Ministry of Agriculture & Rural Development Collaboration for Agriculture & Rural Development 002/04VIE Project Better Breeds of Common Carp (Cyprinus carpio L.) for Small-scale Fish Farmers Milestone 4: On-farm Trials and Uptake of Improved Breeds of Common Carp Christopher M Austin1, Tuan Anh Pham2, Binh Thanh Thai2, Hung Quang Le2 School of Science and Primary Industries, Charles Darwin University, Darwin Northern Territory 0909, Australia Research Institute for Aquaculture No 1, Dinh Bang, Tu Son, Bac Ninh, Vietnam October, 2007 Contents Contents List of Figures List of Table Introduction Materials and methods 2.1 Experimental Design 2.2 Selection of common carp strains 2.3 Common carp rearing and experimental procedures 2.4 Data collection and analysis 11 Results 14 3.1 Fingerling growth rate 14 3.2 Growth and survival of HP3 and LOC strains and effects of feed input 14 3.3 Growth rate and survival of HP3, H3B and LOC strains 17 3.4 Growth rate and survival for HP3, VNW and LOC Strains 19 3.5 Growth rate and survival of HP3, H3B, VNW and LOC strains in low feed input farms controlled for variation among farmer ponds 21 3.6 Common carp biomass production in farms stocked with three common carp strain (HP3, H3B, LOC) 23 3.7 Common carp biomass production comparing farms stocked with two common carp strains (HP3 and LOC) 25 3.8 Demand of the improved common carp seed 27 Conclusion and Recommendations 29 Appendices 33 Reference 34 List of Figures Fig 2.1 Rice field used for farm trials in Yen Bai province .9 Fig 2.2 Farmer’s pond in Thai Nguyen province .9 Fig 2.3 Measuring common carp 11 Fig 2.4 Ethnic people harvesting common cap in rice field in Yen Bai province .12 Fig 2.5 Harvesting common carp in pond in Thai Nguyen 13 Fig 2.6 A farmer is happy with common carp growth .13 Fig 3.1 Daily growth rate of HP3 and LOC common carp strains in each of 18 farms 15 Fig 3.2 Example of relative growth of three strains of common carp in rice field in Yen Bai province after six months of culture .18 Fig 3.3 Daily growth rate of HP3, H3B and LOC common carp strain in each of 11 farms in Yen Bai and Thai Nguyen provinces 18 Fig 3.4 Daily growth rate of HP3, VNW and LOC common carp strain for a period of 10 months in each farm in Yen Bai and Thai Nguyen provinces 20 Fig 3.5 Daily growth rate of HP3, H3B, VNW and LOC common carp strains in farms 22 Fig 3.6 Common carp from HP3 strain after seven months of cultured in a high input feed farm in Thai Nguyen province 23 Fig 3.7 Proportion of genetically improved common carp fry and fingerlings cultured in Vinh Phuc, Thai Nguyen and Yen Bai provinces during 2004-2006 29 List of Table Table 2.1 Farms, pond type, and number of fish stocked of each strain (some farms were remove from the data set because fish escaped during flooding) 10 Table 2.2 Data analyses for common carp culture farm trails 13 Table 3.1 Mean (± SD) of body length and weight of fingerling carp after 60 days of nursing 14 Table 3.2 ANOVA table testing for differences in daily growth rate in relation to the effects of common carp strain (HP3 and LOC) and type of feed input .15 Table 3.3 Daily growth rate of HP3 and LOC common carp strain for period of 10 months in 18 farms in two type of feeding regimes in Yen Bai and Thai Nguyen provinces Superscripts indicate significant differences among groups based on Tukey’s test 15 Table 3.4 ANOVA table testing for differences in survival rate in relation to the effects of common carp strain (HP3 and LOC) and type of feed input .16 Table 3.5 Survival rate of HP3 