FAO FISHERIES TECHNICAL PAPER   384/2 Management guidelines for Asian floodplain river fisheries Part 2: Summary of DFID research by Daniel D. Hoggarth-Vicki J. Cowan Ashley S. Halls Mark Aeron-Thomas MRAG Ltd, London, UK J. Allistair McGregor Centre for Development Studies, University of Bath, UK Caroline A. Garaway Renewable Resource Assessment Group, Imperial College, London, UK A. lan Payne MRAG Ltd, London, UK Robin L. Welcomme Renewable Resource Assessment Group, Imperial College, London, UK

DEPARTMENT FOR INTERNATIONAL DEVELOPMENT OF THE UNITED KINGDOM

DFID

MRAG Ltd

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, 1996

Table of Contents

This document includes outputs from several research projects funded by the Department for International Development (DFID) of the United Kingdom for the benefit of developing countries.
The views expressed are not necessarily those of DFID.

The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

M-43
ISBN 92-5-104262-4

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Preparation of this document

These guidelines summarise a series of studies, funded by the UK Department For International Development (DFID, previously known as ODA) on the management of Asian floodplain river fisheries. Between 1992 and 1997, DFID has funded four separate projects in this area. The research was initiated by a project led by Bath University's Centre for Development Studies (CDS), entitled ‘Poverty, Equity and Sustainability in the Management of Inland Capture Fisheries in South and South-East Asia’. The theme was then taken up by three projects, led by MRAG Ltd, and funded by DFID's Fisheries Management Science Programme (FMSP): ‘River and Floodplain Fisheries in the Ganges’; ‘Fisheries Dynamics of Modified Floodplains in Southern Asia’; and ‘An Evaluation of Floodplain Stock Enhancement’.

The Technical Paper is written in two parts. Part 1 outlines a practical strategy for the management of large floodplain rivers based on the experiences gained by these projects and on other literature from related research. Part 2 includes the more technical data derived from the research projects, on which the guidelines in Part 1 are based. The Part 1 guidelines are presented in a simple and user-friendly style to provide both policy makers and field officers with the tools they need to manage river fisheries, and the technical and institutional background to make them work. The guidelines may also be used in the construction of courses for regional fisheries officers and related extension workers.

Funding for the preparation of this paper was provided by the UK Department For International Development. The Technical Paper was published through FAO to ensure the widest possible dissemination of its ideas. Over the years, the research theme has benefitted from the active participation of a wide range of local collaborators, including staff from: the Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh; the Bangladesh Centre for Advanced Studies (BCAS), Dhaka, Bangladesh; the Bangladesh Institute for Development Studies (BIDS), Dhaka, Bangladesh; the Central Research Institute for Fisheries (CRIFI), Jakarta and Palembang, Indonesia; the Environmental Laboratory of the University of Patna, India; the Coastal Resources Institute (CORIN) of the Prince of Songkla University, Hat Yai, Thailand; the Zoology Department of the University of Allahabad, India; the Zoology Department of the University of Garhwal, India. The many contributions of these collaborators to the ideas in this paper are warmly acknowledged. Special thanks are due to CRIFI's Dr Fuad Cholik, Dr Fatuchri Sukadi, Novenny Wahyudi, Dr Achmad Sarnita, Ondara, Agus Djoko Utomo and Zahri Nasution; to BAU's Dr M.A. Wahab; to MRAG's Prof. John Beddington and Kanailal Debnath; to CDS's Alex Kremer, Claire Hall, Dr Adrian Winnett and Prof. Chris Heady; to CORIN's Dr Somsak Boromthanarat and Dr Awae Masae; to the University of Patna's Dr R. Sinha; to BCAS's Dr Saleemul Huq; to Proshika's Rashed un Nabi; to DFID's Dr John Tarbit, Neil McPherson and Chris Price; and to FAO's Dr Jim Kapetsky.

