The environmental analysis and site selection of mussel and large yellow croaker aquaculture areas based on high resolution remote sensing

Mussel aquaculture and large yellow croaker aquaculture areas and their environmental characteristics in Zhoushan were analyzed using satellite data and in-situ surveys.A new two-step remote sensing method was proposed and applied to determine the basic environmental characteristics of the best mussel and large yellow croaker aquaculture areas.This methodology includes the first step of extraction of the location distribution and the second step of the extraction of internal environmental factors.The fishery ranching index(FRI1,FRI2)was established to extract the mussel and the large yellow croaker aquaculture area in Zhoushan,using Gaofen-1(GF-1)and Gaofen-6(GF-6)satellite data with a special resolution of 2 m.In the second step,the environmental factors such as sea surface temperature(SST),chlorophyll a(Chl-a)concentration,current and tide,suspended sediment concentration(SSC)in mussel aquaculture area and large yellow croaker aquaculture area were extracted and analyzed in detail.The results show the following three points.(1)For the extraction of the mussel aquaculture area,FRI1 and FRI2 are complementary,and the combination of FRI1 and FRI2 is suitable to extract the mussel aquaculture area.As for the large yellow croaker aquaculture area extraction,FRI2 is suitable.(2)Mussel aquaculture and the large yellow croaker aquaculture area in Zhoushan are mainly located on the side near the islands that are away from the eastern open waters.The water environment factor template suitable for mussel and large yellow croaker aquaculture was determined.(3)This two-step remote sensing method can be used for the preliminary screening of potential site selection for the mussels and large yellow croaker aquaculture area in the future.the fishery ranching index(FRI1,FRI2)in this paper can be applied to extract the mussel and large yellow croaker aquaculture areas in coastal waters around the world.

An Improved Chromosome-Level Genome Assembly and Annotation of Belted Beard Grunt(Hapalogenys analis)

Hapalogenys analis(order Lobotiformes)is an economically and ecologically significant fish species.It is a typical sedentary rocky reef fish and is primarily found in the northern Pacific Ocean.Here,we used Hi-C and PacBio sequencing technique to assemble a high-quality,chromosome-level genome for this species.The 539 Mb genome had a contig N50 with a size of 3.43 Mb,while 755 contigs clustered into 24 chromosomal groups with an anchoring rate of 99.02%.Of the total genomic sequence,132.74Mb(24.39%)were annotated as repeat elements.A total of 21360 protein-coding genes were identified,of which 20787 genes(97.32%)were successfully annotated to public databases.The BUSCO evaluation indicated that 96.90%of the total orthologous genes were matched.The phylogenetic tree representing H.analis and 14 other bony fish species indicated that the H.analis genome contained 364 expanded gene families related to olfactory receptor activity,compared with the common ancestor of H.analis and Sciaenidae.Comparative genomic analysis further identified 3584 contracted gene families.Branch-site modeling identified 277 genes experiencing positive selection,which may facilitate the adaptation to rocky reef environments.The genome reported here is helpful for ecological and evolutionary studies of H.analis.

Assessment of Heavy Metals,Polycyclic Aromatic Hydrocarbons,and Perfluorinated Alkyl Substances in two Marine Crustaceans(Oratosquilla oratoria and Portunus trituberculatus)in the Zhoushan Fishing Ground of China East Sea

Heavy metals,polycyclic aromatic hydrocarbons(PAHs),and perfluorinated alkyl substances(PFASs)polluted in 155 samples of two marine crustaceans(Oratosquilla oratoria and Portunus trituberculatus)harvested in the Zhoushan fishing ground in the East China Sea were assessed.The results showed that Pb,Hg,and iAs in the whole edible parts of O.oratoria and P.trituberculatus were at trace levels,far below the limits set by the China’s national standard,whereas the exceeding standard rates of Cd in the whole edible parts of O.oratoria and P.trituberculatus were 98.6%and 75.6%,respectively.Moreover,the average Cd levels and the exceeding standard rates of Cd in the visceral tissues of O.oratoria were significantly higher than those in the muscle tissues(4.64 mg kg^(−1)vs.0.49 mg kg^(−1)and 96.7%vs 30%,respectively).PAHs with high detection frequency in the two marine crustaceans included NA,AC,FL,and PHE.Total contents of 15 PAHs(abbreviated asΣ15 PAHs)in whole edible parts of O.oratoria and P.trituberculatus were 10.75–65.9μg kg^(−1)(mean=18.7μg kg^(−1)and 13.26–181μg kg^(−1)(mean=24.2μg kg^(−1),and those in the muscle and the visceral tissues of P.trituberculatus were 9.58–160μg kg^(−1)(mean=21.1μg kg^(−1)and 18.22–201μg kg^(−1)(mean=32.7μg kg^(−1),respectively.Furthermore,PFASs that were found at high contents included PFOA,PFOS,and PFOSA,and total contents of 23 PFASs(Σ23 PFASs)ranged 0.0162–5.104μg kg^(−1)(mean=0.915μg kg^(−1).Collectively,the present work provides new data on the contamination in two marine crustaceans captured in the Zhoushan fishing ground in the China East Sea,which can be useful for making suggestions on proper consumption amounts of the two marine crustaceans.

