observed in three densities in earthen mini ponds. However, gain in weight and length showed no significant (p<0.05) differences. H. fossilis, C. batrachus showed almost similar survival rates (57.5-59.0%) in all the three stocking densities (100, 150 and 200/square meter) in earthen mini ponds in on-station condition. In terms of gain in weight and length showed no significant (p<0.05) differences in pond conditions. Almost similar result was obtained in terms of growth and survival in on-farm condition.

Evolution and management of the mukene (Rastrineobola argentea) fishery

Rastrineobola argentea locally known as mukene in Uganda, omena in Kenya and dagaa in Tanzania occurs in Lake Nabugabo, Lake Victoria, the Upper Victoria Nileand Lake Kyoga (Greenwood 1966). While its fishery is well established on Lakes Victoria and Kyoga, the species is not yet exploited on Lake Nabugabo. Generally such smaller sized fish species as R. argentea become important commercial species in lakes where they occur when catches of preferred largersized table fish start showing signs ofdecline mostly as a result of overexploitation. With the current trends of declining fish catches on Lake Nabugabo, human exploitation of mukene on this lake is therefore just a matter of time. The species is exploited both for direct human consumption and as the protein ingredient in the manufacture of animal feeds.