Production trends and technical efficiencies of culture-based fisheries in five tropical irrigation reservoirs: A case study from Sri Lanka

Culture-based fisheries (CBF) are increasingly accepted as strategies for enhancing inland fisheries, especially in tropical Asia. In Sri Lanka, CBF development in irrigation reservoirs has gained momentum due to concerted efforts of government fisheries authorities for inland fisheries enhancement. In the present study, production trends of five irrigation reservoirs of Sri Lanka before and after the introduction of CBF were investigated and apparently optimal CBF yields were not realised. Hence, the stochastic frontier production function (SFPF) was employed to quantify technical efficiencies (TE) of CBF. For each reservoir, annual averages of input data from 2005 to 2018 (14 years) were used in the TE analysis. Hence, total sample size for estimation of SFPF was 70. Although CBF production gradually increased in all five reservoirs from 2005 to 2018, there were substantial variations of total fish production across the reservoirs. The SFPF indicated that CBF production could be further increased through more efficient management of inputs (i.e. number of fishers, mean number of fishing days per year and stocking density).     

Impact of Oreochromis mossambicus × O. niloticus (Pisces: Cichlidae) hybridization on population reproductive potential and long-term influence on a reservoir fishery

Abstract Exotic cichlids, introduced to Asia during the second half of the twentieth century, contribute significantly to the reservoir fisheries in the region. The two major cichlid species, Oreochromis mossambicus (Peters) and O. niloticus (L.), tend to interbreed easily. In Sri Lankan reservoirs, introgressive hybridization of these two cichlids takes place. The reproductive biology of O. mossambicus, O. niloticus and their hybrids in three reservoirs in Sri Lanka was evaluated. An imbalance in sex ratio with male dominance was evident. The estimated fecundity for 20-cm fish, using fecundity-total length relationships for various populations, indicated that there was a decline in fecundity in hybrid forms. It is hypothesized that the long-term effect of crosshybridization between the two cichlids might lead to a decline in fish yields in perennial reservoirs of Sri Lanka. The importance of the findings of the present study for the management of the reservoir fisheries in Asia is highlighted.     

Status of the introduced cichlid Sarotherodon mossambicus (Peters) in the reservoir fishery of Sri Lanka: a management strategy and ecological implications

Abstract. The inland fishery in Sri Lanka (6–10°N; 79–82°E) is essentially a fishery confined to man-made lakes and is dominated by the introduced cichlid Sarotherodon mossambicus (Peters). Catch statistics of 20 such major reservoirs indicate that the yield of this species ranges from 64·0 to 918 kg per ha and accounts for between 56 and 99% of the total yield in individual reservoirs. The yield of S. mossambicus is closely related to the fishing pressure exerted. Catch/effort data from the individual reservoir fisheries when analysed collectively simulate changes in a single large fishery. In the fishery the relationship of yield to effort is described by the equation: Y = 4·OX – 53·8X ( r = 0·92; P < 0·001), where Y = yield in kg per ha per annum and X = number of craft-days per ha per annum, indicating that the reservoirs in Sri Lanka remain underfished. However, very high increases in fishing pressure in two reservoirs, for which data are available over a 5-year period, indicate that the increases have resulted in a significant decline in the catch per unit effort. The reasons for the success of the S. mossambicus fishery in individual reservoirs, and also simulation of features of a single large fishery in reservoirs, with widely different hydrological and limnological regimes, are discussed in qualitative terms. It is hypothesized that the abundance is determined by factors other than food availability. Fresh management strategies to optimize the fishery from the point of view of optimal fishing pressure permissible from the present analysis are suggested.     

Co-management without involvement: the plight of fishing communities

This paper discusses the role of fishing communities in the stewardship of their adjacent fish resources, and the benefits associated with community participation in co‐management. Contrary to the view of most fisheries management agencies, local communities are able to design institutions that can successfully restore equity and limit access to the fishery. The dismissal of local concerns may be at the root of biological and social crises in fisheries, and the privatization of common fishing rights world‐wide through individual transferable quotas (ITQs) is contributing to these problems. Community involvement that is embedded into a network of management at larger spatial scales would allow fishing communities to regain some control over their livelihoods. Meaningful co‐management arrangements must go beyond consultation by redirecting the flow of social and economic benefits from the fishery back into communities. Unless geographically defined communities are allowed to share power and responsibility with government fisheries managers, both fish stocks and fishing as a way of life are in danger of vanishing.     