and LOC common carp strains grown for a period of 10 months in 18 farms with two types of feeding rates in Yen Bai and Thai Nguyen provinces Superscripts indicate significant differences among groups based on Tukey’s test 16 Table 3.6 ANOVA table testing for differences in daily growth rate in relation to the effects of common carp strain (HP3, H3B and LOC) 17 Table 3.7 Daily growth rate of HP3, H3B and LOC common carp strains grown for a period of 10 months in 11 farms in Yen Bai and Thai Nguyen provinces Superscripts indicate significant differences among groups based on Tukey’s test 17 Table 3.8 ANOVA table testing for differences in survival rate in relation to the effects of common carp strains (HP3, H3B and LOC) 19 Table 3.9 ANOVA table testing for differences in daily growth rate in relation to the effects of common carp strain (HP3, VNW and LOC) 19 Table 3.10 Daily growth rate of HP3, VNW and LOC common carp strains grown for a period of 10 months in farms in Yen Bai and Thai Nguyen provinces Superscripts indicate significant differences among groups based on Tukey’s test 20 Table 3.11 ANOVA table testing for differences in survival rate in relation to the effects of common carp strains (HP3, VNW and LOC) 21 Table 3.12 ANOVA table testing for differences in daily growth rate in relation to the effects of common carp strain (HP3, H3B, VNW and LOC) 21 Table 3.13 Daily growth rate of HP3, H3B, VNW and LOC common carp strains for period of 10 months in farms in Yen Bai and Thai Nguyen provinces Superscripts indicate significant differences among groups based on Tukey’s test 22 Table 3.14 ANOVA table testing for differences in survival rate in relation to the effects of common carp strains (HP3, H3B, VNW and LOC) and culture types (low and high feed input) 23 Table 3.15 Biomass of common carp strains in 11 farms with strains (HP3, H3B and LOC) and cultured for 300 days in Yen Bai and Thai Nguyen provinces 24 Table 3.16 ANOVA analyses of biomass of HP3, H3B, and LOC common carp strains.25 Table 3.17 ANOVA analysis of biomass of HP3 and LOC common carp strains .25 Table 3.18 Biomass of common carp strains in 18 farms with strains (HP3 and LOC) cultured for 300 days Superscripts indicate significant differences among groups based on Tukey’s test 26 Table 3.19 Biomass of HP3 and LOC common carp strains grown for a period of 10 months in 18 farms with two types of feed input in Yen Bai and Thai Nguyen provinces 27 Table 3.20 Number of hatcheries and fry nursing farmers in provinces 27 Table 3.21 Number of common carp fry produced in five hatcheries in Thai Nguyen, Yen Bai and Vinh Phuc provinces in 2006 28 Table 3.22 Proportion of fry produced from genetically improved common carp lines in five hatcheries in Thai Nguyen, Yen Bai, and Vinh Phuc provinces in 2006 28 Introduction In Vietnam aquaculture plays a very important role in economic development and food security for small scale farmers and contributes 35% of Vietnamese protein consumption Aquaculture production is increasing at rate of 10% per year and contributes significantly to the country’s export income (MOFI, 2007) Common carp is one of the most popular freshwater aquaculture species in Vietnam and is cultured in pond, cages, reservoir and rice field for household consumption and income generation A recent survey of 133 carp farmers indicated that pond and rice field production are the preferred form of culture systems (98%) with the pond culture the most common (Austin et al., 2007a) Most farmers culture common carp with up to other fish