MRAG Ltd is a leading international consulting firm, specializing in aquatic resources management, development, research and assessment, and information technology. The group has extensive experience of working in marine, freshwater, riverine and floodplain environments, and has worked in more than 60 countries for governments, private sector companies and international agencies. MRAG was formed in 1984, currently has a core staff of more than 20 professionals from a range of disciplines, and is located in the Imperial College campus, in the University of London. The group is associated with, and covenants funds to, the Marine Education and Conservation Trust, a charity which supports research and education.

Contact address:
MRAG Ltd
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London SW7 2QA
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Inland fisheries: warm and cold waters
Directors of Fisheries
Fishery Regional Officers
Fisheries Department

Contents

Preface

1   Introduction

1.1   DFID Natural Resources Research

1.2   DFID's 1992–97 Asian River Research Projects

1.2.1   Project R4791 - Poverty, Equity and Sustainability

1.2.2   Project R5485 - The Ganges Basin

1.2.3   Project R5953 - Fisheries Dynamics of Modified Floodplains.…

1.2.4   Project R6494 - Evaluation of Floodplain Stock Enhancement

1.3   The Future Research Programme

2   The Floodplain Environment

2.1   River Catchments and Habitats

2.1.1   River habitats

2.1.2   The ‘flood pulse’ concept

2.1.3   Spatial variability of river systems

2.1.4   Dry season waterbodies

2.2   Flood Variability

2.2.1   Seasonal (within-year) variability

2.2.2   Between-year variability

2.3   Hydrological Modification of Floodplain Rivers

2.3.1   Types of floodplain modification

2.3.2   The Pabna Irrigation and Rural Development Project (PIRDP)

3   Floodplain River Fish

3.1   Introduction

3.2   Characteristics of Floodplain River Fish

3.2.1   Migration patterns - blackfish and whitefish

3.2.2   Habitat preferences

3.2.3   Growth rates

3.2.4   Reproduction

3.2.5   Mortality and survival

3.3   Impact of Fishing on Fish Stocks

3.3.1   Impact of fishing on total catches

3.3.2   Impact of fishing on species composition of catches

3.4   Impact of Floodplain Modification on Fish Stocks

3.4.1   Impact of floodplain modification on potential fish productivity

3.4.2   Accessibility of modified floodplains to migrant fish

3.4.3   Impact of floodplain modification on fish species compositions

3.4.4   Overall impact of floodplain modification on fish catches

4   Floodplain Fisheries

4.1   Floodplain Fishing Gears

4.1.1   Categories of floodplain fishing gears

4.1.2   Dependence of fishing gear use on local conditions

4.1.3   Mesh sizes of floodplain fishing gears

4.1.4   Barrier gears

4.1.5   Chasing gears

4.1.6   Set-and-wait gears

4.1.7   Hoovering gears

4.2   Seasonality of Fishing and Effectiveness of Gears

4.2.1   Seasonality of fishing

4.2.2   Dependence of gear seasonality on local conditions

4.2.3   Seasonal variation in gear effectiveness (catchability)

5   Technical Management of Floodplain Fisheries

5.1   Managing Access to Fishing

5.1.1   Jalkar licensing system - Bangladesh

5.1.2   Regional waterbody licensing systems in South Sumatra, Indonesia

5.1.3   Community-based access-management in Jambi, Indonesia

5.1.4   Access to fishing and the mobility of fishers

5.1.5   Implications of licensing for sustainability

5.1.6   Comparison of licensing systems

5.2   Managing Interactive Multi-Gear Fisheries

5.2.1   Technical interactions between gears

5.2.2   ‘BEAM4’ modeling of the effects of alternative management strategies

5.2.3   Sensitivity of BEAM4 management recommendations

5.2.4   Simple alternatives to BEAM4

5.3   Use of Reserves for Floodplain Fisheries

5.3.1   Year-round reserves

5.3.2   Dry season reserves

5.3.3   Numbers of dry season reserves

5.3.4   Locations of dry season reserves

5.4   Managing Modified Floodplain Fisheries

5.4.1   Implications of fish migrations

5.4.2   Management of sluice gates

5.4.3   Hydrological manipulation

6   Managing Enhancement Fisheries

6.1   Introduction

