As a euryhaline fish species that inhabits estuarine and coastal regions, the spotbanded scat (Selenotoca multifasciata) experiences growth influences during its larval stage due to variations in salinity. Here, we evaluated salinity required by early-stage spotbanded scat juveniles to achieve the highest growth performance, digestive enzyme activity, survival, and antioxidant capacity. We reared spotbanded scat juveniles (all 0.50 ± 0.05 g) in 0–35‰ salinity gradients for 50 days and recorded their survival rate every 10 days. After 50 experimental days, we measured morphological data, stomach and intestinal digestive enzyme activities, and liver antioxidant enzyme activities and malondialdehyde contents. In general, 5–15‰ salinity led to 100% survival. The 5‰ salinity group demonstrated the highest values for the following measures: final wet body weight; weight gain rate; specific growth rate; growth percentage; average daily gain; stomach amylase and lipase specific activities; and intestinal amylase, lipase, trypsin, and pepsin specific activities. However, stomach trypsin and pepsin activities did not demonstrate significant between-group differences (all p > 0.05). The 25‰ salinity group demonstrated the highest liver superoxide dismutase and glutathione peroxidase activities and malondialdehyde content. Finally, the 0‰ salinity group demonstrated the highest liver catalase activity. Thus, spotbanded scat juveniles demonstrate the highest survival rates, growth performance, and digestive enzyme activity at 5‰ salinity and the strongest oxidative stress responses at 25‰ salinity.

Acipenser baeri, one of the critically endangered animals on the verge of extinction, is a key species for evolutionary, developmental, physiology and conservation studies and a standout amongst the most important food products worldwide. Though the transcriptome of the early development of A. baeri has been published recently, the transcriptome changes occurring in the transition from embryonic to late stages are still unknown. The aim of this work was to analyze the transcriptomes of embryonic and post-embryonic stages of A. baeri and identify differentially expressed genes (DEGs) and their expression patterns using mRNA collected from specimens at big yolk plug, wide neural plate and 64 day old sturgeon developmental stages for RNA-Seq. The paired-end sequencing of the transcriptome of samples of A. baeri collected at two early (big yolk plug (T1, 32 h after fertilization) and wide neural plate formation (T2, 45 h after fertilization)) and one late (T22, 64 day old sturgeon) developmental stages using Illumina Hiseq2000 platform generated 64039846, 64635214 and 75293762 clean paired-end reads for T1, T2 and T22, respectively. After quality control, the sequencing reads were de novo assembled to generate a set of 149,265 unigenes with N50 value of 1277 bp. Functional annotation indicated that a substantial number of these unigenes had significant similarity with proteins in public databases. Differential expression profiling allowed the identification of 2789, 12,819 and 10,824 DEGs from the respective T1 vs. T2, T1 vs. T22 and T2 vs. T22 comparisons. High correlation of DEGs’ features was recorded among early stages while significant divergences were observed when comparing the late stage with early stages. GO and KEGG enrichment analyses revealed the biological processes, cellular component, molecular functions and metabolic pathways associated with identified DEGs. The qRT-PCR performed for candidate genes in specimens confirmed the validity of the RNA-seq data. This study presents, for the first time, an extensive overview of RNA-Seq based characterization of the early and post-embryonic developmental transcriptomes of A. baeri and provided 149,265 gene sequences that will be potentially valuable for future molecular and genetic studies in A. baeri.

The mud crab, Scylla paramamosain, has abundant nutrients in the ovary, where numerous lipids accumulate during ovarian maturation. However, the mechanism behind the accumulation of lipids in the ovary of mud crab during ovarian maturation is largely unknown. This study conducted a comparative transcriptome analysis of the ovaries of mud crabs at various stages of ovarian maturation. A total of 63.69 Gb of clean data was obtained, with a Q30 of 93.34%, and 81,893 unigenes were identified, including 10,996 differentially expressed genes (DEGs). After KEGG enrichment of these DEGs, MAPK signaling pathway was significantly enriched during vitellogenesis. Moreover, the expression levels of genes involved in carbohydrate, amino acid, and lipid metabolism were found to be higher during vitellogenesis. The two genes (Sp-Eip75B and Sp-Eip78C) that are homologous to the vertebrate gene PPARγ in the PPAR signaling pathway, were identified. Additionally, genes in MAPK signaling pathway might regulate lipid metabolism through PPAR signaling pathway based on Protein-Protein Interaction (PPI) network. These findings suggest that MAPK signaling pathway plays a critical role in lipid metabolism in the ovary during vitellogenesis, which provides new insights into the mechanism of lipid accumulation during ovarian maturation in mud crabs.

The complete mitochondrial genome of Chionodraco hamatus was obtained, which was 17 457 bp in length. This genome consists of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and a putative control region. Of the 37 genes, 28 were encoded by heavy strand, while 9 were encoded by light strand. Overall base composition of mitogenome is estimated to be 26.38% for A, 17.44% for G, 26.00% for T, 30.18% for C, respectively, with a slight A + T bias (52.38%). The phylogenetic analysis based on 13 concatenated protein-coding genes suggested that C. hamatus as a sister species to Chionodraco myersi was clustered in family Chionodraco. The complete mitochondrial genome sequence of C. hamatus could provide a basic data for the studies on evolution for low temperature adaptability, population structure, molecular systematic, stock evaluation and conservation genetics.

The chub mackerel (Scomber japonicus) is one of the most influential small pelagic fish in the Northwest Pacific Ocean, and accurate modeling approaches and model selection are critical points in predicting the Scomber japonicus fishing grounds. This study investigated the changes in catches and fishing days on no moonlight and bright moonlight days (2014-2022) and compared the differences in predictive performance between the LightGBM and RF models on three datasets under the two modeling approaches [those based on the light fishing vessels operational characteristics (Approach one) and those not (Approach Two)]. The results were as follows: 1) Stronger moonlight intensity (e.g., full moon) can limit the fishing efficiency of light fishing vessels, with most years showing a trend of a higher percentage of fishing days on bright moonlight days than catches percentage, i.e., no moonlight days resulted in higher catches with lower fishing days; 2) Compared to Modeling Approach Two, under Modeling Approach one, RF model achieved better predictive performance on dataset B, while the LightGBM model achieved better predictive performance on both datasets A and B; 3) Overall, the Approach One achieved more satisfactory prediction performance, with the optimal prediction performance on the complete dataset C improved from 65.02% (F1-score of the RF model, Approach Two) to 66.52% (F1-score of the LightGBM model, Approach Two); 4) Under the optimal modeling approach (Approach One) and the optimal model (LightGBM model), the differences in the importance of the variables on dataset A (no moonlight days) and dataset B (bright moonlight days) were mainly centered on the environmental variables, with CV, SLA, and SSS being the most important in dataset A, and CV, DO, and SLA being the most important in dataset B. This study provides a more scientific and reasonable modeling undertaking for the research of light purse seine fishing vessels, which is conducive to guiding fishermen to select the operating area and operating time of the Scomber japonicus fishery more accurately and comprehensively and realizing the balanced development of fisheries in terms of ecology and economy.