Larimichthys Polyactis Research Articles

Updating specific PCR primer for detection of Cryptocaryon irritans from reared Larimichthys polyactis

Artificial breeding of small yellow croaker (Larimichthys polyactis) was recently achieved, providing a bright future for its commercial farming. In May 2019, a disease outbreak occurred among small yellow croakers in an aquaculture farm near Xiangshan Bay, charactering by white spots spotted on the surface of fish skin, gills and fins. The parasite was preliminarily identified as Cryptocaryon irritans based on morphological feature of the parasite and the symptoms on fish. However, the previously published specific primer pairs failed to confirm the existence of C. iriitans. Six nucleotides mismatches were discovered after mapping specific forward primer back to targeted gene. Therefore, an updated PCR specific primer was developed within the 9th highly variable region of 18S rRNA gene and conserved in all C. irritans sequences available in GenBank database. The specificity was verified in silico by Primer-BLAST against GenBank nucleotide. Laboratory cultured ciliates (Mesanophrys, Pseudokeronopsis and Uronema) as well as natural microbial community samples collected from sea water and river water was used as negative control to verify the specificity of the primer in situ. Besides, tank transfer method was used to evaluate the treatment of the parasite infection. By tank transfer method, 2.00 ± 0.61 out of 10 fish that already sever infected were successfully survived after 8 days treatment, meanwhile the control group died out at d 6. More loss to the treatment group during first five days was observed and may attribute to the combined effect from infection and stress the recent domesticated fish suffered during rotation. Therefore, tank transfer method was also effective to prevent small yellow croaker from further infection, however the loss of the small yellow croaker suffered from stress during rotation also needs to be carefully concerned. In conclusion, this study reported the first diagnose of C. irritans infection on small yellow croaker, provided updated specific primer to detect C. irritans infection on fish body and reported the effect of tank transfer on small yellow croaker treatment.

Effect of diluent variation on cryopreservation of large yellow croaker Larimichthys crocea

The aim of this research was to investigate different factors, including cryoprotective agents (CPAs), diluents, dilution ratios, equilibrium times, freezing rates, and thawing methods to optimize cryopreservation protocols for large yellow croaker (Larimichthys crocea). The parameters evaluated were sperm motility, sperm activity index (SAI), survival rate, and DNA damage. Different types of CPAs, such as dimethyl sulfoxide (DMSO), propylene glycol (PG), ethylene glycol (EG), methanol, and glycerol, were tested for sperm preservation. The highest motility, SAI, and survival rate were observed when EG was used. Different diluents such as Stein’s solution, Hank’s balanced salt solution, marine fish Ringer’s solution, artificial seminal plasma (ASP) of small yellow croaker, and Cortland solution were investigated. The highest post-thaw motility was observed upon using ASP as the diluent. Different concentrations of EG were then mixed with ASP to identify the optimal EG concentration. Experimental results showed that the motility (70.33 ± 1.20%), SAI (5), and survival rate (78.30 ± 0.42%) of post-thaw sperm were optimum when 10% EG and ASP were used as the CPA and diluent of cryopreservation, respectively. Post-thaw sperm motility was high at equilibration times below 150 s and at an optimum dilution ratio of 1:1 (sperm: CPA + diluent) and was not significantly different compared with fresh sperm motility. The freezing rate was found to be slow below −10°C/min. The thawing temperature of 45°C was identified as ideal. The percentage of tail DNA in post-thaw sperm at 10% EG and ASP was also investigated and was found to have more significant DNA damage than that in fresh sperm but significantly lower damage than that in post-thaw sperm at EG concentrations of 5%, 15%, and 20% (p < 0.05). The cryopreservation protocols obtained in this study will be useful in large yellow croaker hatcheries.

A Transient Hermaphroditic Stage in Early Male Gonadal Development in Little Yellow Croaker, Larimichthys polyactis.