Yield predictive models for Sri Lankan reservoir fisheries

Tropical reservoirs are primarily constructed for irrigation, generation of hydroelectricity and water supply schemes. Development of inland fisheries is a secondary use of most reservoirs. In Sri Lanka, most reservoirs are scattered in the rural areas of the country so that investigation of the fisheries of individual reservoirs with a view to developing management plans is prohibitive. The present study was instigated to explore the possibilities of developing suitable yield predictive models, which can be used in developing management strategies for the Sri Lankan reservoirs. The study was carried out in 11 perennial reservoirs of Sri Lanka. Basic limnological parameters (conductivity, dissolved phosphorus, total phosphorus, chlorophyll a [chl a] content and alkalinity) were determined in each of these reservoirs. Daily data on fish catch and fishing effort were collected in each reservoir. Data on catchment areas (CA), reservoir area (RA) and reservoir capacity (RC) were obtained from the irrigation and survey departments. It is evident that chl a is positively influenced by nutrients (dissolved phosphorus and total phosphorus), morphoedaphic indices derived as alkalinity to mean depth (MEIa) and conductivity to mean depth (MEIc) ratios and CA/RC ratios. MEIa and MEIc are also positively influenced by CA/RC ratios. All these morphological and edaphic parameters were found to positively influence fish yield in reservoirs. As fishing intensity (FI) is also a major determinant of fish yields, fish yield was better accounted by multiple regression models in which FI and individual morphological and edaphic parameters were used as independent variables. Of these multiple regression relationships, the best predictive power for fish yield (Y in kg ha?1 yr?1) was found by Y=18.9+6.78 FI+0.0073 CA/RC where FI is expressed as boat‐days ha?1 yr?1 and CA and RC are in km2 and km3, respectively. In this relationship, FI and CA/RC account for about 68% of the variation in fish yield.     

The challenge of sustainable use of the Danube Delta Fisheries, Romania

The Danube Delta was designated a Biosphere Reserve in 1990. Subsequently the sustainable use of the fish stocks within the reserve became a challenge for management. The fisheries exploit a variety of habitats distributed over about 580 000 ha of wetland. They yield between 5000 and 10 000 t year^–1, equivalent in value to 6.3 million US$, making this one of the most important inland fisheries in Europe. Approximately 15 000 inhabitants within the Delta and a further 160 000 from adjacent regions depend fully or partly on the fishery resource. The fisheries are diverse, consisting of lake, river, marine coastal and anadromous fisheries. Fisheries in the Delta operated under an open access system during the transition from a fully controlled state economy to a market economy. New fishing regulations have been established to minimise the risk of the fisheries collapsing as a result of the open access regime. Core regulations including close seasons and closed areas, minimum mesh sizes and fish lengths, output controls (catch quota), and input regulations (limited access to fishery) were introduced.     

The development of the Finnish inland fisheries system

The efficiency of Finnish inland fisheries administration has improved during the past 15 years because of changes in fisheries legislation. The establishment of regional management units particularly has improved the practice of co-management, which has allowed the participation of many relevant interest groups in the decision-making process. The long-term private market equilibrium supply for recreational fishing with active types of gear accounted for 50% of the Finnish lake surface area. Presently the public sector has become involved in the supply of recreational fishing licences. The improvement in the system owes much to political initiatives. As regards commercial fishing, state-ownership of fishing grounds is a channel for recruitment into the occupation. Private ownership has led to a suboptimal allocation of fisheries resources, particularly in the commercial branch of the industry. However, by giving priority to social instead of economic goals the statutory fishery associations will help to maintain social and community values, which are locally important.     

EVALUATION OF COMMUNITY PARTICIPATION FOR THE DEVELOPMENT OF CULTURE-BASED FISHERIES IN VILLAGE RESERVOIRS OF SRI LANKA

In this paper, an attempt is made to identify the socioeconomic characteristics of a community that influence the development and management of culture-based fisheries in village reservoirs of Sri Lanka. Socioeconomic data were collected from 46 agricultural farming communities associated with 47 village reservoirs in Sri Lanka. Principal component analysis indicated that scores of the first principal component were positively influenced by socioeconomic characteristics that are favorable for making collective decisions. These included leadership of the officers, age of the group, percentage of active members of the group, percentage of kinship of the group, percentage of common interest of the group, and percentage of participation of the group. The size of the group had a negative effect on the first principal component. The principal component scores of communities were positively related to willingness to pay (P < 0.001). The communities with socioeconomic characteristics favoring collective decision making were in favor of culture-based fisheries. Homogeneity of group characteristics facilitated successful development of culture-based fisheries.     

