Prediction of fillet yield in hatchery populations of Asian sea bass, Lates calcarifer (Bloch, 1790) using body weight and measurements

Abstract The purpose of this study was to develop and validate prediction equations for fillet traits in Asian sea bass. Ninety-day old fish (average weight = 9.48 ± 0.35 g; length = 8.78 ± 0.6 cm) from four hatchery stocks (Chachoengsao, Chon Buri, Chumphon, and Samut Songkram) were raised in earthen ponds. After 300 days, weight and body measurement data of live fish (n = 400) were collected. Mean individual weight was greatest for the Chacheongsao stock (1166.32 ± 23.42 g) and was similar for the other stocks, ranging from 982.96 ± 25.07 to 997.44 ± 24.71 g. Fillet percentage varied slightly from 47.33 to 49.88%. Positive high correlations were observed for weight and body measurements with fillet weight, whereas there were significant but weak correlations for body measurements with fillet yield. Prediction equations developed from body weight using simple linear regression models yielded R 2 values of 0.97–0.98 for fillet weight for each stock. Correlations between values predicted from the body weight models and actual values were 0.98–0.99 for fillet weight. Stepwise regression was performed to develop prediction models for fillet yield from body measurements. The best fillet yield prediction models identified length and an additional 2–3 measurement as potential predictors depending on the population. Prediction biases were close to zero despite low to moderate (r values of 0.20–0.51) degrees of predictive power of the models. However, prediction models for fillet yield should be further developed to increase predictability and be applicable to new data

Dynamic Data Feed to Bayesian Network Model and SMILE Web Application

Abstrac

Microsatellites revealed no genetic differentiation between hatchery and contemporary wild populations of striped catfish, Pangasianodon hypophthalmus (Sauvage 1878) in Vietnam

Aquaculture of the striped catfish, Pangasianodon hypophthalmus (Sauvage 1878), in Vietnam has become one of the fastest growing primary food production sectors in the world. Although a demand on quantity of fingerlings is currently reached, it is likely that the long term quality of the stocks may be uncertain due to lacking of genetic broodstock management measures. The present study employed five microsatellite loci to investigate levels of genetic variation of the stripped catfish of the current wild stocks as well as of the selected hatcheries in Vietnam. The study included four hatchery populations and two wild populations spawned in 2005 in the Mekong and Bassac Rivers, and one wild population (spawned in 2006) in the Bassac River. The results showed no genetic differentiation among populations as revealed by FST and a model-based clustering method. AMOVA also showed no genetic differentiation between pooled wild and pooled hatchery populations while variation within groups was significant. Genetic variation of wild (mean number of alleles per locus, A = 4.80&ndash;6.20; allelic richness, Ar = 4.54&ndash;5.06; mean effective number of alleles per locus, Ae = 2.86&ndash;3.20; observed heterozygosity, Ho = 0.62&ndash;0.65; expected heterozygosity, He = 0.62&ndash;0.64) and hatchery populations (A = 4.60&ndash;5.20; Ar = 4.10&ndash;4.83; Ae = 2.80&ndash;3.11; Ho = 0.61&ndash;0.66; He = 0.61&ndash;0.64) were not statistically different. There were no evidences for recent genetic bottleneck in all populations. Therefore it is implied that the hatchery stocks of striped catfish in Vietnam were founded from sufficient numbers of brooders and current population size is large. The domestication process is in an early stage.</div

Mineralogical and Geochemical Characteristics of the H-Pit of the Chatree Gold Deposit, Central Thailand: A Case Study for Assessment of Acid Rock Drainage and Heavy Metal Sources

H-pit is one of the significant ore lenses of the Chatree mine in Thailand. Au-Ag mineralization mainly occurs as veins, stockworks, and minor breccias hosted by volcanic and volcaniclastic rocks. Disseminated pyrites are commonly present near mineralized veins in the hanging wall zone. This study aims to assess the acid rock drainage (ARD) potential and heavy metal content from the H-pit area. The results indicate that hanging wall rock is a potential acid-forming (PAF) material related to disseminated pyrite formed by hydrothermal alteration. In contrast, the footwall and ore zone materials are classified as non-acid forming (NAF). Because the ore zone has calcite in the veins, it may help buffer the material’s acidity. The results of heavy metal analysis reveal that the ore zone has significantly higher contents of As, Cd, Cu, Pb, and Zn than those in the hanging wall and footwall zones. Moreover, the hanging wall and footwall materials have exceeding values for As, Cd, and Zn compared to those in typical igneous rocks. These heavy metals are interpreted to be sourced from (1) the primary composition in base metal sulfides (e.g., Cu, Pb, and Zn), (2) the substitution of trace elements in sulfides (e.g., As and Cd), and (3) the substitution of trace elements in calcite (e.g., Mn), as evidenced in the EPMA results. In conclusion, the hanging wall rocks in this study containing high sulfur in proximity to the ore zone are a PAF material with heavy metal contaminant sources, whereas the footwall and ore zone materials have a lower potential to be such sources at the Chatree mine

Genome-wide association study and genomic prediction for resistance against Streptococcus agalactiae in hybrid red tilapia (Oreochromis spp.)