species, both indigenous (silver carp, black carp) and exotic (silver grass carp, bighead, rohu, mrigal, pirapitinga, Tilapia) In polyculture ponds, common carp is the predominate species making up 30.1% of the biomass based on a recent survey (Austin et al., 2007a) The level of culture intensity for common carp varies from small scale extensive farming, with fish deriving all their nutrition from natural pond productivity, through semiintensive farming using fertilization from organic material such as bran, agriculture byproducts and household wastes to high intensive culture system with high stocking densities and the use of manufactured fish foods Semi-intensive culture systems are the most popular in Vietnam using ponds or a combination of ponds and rice field cultivation (Austin et al., 2007a) There are many factors that affect production and yield of farmed fish species, including seed (fry and fingerlings) quality, feed type and rate, fertilisation and pond management, including water exchange Of these, seed quality, which is directly related to the genetic quality of the broodstock used to produce the fry and fingerlings, has been identified as being of major concern to researchers (Thai et al., 2006; 2007), but which is not generally understood by farmers to be a potential issue affecting farm productivity (Austin et al., 2007a) In Vietnam there are many different local varieties of common carp that have been used by farmers but they usually have small size and low growth rate (Tran, 1983) Over recent times the Research Institute for Aquaculture No.1 (RIA-I) has bred genetically improved common carp strains to enhance the productivity of small scale fish farms that utilise this species This program has used crossbreeding and mass and family selection methodologies to produce genetically improved strains and is considered to have achieved an average increase of 5% in growth rate per generation over a number of generations (Thien and Thang, 1992) However, all the selective breeding and associated growth trials have been conducted in research ponds, often without the availability of unselected lines as control populations for comparative studies As a consequence, on-farm growth trials of different strains were undertaken to allow for a more effective analysis of carp growth under environments directly relevant to small scale carp farmers and as a strategy to encourage uptake by farmers of genetically improved strains This report presents, firstly, a report on the statistical analysis of growth and production of different common carp strains in small scale farmer ponds in Yen Bai and Thai Nguyen provinces The farmers participating in this research project included those using both pond and rice field culture from mostly highland environments All farmers had previously participated in the socio-economic survey and one of two workshops on fish breeding and genetic improvement conducted as part of this project Secondly, a survey of the uptake of improved breeds by producers is presented Materials and methods 2.1 Experimental Design The original objective of the on-farm trials was to compare a genetically improve carp strain and a local strain communally reared in six ponds owned by different farmers With additional support from the Research Institute of Aquaculture No (RIA1), the experimental objectives were scaled up to include 37 separate farmers and four strains The majority (34) of farmers used ponds as their culture systems with six farmers using rice field systems, which reflects the proportion of