Protosalanx Chinensis Research Articles

Analysis of the genetic structure of the introduced clearhead icefish (Protosalanx chinensis) populations in northern China.

When species are introduced to a new environment, they can quickly adapt to the environment and may differ from the indigenous species. The indigenous population of Protosalanx chinensis has a high level of genetic diversity, but it is unclear on the genetic diversity of the introduced populations in northeast China, which supports the major production of P. chinensis in the world. A total of 556 individuals of P. chinensis were collected during 2016-2021, from Lianhuan Lake (LHL), Xingkai Lake (XK), and Shuifeng Reservoir (SF), and one population was collected from the indigenous Taihu Lake (TH). Overall, 36 haplotypes were detected, and the genetic differences in P. chinensis populations within and between river basins were investigated. The nucleotide diversity (π) of the populations ranged from 0.0005 to 0.0032, and the haplotype diversity (Hd) ranged from 0.455 to 0.890, with the highest genetic diversity in the TH population, followed by the SF population, and lower genetic diversity in the XK and LHL populations. The analysis of the genetic differentiation index (Fst) and the genetic distance between populations showed that there was significant genetic differentiation between the TH population and the other populations. More sampling points have been set up in LHL for further analysis; the Dalong Lake (DL) and the Xiaolong Lake (XL) populations were far from the other populations within the LHL population. In this study, we didn't find a correlation between population size, stability, and genetic diversity, and the ecological measures of management should be decisive to the population dynamics. These results provide a basis for the rational utilization and effective management of P. chinensis.

Resource differences in the populations of Protosalanx chinensis between Dalong Lake and Amuta Lake in Daqing, Northeast China

The population structure of Protosalanx chinensis is affected by a variety of factors, including water environment, intraspecific differentiation, interspecific competition and commercial fishing. To investigate the growth performance and the current status of resource utilization of P. chinensis in two important fish farming grounds (Dalong Lake and Amuta Lake) in Daqing, Northeast China, we collected 1513 P. chinensis samples from April to December 2018 for measurement and recording the basic biological characteristics. We estimated the parameters including population growth, mortality and exploitation using Von Bertalanffy growth formula, Beverton-Holt model, Pauly's empirical formula and length-based Bayesian biomass estimation method. The results showed that the asymptotic body lengths of Dalong Lake (n=660) and Amuta Lake (n=853) populations were 183.75 and 169.10 mm, respectively. The growth performance indices were both 4.85, and the body mass growth equations were Wt=29.29×(1-e-2.1(t+0.07))3.2977 and Wt=28.72×(1-e-2.5(t+0.07))3.4168, respectively. The ages at inflection were 0.49 a and 0.43 a, and the condition factors were 5.30×10-4±1.38×10-4 and 4.00×10-4±1.61×10-4. The exploitation rates were 0.60 and 0.61, and the relative catch per unit of supplementation were 0.069 and 0.075, respectively. The current differences in population resources between Dalong Lake and Amuta Lake in Daqing were mainly manifested in the parameters related to growth characteristics. The main reason for such differences was changes in the survival conditions of P. chinensis populations after the period of dietary transition induced by the density differences.

Chromosome-Level Genome Assembly of Protosalanx chinensis and Response to Air Exposure Stress.

Protosalanx chinensis is a suitable particular species for genetic studies on nearly scaleless skin, transparency and high sensitivity to hypoxia stress. Here, we generated a high-quality chromosome-level de novo assembly of P. chinensis. The final de novo assembly yielded 379.47 Mb with 28 pseudo-chromosomes and a scaffold N50 length of 14.52 Mb. In total, 21,074 protein-coding genes were predicted. P. chinensis, Esox lucius and Hypomesus transpacificus had formed a clade, which diverged about 115.5 million years ago. In the air exposure stress experiment, we found that some genes play an essential role during P. chinensis hypoxia, such as bhlh, Cry1, Clock, Arntl and Rorb in the circadian rhythm pathway. These genomic data offer a crucial foundation for P. chinensis ecology and adaptation studies, as well as a deeper understanding of the response to air exposure stress.