Animal taxa show remarkable variability in sexual reproduction, where separate sexes, or gonochorism, is thought to have evolved from hermaphroditism for most cases. Hermaphroditism accounts for 5% in animals, and sequential hermaphroditism has been found in teleost. In this study, we characterized a novel form of the transient hermaphroditic stage in little yellow croaker (Larimichthys polyactis) during early gonadal development. The ovary and testis were indistinguishable from 7 to 40 days post-hatching (dph). Morphological and histological examinations revealed an intersex stage of male gonads between 43 and 80 dph, which consist of germ cells, somatic cells, efferent duct, and early primary oocytes (EPOs). These EPOs in testis degenerate completely by 90 dph through apoptosis yet can be rescued by exogenous 17-β-estradiol. Male germ cells enter the mitotic flourishing stage before meiosis is initiated at 180 dph, and they undergo normal spermatogenesis to produce functional sperms. This transient hermaphroditic stage is male-specific, and the ovary development appears to be normal in females. This developmental pattern is not found in the sister species Larimichthys crocea or any other closely related species. Further examinations of serum hormone levels indicate that the absence of 11-ketotestosterone and elevated levels of 17-β-estradiol delineate the male intersex gonad stage, providing mechanistic insights on this unique phenomenon. Our research is the first report on male-specific transient hermaphroditism and will advance the current understanding of fish reproductive biology. This unique gonadal development pattern can serve as a useful model for studying the evolutionary relationship between hermaphroditism and gonochorism, as well as teleost sex determination and differentiation strategies.

KIFC1 functions in nuclear reshaping and midpiece formation during the spermatogenesis of small yellow croaker Larimichthys polyactis

The C-terminal kinesin motor protein (KIFC1) has essential functions in spermatogenesis. To evaluate molecular mechanisms of KIFC1 during teleost fish spermatogenesis, there was cloning and sequencing the kifc1 cDNA in the testis of Larimichthys polyactis. Quantitative PCR results indicated there were Lp-kifc1 mRNA transcripts in the testes. Results from conducting fluorescence in situ hybridization and immunofluorescence procedures indicated there were trends in relative abundance changes in Lp-kifc1 mRNA transcripts that were associated with abundance of Lp-KIFC1 protein during spermatogenesis. The Lp-KIFC1 protein was detected at all stages of spermatogenesis. There was minimal Lp-KIFC1 in the cytoplasm of spermatogonia, with content being greater and concentrated in the perinuclear region in spermatocytes and during early/mid-stages of development of spermatids. There were large abundances of Lp-KIFC1 in spermatids at the mid-developmental stage. In late-developing spermatids, Lp-KIFC1 content was less and concentrated in the bottom of the nucleus, where the midpiece formed. There was a small Lp-KIFC1 in the midpiece of mature sperm. These findings indicate Lp-KIFC1 may have functions in L. polyactis spermatogenesis. Results from conducting immunofluorescence procedures indicated Lp-KIFC1 was co-localized microtubules and mitochondria throughout spermatogenesis. There were large abundances of Lp-KIFC1 and tubulin in spermatids during the mid-developmental stage, when there is a decrease in size and reshaping of the nucleus. During midpiece formation, there was co-localization of the Lp-KIFC1 and mitochondria in the spermatid perinuclear region to the midpiece. These findings indicate Lp-KIFC1 is involved in nuclear reshaping and midpiece formation during spermatogenesis in L. polyactis.

Dual-frequency sequential ultrasound thawing for improving the quality of quick-frozen small yellow croaker and its possible mechanisms

The effect of ultrasound thawing with different frequencies and working modes, including mono-, dual- and tri-frequency, on the physicochemical quality, water holding capacity, microbial evaluation, microstructure, as well as moisture migration and distribution of quick-frozen small yellow croaker (Larimichthys polyactis) were evaluated. The results showed that the quality of samples thawed by sequential ultrasound working modes was higher than that of the simultaneous ultrasound and mono-frequency ultrasound working modes. Specifically, the samples thawed by combined dual-frequency sequential ultrasound (DSEU) at 20/40 kHz was close to fresh samples, which had better physicochemical quality (higher hardness, springiness, resilience, chewiness and lower TVB-N values, TBARS values, K-values), water-holding capacity (lower thawing loss and cooking loss), and microstructure, higher immobilized water content, lower free water content, and less microbial colonies, compared with other ultrasonically thawed samples. Therefore, the DSEU at 20/40 kHz can improve the quality of the samples better than other thawing methods.