Streptococcosis is a major disease that causes severe mortality in tilapia aquaculture worldwide. Although the conventional BLUP family selection to enhance disease resistance in a commercial red tilapia stock was successful, the response was low due to the low heritability of the traits. An alternative strategy is the utilization of genomic information to identify the best performing candidates within families. In this study, we performed genome-wide association studies for red tilapia resistance to Streptococcus agalactiae using 11,480 SNPs within 110 families represented by 1020 fish. Nineteen SNP markers were found to explain similar to 10% of the genetic variation. We compared the accuracies of genomic prediction using the pedigree-based (PBLUP), marker-based (GBLUP), and Bayesian models. The prediction accuracy was assessed by performing ten replicates of five-fold cross-validation. In each replicate, approximately 80% of the data (n similar to 816) were sampled for the training set and the remaining data (n similar to 204) were used for the validation. The BayesB model yielded the highest accuracies (0.31 and 0.20) followed by GBLUP (0.25 and 0.15) and PBLUP (0.15 and 0.06) for days to death and binary trait

Mineralogical and Geochemical Characteristics of the H-Pit of the Chatree Gold Deposit, Central Thailand: A Case Study for Assessment of Acid Rock Drainage and Heavy Metal Sources

H-pit is one of the significant ore lenses of the Chatree mine in Thailand. Au-Ag mineralization mainly occurs as veins, stockworks, and minor breccias hosted by volcanic and volcaniclastic rocks. Disseminated pyrites are commonly present near mineralized veins in the hanging wall zone. This study aims to assess the acid rock drainage (ARD) potential and heavy metal content from the H-pit area. The results indicate that hanging wall rock is a potential acid-forming (PAF) material related to disseminated pyrite formed by hydrothermal alteration. In contrast, the footwall and ore zone materials are classified as non-acid forming (NAF). Because the ore zone has calcite in the veins, it may help buffer the material’s acidity. The results of heavy metal analysis reveal that the ore zone has significantly higher contents of As, Cd, Cu, Pb, and Zn than those in the hanging wall and footwall zones. Moreover, the hanging wall and footwall materials have exceeding values for As, Cd, and Zn compared to those in typical igneous rocks. These heavy metals are interpreted to be sourced from (1) the primary composition in base metal sulfides (e.g., Cu, Pb, and Zn), (2) the substitution of trace elements in sulfides (e.g., As and Cd), and (3) the substitution of trace elements in calcite (e.g., Mn), as evidenced in the EPMA results. In conclusion, the hanging wall rocks in this study containing high sulfur in proximity to the ore zone are a PAF material with heavy metal contaminant sources, whereas the footwall and ore zone materials have a lower potential to be such sources at the Chatree mine

MtDNA diversity of the critically endangered Mekong giant catfish (Pangasianodon gigas Chevey, 1913) and closely related species : implications for conservation

Catfishes of the family Pangasiidae are an important group that contributes significantly to the fisheries of the Mekong River basin. In recent times the populations of several catfish species have declined, thought to be due to overfishing and habitat changes brought about by anthropogenic influences. The Mekong giant catfish Pangasianodon gigas Chevey, 1913 is listed as Critically Endangered on the IUCN Red List. In the present study, we assessed the level of genetic diversity of nine catfish species using sequences of the large subunit of mitochondrial DNA (16S rRNA). Approximately 570 base pairs (bp) were sequenced from 672 individuals of nine species. In all species studied, haplotype diversity and nucleotide diversity ranged from 0.118&plusmn;0.101 to 0.667&plusmn;0.141 and from 0.0002&plusmn;0.0003 to 0.0016&plusmn;0.0013, respectively. Four haplotypes were detected among 16 samples from natural populations of the critically endangered Mekong giant catfish. The results, in spite of the limited sample size for some species investigated, indicated that the level of genetic variation observed in wild populations of the Mekong giant catfish (haplotype diversity=0.350&plusmn;0.148, nucleotide diversity=0.0009&plusmn;0.0008) is commensurate with that of some other related species. This finding indicates that (1) wild populations of the Mekong giant catfish might be more robust than currently thought or (2) present wild populations of this species carry a genetic signature of the historically larger population(s). Findings from this study also have important implications for conservation of the Mekong giant catfish, especially in designing and implementing artificial breeding programme for restocking purposes.</div