Whole genome sequencing was performed on three samples of four finger threadfin Eleutheronema tetradactylum (KET 25 , KET 29 and KET 30) using illumina NextSeq500 platform using 2 × 150 bp chemistry. 8,390,317, 7,085,775 and 8,461,589 high quality reads were obtained after trimming low quality reads and adapter sequence. These high quality reads obtained were used for de novo assembly and obtained a number of scaffolds. From these scaffolds of vast sequenced data, we were able to identify 60246, 46107 and 60907 Simple Sequence Repeats (SSR) markers in KET 25 , KET 29 and KET 30 respectively, which will be useful in population genetic analysis and other diversity studies in Indian salmon. The gene prediction on assembled scaffolds predicted 31,943 genes for KET 25 ; 26,487 genes for KET 29 and 31,654 genes for KET 30 with average gene size of 458bp, 424bp and 459bp respectively. A total of 30,209, 25,107 and 29,943 genes were annotated against the NCBI Nr database for the samples respectively. E. tetradactylum is a commercially important fish species for many countries. This is the first report on the identification of genomic SSR markers in E. tetradactylum using NGS technology. This study provides an insight of baseline knowledge of the genome sequence of Indian salmon for future studies.

SummaryThe Indian oil sardine, Sardinella longiceps, is an important pelagic species in Indian waters, and shows divergent morphology while in sympatry. The reasons behind this divergent morphology were investigated using morphometric, genetic and nutritional analyses. Twenty-one morphometric characters (as percentage of standard length) and eight meristic characters were studied in the three variants to assess whether they are significantly diverged. Distinct clustering of morphotypes was evident in the principal component analysis on log-transformed ratios of morphological characters with PC1 and PC2, explaining 50.7% and 17

Mangrove red snapper, Lutjanus argentimaculatus is a commercially important fish. The genetic stock structure of L. argentimaculatus from Indian waters was identified using mitochondrial ATPase 6 and ATPase 8, and cytochrome b (Cytb) genes. A 842 bp region of ATPase 6/8 genes and 1105 bp region of Cytb gene were amplified in 120 samples from six different locations along the Indian coast and obtained 58 and 66 haplotypes, respectively. The high haplotype and low nucleotide diversity values along with mismatch distribution, Tajima's D and Fu's F analysis suggested a genetic bottleneck events or founder effect, with subsequent population expansion in L. argentimaculatus. Coefficient of genetic differentiation (F) values was low and nonsignificant for both ATPase 6/8 gene and Cytb genes indicating low genetic differentiation in L. argentimaculatus which can be managed as a unit stock in Indian waters.

Age and growth characteristics of the Indian oil sardine (Sardinella longiceps) was studied by interpreting microstructures on hard parts. Microstructures were validated to the time scales by observing their frequency of formation on hard parts of the fishes reared in confinement. Among the hard parts, sagittal otolith alone was found suitable for ageing the species as frequency of microstructure formation on them followed definite time scale. The estimates of age at length data and growth parameters from otolith analysis indicated faster growth in the species than the earlier reports by other methods. Despite an expected sexual divergence in their growth, results show identical growth in both sexes. It further highlighted the prevalence of very distinct temporal growth variation driven by habitat environment indicating significance of hard part studies on ecological understanding of fishes. It also aided in tracing the precise time of birth with high precision, identifying the cohorts that supported the fishery and possible inter-regional migration of the species. The data generated from hard part ageing would aid in better eco-biological understanding of species, precise stock assessment outputs and fishery forecasting.