Study of freshness monitoring on small larimichthys polyactis based on multiple sensor array system and non-linear data analysis method

ABSTRACT In this paper, freshness monitoring model on small larimichthys polyactis based on multiple sensor array system (MSAS) combined with total volatile basic nitrogen (TVB-N) examination was studied. Larimichthys polyactis was obtained and prepared as detecting samples. MSAS was developed based on volatile gas content of the fish samples. Meanwhile, TVB-N was examined to provide quality reference for MSAS measurement. MSAS responding data were processed by principal component analysis (PCA) and non-linear signal analysis model. Larimichthys polyactis freshness deciding model was developed by non-linear fitting between signal processing features and TVB-N parameters. Results indicated that the method studied in this work presented good freshness deciding accuracy for larimichthys polyactis. This method also presented some advantages including rapid analysis, easy operation, and low cost. It is promising in aquatic products quality raped determination.

The spatial niche and differentiation of major fish species in the waters east of the Zhoushan Islands in spring and autumn

Based on data from the fishery resources survey in the waters east of the Zhoushan Islands in April (spring) and October (autumn) in 2018, the index of relative importance was used to determine the importance of various fish species in the survey area. The niche breadth and overlap of major fish species were examined using the mean crowding, Shannon, and Pianka indices. Our results showed that there were 10 and 12 major fish species in spring and autumn, respectively. The niche breadth of major fish species in spring and autumn were 0.06–2.01 and 0.34–2.19, respectively, indicating differences between the two seasons. <italic>Larimichthys polyactis</italic> was the only wide-niche species (<italic>B</italic>_{<italic>i</italic>}≥2.0) in spring, whereas four were found in autumn: <italic>Johnius grypotus</italic>, <italic>Miichthys miiuy</italic>, <italic>Larimichthys polyactis,</italic> and <italic>Amblychaeturichthys hexanema</italic>. There were six medium-niche species (2.0&gt;<italic>B</italic>_{<italic>i</italic>}≥1.0) in both spring and autumn, whereas there were three narrow-niche species (1.0&gt;<italic>B</italic>_{<italic>i</italic>}&gt;0) in spring and two in autumn. The degree of niche overlap was unbalanced in the two seasons. There were 20 pairs of species with significant overlap in the spring niche, accounting for 44.44% of the total number of pairs, with a relatively high degree of overlap. Conversely, the major fish species overlap in autumn was low, with 16 pairs of species with significant overlap, accounting for only 24.24% of the total number of pairs. Redundancy analysis (RDA) showed that temperature and salinity were the factors directly affecting the distribution of the major fish species, though depth was also an important factor affecting the obvious niche differentiation of major fish species in spring and autumn.

Heterogeneity of growth and maturity of Larimichthys polyactis in the offshore waters of southern Zhejiang, China

The variations of life history traits have been observed for many fish species, which gains much concerns in the study of aquatic biology and ecology. In this study, the biological characteristics were explored for yellow croaker (Larimichthys polyactis) in the offshore waters of southern Zhejiang, based on 4920 individuals collected from 13 fishery-independent seasonal surveys from autumn 2015 to autumn 2018. Linear mixed effects models were used to estimate the growth, maturity characteristics, and their heterogeneity. The body length of yellow croaker samples ranged from 13 to 215 mm with the dominant body of 110 to 154 mm. The body weight ranged from 0.5 to 182.2 g, with the dominant body weight from 20 to 55 g. The results showed that the linear mixed effects models with random effects from season, gender, and year performed best for length-weight relationship, with the lowest AIC and RMSE values. The effects of season were much larger than those of genders and years. When the length exceeded 160 mm, the weight gain rate of yellow croaker was faster in spring and summer, lower in autumn and winter, while the male individuals gained more weight than the females with the same body length. Among 4841 individuals of specimens with gonadal data, the individuals at maturity Ⅱ stage occupied 50.4%, and the individuals at maturity stage contributed to 19.6%. The results from the best linear mixed effects model showed that season had the most significant influence on the maturity of yellow croaker. The 50% maturity length (L50%) was much lower in winter (124.6 mm) with no much difference between other seasons, indicating that yellow croaker matures earlier in winter. Our results indicated that linear mixed effect model could reflect the biological heterogeneity of yellow croaker conveniently and that the growth and maturity of yellow croaker had significantly sexual and temporal variations, which should be considered in the stock assessment and fishery management for yellow croaker.