6.2   List of Projects Reviewed

6.3   Issues in the Design of Enhancement Projects

6.4   A Framework for Evaluation of Floodplain Stock Enhancement

6.4.1   Stock enhancement activities

6.4.2   Institutional arrangements for enhancement

6.4.3   A proposed framework to evaluate enhancement fisheries

6.5   Insights for Enhancement Fisheries

6.5.1   Institutions involved and their respective roles

6.5.2   Use rules required

6.6   Key Lessons

6.6.1   Lessons for an institutional strategy for enhancement

6.6.2   Lessons for a technical strategy for enhancement

6.7   Summary

7   Participatory Management of Floodplain Fisheries

7.1   Introduction

7.2   Government Management of Floodplain Fisheries

7.2.1   Central government leadership

7.2.2   Implementation failure

7.2.3   The value of the fishery

7.3   The Spatial Interplay of Social and Biological Conditions

7.3.1   Waterbody morphology - the importance of boundaries

7.3.2   Human settlement - the importance of resource ownership

7.3.3   Fish mobility - local blackfish and migrant whitefish

7.4   Participatory Management: Individuals, Communities and Government(s)

7.4.1   Individuals

7.4.2   Communities

7.4.3   Government

7.5   Conclusions: The Prospects for Participatory Management

8   References

List of Tables

Table 1.1    Study sites of the four DFID Asian River fishery research projects

Table 1.2    Research collaborators of the four DFID research projects

Table 2.1    Habitat types found at the Bangladesh and Indonesia study sites

Table 2.2    Relative sizes and water retention of five categories of dry season waterbodies, inside and outside the PIRDP flood control, drainage and irrigation scheme, NW Bangladesh (after Hoggarth et al, in press (b))

Table 2.3    Comparative flood indices inside and outside the PIRDP's Talimnagar and Baulikhola sluice gates in 1995 and 1996 (from MRAG, 1997).

Table 3.1    Estimated mean lengths at maturity (Lm₅₀, in cm, with sample sizes in parenthesis) for key fish species at the PIRDP study site (from Halls et al, in press (a)).

Table 3.2    Estimates of mean total mortality rate z for key species inside and outside the Bangladesh PIRDP study site, with probability (p) of no difference between the two regions. Due to the absence of significant (p > 0.05) differences in mortality rates between regions, estimates of Z from both locations are pooled to give an overall and equivalent mean survival rates S(%), with 95% confidence intervals. Numbers in parentheses give sample sizes (from Halls et al, in press (a))

Table 3.3    Tag recapture rates for anchor-tagged key species in Bangladesh and Indonesia (project R5953, from MRAG, 1997 and Halls et al, in press (b)).

Table 3.4    Estimated escapement (kg/ha) of fish at the end of the dry season, inside and outside the PIRDP flood control scheme (from Hoggarth et al, in press (b)).

Table 3.5    Total numbers of fish species recorded in catches from dry season waterbodies in the early (November to March) and late (April and May) dry season, inside and outside the PIRDP flood control scheme, by waterbody type (‘-’ indicates zero catches or missing species composition data; from Hoggarth et al, in press (b)).

Table 3.6    Percentages of tagged fish recaptured in different habitat regions at the Indonesian River Lempuing study site, suggesting variations in fishing mortality between habitats (project R5953; summarised from MRAG, 1997).

Table 3.7    Comparison of fishing and catch rates at the R5953 Bangladesh and Indonesian study sites (summarised from MRAG, 1997)

Table 3.8    Summary table indicating where the growth performance measures and explanatory variables were found to be significantly greater in relation to the sampling location and hydrological year (NS = no significant difference; Halls et al, in press (a)).

Table 3.9    Seasonal fish migration phases at the PIRDP's Talimnagar and Baulikhola sluice gates during the 1996 flood season, summarising catch data in Figure 3.12 (from Hoggarth et al, in press (b)).

Table 3.10  Total catches (kg) at the Baulikhola and Talimnagar sluice gates, subdivided by migration phase and gear type (from Hoggarth et al, in press (b)).