Are the exploitation pressures on the Nile perch fisheries resources of Lake Victoria a cause for concern?

Abstract Lake Victoria is one of the African Great Lakes, and an important source of affordable protein food in the form of fish. It provides employment, income, and export earnings to the riparian communities. Despite this importance there are major concerns about the status and exploitation of the fisheries. This study assesses if current extraction rates/yield of Nile perch, Lates niloticus (L.), from Lake Victoria are sustainable for the foreseeable future. The paper reviews trends in catch and effort in the Nile perch fishery and models the expected scenarios using ECOPATH. The fishery exhibits, classic indicators of intensive fishing, erring towards overexploitation, including: (i) decline in total estimated catch of Nile perch in recent years from the peaks in the 1990s. This is coupled with a shift in contribution of catches from higher trophic level species (Nile perch) to lower trophic level (dagaa) species. (ii) Three major trends in the fishing effort are evident: (a) almost doubling of the number of fishers and fishing boats between 1990 and 2000, and the even greater expansion between 2000 and 2002; (b) a large scale increase in the number of gears operational in the lake; and (c) the propensity for use of ‘illegal’ gears. (iii) Catch‐per‐unit‐effort has declined from about 80 to 45 kg per boat day. (iv) Predictive modelling (ECOSIM) of the future of the Nile perch fisheries under a scenario of increased fishing effort suggests that the fisheries are unsustainable and will decline in the long term. It appears that the Nile perch stocks in the three riparian countries are under intense fishing pressure, and unless concerted action is taken, the potential for degradation of the resources is prevalent. In view of the importance of these fisheries, it is recommended that a precautionary approach to further intens‐ification of the fisheries is adopted until such time empirical evidence shows that the fisheries are capable of further expansion and intensification. The main options for management are devolvement of responsibilities for the fisheries to the communities, enforcement of existing regulations, improved monitoring and data collection processes, reducing post‐harvest losses and increasing the value of the products to the export market.     

Comparative analysis of artisanal and recreational fisheries for Dentex dentex in a Marine Protected Area

The common dentex, Dentex dentex (L.), is an iconic marine coastal fish in the Mediterranean Sea. This study was performed in the Bonifacio Strait Natural Reserve (BSNR), (NW Mediterranean Sea). The aims were to: (1) evaluate temporal variation of the artisanal fishing of common dentex (2000–2012); (2) compare and quantify catch rates, fishing techniques and catch composition for artisanal and recreational fisheries, and determine the influence of management measures by both activities; and (3) estimate the production of both artisanal and recreational fisheries. Fishery data were collected from different artisanal fishing surveys (onboard fishing vessels and landings) and recreational fishing surveys (roving). The gears with the highest rates of exploitation were longline (3554 g per 100 hooks) and Trolling (351 g boat^?1 h^?1 ±SE), respectively, for artisanal and recreational fishing. This study showed that catches by both activities were quantitatively higher in partially protected areas than outside them. Production estimations suggest that the recreational fishery contributes significantly to fishing mortality and that it can magnify the negative effects of artisanal fisheries. Specific measures are needed for the sustainable fishery management of common dentex.     

Investigation of the Negombo estuary (Sri Lanka) brush park fishery, with an emphasis on community-based management

The Negombo estuary brush park fishery in Sri Lanka was investigated from June 1998 to March 1999. The mean fish yield (all species) in the fishery was 12.46 t ha⁻¹ yr⁻¹. Fin fish species formed about 91% of the yield and the rest was formed by penaeid shrimps and crabs. Fish yield and the twig density in the brush park exhibited a second order polynomial relationship indicating a minimum yield at an intermediate value of twig density in the brush parks. The relationship between fish yield and duration of implantation of brush parks showed an optimal period of 30–40 days for high fish yields. Income levels of fishermen, availability of construction material and suitable sites for implantation of brush parks are some of the factors determining size and number of brush parks per fisherman and duration of installation. Indigenous knowledge within the fishing community about the effect of salinity variations, twig density and mangrove species used on the harvests greatly contribute to effective operation of this fishing practice. Cultivation of mangroves to obtain twigs and branches is a unique feature in this estuary. Indigenous knowledge on mangroves has led to the adoption of sound silvicultural practices. Although cultivating mono-specific mangrove stands may not increase diversity of mangrove forests, it reduces denudation of naturally occurring mangrove forests because of brush park construction, and retains habitats for other organisms. Mangrove management plans in the Negombo estuary should therefore be viewed and treated in an integrated manner that takes into account both resource and social components.     

