Poyang Lake, the largest freshwater lake in China, possesses abundant fishery resources, but its fish stock status is still unclear. In this work, the stock status of and fishing efforts of nine major economic fishes in the Poyang Lake were estimated from 2000 to 2019 with a catch-based maximum sustainable yield (CMSY) model based on catch and resilience data. It was further predicted whether the biomass of those fishes could be restored to support maximum sustainable yield (B_msy) under the policy of “Ten years fishing moratorium in the Yangtze River”. The results showed that goldfish Carassius auratus, grass carp Ctenopharyngodon idella, and black carp Mylopharyngodon piceus suffered from higher fishing efforts and low biomass in the past 20 years; bighead carp Hypophthalmichthys nobilis, yellow catfish Tachysurus fulvidraco, and common carp Cyprinus carpio responded differently to their fishing efforts; silver carp Hypophthalmichthys molitrix, Amur catfish Silurus asotus, and mandarin fish Siniperca chuatsi were underexploited. Six species were overfished in 2019, and their biomass would be expected to recover for sustainable exploitation during the fishing moratorium, except for M. piceus. This study provided a case study of feasible freshwater fishery evaluation in limnetic ecosystems.

Background: Red swamp crayfish (Procambarus clarkii) is one of the most economically important farmed aquatic species in China. However, it is also a famous invasive species in the world. Methods: The present study simulated near current (1970-2000) and future (2030s, 2050s) suitable distribution areas of P. clarkii aquaculture in China under 4 climate scenarios (SSP126, SSP245, SSP370 and SSP585) and screened out the dominant factors affecting the distribution as well, using the MaxEnt model with 60 effective distribution points. Result: The results showed that mean AUC was 0.986, which indicated a better forecast. The highly suitable aquaculture areas for crayfish were Hubei, Hunan, and Anhui Province. The important environmental factors affecting the distribution of P. clarkii were mean temperature of warmest quarter, precipitation of wettest quarter, isothermality and temperature seasonality. Compared to the present-day predictions, the total area of suitable distribution (general-, medium- and high-suitability) gradually increased in the 2030s and 2050s. The ranking of the total area under different climate change scenarios were SSP370 greater than SSP585 greater than SSP126 greater than SSP245 in the 2030s and SSP585 greater than SSP370 greater than SSP126 greater than SSP245 in the 2050s, indicating that as the greenhouse gas emissions increase, the distribution of P. clarkii was likely to increase. It was of note that the area of high-suitability distribution for SSP585 greatly increased, but for SSP245 greatly decreased in the 2050s. This suggested that we should attach great importance to the ecological risk of crayfish in China and prevent the blind development of the industry.

This study provides a systematic and multidimensional evaluation of flesh quality differences between triploid (T-PZ) and allotetraploid (A-PZ) Pengze crucian carp, addressing a significant gap in genetic improvement of this economically important aquaculture species. By integrating proximate composition analysis, detailed amino acid and fatty acid profiling, volatile flavor compounds, texture characteristics, and non-targeted muscle metabolomics, we delineated the distinct quality attributes associated with each cytotype. The results showed that T-PZ possessed significantly higher crude protein and histidine content, along with a superior flavor profile characterized by lower relative levels of fishy odor-associated aldehydes such as hexanal, heptanal, and nonanal. In contrast, A-PZ exhibited significantly elevated crude lipid, total fatty acid, SFA, MUFA, PUFA, and EPA + DHA contents; a higher essential amino acid index; and improved tenderness indicated by significantly lower hardness and chewiness. Metabolomic analysis identified 216 significantly different metabolites, notably enriched in key pathways including glycine, serine, and threonine metabolism; arginine biosynthesis; and glycerophospholipid metabolism. These comprehensive findings elucidate the complementary nutritional and sensory strengths of the two ploidy forms, thereby establishing a crucial scientific foundation for targeted, quality-driven breeding programs aimed at optimizing flesh quality in Pengze crucian carp for the aquaculture industry.

Background: Chinese pond turtle (CPT, Mauremys reevesii) is a typical species with temperature-dependent sex determination (TSD). Pond slider turtle (PST, Trachemys scripta) is considered one of the worst invasive species in the world. In order to analyze the adaptive evolution of fecundity traits in CPT and TSD, the rapidly evolving gene families were obtained and functional enrichment analysis was performed. At the same time, CPT and PST species-specific genes were also enriched for their fecundity traits. Methods: Orthofinder software was employed to search homologous genes based on protein sequence. CAFÉ software was used to obtain the expansion and contraction gene families of CPT and PST. Then, GO terms and pathway enrichment analyses were performed using TBtools software and Swissprot database. Result: In CPT, 159 rapid expansion gene families GO enrichment results showed that the reproductive activities related pathways were mainly three significant enrichment process, spermatogenesis, steroid hormone mediated signaling pathway and male gamete generation. 2 rapidly contraction gene families showed that there was no significant enrichment pathway related to reproduction. The pathway of significant enrichment were RNA biosynthetic process, regulation of RNA metabolic process and regulation of cellular metabolic process. The gene families unique to the species were significantly enriched in pathways DNA replication-dependent nucleosome organization, DNA replication-dependent nucleosome assembly and negative regulation of megakaryocyte differentiation. In PST, 15 rapid expansion gene families GO enrichment results showed that the most significant GO terms mainly consisted of biological processes which were involved in endocrine process, regulation of endocrine process and cellular response to steroid hormone stimulus, but spermatogenesis and male gamete generation gene families also expanded. 58 rapidly contraction gene families showed that the pathways of significant enrichment were endocrine process, cellular response to steroid hormone stimulus and regulation of endocrine process. At the same time, estrogen secretion, binding of sperm to zona pellucida and sperm-egg recognition gene family also rapidly contraction. The gene families unique to the species were significantly enriched in pathways adenylate cyclase-activating G protein-coupled receptor signaling pathway, double-strand break repair and regulation of potassium ion transport.