Effects of Photoperiod and Water Temperature on Male Sex Steroid Levels in Cultured Small Yellow Croaker (Larimichthys polyactis)

Effects of Photoperiod and Water Temperature on Male Sex Steroid Levels in Cultured Small Yellow Croaker (Larimichthys polyactis)

Extraction Hydrolysates from Larimichthys Polyactis Swim Bladder Using Enzymatic Hydrolysis

As a kind of biopolymer, hydrolysates of fish swim bladder, safer than those of land mammals, are widely used in food, cosmetics as well as pharmaceutical and biomedical fields for their biocompatibility, biodegradability, and weak antigenicity. To enhance hydrolysate production, in this paper, the papain and alcalase hydrolysis processes of larimichthys polyactis swim bladder were optimized with orthogonal experiments. With 89.5% hydrolysate yield, the optimal processing conditions for alcalase were solid-liquid ratio of 1:30, enzyme concentration of 0.7%, and extraction time of 6 h. As for papain, under the optimal processing conditions: solid-liquid ratio of 1:20, enzyme concentration of 0.5%, and extraction time of 8 h, the hydrolysate yield was 65.1%. To obtain higher hydrolysate yields, the ultrasonic pretreatments were implemented before the optimal enzyme hydrolysis processes. With ultrasonic waves of 100 W for 50 min, the hydrolysate yields were increased 2.1% (alcalase) and 4.5% (papain), respectively. The Fourier Transform Infrared (FTIR) spectroscopic analysis revealed that the hydrolysates extracted by papain exist in triple-helical forms. The Ultra-Violet (UV) absorption spectra indicated that the aromatic amino acids in the hydrolysates had strong absorptions in the wavelength range of 240 nm–300 nm. The results of this research demonstrate that the alcalase hydrolysates have better solubility in water and the solution is more stable under ambient temperature. However, the hydrolysates extracted by papain have a gel property and are insoluble in weak acid at room temperature, which is more suitable for applications in feedstock of biomedical.

Assessment of fishery resources using environmental DNA: Small yellow croaker (Larimichthys polyactis) in East China Sea.

Species distribution monitoring and biomass assessment are crucial for fishery management and resource conservation. However, traditional methods such as motor trawling are costly and less effective than the novel environmental DNA (eDNA) approach. This study employs eDNA approach to investigate horizontal and vertical distributions of small yellow croaker (Larimichthys polyactis), an economically important species, in the East China Sea. The analysis of 171 eDNA samples collected from 44 stations using the species-specific primers and Taqman probe suggests a presence of small yellow croaker at 28 sampling layers in 44 stations. Significant differences in croaker eDNA concentrations were revealed among sampling stations and layers, consistent with previous findings through motor-trawl capture offshore and nearshore ichthyoplakton surveys, indicating small yellow croaker exhibits strong regional distribution and layer preference. In addition, we found a high eDNA concentration of small yellow croaker in the surface waters beyond the motor-trawl prohibition line, which confirms spawning grounds have been expanded from nearshore to offshore areas. Such expansion of spawning grounds could be a response by small yellow croaker to stressors such as overfishing, climate change, and nearshore environment contamination. To identify environmental variables potentially associated with small yellow croaker presence and absence, we conducted a correlation analysis between eDNA concentration and environmental variables, and the results provide a guideline for further investigation of fishery resources in the future. In conclusion, this study demonstrates the power of the eDNA approach in monitoring small yellow croaker at extensive geographic scales. The developed protocols and the findings are expected to assist in long-term monitoring and protection programs and benefit sustainable fishery in small yellow croaker.