The Resource Status of Plankton after Stocked Protosalanx chinensis Population Collapse in a Lake of Northeastern China

In order to understand the relative strength of top-down and bottom-up control in lakes of grazing alien fish, Protosalanx chinensis, investigations were designed in Lake Longhu (Lake L, P. chinensis introduced in 2013) and Lake Qijia (Lake Q, P. chinensis free). Plankton samples were collected bimonthly through the whole life cycle of P. chinensis (from February to December in 2018). A total of 133 phytoplankton and 68 zooplankton species were recorded in the two lakes. The total density and biomass of phytoplankton and zooplankton were 991.89 × 104 ind/L and 9.2418 mg/L as well as 5212 ind/L and 20.2646 mg/L, respectively. This study revealed that P. chinensis grazing did not deplete the zooplankton resources in the lake where it was stocked. Biodiversity in Lake L was not significantly different from that in Lake Q based on both phytoplankton and zooplankton. Overall, the over grazing of P. chinensis was not found in Lake L. Nevertheless, compared to Lake Q, the correlation between phytoplankton and zooplankton was weakened in Lake L, which meant there were still some effects of stocking P. chinensis on the ecological equilibrium of the plankton community, although no dramatic influences were found in Lake L yet. We also found that P. chinensis and Cladocera were significantly correlated, which should account for the top-down influences. Long-term successive investigations are suggested for sustainable resource utilization and maintaining biological balance.

Feeding Selectivity and Diet Shift of Protosalanx chinensis during Spring in Lake Dalong, Northeastern China

Ontogenetic niche shifts have played an important role in the life history and ecological functions of fish. The clearhead icefish (Protosalanx chinensis, Basilewsky, 1855) is a small, pelagic, and commercially important fish that mainly feeds on zooplankton and will transition to feeding on fish when prey fish are available, though its life span is only about one year. In fact, we know little about the food selectivity and diet shifting of P. chinensis before its transition to feeding on fish. To reveal the food selectivity of P. chinensis before its transition to feeding on fish, the gut contents and environmental zooplankton community were investigated simultaneously in Lake Dalong of Northeastern China from April to June 2021. The results showed that P. chinensis experienced a diet shift from copepoda to cladocera during spring in Lake Dalong. From April to early June, both the size of cladocera and copepoda in guts increased as the size of P. chinensis increased. However, the favorite category changed to the smaller cladocera in late June, when the density of the smaller cladocera was rather high relatively. Considering June was the critical period for P. chinensis to prepare for transitioning to feeding on fish, the food resources availability must be seriously considered for sustainable aquaculture of P. chinensis. It was hypothesized that there was a trade-off of feeding selectivity between the size and density of the prey.

Genomic insights into the postintroduction failure of the Asian icefish Protosalanx chinensis in China.

Biological introductions provide a natural ecological experiment unfolding in a recent historical timeframe to elucidate how evolutionary processes (such as founder effects, genetic diversity and adaptation) shape the genomic landscape of populations postintroduction. The Asian icefish, Protosalanx chinensis, is an economically important fishery resource, deliberately introduced into dozens of provinces across China for decades. However, while invading and disturbing the local ecosystem, many introduced populations declined, disappearing mysteriously in a very short time. The way in which various evolutionary forces integrate to result in invasion failure of an introduced population remains unknown. Here, we performed whole-genome sequencing of 10 species from the Salangidae family and 70 Asian icefish (Protosalanx chinensis) individuals from 7 geographic populations in China, aiming to characterize the evolutionary fate of introduced populations. Our results show that compared to other Salangidae species, P. chinensis has low genetic diversity, potentially due to the long-lasting decline in population size. In a recently introducted population, Lugu lake, severe sampling effects and a strong bottleneck further deteriorated the genomic landscape. Although the introduced population showed signs of reduced genetic load, the purging selection efficiency was low. Our selective sweep analysis revealed site frequency changes in candidate genes, including gata1a and hoxd4b, which could be associated with a decrease in dissolved oxygen in the deep-water plateau lake. These findings caution against the widespread introduction of P. chinensis in China and lay the groundwork for future use of this economically species.