Table 3.11  Numbers of tagged fish released and recaptured, by species, and the numbers which penetrated the PIRDP sluice gates, during 1995/96 (from Halls et al, in press (b).

Table 3.12  Estimated total annual productivity (kg ha^-1y^-1) inside and outside the PIRDP (from MRAG, 1997).

Table 4.1    Descriptions of the fishing gears used at the Bangladesh PIRDP study site, with their positions fished and mesh sizes (after MRAG, 1997)

Table 4.2    Descriptions of the fishing gears used at the Indonesian River Lempuing study site, with their positions fished and mesh sizes (after MRAG, 1997)

Table 4.3    Estimated relative catches from different gear categories from the Bangladesh PIRDP and Indonesian River Lempuing sites (after MRAG, 1997)

Table 6.1    Objectives of the eight projects reviewed by Project R6494 - An evaluation of Floodplain Stock Enhancement

Table 7.1    Prospects for management compliance under different types of community structure and authority

Table 7.2    The importance of spatial characteristics of inland fisheries for their prospects for participatory management

List of Figures

Figure 2.1    Map of the Hail Haor study site in NE Bangladesh (Project R4791; from MRAG, 1994)

Figure 2.2    Map of the PIRDP study site in NW Bangladesh (Project R5953; from Halls et al, in press (b))

Figure 2.3    Map of the River Lempuing and Jambi study sites in Sumatra, Indonesia (Projects R4791 and R5953; from Hoggarth et al, in press (a))

Figure 2.4    Time series of the monthly mean water levels at the Lubuk Lampam CRIFI field station gauge on the Lempuing River (Project R4791, gauge broken from January to September, 1992; from MRAG, 1994)

Figure 2.5    Maximum and minimum mean monthly water levels (open bars) and average flood season (January–April) and dry season (July–September) water levels (black bars) on the Lempuing River in years 1975 to 1993 (Project R4791, data not available for 1992 and dry season 1993, from Hoggarth and Utomo, 1994)

Figure 2.6    Area inundated by flooding in Bangladesh, 1954–1988 (from Halls, 1998, redrawn from Ahmad, 1989)

Figure 2.7    Map of the Pabna Irrigation and Rural Development Project (PIRDP) in NW Bangladesh (from SWMC, 1994). The R5953 study site straddled the embankment in the SE of the PIRDP (compare with Figure 2.2).

Figure 2.8    Daily water heights measured inside (thick lines) and outside (thin lines) the PIRDP Talimnagar and Baulikhola sluice gates, and daily sluice gate apertures in 1995 and '96 (from Hoggarth et al, in press (b)).

Figure 3.1    Percentages of tagged fish of each key species, released in each month, and subsequently recaptured in either the same or the next calendar month in a different location. Figures above bars indicate the total numbers of tagged fish recaptured within the same or the next calendar month as release (from Halls et al, in press (b)).

Figure 3.2    Recaptures of tagged fish of each key species at the Bangladeshi PIRDP study site. Lines with arrows connect the release and recapture locations of migrating fish; bold lines show fish which crossed the PIRDP embankment. Circles indicate fish recaptured at their release locations, with Ø = number of fish indicated by the largest circle in each plot. n = total number of tag recaptures. Squares indicate the positions of the PIRDP sluice gates (see Figure 2.2) (from Halls et al, in press (b)).

Figure 3.3    Percentages of tagged key fish species in Bangladesh, migrating at least the specified distances from their release locations (from Halls et al, in press (b)).

Figure 3.4    Recaptures of tagged fish of each key species at the Indonesian River Lempuing study site. Lines with arrows connect the release and recapture locations of migrating fish. Circles indicate fish recaptured at their release locations, with Ø = number of fish indicated by the largest circle in each plot. n = total number of tag recaptures (from MRAG, 1994).