Understanding patterns of distribution shifts and range expansion/contraction for small yellow croaker (Larimichthys polyactis) in the Yellow Sea

AbstractDetecting and analyzing patterns of distribution shifts and range expansion/contraction is important to understand population dynamics and changes in stock status. Here, we develop a spatio‐temporal model for yellow croaker (Larimichthys polyactis), which was fitted to bottom trawl survey biomass data collected in the Yellow Sea in the winter of 2001–2017. The model accounts for both spatial and spatio‐temporal structure and can potentially include the effects of surface temperature and of an annual index, the Pacific Decadal Oscillation, represented using a recently developed spatially varying coefficient model. We selected a spatio‐temporal model with no covariates based on Akaike's information criterion. The center of gravity for yellow croaker was found to move northwest between 2001 and 2010, and then southwest over the period 2010–2017. These results reflected the predicted progressive disappearance of yellow croaker density hotspots (i.e., highest density areas) in the north and southeast areas of the Yellow Sea, which resulted in the central area of the Yellow Sea becoming the only yellow croaker density hotspot in 2017. This finding has important implications for fisheries management in the context of the China–South Korea fisheries agreement, as it indicates a measurable displacement of yellow croaker biomass toward China. The exclusion of covariates from the spatio‐temporal model was not expected a priori and may be due to the facts that environmental variations are not pronounced in winter in the Yellow Sea and that the representation of spatial and spatio‐temporal structure in spatio‐temporal models accounts for a large proportion of the variability in the data.

Identification of keystone predators in Haizhou Bay food web based on the revised SURF index

Keystone predator species play an important role in regulating the number, richness and distribution of prey species. Based on the bottom trawl surveys in Haizhou Bay, keystone predator species in fish communities were identified by the revised SURF (supportive role to fishery ecosystems) index. Conger myriaster, Saurida elongata, Hexagrammos otakii, Chelidonichthys spinosus, and Larimichthys polyactis were the keystone predators in the fish community. They had high number of nodes degree, and were also the main predators of many species. Further, they had strong ability of clustering. The fluctuations of their density would have great impacts on ecosystem energy flow and food web structure. The method not only considered the feeding ratio between species, but also took the amount of catch and abundance of species as important factors in the identification of keystone predators. Compared with the traditional method, this method had great improvement and provided a new one for the identification of key predators. Our results showed that the strong inter-specific interactions played an important role in maintaining the structure and function of food webs. Protection of key predators would benefit the stability of biological communities and species diversity. Therefore, ecosystem-based fisheries management (EBFM) should give priority to the protection of key species. The important economic fish species, C. myriaster and L. polyactis, should be protected with high priority as they suffered from higher fishing pressure.

Assessment and Management of Small Yellow Croaker (Larimichthys polyactis) Stocks in South Korea

We aimed to determine the appropriate annual total allowable catch (TAC) levels for the small yellow croaker (Larimichthys polyactis). A Bayesian state-space model was used to assess the species stock. This model has been widely used after research confirmed its reliability over other models. However, setting prior distributions for analyzing this model remains controversial. Therefore, a sensitivity analysis was conducted using the model with different prior distributions and biomass growth functions. Informative and non-informative prior distributions were compared using Schaefer and Fox growth functions. Considering the results of the sensitivity analysis, the assumption of inverse-gamma prior distribution of K, a non-informative distribution, with the Fox function could yield relatively superior estimates than those obtained from other assumptions. Moreover, changing the growth function could have a greater effect on the fitness of the model estimates than changing prior distribution. Therefore, future fishery stock analyses based on this model should consider the effectiveness of various growth functions in addition to the sensitivity analysis for prior distributions. Furthermore, the biomass of small yellow croaker will decrease if the catch increases by 10%. Therefore, the annual TAC levels should be set below the maximum sustainable yield (21,301 tons) for effective small yellow croaker stock management.

