Mitochondrial ATPase 6/8 genes to infer the population genetic structure of silver pomfret fishPampus argenteusalong the Indian waters

The concept of "state fishes of India": Current status, knowledge gaps, and strategic plans for conservation and sustainable utilization

The concept of "state fishes of India" highlights the importance and significance of the prioritized fish species distributed across various states within the country. This review article systematically documents the current status of state fishes from various perspectives, identifies the prevailing knowledge gaps, and also highlights the issues and strategic plans essential for the conservation and sustainable utilization of these valuable genetic resources. A total of 8357 publications were checked for the consolidated information on state fish species, and the appropriate items were selected under eight categories: biology, physiology and nutrition, aquaculture, habitat and environmental parameters, genetics and biotechnology, harvest and postharvest, fish health management, and others. The synthesized information was used to present the current status of research and development on state fish species. The knowledge gaps that are to be addressed are also depicted under the perspectives of fisheries management and conservation aquaculture. Based on the findings, strategic plans for the targeted conservation programmes are proposed and discussed under various in situ and ex situ conservation measures. Further, the departmental processes involved in the declaration, the importance of stakeholder involvement, namely, local communities and policymakers, in fostering effective conservation measures, and planning for utilization of these valuable fish genetic resources are also indicated.

Genetic analyses reveal panmixia in Indian waters and population subdivision across Indian Ocean and Indo-Malay Archipelago for Decapterus russelli

The Indian Scad, Decapterus russelli is an important pelagic carangid widely distributed throughout the Indian Ocean and the Indo-West Pacific. Despite being widely distributed in the Indian Ocean, the information regarding genetic structuring and diversity has been lacking compared to its Indo Malay Archipelago counterparts. The present study was conducted to investigate the genetic stock structure of D. russelli based on mitochondrial (Cyt b) and nuclear (DrAldoB1) markers along Indian waters. The results indicated the presence of a single panmictic stock across the Indian Ocean region. High haplotype diversity associated with low nucleotide diversity suggested a population bottleneck followed by rapid population growth. Phylogenetic analysis revealed the absence of geographical clustering of lineages with the most common haplotype distributed globally. The pelagic life style, migratory capabilities, and larval dispersal may be the contributing factors to the observed spatial homogeneity of D. russelli. However, significant genetic differentiation was observed between the populations from Indian Ocean and Indo-Malay Archipelago. Hierarchical molecular variance analysis (AMOVA), pairwise FST comparisons and SAMOVA showed existence of two distinct genetic stocks of D. russelli in the Indian Ocean and IMA. The observed interpopulation genetic variation was high. A plausible explanation for the genetic differentiation observed between the Indo-Malay Archipelago and the Indian Ocean regions suggest the influence of historic isolation, ocean surface currents and biotic and abiotic features of the ocean. Also, there was a significant relationship between genetic distance and geographical distance between population pairs in a manner consistent with isolation-by-distance. These resulted in the evolution of a phylogeographic break for this species between these regions. The findings of these results suggest that D. russelli from the Indian Ocean shall be managed in its entire area of distribution as a single stock. Further, the Indian Ocean and Indo-Malayan stocks can be managed separately.

A Current Update on the Distribution, Morphological Features, and Genetic Identity of the Southeast Asian Mahseers, Tor Species

Simple Summary

The mahseer, particularly the Tor species, is of significant cultural and economic importance as a high-value freshwater food fish in the Southeast (SE) Asian region. However, overexploitation of natural stocks because of high demand and their deteriorating habitat has resulted in a marked decline of Tor species in the wild. There are 13 Tor species that inhabit SE Asian rivers. All these species share distinct morphology, which is the presence of the median lobe. The unique characteristics, including body color, mouth position, and number of lateral scales, distinguish one species from another. Nonetheless, the taxonomy of the Tor species remains unstable and confusing, with contradictory data presented by different authors from different countries for a single Tor species. Therefore, in this review, we have gathered data for the SE Asian Tor species, outlining their distribution, morphology, and genetic identification. In addition, the present review also proposes a list of valid Tor species in the SE Asian region. The proposed list will serve as a standard and template for improving SE Asia’s Tor taxonomy, enhancing the study’s continuity, and a better understanding of specific Tor species.