Figure 3.5    Percentages of tagged fish of each key species at the PIRDP study site, recaptured in each month, in river/canal habitats (dark grey bars), floodplain habitats (light grey bars, including dry season pools), and ‘beel’ lake habitats (black bars). Figures above bars indicate the total number of recaptures (from Halls et al, in press (b)).

Figure 3.6    Bi-monthly fork length frequencies of Wallago attu, combined across non-selective gear types, in the Inside (‘modified’) and Outside regions of the PIRDP study site. X-scale = 0–127cm in 1cm classes (from Halls et al, in press (a)).

Figure 3.7    Fraction of mature male and female fish of each key species plotted against their lengths. Solid circles and solid lines, and open circles and broken lines indicate data and corresponding logistic model fits, for fish sampled from inside and outside the PIRDP, respectively (from Halls et al, in press (a)).

Figure 3.8    Changes in the mean monthly gonado-somatic index (GSI) with 95% confidence intervals for sampled female A. testudineus, C. striatus, G. giuris, P. sophore and W. attu from inside (solid line) and outside (broken line) the PIRDP during the 24 month sampling period (January 1995 to December 1996). Where no confidence interval is shown, only one fish was sampled. The top plot shows the changes in mean monthly water height (ft) inside (solid line) and outside (broken line) the PIRDP at Talimnagar sluice (from Halls et al, in press (a)).

Figure 3.9    Bimonthly fork length frequencies of the catfish Mystus nemurus, combined across non-selective gear types at the River Lempuing study site, with an approximate growth curve fitted ‘by eye’ (X-axis scale = 0–55cm; from MRAG, 1997).

Figure 3.10  Estimated total catches scaled by high water floodplain area, plotted against fisherman densities for the three study sites and other tropical floodplain fisheries in Asia, Africa and South America (from Hoggarth and Kirkwood, 1996).

Figure 3.11  Between site comparisons of the relative catches and mesh sizes of the most important gear types, and the catches of fish species with maximum lengths in three different size classes (from Hoggarth and Kirkwood, 1996).

Figure 3.12  Total daily catches (kg) of inwardly migrating fish (thin lines) and outwardly migrating fish (thick lines), by the three interceptory gear types at the PIRDP's Baulikhola and Talimnagar sluice gates during the 1996 flood season. Lower right graph shows daily water heights and periods of sluice gate opening, for comparison (data missing in mid-October; from Hoggarth et al, in press (b)).

Figure 3.13  MDS ordinations comparing species assemblages inside (black symbols) and outside (open symbols) FCDI schemes in three habitats and four regions in Bangladesh (from Halls et al, in press (b)).

Figure 3.14  Average abundance (seine net CPUE) of species sampled from inside (solid bars) and outside (open bars) FCDI schemes in the NW region. Species are arranged from top to bottom in descending order of their contribution to the average dissimilarity between the two groups of sites (from Halls et al, in press (b)).

Figure 3.15  Total monthly catches (t) in the four study regions of the PIRDP site in 1995 and '96 (from Hoggarth et al, in press (b)).

Figure 4.1    Between site comparisons of the seasonality of water levels and fish catches from selected, important gear types (from Hoggarth and Kirkwood, 1996).

Figure 4.2    Average monthly catches (left) and total annual catches (right) in years 1986–92, from the six main river gears at the Lubuk Lampam auction unit on the River Lempuing (1988 catch data not available by gears; from Hoggarth and Utomo, 1994).

Figure 4.3    Subsampled daily fish catches (up to six days of data per month) of kilung floodplain/lake barrier traps and tuguk/corong riverine barrier traps during 1995 at different locations in the River Lempuing, Indonesia. Lake Danau Besar is larger and further from the main river than Lake Lebung Sulit; the forest river region is upstream of the savanna river region. (after MRAG, 1997)

Figure 4.4    Percentages of tagged fish of each key species, released in each month, and subsequently recaptured in either the same or the next calendar month at the Bangladesh PIRDP study site. Figures above bars indicate the total numbers of tagged fish released (from Halls et al, in press (b)).