A non-exhaustive survey revealed possible genetic similarity in mitochondrial adaptive evolution of marine fish species in the northwestern Pacific.

Mitochondrial coding genes involved in the oxidative phosphorylation pathway play vitally important roles in energy production and thermal adaptation. Investigating the underlying molecular mechanism of mitochondrial adaptive evolution is crucial for understanding biodiversity and ecological radiation. In this study, we collated population genetic studies of marine fish species in the northwestern Pacific based on mitochondrial cytochrome b gene sequences, to investigate whether similar patterns could be detected in mitochondrial adaptive evolution. After filtering, nine studies containing eight marine fish species (Ammodytes personatus, Boleophthalmus pectinirostris, Larimichthys polyactis, Mugil cephalus, Pampus argenteus, Platycephalus sp.1, Sebastiscus marmoratus, and Trachidermus fasciatus) belonging to eight different families were retained. Multiple codon-based approaches were used to identify potential sites under selection in each species. By comparison, our results showed that the posterior part of the mitochondrial cytochrome b gene (particularly codon 372 and its neighboring sites) seemed to be involved in the adaptive evolution process, suggesting potential genetic similarity among distantly related species. We also summarized four types of adaptive patterns in the reviewed species, and suggest that the level of genetic differentiation and mitochondrial adaptive evolution might be correlated. Further studies are needed to confirm such relationship by detecting RNA-level evidence and investigating more species and samples.

Population dynamics modelling with spatial heterogeneity for yellow croaker (Larimichthys polyactis) along the coast of China

As one of the top four commercially important species in China, yellow croaker (Larimichthys polyactis) with two geographic subpopulations, has undergone profound changes during the last several decades. It is widely comprehended that understanding its population dynamics is critically important for sustainable management of this valuable fishery in China. The only two existing population dynamics models assessed the population of yellow croaker using short time-series data, without considering geographical variations. In this study, Bayesian models with and without hierarchical subpopulation structure were developed to explore the spatial heterogeneity of the population dynamics of yellow croaker from 1968 to 2015. Alternative hypotheses were constructed to test potential temporal patterns in yellow croaker’s population dynamics. Substantial variations in population dynamics characteristics among space and time were found through this study. The population growth rate was revealed to increase since the late 1980s, and the catchability increased more than twice from 1981 to 2015. The East China Sea’s subpopulation witnesses faster growth, but suffers from higher fishing pressure than that in the Bohai Sea and Yellow Sea. The global population and two subpopulations all have high risks of overfishing and being overfished according to the MSY-based reference points in recent years. More conservative management strategies with subpopulation considerations are imperative for the fishery management of yellow croaker in China. The methodology developed in this study could also be applied to the stock assessment and fishery management of other species, especially for those species with large spatial heterogeneity data.

Identification of a large dataset of SNPs in Larimichthys polyactis using high-throughput 2b-RAD sequencing.

The small yellow croaker (Larimichthys polyactis) is one of the most commercially exploited marine fishes along the coast of the Yellow-Bohai Sea and the East China Sea. In this study, we used next-generation high-throughput 2b-RAD-seq technology to identify novel SNPs in L.polyactis. We scored a total of 1374008 putative SNPs genome-wide. Further filtration yielded a final dataset of 6457 high-quality SNPs. These SNP markers presented sufficient power in detecting genetic distinction between two wild samples from the Yellow-Bohai Sea and one captive sample from the East China Sea, and inbreeding reflected by strong heterozygote deficiency within the samples; some of the genetic polymorphisms are diagnostic among the samples and related to biological functions. The panel of SNPs could be used as powerful tools in further population genetic and stock assessment research in L.polyactis as it has relatively scarce genomic resources. The findings from this study will advance our understanding of population and functional genomics for facilitating fishery resource management and developing desirable characteristics for the benefit of culture and farming of L.polyactis.