these different farming systems in these provinces based on the socio-economic survey (Austin et al., 2007a) (Fig 2.1&2.2) Farms were classified according to their levels of feed inputs as either high or low to determine if this important management aspect influenced the relative performance of the different carp strains Farmers who did not provide food more than once per month were classified as having “Low” input pond systems and those who fed at least once per week or more frequently were classified as having “High” input pond systems The experiment was conducted over a 12 months period from March 2006 to March 2007, which included spawning and fry rearing March – May, 2006 and fingerling grow out May 2006 to March 2007, which largely coincides with the normal carp farming culture cycle The trials were conducted in pond systems owned by 20 households in each of the Thai Nguyen and Yen Bai provinces Representatives of these households were interviewed for the socioeconomic survey and participated in one of the farmer workshops on fish breeding and selection held as part of this project As described in more detail below the experimental design could not be achieved due to differential reproduction and survival of fry Thus different farms were stocked with different numbers of strains and in varying combinations Further, fish could not be harvested from several farms due to flooding and other management problems Appendix lists the farms that participated in the project, and details of their culture systems and fish that were stocked and if data collection at harvest was possible 2.2 Selection of common carp strains Fours common carp strains were used for growth trials and included one strain (HP3) recently produced through hybridization between the three blood Hungarian strain and a recently imported pure line of Hungarian carp, the three blood Hungarian strain (H3B), an unselected Vietnamese strain (VNW) and a locally available strain (LOC) produced from broodstock available from the Yen Bai provincial hatchery Genetic analysis of this strain (Thai et al., 2006: 2007) indicates it represented a mixture of Indonesian, Hungarian and Vietnamese strains with the latter strain predominating Fig 2.1 Rice field used for farm trials in Yen Bai province Fig 2.2 Farmer’s pond in Thai Nguyen province 2.3 Common carp rearing and experimental procedures Common carp breeding was undertaken at the National Broodstock Centre Hai Duong Broodstock of each experimental strain were induced to breed on the same day, using standard practices for gamete stripping and fertilization (Thai and Ngo, 2004) Between 10 -12 families of fish were obtained from each strain After fertilization eggs produced from 10 different families of the one strain were pooled and raised in 200l upwelling incubators After 4-5 days when larvae had reached 8-12 mm they were transferred to four ponds and stocked at a rate of 100 larvae/m2 and grown for a period of two months Every effort was made to keep the conditions under which the fry and fingerlings of each strain were raised as similar as possible, especially in relation to stocking density and feeding regime When the fingerlings had reached of 3-5g, they were tagged by using Coded Wire Tag (CWT) The strains of common carp lines were marked by placing the CWTs on different locations on the body The tagged fish were stocked into 40 ponds or pond-rice field systems over a two day period Communally stocked fish were in equal proportions with the exception of three ponds The details of the fish stocked