Abstract

The king of rivers or mahseer comprises three genera: Tor, Neolissochilus, and Naziritor, under the Cyprinidae family. The Tor genus has been classified as the true mahseer due to the presence of a median lobe among the three genera. The Tor species are widely distributed across Southeast (SE) Asia, and 13 Tor species have been reported previously: Tor ater, Tor dongnaiensis, Tor douronensis, Tor laterivittatus, Tor mosal, Tor mekongensis, Tor putitora, Tor sinensis, Tor soro, Tor tambra, Tor tambroides, Tor tor and Tor yingjiangensis. However, the exact number of valid Tor species remains debatable. Different and unstandardized approaches of applying genetic markers in taxonomic identification and morphology variation within the same species have further widened the gap and ameliorated the instability of Tor species taxonomy. Therefore, synchronized and strategized research among Tor species researchers is urgently required to improve and fill the knowledge gap. This review is a current update of SE Asia’s Tor species, outlining their distribution, morphology, and genetic identification. In addition, the present review proposes that there are ten valid Tor species in the SE Asian region. This list will serve as a template and standard to improve the taxonomy of the SE Asian Tor species, which could serve as a basis to open new directions in Tor research.

Gill transcriptomes reveal expression changes of genes related with immune and ion transport under salinity stress in silvery pomfret (Pampus argenteus)

Salinity is a major ecological factor in the marine environment, and extremely important for the survival, development, and growth of fish. In this study, gill transcriptomes were examined by high-throughput sequencing at three different salinities (12 ppt as low salinity, 22 ppt as control salinity, and 32 ppt as high salinity) in an importantly economical fish silvery pomfret. A total of 187 genes were differentially expressed, including 111 up-regulated and 76 down-regulated transcripts in low-salinity treatment group and 107 genes differentially expressed, including 74 up-regulated and 33 down-regulated transcripts in high-salinity treatment group compared with the control group, respectively. Some pathways including NOD-like receptor signaling pathway, cytokine-cytokine receptor interaction, Toll-like receptor pathway, cardiac muscle contraction, and vascular smooth muscle contraction were significantly enriched. qPCR analysis further confirmed that mRNA expression levels of immune (HSP90A, IL-1β, TNFα, TLR2, IP-10, MIG, CCL19, and IL-11) and ion transport-related genes (WNK2, NPY2R, CFTR, and SLC4A2) significantly changed under salinity stress. Low salinity stress caused more intensive expression changes of immune-related genes than high salinity. These results imply that salinity stress may affect immune function in addition to regulating osmotic pressure in silvery pomfret.

New insights from nuclear and mitochondrial markers on the genetic diversity and structure of the Indian white shrimp Fenneropenaeus indicus among the marginal seas in the Indian Ocean

Genetic variation in wild stocks of a major commercial shrimp, Fenneropenaeus indicus, from the marginal seas in the Indian Ocean was analysed using polymorphic microsatellite loci and mitochondrial COI gene. The average observed heterozygosity (Ho = 0.44 ± 0.02) and the expected heterozygosity (He = 0.73 ± 0.01) were high across loci and populations indicating high microsatellite variation. Pairwise F_ST and Bayesian clustering indicated the occurrence of four genetically distinct stocks out of the eight sampled populations with implications for specific management approaches. Mantel test for isolation by distance proved that genetic differentiation is not related to geographic distance between populations. Mitochondrial COI sequence analysis showed concordant differentiation pattern as well indicated the relevance of COI in population genetics of shrimps. Pairwise ɸST and phylogenetic and Bayesian analyses revealed four distinct clades, as observed with nuclear markers. Divergence time analysis revealed the origin and initial divergence of F. indicus corresponds to late Miocene and divergence to phylogroups in the Pleistocene. BSP analysis presented a long stable population size with a slight decrease in the late Pleistocene and gradually expanded to the current status. The information here will be useful in commercial shrimp breeding and selection programmes and management of natural stocks of Indian white shrimp.

Hints for panmixia in Scomberomorus commerson in Indian waters revealed by mitochondrial ATPase 6 and 8 genes

Scomberomorus commerson is an economically important migratory fish distributed worldwide. The genetic stock structure of S. commerson distributed along the Indian waters was identified using mitochondrial ATPase 6 and 8 genes. A total of 842 bp sequence of ATPase 6/8 genes obtained in this study revealed 23 haplotypes with mean low nucleotide diversity and high haplotype diversity. Co-efficient of genetic differentiation (FST) values obtained for pair wise populations were low and non-significant with an overall value of -0.02074. The high haplotype and low nucleotide diversity values together with mismatch distribution analysis suggested a history of genetic bottleneck events or founder effect, with subsequent population expansion in S. commerson. The findings of the present study indicated the panmixia nature of the species which can be managed as a unit stock in Indian waters.