Transcriptome Sequencing Analysis Reveals Dynamic Changes in Major Biological Functions during the Early Development of Clearhead Icefish, Protosalanx chinensis

Early development, when many important developmental events occur, is a critical period for fish. However, research on the early development of clearhead icefish is very limited, especially in molecular research. In this study, we aimed to explore the dynamic changes in the biological functions of five key periods in clearhead icefish early development, namely the YL (embryonic), PM (first day after hatching), KK (fourth day after hatching), LC (seventh day after hatching), and SL (tenth day after hatching) stages, through transcriptome sequencing and different analysis strategies. A trend expression analysis and an enrichment analysis revealed that the expression ofgenes encoding G protein-coupled receptors and their ligands, i.e., prss1_2_3, pomc, npy, npb, sst, rln3, crh, gh, and prl that are associated with digestion and feeding regulation gradually increased during early development. In addition, a weighted gene co-expression network analysis (WGCNA) showed that eleven modules were significantly associated with early development, among which nine modules were significantly positively correlated. Through the enrichment analysis and hub gene identification results of these nine modules, it was found that the pathways related to eye, bone, and heart development were significantly enriched in the YL stage, and the ccnd2, seh1l, kdm6a, arf4, and ankrd28 genes that are associated with cell proliferation and differentiation played important roles in these developmental processes; the pak3, dlx3, dgat2, and tas1r1 genes that are associated with jaw and tooth development, TG (triacylglycerol) synthesis, and umami amino acid receptors were identified as hub genes for the PM stage; the pathways associated with aerobic metabolism and unsaturated fatty acid synthesis were significantly enriched in the KK stage, with the foxk, slc13a2_3_5, ndufa5, and lsc2 genes playing important roles; the pathways related to visual perception were significantly enriched in the LC stage; and the bile acid biosynthetic and serine-type peptidase activity pathways were significantly enriched in the SL stage. These results provide a more detailed understanding of the processes of early development of clearhead icefish.

Recombinant Mitochondrial Genomes Reveal Recent Interspecific Hybridization between Invasive Salangid Fishes.

The interspecific recombination of the mitochondrial (mt) genome, if not an experimental artifact, may result from interbreeding of species with broken reproductive barriers, which, in turn, is a frequent consequence of human activities including species translocations, habitat modifications, and climate change. This issue, however, has not been addressed for Protosalanx chinensis and other commercially important and, simultaneously, invasive salangid fishes that were the product of successful aquaculture in China. To assess the probability of interspecific hybridization, we analyzed the patterns of diversity and recombination in the complete mitochondrial (mt) genomes of these fishes using the GenBank resources. A sliding window analysis revealed a non-uniform distribution of the intraspecific differences in P. chinensis with four highly pronounced peaks of divergence centered at the COI, ND4L-ND4, and ND5 genes, and also at the control region. The corresponding divergent regions in P. chinensis show a high sequence similarity (99–100%) to the related salangid fishes, Neosalanx tangkahkeii and N. anderssoni. This observation suggests that the divergent regions of P. chinensis may represent a recombinant mitochondrial DNA (mtDNA) containing mt genome fragments belonging to different salangid species. Indeed, four, highly significant (pairwise homoplasy index test, P < 0.00001) signals of recombination have been revealed at coordinates closely corresponding to the divergent regions. The recombinant fragments are, however, not fixed, and different mt genomes of P. chinensis are mosaic, containing different numbers of recombinant events. These facts, along with the high similarity or full identity of the recombinant fragments between the donor and the recipient sequences, indicate a recent interspecific hybridization between P. chinensis and two Neosalanx species. Alternative hypotheses, including taxonomical misidentifications, sequence misalignments, DNA contamination, and/or artificial PCR recombinants, are not supported by the data. The recombinant fragments revealed in our study represent diagnostic genetic markers for the identification and distinguishing of hybrids, which can be used to control the invasive dynamics of hybrid salangid fishes.

Life-history traits and intra-cohort divergence of clearhead icefish (Protosalanx chinensis), indicating cannibalism increased fitness

Cannibalism is considered one of the causes of intra-cohort size divergence in fish and is usually believed to result in increased fitness in terms of survival and reproduction, but direct evidence of this is lacking. Population demographics of the clearhead icefish (Protosalanx chinensis) from Lake Xingkai (Khanka) were investigated for one year. Size-frequencies exhibited a bimodal distribution from July through January, where the population diverged into an upper and a lower modal group based on size. Stomach content analysis confirmed the occurrence of cannibalism, where fish belonging to the larger, upper modal group preyed upon those of the smaller, lower modal group. We found P. chinensis does not spawn until all of the oocytes have reached maturity and then a single spawning event occurs although the oocytes may develope asynchronously in the ovary. Upper modal group females matured slightly earlier than those of the lower modal group, and reproductive investment was considerably greater in the upper modal group than the lower modal group. The lower modal males made up the majority of the population after the spawning period, which meant they may have few opportunities to participate in reproduction. Therefore, piscivory and cannibalism of P. chinensis appears to have increased fitness of the fish belonging to the upper modal group and greatly reduced the fitness of those belonging to the lower modal group.