in farms is given Table 2.1 Table 2.1 Farms, pond type, and number of fish stocked of each strain (some farms were remove from the data set because fish escaped during flooding) Farm Provinces Culture Area systems (m ) Hoan Yen Bai Ricefield 1000 Ly Yen Bai Pond 800 Thuan Yen Bai Pond 1000 Tap Thai Nguyen Pond 800 1000 Tuan Thai Nguyen Pond Chung Yen Bai Pond 1000 Lien Yen Bai Ricefield 1500 Hom Yen Bai Ricefield 800 Tho Yen Bai Pond 450 Dieu Thai Nguyen Pond 600 Ha Thai Nguyen Pond 1500 1000 Lieu Thai Nguyen Pond Canh Thai Nguyen Pond 400 Luat Thai Nguyen Pond 1000 Nhan Yen Bai Pond 1500 Truong Thai Nguyen Pond 500 1000 Que Thai Nguyen Pond Vinh Thai Nguyen Pond 800 Ke Thai Nguyen Pond 550 Thong Yen Bai Pond 1000 Lich Thai Nguyen Pond 500 Trung Thai Nguyen Pond 400 Feed Strain and No of fish stocked input HF LF LF HF LF HF LF LF HF LF LF LF HF LE LE HF LF LF LF LF LF LF HP3 H3B VNW LOC Total 100 100 100 300 120 120 240 100 100 100 300 120 120 240 100 100 100 300 100 100 100 300 113 113 113 113 450 80 80 80 240 75 75 150 100 100 200 113 113 113 113 450 145 55 100 300 60 60 120 100 100 100 300 113 113 113 113 450 75 75 150 100 50 150 300 80 80 80 240 90 90 180 100 100 100 300 75 75 150 60 60 120 HF: High feeding rate LF: Low feeding rate 20 Table 3.10 Daily growth rate of HP3, VNW and LOC common carp strains grown for a period of 10 months in farms in Yen Bai and Thai Nguyen provinces Superscripts indicate significant differences among groups based on Tukey’s test Strain VNW LOC Mean Std Min Max 112 HP3 N a 0.20 0.10 1.50 b 0.12 0.03 0.66 c 0.10 0.02 0.78 c 0.14 0.05 0.98 96 99 Total 307 0.31 0.22 0.18 0.24 0.60 HP3 DRG (g) 0.50 VNW 0.40 LOC 0.30 0.20 0.10 0.00 Ha Lien Hom Nhan Chung Farm Fig 3.4 Daily growth rate of HP3, VNW and LOC common carp strain for a period of 10 months in each farm in Yen Bai and Thai Nguyen provinces The results of the survival rate of three common carp strains (HP3, VNW and LOC) showed no significant differences between farms (Table 3.11) Although survival rate of HP3 was the highest (20.57%) there had no significant difference comparing with other two strains (VNW = 17.98% and LOC = 18.49%) 21 Table 3.11 ANOVA table testing for differences in survival rate in relation to the effects of common carp strains (HP3, VNW and LOC) Source Corrected Model Intercept Farm Strain Error Total Corrected Total Type III Sum of Squares 87.19 5417.29 68.18 19.01 50.94 5555.42 138.13 df Mean Square 14.53 5417.29 17.04 9.51 6.37 15 14 F 2.28 850.77 2.68 1.49 Sig 0.14 0.00 0.11 0.28 3.5 Growth rate and survival of HP3, H3B, VNW and LOC strains in low feed input farms controlled for variation among farmer ponds Growth data from all four strains, HP3, H3B, VNW and LOC were compared in low input farms in which they were raised communally Significant differences were observed for both strain and farmer as presented Table 3.12 Table 3.13 gives the average growth rate for the strains Post hoc tests indicated significant differences among strains with HP3 > H3B = VIET > LOC Daily growth rate of each strain and farm are presented in Fig 3.5 Table 3.12 ANOVA table testing for differences in daily growth rate in relation to the effects of common carp strain (HP3, H3B, VNW and LOC) Source Corrected Model Intercept Farm Strain Error Total Corrected Total Type III Sum of Squares 1.53 7.89 0.92 0.62 0.55 10.65 2.08 df Mean Square 0.31 7.89 0.46 0.21 242 0.00 248 247 F 135.15 3480.33 203.09 91.25 Sig 0.00 0.00 0.00 0.00 22 Table 3.13 Daily growth rate of HP3, H3B, VNW and LOC common carp strains for period of 