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Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin
Page 1 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin ISSN: 1683-1489 Mekong River Commission MRC Technical Paper No. 33 August 2013 C a m b o d i a . L a o P D R . Tha i l a n d . Viet N a m For sustainable development Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Mekong River Commission MRC Technical Paper No. 33 August 2013 Published in Phnom Penh, Cambodia in July 2013 by the Mekong River Commission Cite this document as: Halls, A.S.; Paxton, B.R.; Hall, N.; Hortle, K.G.; So, N.; Chea, T.; Chheng, P.; Putrea, S.; Lieng, S.; Peng Bun, N.; Pengby, N.; Chan, S.; Vu, V.A.; Nguyen Nguyen, D.; Doan, V.T., Sinthavong, V.; Douangkham, S.; Vannaxay, S.; Renu, S.; Suntornratana, U.; Tiwarat, T. and Boonsong, S. (2013). Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin. MRC Technical Paper No. 33, Mekong River Commission, Phnom Penh, Cambodia, 130pp. ISSN: 1683-1489. The opinions and interpretations expressed within are those of the authors and do not necessarily reect the views of the Mekong River Commission. Cover Photo: J. Garrison Editors: T. Hacker, T.R. Meadley and P. Degen Graphic design and layout: C. Chhut Ofce of the Secretariat in Phnom Penh (OSP) 576 National Road, #2, Chak Angre Krom, P.O. Box 623, Phnom Penh, Cambodia Tel. (855-23) 425 353 Fax. (855-23) 425 363 Ofce of the Secretariat in Vientiane (OSV) Ofce of the Chief Executive Ofcer 184 Fa Ngoum Road, P.O. Box 6101, Vientiane, Lao PDR Tel. (856-21) 263 263 Fax. (856-21) 263 264 © Mekong River Commission E-mail: mrcs@mrcmekong.org Website: www.mrcmekong.org iii Table of contents List of Tables v List of Figures vii Abbreviations and Acronyms xi Glossary of parameters xii Glossary xiii Acknowledgements xvi Summary xvii 1. Introduction 1 1.1 Background 1 1.2 The aims of the paper 2 1.3 Relevance to FEVM Logframe Outputs and Activities 2 1.4 Structure of the paper 2 2 The Cambodian Dai Fishery Monitoring Programme 3 2.1 Introduction 3 2.2 Description of the shery 3 2.3 Monitoring programmes 5 2.4 Status and trends of resources 6 2.4.1 Catch composition 6 2.4.2 Trends in species composition and diversity 7 2.4.3 Trends in catch, indices of abundance and biomass and sh size (weight) 7 2.5 Hydrological inuences 10 2.6 Management effects 11 2.7 Conclusions 11 3. The Lao Lee Trap Fishery Monitoring Programme 13 3.1 Introduction 13 3.2 Description of the shery 13 3.3 Monitoring programmes 13 3.4 Status and trends 17 3.4.1 Catch composition 17 3.4.2 Trends in species composition and diversity 17 3.4.3 Inter-annual variation in relative biomass and hydrological effects 17 3.4.4 Intra-annual variation and hydrological effects 20 3.5 Conclusions 23 4. Fish Abundance and Diversity Monitoring Programmes (Small-Scale Artisanal Fisheries) 25 iv 4.1 Introduction 25 4.2 Monitoring programmes 25 4.3 Resource status and trends 30 4.3.1 Species composition 30 4.3.2 Trends in species diversity 31 4.3.3 Trends in relative sh abundance and biomass indices 36 4.3.4 Trends in growth 38 4.3.5 Abundance, biomass, growth and ooding 41 4.3.6 Other sites and species-wise analyses 41 4.4 Conclusions 41 5. Larvae Density Monitoring Programme 45 5.1 Introduction 45 5.2 Monitoring programmes 45 5.3 Status and trends 47 5.3.1 Species composition 47 5.3.2 Trends (all species) 49 5.3.3 Trends by species 52 5.4 Origin of ichthyoplankton drift 57 5.5 Summary and conclusions 57 6. Integrated analyses 61 6.1 Introduction 61 6.2 Methodology 62 6.2.1 The timing and extent of sh migrations 62 6.2.2 Spawning locations 62 6.2.3 Recruitment effects on stocks migrating from the TS-GL 63 6.2.4 Extent of sh migrations from the TS-GL 63 6.2.5 Extent of ood effects on sh growth 64 6.2.6 Management effects 64 6.2.7 Selected species 65 6.3 Results 66 6.3.1 Fish migrations 66 6.3.2 Spawning locations 75 6.3.3 Recruitment effects on stocks migrating from the TS-GL 78 6.3.4 Extent of sh migrations from the TS-GL 85 6.3.5 Extent of ood effects on sh growth 88 6.3.6 Management effects and recruitment 89 6.4 Summary and conclusions 91 7. Conclusions and recommendations 95 8. References 101 9. Annex 105 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Page v List of Tables Table 1 Estimates of total annual catch 1938–1988 5 Table 2 Species composition of the catch for the 2009–10 shing season 6 Table 3 Sites monitored under both the AMCF and FEVM catch monitoring programmes (2003–2010) 29 Table 4 Summary statistics for the catch monitoring programmes 30 Table 5 Annual trends in estimates of species richness indices 33 Table 6 Annual trend in estimates of relative abundance, biomass and mean body weight 38 Table 7 Estimates of geometric (GM) and arithmetic (AM) mean daily larvae density at the Mekong and Tonle Sap sampling locations, Cambodia, between June and September, 2002–2009 . 52 Table 8 Species exhibiting peaks in their larvae density estimates at the Mekong (MK) and Tonle Sap (TS) sampling locations in 2005 and 2008 . 