Insights into the Evolution of Neoteny from the Genome of the Asian Icefish Protosalanx chinensis.

SummarySalangids, known as Asian icefishes, represent a peculiar radiation within the bony fish order Protacanthopterygii where adult fish retain larval characteristics such as transparent and miniaturized bodies and a cartilaginous endoskeleton into adulthood. Here, we report a de novo genome of Protosalanx chinensis, the most widely distributed salangid lineage. The P. chinensis genome assembly is more contiguous and complete than a previous assembly. We estimate that P. chinensis, salmons, trouts, and pikes diverged from a common ancestor 185 million years ago. A juxtaposition with other fish genomes revealed loss of the genes encoding ectodysplasin-A receptor (EDAR), SCPP1, and four Hox proteins and likely lack of canonical fibroblast growth factor 5 (FGF5) function. We also report genomic variations of P. chinensis possibly reflecting the immune system repertoire of a species with a larval phenotype in sexually mature individuals. The new Asian icefish reference genome provides a solid foundation for future studies.

The mitochondrial genome of clearhead icefish Protosalanx chinensis (Salmoniformes: Salangidae)

The complete mitochondrial genome of Protosalanx chinensis was determined to be 16,879 bp in length. It consists of 13 protein-coding genes, 22 tRNAs, 2 ribosomal RNAs, and a control region. The gene composition and the structural arrangement of the P. chinensis complete mtDNA were identical to most of the other vertebrates. The molecular data here we presented could play a useful role to study the evolutionary relationships and population genetics of Salangidae fish.

Length-weight relationships of seven freshwater fishes from the JiangSu province, China

The length-weight relationships (LWRs) are presented for seven freshwater fish species (Odontobutis potamophila, Protosalanx chinensis, Acheilognathus chankaensis, Megalobrama skolkovii, Pelteobagrus vachelli, Macropodus chinensis, Pseudobrama simoni) from JiangSu province in China. A total of 1340 specimens were sampled and measured between August 2012 and September 2013. No information regarding the LWRs of these species was available in FishBase.

Transplantation of Icefish (Salangidae) in China: Glory or Disaster?

AbstractChina has a long history of aquaculture, and it contributes the largest aquaculture production worldwide. Aside from expanding aquaculture area and maximizing unit yield, introducing new potential species is greatly encouraged. Icefish (Salangidae) from Taihu Lake have been introduced into other lakes and reservoirs throughout the country since 1979. Neosalanx tangkahkeii was introduced into the southern part of China, and Protosalanx chinensis was introduced into the northern part of China, and both species have been introduced into a small part of central China and Yunnan Province in southwest China. Only one‐third of the transplantation was successful, and most of their yields experienced a burst‐down course. Intrinsic traits of icefish including annual life cycle, higher fecundity, lower trophic level, together with sufficient environment capacity supported the population forming and burst, while overfishing, pollution and short of food could result in the failure of the transplantation. The introduction of icefish brought in economic benefits, but severely threatened biodiversity, especially in plateau lakes in Yunnan Province, caused possible hybridization and carried diseases. According to different environmental conditions and economic needs at regional scale, further transplantation of icefish would face respective fate as resource conservation, rapid development, limitation and insignificance. Increasing attentions on environmental protection and sustainable resource utilization require a fresh evaluation and adjustment of icefish transplantation to achieve an ecologically healthy aquaculture.

Use of Elemental Fingerprint Analysis to Identify Localities of Collection for the Large Icefish Protosalanx chinensis in Taihu Lake, China

Use of Elemental Fingerprint Analysis to Identify Localities of Collection for the Large Icefish Protosalanx chinensis in Taihu Lake, China

Molecular characterization of icefish, (Salangidae family), using direct sequencing of mitochondrial cytochrome b gene