10 months in farms in Yen Bai and Thai Nguyen provinces Superscripts indicate significant differences among groups based on Tukey’s test Strain N HP3 71 H3B 62 VNW LOC 58 57 Total 248 Mean a 0.26 Std Min Max 0.08 0.10 0.46 0.17 b 0.09 0.04 0.38 0.17 b 0.07 0.03 0.38 c 0.06 0.02 0.24 C 0.08 0.05 0.37 0.13 0.18 HP3 0.35 H3B 0.30 DRG (g) 0.40 VNW 0.25 LOC 0.20 0.15 0.10 0.05 0.00 Lien Ha Nhan Farm Fig 3.5 Daily growth rate of HP3, H3B, VNW and LOC common carp strains in farms The results of survival rate comparisons among four common carp strains (HP3, H3B, VNW and LOC) are showed in Table 3.14 There are significant differences between fish survival rate among farms (P0.05) 23 Table 3.14 ANOVA table testing for differences in survival rate in relation to the effects of common carp strains (HP3, H3B, VNW and LOC) and culture types (low and high feed input) Source Corrected Model Intercept Farm Strain Error Total Corrected Total Type III Sum of Squares 90.87 4161.47 57.19 33.68 25.17 4277.52 116.04 df Mean Square 18.17 4161.47 28.60 11.23 4.20 12 11 F 4.33 991.99 6.82 2.68 Sig 0.05 0.00 0.03 0.14 Fig 3.6 Common carp from HP3 strain after seven months of cultured in a high input feed farm in Thai Nguyen province 3.6 Common carp biomass production in farms stocked with three common carp strain (HP3, H3B, LOC) Common carp production was compared for strains in 11 farms Biomass of common carp from 11 farms is presented in Table 3.23 Significant differences were observed between farms and strains of common carp (Table 3.24) The pair-wise comparison indicated difference in biomass of common carp between farms and between strains using Tukey’s test Biomass of three common carp strains ranged from 3.16g/m2 (LOC) to 4.80g/m2 (HP3) 24 Table 3.15 Biomass of common carp strains in 11 farms with strains (HP3, H3B and LOC) and cultured for 300 days in Yen Bai and Thai Nguyen provinces Farm Hoan Thuan Tuan Lieu Luat Que Vinh Thong Lien Ha Nhan Area Culture Strains (m2) systems 1000 HF HP3 H3B LOC 1000 LF HP3 H3B LOC 1000 LF HP3 H3B LOC 1000 LF HP3 H3B LOC 1000 LF HP3 H3B LOC 1000 LF HP3 H3B LOC 800 LF HP3 H3B LOC 1000 LF HP3 H3B LOC 1500 LF HP3 H3B LOC 1500 LF HP3 H3B LOC 1500 LF HP3 H3B LOC Stocking N Weight (g) 100 3.38 100 2.82 100 2.29 100 3.38 100 2.82 100 2.29 100 3.38 100 2.82 100 2.29 145 3.38 55 2.82 100 2.29 100 3.38 100 2.82 100 2.29 100 3.38 50 2.80 150 2.29 80 3.38 80 2.82 80 2.29 100 3.38 100 2.82 100 2.29 113 3.38 113 2.82 113 2.29 113 3.38 113 2.82 113 2.29 113 3.38 113 2.82 113 2.29 Harvesting NWeight (g) Sur (%) DGR 51 385.08 51.00 1.28 62 292.33 62.00 0.97 56 249.49 56.00 0.83 20 97.43 20.00 0.32 19 82.82 19.00 0.28 19 67.90 19.00 0.23 30 59.87 30.00 0.20 26 51.43 26.00 0.17 29 49.89 29.00 0.17 40 61.88 27.27 0.21 10 70.55 19.00 0.24 12 44.82 11.72 0.15 15 28.61 15.00 0.10 14 22.45 14.00 0.07 17 16.10 17.00 0.05 36 59.35 36.00 0.20 11 56.74 21.00 0.19 33 53.68 22.00 0.18 20 62.73 25.00 0.21 15 53.78 18.89 0.18 22 46.51 27.50 0.16 22 49.00 22.00 0.16 21 44.00 21.00 0.15 22 35.67 22.00 0.12 25 83.96 22.12 0.28 20 58.72 17.70 0.20 30 41.66 26.55 0.14 20 102.67 17.70 0.34 21 79.93 18.58 0.27 22 54.24 19.47 0.18 21 59.88 18.58 0.20 16 20.61 14.16 0.07 19 15.66 16.81 0.05 Biomass Adjusted (g/m2) (g/m2) 19.30 29.72 17.84 27.45 13.74 20.96 1.61 2.92 1.29 2.36 1.06 1.94 1.46 2.69 1.05 2.01 1.22 2.17 1.96 2.53 0.58 2.01 0.30 0.79 0.09 0.64 0.03 0.47 0.05 0.41 1.80 3.20 0.46 1.79 1.43 1.77 1.23 2.35 0.73 1.52 1.05 1.92 0.74 1.62 0.64 1.39 0.56 1.18 1.14 2.79 0.57 1.56 0.66 1.66 1.11 2.73 0.91 2.23 0.62 1.58 0.58 1.67 