Importance of recreational fisheries in the Guadiana River Basin in Portugal

The rapid expansion of recreational fishing in Portugal over the last 20 years, along with the multiplicity of pressures affecting inland fisheries, demands the urgent recognition of the social and economic values. Sport-angling information is still inadequate to formulate management actions. To address this issue, a regional survey on freshwater recreational fishing in all the municipalities of the Guadiana River Basin was carried out in 1999. The survey, based on 1998 data, provided information on the profile of anglers, preferences as regards reservoirs and sections of rivers fished, frequency of fishing trips, motivation, expenditure, fish species caught, an estimation of total catch and its destination, interest in competitions, enforcement and personal opinions. The results recommended improved communication and feedback between users, and mechanisms for future regional development and management of recreational fisheries.     

Policy needs to improve marine capture fisheries management and to define a role for marine protected areas in Indonesia

Abstract  Management of Indonesia's marine capture fisheries faces a huge dilemma: evidence suggests that most, if not all, of Indonesia's capture fisheries are fully or overexploited, but the fishery sector is still expected to contribute to the increase of Indonesia's gross national product (GNP) through an increase in total catches. Furthermore, the current practice of using catch-effort data and Maximum Sustainable Yield (MSY) models to inform Indonesia's fisheries policies is flawed, putting sustainability and long-term profitability of Indonesia's fisheries at risk. It is argued that the following shift in capture fisheries management policy must be achieved to ensure the survival of Indonesia's fish stocks and fisheries:
1  a shift in fisheries policy from development-oriented management towards management for sustainability;
2  acceptance by fisheries managers that 'untapped resources' may not exist or cannot be exploited profitably;
3  acceptance by fisheries managers that any transfer of fishing effort between fishing grounds may contribute to collapse of local fisheries;
4  a shift in fisheries management from MSY models to eco-system based management, wherein Marine Protected Areas should play an important role.     

Inland fisheries of the Mayan Zone in Quintana Roo, Mexico: Using a combined approach to fishery assessment for data-sparse fisheries

In Southern Mexico and Central America, inland fisheries form part of the livelihood portfolio of an as-yet unknown number of rural communities. This paper reports on the first comprehensive study of such fisheries located in common property lands (ejidos) of the Mayan Zone in Quintana Roo, Mexico. Given the “data-sparse” nature of these fisheries, with a lack of data available on their current status and on participation levels, a fishery assessment approach was used which included methods from both the natural and social sciences, with a focus on survey methods applied to fishery users, water, fish and creel surveys. Moreover, local knowledge of community residents complemented scientific knowledge in a substantial part of the research. The results, from 48 fishing sites (four with sub-saline waters, the remainder freshwater) indicated (1) a resource base of multi-specific nature with a total of 18 bony fish species in the study area, (2) artisanal (small-scale) fisheries, with very basic technology (notably hand-lines) utilized primarily through barefoot fishing along the shores, or with the aid of rafts and canoes, (3) seasonal fishing, primarily during the dry season (February to May), due to greater accessibility of the sites in those periods, but also related to the end of work on major local livelihoods, (4) both indigenous (Mayan) and non-indigenous fishers, of ages ranging from teenage to senior adults, for most of whom the major occupation was slash-and-burn agriculture, and (5) a mainly male-oriented fishery, but with some women involved in five out of nine ejidos studied. While the key motivation of fishers was subsistence, the study found, for the first time in this form of fishery, that recreation was also a significant goal of many participants. In terms of methodology, the study demonstrated the importance of cross-validating the accuracy of information from informants interviewed in the type of social surveys used here. This combined assessment approach proved effective in providing new information on these previously under-studied fisheries, and may be useful in similar data-sparse situations elsewhere.     