The Salangidae fish family includes the genera Neosalanx and Protosalanx, known as icefish or silverfish, which are imported frozen from China to Italy. The variable morphological characteristics and the small size make their particular species extremely difficult to identify. As a consequence it is not feasible to verify the precise identity of the product on the market. This means that Chinese fish can be used to fraudulently replace some much more expensive Italian species, which are similar in shape and size. Ten specimens of Neosalanx taihuensis directly collected from Lake Taihu and two hundred specimens of icefish collected from forty markets (twenty-seven from Italy and thirteen from China) were examined by direct sequencing of a portion of mitochondrial DNA belonging to the cytochrome b (cytb) gene in order to identify them at a specie level and to investigate any potential mislabelling. A BLAST analysis of the obtained sequences identified 90% of market samples as N. taihuensis, which rose to 93% when only products collected in Italy were considered. A phylogenetic tree was also constructed and the high bootstrap values obtained further supported our findings. Our results are also in agreement with some reports by Chinese authors, who describe this species as the most exploited of the Salangidae family in China in terms of internal consumption and exports. Furthermore, these findings corroborate the documentation collected from all over Italy, which reports N. taihuensis as being the only regularly imported species of icefish. The other species of salangids identified were Neosalanx anderssoni and Protosalanx chinensis. Overall, 15% of samples collected on the Italian market were mislabelled, thus confirming the existence of commercial frauds. By verifying the presence of one main icefish species on the Italian market (N. taihuensis), this study has contributed in identifying a precise target for inexpensive and rapid molecular analytical methods aimed at detecting and preventing fraud involving icefish.

&lt;i&gt;Neosalanx pseudotaihuensis&lt;/i&gt;--a new transplant object of icefish

近太湖新银鱼不仅在形态上与太湖新银鱼很相似,而且它们的个体大小、生长速度、食性等方面也十分相近。近几年在湖北地区的湖泊、水库相继发现了近太湖新银鱼,并在湖北省广水市徐家河水库成为优势种类,形成了较大生产规模。从目前研究的结果来看,近太湖新银鱼也是适宜我国湖泊、水库移植的银鱼种类。;Icefishes(Salangidae) are very important and valuable fishes in the inland waters of China.The N.taihuensis was successfully introduced from Taihu Lake to Dianchi Lake by the scientific workers in Nanjing Institute of Geography & Limnology, CAS in the end of 1970s.Up to mow, there are only two species for successful transplantation, one is N.taihuensis, the other Protosalanx chinensis, although more than 20 species of icefish have been found and identified in China.Neosalaruc pseudotaihuensis is a new species which was nominated by Zhang Yulin in 1987.It is similar to N.taihuensis not only in form, but also in body size, growth speed and food selestissty.In recent years, it has found its distribution in some lakes and reservoirs in Hubei Province, and becomes dominant and forms a larger productive scale in Xujiahe Reservoir,Guangshui City,Hubei Province.The research reveals that N. pseudotaihuensis is a new icefish species which can be transplanted to lakes and reservoirs.

Taxonomy, biology and abundance of icefishes, or noodlefishes (Salangidae), in the Yellow River estuary of the Bohai Sea, China

Four species of icefishes were sampled in the Yellow River estuary of the Bohai Sea from April 1984 to April 1985 and from February 1988 to June 1989. Morphological analysis showed that they belonged to three subfamilies of Salangidae: one species from Protosalangicae, Protosalanx chinensis; two species from Salanginae, Salanx ariakensis and Salanx prognathus; and one species, Neosalanx andersoni, from Salangichthyinae, a new subfamily. External morphological characteristics, population composition, growth, maturity, food habits, longevity, fecundity, abundance and distribution of these icefishes are described. Based on these analyses, a clear outline of taxonomy, zoogeography aod biology of icefishes in the Yellow River estuary of the Bohai Sea was established.

Taxonomy, biology and abundance of icefishes, or noodlefishes (Salangidae), in the Yellow River estuary of the Bohai Sea, China

Four species of icefishes were sampled in the Yellow River estuary of the Bohai Sea from April 1984 to April 1985 and from February 1988 to June 1989. Morphological analysis showed that they belonged to three subfamilies of Salangidae: one species from Protosalangicae, Protosalanx chinensis; two species from Salanginae, Salanx ariakensis and Salanx prognathus; and one species, Neosalanx andersoni, from Salangichthyinae, a new subfamily. External morphological characteristics, population composition, growth, maturity, food habits, longevity, fecundity, abundance and distribution of these icefishes are described. Based on these analyses, a clear outline of taxonomy, zoogeography aod biology of icefishes in the Yellow River estuary of the Bohai Sea was established.