0.01 0.44 0.03 0.40 25 Table 3.16 ANOVA analyses of biomass of HP3, H3B, and LOC common carp strains Source Type III Sum of Squares Corrected Model 1634.65 Intercept 519.00 Farm 1619.77 Strain 14.88 Error 33.24 Total 2186.89 Corrected Total 1667.90 df Mean Square F 12 136.22 81.95 519.00 312.23 10 161.98 97.45 7.44 4.48 20 1.66 33 32 Sig 0.00 0.00 0.00 0.02 3.7 Common carp biomass production comparing farms stocked with two common carp strains (HP3 and LOC) ANOVA analysis of biomass of common carp showed that there were significant differences in biomass between farms, feed input, and the strains (Table 3.25) The biomass of common carp in two feed input systems are given in Table 3.26 and Table 3.27 The average common carp biomass for each strain in both high and low feed input systems is given in Table 3.27 Table 3.17 ANOVA analysis of biomass of HP3 and LOC common carp strains Source Corrected Model Intercept Farm Strain Feed input Strain * Feed input Error Total Corrected Total Type III Sum of Squares 1416.77 1478.65 557.10 14.75 844.86 3.69 32.62 2198.60 1449.39 df Mean Square 19 74.57 1478.65 16 34.82 14.75 844.86 3.69 16 2.04 36 35 F 36.58 725.34 17.08 7.24 45.84 1.81 Sig 0.00 0.00 0.00 0.23 0.00 0.20 26 Table 3.18 Biomass of common carp strains in 18 farms with strains (HP3 and LOC) cultured for 300 days Superscripts indicate significant differences among groups based on Tukey’s test Farm Area Culture Strains (m2) systems Hoan 1000 HF HP3 LOC Thuan 1000 LF HP3 LOC Tap 800 HF HP3 LOC Tuan 1000 LF HP3 LOC Chung 1000 HF HP3 LOC Lien 1500 LF HP3 LOC Hom 800 LF HP3 LOC Dieu 600 LF HP3 LOC Ha 1500 LF HP3 LOC Lieu 1000 LF HP3 LOC Luat 1000 LF HP3 LOC Nhan 1500 LF HP3 LOC Truong 500 HF HP3 LOC Que 1000 LF HP3 LOC Vinh 800 LF HP3 LOC Ke 550 LF HP3 LOC Thong 1000 LF HP3 LOC Lich 500 LF HP3 LOC Stocking N Weight (g) 100 3.38 100 2.29 100 3.38 100 2.29 120 3.38 120 2.29 100 3.38 100 2.29 100 3.38 100 2.29 113 3.38 113 2.29 80 3.38 80 2.29 100 3.38 100 2.29 113 3.38 113 2.29 145 3.38 100 2.29 100 3.38 100 2.29 113 3.38 113 2.29 75 3.38 75 2.29 100 3.38 150 2.29 80 3.38 80 2.29 90 3.38 90 2.29 100 3.38 100 2.29 75 3.38 75 2.29 Harvesting N Weight (g) Sur (%) 51 385.08 51.00 56 249.49 56.00 20 97.43 20.00 19 67.90 19.00 17 756.38 14.17 30 465.74 25.00 30 59.87 30.00 29 49.89 29.00 18 166.64 18.00 19 98.03 19.00 25 83.96 22.12 30 41.66 26.55 19 64.88 24.00 16 58.09 21.00 22 95.20 22.00 23 37.40 23.00 20 102.67 17.70 22 54.24 19.47 40 61.88 27.27 12 44.82 11.72 15 28.61 15.00 17 16.10 17.00 21 59.88 18.58 19 15.66 16.81 22 200.71 29.33 27 156.85 36.00 36 59.35 36.00 33 53.68 22.00 20 62.73 25.00 22 46.51 27.50 20 61.88 22.22 23 87.15 25.56 22 49.00 22.00 22 35.67 22.00 20 57.99 26.67 22 44.39 29.33 DGR 1.28 0.83 0.32 0.23 2.52 1.55 0.20 0.17 0.56 0.33 0.28 0.14 0.22 0.19 0.32 0.12 0.34 0.18 0.21 0.15 0.10 0.05 0.20 0.05 0.67 0.52 0.20 0.18 0.21 0.16 0.21 0.29 0.16 0.12 0.19 0.15 Biomass Adjusted (g/m2) (g/m2) 19.30 29.72 13.74 21.15 1.61 2.92 1.06 1.94 15.57 16.07 17.12 17.47 1.46 2.69 1.22 2.17 2.66 4.50 1.63 2.79 1.14 2.79 0.66 1.66 1.22 2.34 0.99 1.83 2.93 3.14 1.05 1.29 1.11 2.73 0.62 1.58 1.96 2.53 0.30 0.79 0.09 0.64 0.05 0.41 0.58 1.67 0.03 0.40 8.32 8.83 8.13 8.47 1.80 3.20 1.43 1.77 1.23 2.35 1.05 1.92 1.70 2.06 3.27 3.34 0.74 1.62 0.56 1.18 1.81 2.32 1.61 1.95 27 Table 3.19 Biomass of HP3 and LOC common carp strains grown for a period of 10 months in 18 farms with two types of feed input in Yen Bai and Thai Nguyen provinces Strains Feed input Low (g/m2) High (g/m2) HP3 2.36 ± 1.15a 14.78 ± 2.15b LOC 