Effect of Different Dietary Protein and Lipid Levels on the Growth,Body Composition,and Intestinal Digestive Enzyme Activities of Juvenile Yellow Drum Nibea albiflora(Richardson)

An 8-week feeding trial was conducted to determine the optimal dietary protein-to-lipid ratio for juvenile Nibea albiflora with an initial weight of(11.76 ± 0.20) g.Nine experimental diets containing different concentrations of protein(40%,47%,or 54%) and lipids(5%,9%,or 13%) in a 3 × 3 factorial experimental design were tested in triplicate groups of fish,while the protein-to-energy(P/E) ratios of the diets varied in the range of 19.74–28.32 mg k J^(-1).Results showed that fish fed diets containing 9% or 13% lipids with 54% protein exhibited significantly higher weight gains and specific growth rates than those fed other diets.The feed conversion rate of fish fed the diet with 40% protein and 5% lipids was significantly poorer than that of fish fed other diets.The protein efficiency rate of fish fed diets with 5% lipids was significantly lower than that of fish fed 9% or 13% lipid diets.Carcass lipid and energy contents were positively correlated with dietary lipid level regardless of protein level.Fish fed a 54% protein diet showed the highest trypsin activity.The intestinal lipase activity of fish fed the diet containing 13% lipids was significantly higher than that of fish fed 5% or 9% lipid diets.These results demonstrate the high protein dietary requirements of N.albiflora.A diet containing 54% protein and 9%–13% lipids with a P/E ratio of 26.2–27.81 mg protein k J^(-1) can be considered optimal for juvenile N.albiflora.

Implementing geostatistical analysis to study spatio-temporal distribution patterns of swimming crabs(Portunus trituberculatus)

This study attempted to compare the performance of local polynomial interpolation,inverse distance weighted interpolation,and ordinary kriging in studying distribution patterns of swimming crabs.Cross-validation was used to select the optimum method to get distribution results,and kriging was used for making spatial variability analysis.Data were collected from 87 sampling stations in November of 2015(autumn)and February(winter),May(spring)and August(summer)of 2016.Results indicate that swimming crabs widely distributed in autumn and summer:in the summer,they were more spatially independent,and resources in each sampling station varied a lot;in the winter and spring,the abundance of crabs was much lower,but the individual crab size was bigger,and they showed the patchy and more concentrative distribution pattern,which means they were more spatially dependent.Distribution patterns were in accordance with ecological migration features of swimming crabs,which were affected by the changing marine environment.This study could infer that it is applicable to study crab fishery or even other crustacean species using geostatistical analysis.It not only helps practitioners have a better understanding of how swimming crabs migrate from season to season,but also assists researchers in carrying out a more comprehensive assessment of the fishery.Therefore,it may facilitate advancing the implementation in the pilot quota management program of swimming crabs in northern Zhejiang fishing grounds.

Advancing multispecies fishery management in China:Lessons from international experience

China’s 13th Five-Year Plan elevated the national mandate for environmental sustainability.Chinese fisheries are characterized by full retention of high diversity catch harvested using unselective gears,creating ecological risks.Therefore,China launched pilot projects in management by Total Allowable Catch(TAC)in five coastal provinces in 2017 and 2018 to build experience with output controls.Fujian province launched an important pilot in its swimming crab fishery,the first to adopt a multispecies approach.To guide Fujian and other provinces in multispecies management,a workshop in April 2018 shared international experience.The workshop considered 13 case studies spanning a wide range of underlying scientific models and types of harvest controls.Multispecies harvest controls based on simple survey-or index-based models that aggregate trends for many species are typically operationally easier for managers and fishers.However,inadequate management can cause declines of individual species,sometimes leading to adoption of species-specific models and then species-specific harvest controls.This transition often incurs economic costs through scientific and management demands,and constraints on harvest of co-occurring species.The lessons revealed by the case studies suggest multispecies TACs might be effective in the Fujian swimming crab fishery given the modest number of species with similar and productive life history traits,and the market demand for all species.Continued experimentation with different management approaches through pilot projects can enable China to maintain progress toward sustainable fisheries goals under the 14th Five-Year Plan.