Community‐based monitoring of small‐scale fisheries with digital devices in Brazilian Amazon

Fisheries management is potentially a short‐term measure for reducing floodplain fisheries degradation. This objective can only be achieved if adequate measures to improve fishery governance and ecosystem conservation are taken. The monitoring of fisheries management is likely to be important for understanding the effectiveness of local rules and the impacts on aquatic biodiversity. Given that monitoring is the periodic assessment of fish stock characteristics regarding reference data, adopting tools and procedures for monitoring at different scales is a challenging task. Information and Communication Technologies (ICT) have enabled local communities to gather data on key resources in a cost‐effective way. This article presents a community‐based monitoring of fisheries based of smartphones that supports the annual fishing quotas and legal harvest permits procedures. The precision of community‐based monitoring data is assessed and a model to integrate these data into a large‐scale monitoring scheme examined. Data collection performance was evaluated at communities in the Kaxinawá Nova Olinda Indigenous Territory, in the State of Acre, where fishery management was monitored. The results indicate that voluntary collectors are able to provide data with precision comparable with government agency measurements, but at lower cost.     

Subsistence fishing in two communities of the Lacandon Forest, Mexico

Abstract  Subsistence fishing was surveyed in the communities of Nueva Esperanza and Loma Bonita of the Lacandon Forest in the Usumacinta River Basin of Chiapas, Mexico from March to August 2005. Thirty fish species, four turtles and two crustaceans were harvested. The most prevalent species in terms of biomass extracted were the pantano cichlid, Herichthys pearsei (Hubbs), grass carp, Ctenopharyngodon idella (Valenciennes), northern checkmark cichlid, Vieja intermedia (Günther), bigmouth sleeper, Gobiomorus dormitor Lacepède, machaca, Brycon guatemalensis Regan, and blue catfish, Ictalurus furcatus (Lesueur). Ten fishing gears were employed in four habitat types. Fishing patterns, fishing gears employed, species harvested, biomass extracted and catch rates differed between localities. The uniqueness of local fisheries should be considered in further studies and management policies for conservation of fish populations.     

Economic evaluation of inland fisheries in England and Wales

Recreational inland fisheries are recognized to have considerable socio-economic benefits, not only for individuals participating directly but also for others in both local and wider communities. In England and Wales the Environment Agency (EA) has a duty to maintain, improve and develop inland fisheries. At present, there are no recent economic evaluations of the whole range of UK inland fisheries for the EA to refer to when confronted with resource issues. There is a particular need to explore the benefits of fisheries to the wider community, in order to secure more resources for management and protection of fisheries. Preliminary results from a multi-modular project to study the economic values associated with recreational fisheries in England and Wales are presented. Topics examined included recreational anglers' consumer surplus, general public non-use values of fisheries, social benefits of recreational fishing and impacts of fisheries on local communities.     

Developing co-management in an artisanal gill net fishery of a deep hydro-electric reservoir in Sri Lanka

Abstract Victoria, is a recently (1984) impounded, deep, hydro-electric reservoir in Sri Lanka with an established commercial fishery. Participatory appraisal of the fishing community revealed decreasing reliance on fishing income with many fishermen moving away to supplementary occupations because of declining fish catches. Illegal fishing and theft of fishing gear resulting from open access, difficulties encountered in enforcing fisheries regulations and the need for fishermen to find alternative sources of income during low water levels are the major management problems. The top–down centralized management approach previously practised was ineffective in addressing any of these issues. Therefore, the possibilities and limitations for introducing co-management as an alternative management strategy were discussed. Financial hardship coupled with perceived benefits through state sponsored welfare schemes caused a positive attitude change among fishermen, making them respond favourably to fishery management. Establishing a licensing system for controlled access, ensuring greater user-group participation through equitable distribution of state sponsored benefits among members, attempting to enforce penalties for illegal fishing linked with surprise checks to enforce management regulations, and obtaining stakeholder perceptions regarding management issues are some of the recent steps taken by the Fishermen's Co-operative Society which would positively contribute towards developing effective co-management in this reservoir.     

渔业协会、渔村社区组织及其渔业资源管理功能

改革开放以来,随着渔业经济的快速发展,我国的渔业发展面一临着渔业资源严重枯竭、渔业监管困难、渔民收入增长幅度放缓等诸多问题。为此学术界在渔业资源管理方法上提出了许多意见,同时也存在着一些分歧。文章通过理论推演,结合文献数据,探讨了渔村社区组织与我国渔业协会的关系,分析了包括渔业协会在内的渔村社区组织对渔业资源管理的作用,通过对代表性渔业资源管理理论的利弊分析,剖析了渔民协会等渔村社区组织的渔业资源管理职能。同时指出由于渔业协会在资源管理中具有重要作用,但因其自身也存在着一定局限性,因此,培育渔业协会、完善其资源管理职能,实行基于渔业协会等渔村社区组织的合作管理也就成为我国加强渔业资源管理的一种制度选择。