Growth and maturity heterogeneity of three croaker species in the East China Sea

Big head croaker (BC) Collichthys lucidus, Large yellow croaker (LC) Larimichthys crocea, and Yellow croaker (YC) Larimichthys polyactis are important ecological and commercial species along the coastal seas of China. Based on samples collected from seasonal bottom trawl surveys in the southern East China Sea from 2015 to 2018, we analyzed the growth and maturity characteristics of these three croaker species. Simple linear model, mixed-effects model and hierarchical methods were conducted in this study to evaluate the variations in growth and maturity among sexes, seasons and years for each species. Our results showed that, mixed-effects model performed better than simple linear models, while hierarchical methods could reveal variations in different life stages. Female LC and YC tended to gain more weight at the same length and matured earlier than the male for LC and YC. The individuals tended to gain more weight in spring and fall, while all croakers had larger weight at the same length and matured earlier from 2015 to 2017 compared to those in 2018. Results from the hierarchical model indicated that for all captured croakers, individuals with bigger sizes were mostly females, especially for LC. Big head croaker and LC tend to gain more weight in spring, while YC tends to gain less weight in winter. Mixed-effects models and hierarchical methods can be incorporated to provide more information about the heterogeneity of fish life history traits. These results will help provide more insights related to the growth and maturity of these three important species in the East China Sea. Also, the methodology applied in this study may be used on the life history research for species with multiple data sources.

Using fisheries‐independent survey data to reinforce China’s data‐limited fisheries management: Management strategy evaluation of survey‐based management procedures

AbstractFisheries‐independent survey data are vital to stock assessment and management because they provide reliable information on stock status. Although survey data have been increasingly recognised for their contributions to fisheries management, they have often not been adequately used to provide quantitative management recommendations for China's fisheries that are subject to limited data. In the present study, a framework was proposed to integrate two types of survey‐based management procedures (MPs) into China's fisheries management: the slope‐based MP and the target‐based MP. Specifically, the former generates fishing effort limits based on the trend in recent years’ abundance index, while the latter sets effort limits based on a static abundance index target. To test the performance of these MPs, management strategy evaluation was performed using a simulated fishery based on the small yellow croaker, Larimichthys polyactis (Bleeker) in Haizhou Bay, China. The sensitivity of MPs was investigated under different algorithm parameterisations and historical exploitation levels. Additionally, their robustness was evaluated in the face of survey uncertainty and changes in recruitment success. Both MPs could effectively improve the stock status compared with the status quo management when appropriately parameterised regardless of exploitation history. The target‐based MP was more robust to survey uncertainty than the slope‐based MP. Non‐stationary changes in recruitment success strongly impaired the management effects, while using recruitment‐specific instead of the age‐aggregated abundance index could slightly enhance their performance. This work indicates that survey‐based MPs can address the current challenges in China's fisheries management and reinforce the status quo management practice with limited data and highlights the potential risks.

Effect of multi-frequency ultrasound thawing on the structure and rheological properties of myofibrillar proteins from small yellow croaker

The influence of multi-frequency combined ultrasound thawing on primary, secondary, and tertiary structures, electrophoresis pattern, particle size distribution, zeta potential values, thermal stability, rheological behavior, and microstructure of small yellow croaker myofibrillar proteins (MPs) were studied. Four treatments were used for thawing small yellow croakers: flow water thawing (FWT), mono-frequency ultrasonic thawing (MUT), dual-frequency ultrasonic thawing (DUT), and tri-frequency ultrasonic thawing (TUT). Compared with fresh samples (FS), the MPs of the sample pretreated by DUT had non-significant effect on protein primary (including free amino groups and surface hydrophobicity), secondary, tertiary structures, electrophoresis pattern, and microstructure. MPs pretreated by DUT had less aggregation and degradation. Besides, DUT treatment increased the thermal stability of MPs. The ultrasound had significant effects on the rheological properties of MPs. Overall, DUT effectively minimized the changes in MPs structure and protected the protein thermal stability and rheological behavior during the thawing process.