Figure 5.1    Locations of the fourteen licensed ‘Jalkar’ waterbodies at the Bangladesh PIRDP study site, licensed for access to fishing by the Bangladesh Government's Ministry of Land (from MRAG, 1997).

Figure 5.2    Estimated monthly catches (tonnes) during 1995, taken in the four capture regions by fishermen from the three residence regions, at the Bangladesh PIRDP study site (from MRAG, 1997).

Figure 5.3    Length frequencies of Notopterus notopterus (left) and Helostoma temminckii (right), taken from six different commercial gear types during four sampling periods, in 1993, from the River Lempuing in Indonesia (length scale from 1 to 35cm; TrapBR = combined bamboo and rattan traps, R&L = single hooks fished on rod and lines, Ngk Pg = ngesek pinggiran - see gear descriptions in Table 4.2; from Hoggarth and Utomo, 1994).

Figure 5.4    Comparison of the total catches of five fish species guilds by the ten most important gear types at the River Lempuing study site (see Section 4.1 and Table 4.2 for gear descriptions; from Hoggarth and Kirkwood, 1996).

Figure 5.5    BEAM4 predictions on the % changes in the catches of different gear types caused by the four management scenarios (symbols, as denoted in legends) at the three R4791 study sites (from Hoggarth, 1994)

Figure 5.6    Sensitivity of the BEAM4 model predictions for the Lempuing fishery, as indicated by the % changes to the catches of each gear type in the base model (bars), and with four altered inputs (symbols, as denoted in legends, with M = natural mortality, L50 = length at 50% selectivity, C = observed catch; from Hoggarth, 1994).

Figure 5.7    Schematic representation of the FPFMODEL showing the process by which the biomass in week w becomes the biomass in the following week w+1. The weekly process is repeated for the 52 weeks of the year, after which recruitment is added in week 52. The process is then repeated iteratively over several years until equilibrium is reached. Solid lines indicate direct influences or operations and broken lines indicate indirect influences or occasional operations (adapted from Welcomme and Hagborg 1977).

Figure 5.8    Contour plots of equilibrium yield (t) for P. sophore at the PIRDP generated by the FPFMODEL for different combinations of mean flood and dry season water height and for a range of fishing mortality, F rates (a) F = 0.2; (b) F = 1; (c) F = 2; (d) F = 3. (from Halls 1998)

Figure 6.1    Sequence of activities undertaken in stock enhancement of a floodplain

Figure 6.2    Framework for analysis of common-pool resource management (adapted from Oakerson, 1992)

Figure 6.3    Process of floodplain enhancement (adapted from Oakerson, 1992)

Preface

Attitudes to the management of natural resources are changing world-wide. These changes arise mainly from concerns about the state of the resources as they come under increasing pressure to satisfy a range of demands. Most important among these is the need for food, especially in tropical areas, which is forcing local populations to overexploit animals and plants. In addition, the sustainability of the living resources is threatened by impacts from other users by pollution and environmental modification. In general the capacity of present agricultural and industrial technologies to exploit and damage has far outstripped the capacity of societies to interpret, assimilate and control such changes. Efforts to do so show that present difficulties result from political, social and economic factors rather than from a lack of technological solutions. Concerns over these trends led to the convening of the United Nations Conference on the Environment and Development in 1992 and the acceptance of its Agenda 21. This highlighted the problems and, through Government commitment, provided a moral framework and guidelines for the sustainable use of natural resources. At the same time the Convention on Biodiversity was formulated and has now been accepted or acceded to by 176 Countries. The Convention is binding on its signatories and at present provides the only international legal framework for conservation and sustainable use.