55 Table 9 Characteristics of species exhibiting peak larvae densities in 2005 and 2008 at the Tonle Sap and Mekong River sampling locations 56 Table 10 ANOVA results to test the dependence of log e -transformed larvae density (LNTS) in the Tonle Sap on inowing volume of water (Q) accounting for differences among species (SP) 59 Table 11 The species selected for the correlation/function analysis. 65 Table 12 Coefcients of linear regressions between estimates of larvae density in the Mekong River at Phnom Penh 76 Table 13 Coefcients of linear regressions between estimates of larvae density in the Tonle Sap at Phnom Penh and spawning stock biomass at the 10 locations 77 Table 14 Regression coefcients of the linear relationship between estimates of the arithmetic mean daily larvae density-based recruitment index and log e -transformed dai catch rates 84 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Page vi Table 15 Regression coefcients of the linear dependence of relative spawning stock biomass at locations in the LMB 86 Table 16 Regression coefcients of the linear dependence of relative abundance of spawning stock size at locations in the LMB 87 Table 17 Regression coefcients of the linear dependence of mean body weight of species sampled at sher catch monitoring locations in the basin during February each year on the ood extent and duration in the TS-GL system 88 Table 18 Results of the GLM to test the dependence of dai catch rates on the quantity of fence 89 Table 19 Statistics of conscation and destruction of illegal shing gears (2000–2009). 105 Table 20 Percentage contributions of sh species to total catch weight reported under the sher catch monitoring programmes, all gears and habitats 106 Table 21 Monthly estimates of catch weight (kg) at the sher catch monitoring sites (2003–2010) 117 Table 22 Monthly estimates of the number of sh caught at the sher catch monitoring sites (2003–2010) 118 Table 23 Monthly estimates of the mean weight (kg) of sh caught at the sher catch monitoring sites (2003–2010) 119 Table 24 Monthly estimates of the number of species reported (S) at the sher catch monitoring sites (2003–2010) 120 Table 25 Monthly estimates of the Margalef index at the sher catch monitoring sites (2003–2010) 121 Table 26 Monthly estimates of the species richness index (SRI) at the sher catch monitoring sites (2003–2010) 122 Table 27 Monthly estimates of sher catch rates (No/day) at the sher catch monitoring sites (2003–2010) 123 Table 28 Monthly estimates of sher catch rates (kg/day) at the sher catch monitoring sites (2003–2010) 124 Table 29 Pearson coefcients for correlations between average daily catch rates (kg/day) by month at sher catch monitoring locations. 125 Page vii List of gures Figure 1 The stationary trawl or (Loh Dai) shery of the Tonle Sap-Great Lake (TS-GL) System, Cambodia . 4 Figure 2 Illustration of the within-season variation in daily catch rates for the 2000–01 season 7 Figure 3 Mean log e -transformed dai catch rates (kg/dai/day) values by lunar phase for the seasons 1997–98 to 2008–09 8 Figure 4 Inter-annual trends in (a) total catch, (b) effort and (c) CPUE (1997–08 to 2009–10) 9 Figure 5 Trends in mean sh weight (all species combined) and the ood index 10 Figure 6 The Location of the Lee trap shery monitoring programme in southern Lao PDR 15 Figure 7 Species composition of the sampled catch from lee traps in Hoo Som Yai Channel, 2009 17 Figure 8 The average multispecies assemblage catch rate in the Hoo Som Yai Channel, 1997–2009 18 Figure 9 Estimates of CPUE by sampling year for the 14 species monitored from 1997–2009. 19 Figure 10 Average multi-species catch rate in June each year (1997–2008) plotted as a function of mean water level at Pakse in the same month 20 Figure 11 Mean daily lee trap CPUE for the multi-species assemblage migrating through the HSY channel and water level measured at Pakse 21 Figure 12 Estimates of daily log e -transformed CPUE for the most frequently caught species in the HSY in 2008 plotted as a function of water level at Pakse 22 Figure 13 The locations of the AMCF catch monitoring programme (2003–2005). 27 Figure14 The locations of the FEVM catch monitoring sites (2007–2010). 28 Figure 15 An example comparison of the log-linear relationship between monthly estimates of S and sampling effort measured in terms of N and shing days (D) for the Banfang site, Cambodia, monitored under the AMCF programme (2003–2005). 32 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Page viii Figure 16 Intra-annual (monthly) variation in the estimates of the Margalef and SRI species richness indices at sites monitored under both the AMCF and FEVM programmes 34 Figure 17 Monthly estimates of the Margalef and SRI species richness indices at sites monitored under both the AMCF and FEVM programmes 35 Figure 18 Average monthly variation in the indices of sh abundance and biomass at the 10 sites monitored under the AMCF and FEVM programmes (2003–2010). 37 Figure 19 Monthly estimates of the relative sh abundance and biomass indicated by log e -transformed average sher catch rates per day at those sites monitored under both the AMCF and FEVM programmes. 39 Figure 20 Average monthly variation in mean sh weight and monthly estimates of mean sh weight at sites monitored under both the AMCF and FEVM programmes. 