1.59 ± 1.15a 12.47 ± 2.15b 3.8 Demand of the improved common carp seed A survey on demand for genetically improved common carp strain was conducted in three provinces (Yen Bai, Thai Nguyen and Vinh Phuc) which have a high level of common carp aquaculture In these provinces common carp are cultured mostly in two different farming systems consisting of ponds and flooded rice fields The provinces differ in that Yen Bai is a mountainous region, Thai Nguyen is partly mountainous with midlands while Vinh Phuc is a delta area A total of 25 common carp hatcheries and nursery producers were surveyed Details of interviewees are presented in Table 3.30 Table 3.20 Number of hatcheries and fry nursing farmers in provinces Provinces Interviewee Hatchery producer Nursery farmer 10 25 20 Yen Bai Thai Nguyen Vinh Phuc Total The results of the survey showed the number of common carp seed produced was highly variable among fish hatcheries The proportion of common carp produced ranged from 10.0% to 66.7% with an average of 37.4% of the total freshwater fish species produced (Table 3.31) Most of hatcheries surveyed have produced both local (VNW) and genetically improved common carp (three blood lines) (Table 3.32) It can be seen from Table 3.32 the proportion of genetically improved common carp produced in hatcheries ranged from 16.7% to 100% and the average proportion of improved genetically common carp was 48.7% 28 Table 3.21 Number of common carp fry produced in five hatcheries in Thai Nguyen, Yen Bai and Vinh Phuc provinces in 2006 Hatchery Dong Ly No of fry (x 1000) 1,200 No of common carp fry Proportion of carp fry (x 1000) (%) 500 41.67 Van Chan 60,000 30,000 50.00 Phu Binh 120,000 24,000 20.00 30,000 20,000 66.67 Vu Di 120,999 12,000 9.92 Total 332,199 86,500 26.04 Cu Van Table 3.22 Proportion of fry produced from genetically improved common carp lines in five hatcheries in Thai Nguyen, Yen Bai, and Vinh Phuc provinces in 2006 Hatchery Province No of carp fry (x 1000) No of Local strain (x 1000) Dong Ly Yen Bai 500 Van Chan Yen Bai 30,000 Phu Binh Thai Nguyen 24,000 Cu Van Thai Nguyen 20,000 Vu Di Vinh Phuc 12,000 86,500 Total Improved strain (x 1000) Propotion of improved strain (%) 500 100.00 25,000 5,000 16.67 24,000 9,600 40.00 20,000 100.00 5,000 7,000 58.33 54,000 42,100 48.67 Hybrid (Hungary x Vietnamese) and stocks derived from the genetically improved three blood lines (Hungarian, Vietnamese and Indonesian) with faster growth performance are preferred by most of the nursery farmers interviewed in three provinces However, many of the nursery farmers are not confident in identifying differences between hybrid and other genetically improved and local Vietnamese strains The main basis for determining the quality of common carp seed is the perceived reputation of the hatchery based on the farmers evaluation of the survival and growth performance of their fish in grow-out systems The results of a 2006 survey of 20 carp nursery farmers indicated that 95% of farmers cultured genetically improved strains 29 Based on data collected in earlier surveys it can be seen that demand for genetically improved common carp by nursery farmers is increasing in the three provinces, over the period 2004-2006 (Fig 3.9) While the demand for genetically improved common carp seed by nursery farmers in the three provinces investigated has been increasing it varies greatly between provinces The demand for seed from genetically improved carp strains was found to be very high in Thai Nguyen (>80%), and much lower in Vinh Phuc and Yen Bai (