Inevitably these developments have had their effect on fisheries. Most of the worlds fisheries are overexploited or are about to become so. Nowhere is this more evident than in inland waters, especially rivers, which are almost without exception heavily or excessively fished. Added to this is the high degree of alternative use of water for industry, agriculture, power generation, urban supply and transport, all of which influence the amount of water in the system and the structure of the environment. As populations and levels of income rise so does the demand for water for these various uses and this commodity is now seen as limiting development and human well being in many parts of the world. Unfortunately fisheries is one of the least valued of the various users of water and in many areas institutions making decisions on the allocation of water do not even consider fish. As a result rivers are one of the most endangered ecosystems and their faunas are especially under threat of species extinction and population disturbance. To counteract these threats fisheries managers have to represent the interests of their sector in decision-making mechanisms at all levels. At the same time fisheries have to rationalise their own operations. One of the first steps in this process has been the adoption by countries of the Code of Conduct for Responsible Fisheries. This Code, adopted by the Food and Agriculture Organisation's Committee of Fisheries in 1995, furnishes voluntary guidelines on the organisation of fisheries at national level. It, together with the Convention on Biological Diversity, also emphasises the need for countries to regulate their aquatic environment for conservation of aquatic biodiversity and for sustainable fisheries.

Many of the ideas presented at these International forums are now being expressed at national level. As a result the objectives for management in many parts of the World are changing rapidly as policy makers adjust to the new vision of the resource. Frequently such changes exceeds the capacity of legislators to formulate new laws and it is probably better at present to retain flexibility through more generalised regulations until a more stable consensus emerges. At their meetings major discussions centre around mechanisms to ensure equity at national and international levels, and attempts to reconcile the conflict between conservation and use which lies at the heart of sustainable development. Furthermore, existing institutions and mechanisms have proved inadequate even for the management of food fisheries so new approaches to organising society for this purpose have to be sought. Three trends appear to be conditioning the direction of management at present.

• The emergence of new conservation oriented objectives for natural resources management. This objective arises directly from the Convention on Biological Diversity and the Code of Conduct for Responsible Fishing and is more evident in temperate countries where abundant food supplies reduce dependence on river and lake fish. Nevertheless there is a growing trend to take these attitudes into account in attempting to make food fisheries more sustainable.

• Changing patterns of use within the fishery. These arise mainly from demographic shifts throughout the world, principally human movements away from the rural to the urban. This has two effects. Firstly there is a need for fisheries for urban supply rather than satisfaction of local demand. Such fisheries tend to inflate the pressure on the resource by increasing prices and selecting for the larger fish in the assemblage. Secondly there is a global trend to reserve all or part of the resource for recreational rather than food fisheries. Usually the unit value of the recreational fishery is far higher than the food fishery. Where there is strong urban demand, recreational interests and pressure groups tend to displace the food fishery with drastic effects on food supplies and employment.

• The emergence of new philosophies for participatory management. Two divergent trends are apparent here. On one hand there is the suppression of national authority through economic integrating organisations which is especially important in the case of fisheries where the basin approach is crucial for the protection of migratory or transboundary stocks. On the other hand there is a trend for national powers to be devolved to local authorities within the country. This trend is further decentralised in the case of co-management systems where the fishermen's communities share responsibility for management. As the centralised nation state has been the preferred institution for management until recently these new approaches need to be developed and tested.

The study of large rivers and adequate understanding of how they function for fish and fisheries is fairly recent. For this reason the incorporation of these ideas into management of large floodplain rivers of the tropics is it is still developing. Further studies are needed particularly on the policy, social and economic aspects of the fisheries. There is also a need for research on the biology of individual systems to determine their state of exploitation and degree of modification by other users. This study presents the result of four research projects in South and South-East Asia. It also presents guidelines for management derived from these studies, adapted particularly to the large rivers of the region. These guidelines are intended to support the FAO Code of Conduct for Responsible fisheries and as such are aimed primarily at securing the sustainability of floodplain resources in order to secure a continuing supply of protein rich food. The Marine Resources Assessment Group carried out the work in association with several other overseas and UK institutes. Funding for this paper was provided by the UK Department For International Development. The Technical Paper was published through FAO to ensure a wide dissemination of its ideas.

The Technical Paper is in two parts:

The Technical Paper is aimed to provide fisheries administrators and scientists at policy making, executive and field levels with the tools they need to make decisions on the allocation of riverine resources and management of river fisheries. The material provided (especially in Part 1) may also be used in the construction of courses for extension workers.

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