40 Figure 21 Estimates of indices of average sh abundance, biomass and mean weight in February each year, plotted as a function of the ood index for the six sites in Cambodia 43 Figure 22 The location of the sh larvae density monitoring sites in Cambodia and Viet Nam 46 Figure 23 Species composition of larvae samples taken from the Tonle Sap and Mekong River sampling sites 2002–2009 48 Figure 24 The number of species identied in larvae samples taken between June and September each year plotted as a function of the number of sampling days during the same period. 49 Figure 25 Daily estimates of mean larvae density in the Tonle Sap and Mekong River, Cambodia, 2002–2009 50 Figure 26 Estimates of mean log e -transformed daily larvae density between June and September for the Mekong river and Tonle Sap, 2002-2009 51 Figure 27 Estimates of arithmetic mean daily larvae density (June–September), 2002 – 2009, all species. 52 Figure 28 Mean daily larvae density estimates (x 1000) between June and September, 2004–2009 for the Tonle Sap sampling site . 53 Figure 29 Mean daily larvae density estimates (x 1000) between June and September, 2004–2009 for the Mekong river sampling site 54 [...]... reviewing the size of samples taken by each monitoring programme to detect acceptable minimum detectable differences in index estimates Other recommendations to improve the four monitoring programmes and their databases are described Page xix Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Page xx 1 Introduction 1.1 Background Four major monitoring programmes. .. Page 3 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Figure 1 Page 4 The stationary trawl or (Loh Dai) fishery of the Tonle Sap-Great Lake (TS-GL) System, Cambodia The solid yellow circles indicate the position of a row of dais The Lao Lee Trap Fishery Monitoring Programme 2.3 Monitoring programmes The fishery has been monitored intermittently since the. .. impact monitoring purposes Page 1 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Moreover, comparing variation in these indicators among monitoring sites can potentially provide information on the spatial extent of stocks as well as the extent over which resources respond in a similar manner to inter-annual variation in environmental conditions including... significant trend in the biomass of fish migrating upstream at the Khone Falls in southern Lao PDR was detected between 1997 and 2009 Furthermore, no consistent trends in the indices of Page xvii Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin relative abundance, biomass or species richness were observed among 10 fisher catch monitoring locations that... responsible for the very high catches observed during 2004–05 and 2005–06 Factors that might have been responsible for the high levels of recruitment during these two fishing seasons are examined in Section 6 Page 11 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Page 12 3 The Lao Lee Trap Fishery Monitoring Programme 3.1 Introduction Important fisheries are... predominantly bedrock channel vary between 0.5 m Page 13 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Plate 1 Harvesting fish from a lee trap in the Hoo Som Yai channel, southern Lao PDR Photos: B.R Paxton and S Viravong over the dry season and roughly 3.5–4.0 m over the wet season (Singhanouvong, 1996) Although the Hoo Sahong to the west of the HSY... 1996) The Hoo Som Yai is one of the smaller channels that pass over the Great Fault Line on the main stem of the Mekong River It diverges from the Khonephapeng channel above the falls of the same name The HSY then flows in a narrow vegetated channel between 10 and 20 m wide for roughly 800 m before rejoining the main channel another 600 m downstream of the falls in Northern Cambodia Water depths in the. .. including hydrology Comparing time series from these four monitoring programmes in a more integrated manner assists the interpretation of their respective trends 1.2 The aims of the paper This paper aims to describe the status and trends of fisheries resources at monitoring locations across the Lower Mekong basin It also explores the spatial and temporal dynamics of widely abundant species in an attempt to... Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Catch rates consistently peak during the second quarter of the lunar cycle and are lowest during the 4th quarter (Figure 3), (Halls et al., 2011) Here, the lunar quarters relate to 4 consecutive 7 day periods starting from the new (dark phase) moon Quarter 2 therefore relates to the period of approximately 7–14 days after the. .. long-term trends in these indices were examined Correlations and functional dependencies in the indices through space and time were also examined and tested in an attempt to elucidate the extent of fish migrations and identify spawning locations in the basin, and to improve understanding of the life-cycles and dynamics of fish stocks in the basin Significant long-term (1997–2010) trends in the indices were . sustainable development Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Mekong River Commission MRC Technical. rates 84 Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin Page vi Table 15 Regression coefcients of the linear