Genome-Wide Characterization of the Hyaluronidase Gene Family and Their Potential Roles in Viviparous Black Rockfish(Sebastes schlegeli)

Black rockfish(Sebastes schlegelii)has evolved viviparous reproduction mode.Different from the oviparous fishes,the spermatozoa of black rockfish are stored on the surface of ovarian follicle for over four months until the egg mature in ovary,while the adaptive evolution of fertilization-related genes remains to be studied.In the present study,based on the genome and transcriptome information of black rockfish,a total of 10 hyaluronidase genes were identified by phylogenetic and sequence analyses,including hyal1,hyal2,hyal3,hyal4,hyal6 and spam1a,spam1b,spam1c and spam1d.The spam1 subfamilies,including spam1a,spam1b,spam1c and spam1d,were significantly expanded compared to other species.The adaptive evolution of hyaluronidase was further investigated by selection pressure analysis of branch model and branch site model.The results showed that only spam1 subfamily was positively selected with a large number of positive selection sites,and the evolution rate was significantly higher thanthose of other teleosts.Two positively selected sites,LYS-171 and GLY-164,were located in the neutral hyaluronidase activity domain,which was pivotal for SPAM1 to participate in enzymatic hydrolysis of the extracellular hyaluronic acid matrix and mediate acrosome reaction in mammals.Furthermore,spam1 was mainly expressed in spermatocytes,secondary spermatocytes,and spermatids of testis,whereas it was not found in metamorphic sperm and mature sperm based on the spatiotemporal expression analysis.All results indicated that spam1 might originate from the testis and might be an adaptation of viviparous trait in black rockfish.

First record of abnormal body coloration in a rockfish Sebastes koreanus(Scorpaenoidei:Sebastidae)from coastal water of China based on morphological characteristics and DNA barcoding

The first record of abnormal body coloration in Sebastes koreanus Kim and Lee,1994,from the Yellow Sea of China,was documented based on morphological characteristics and DNA barcoding.The two rockfish specimens were collected from the coastal waters of Qingdao,China,and the whole body and all fins of them were red.Of the two red-colored rockfish,there were tiny deep red spots on each fin,2 red radial stripes behind and below the eyes and 1 large deep red blotch on the opercula,while the similar stripe and spot patterns are also present in the S.koreanus specimens with normal body coloration.The countable characteristics of the two specimens are in the range of the morphometry of S.koreanus.To further clarify the species identity and taxonomic status of the two specimens,DNA barcode analysis was carried out.The genetic distance between the red-colored rockfish and S.koreanus was 0,and the minimum net genetic distances between the red-colored rockfish and other Sebastes species except for S.koreanus were 3.0%,which exceeds the threshold of species delimitation.The phylogenetic analysis showed that the DNA barcoding sequences of the two red-colored rockfish clustered with the S.koreanus sequences.The above results of DNA barcode analysis also support that the two red-colored rockfish could be identified as the species of S.koreanus.The mechanism of color variation in S.koreanus is desirable for further research and the species could be an ideal model to study the color-driven speciation of the rockfishes.

Characterization of a CD209-Like Lectin in Black Rockfish(Sebastes schlegelii):Structure Features and Binding Activities as a Pathogen Recognition Receptor

CD209,a transmembrane lectin belonging to the C-type lectin family,can recognize carbohydrates on the surface of host cells and invading pathogens,and play an important role in cell adhesion and migration,pathogen recognition and immune activation.Although well characterized in mammals,CD209 is still under-researched in fish.Here,we report a CD209-like gene,which was named SsCD209like,in black rockfish Sebastes schlegelii,and analyzed its structure features,expression patterns and ligand-binding activities.SsCD209like displays structural similarities to mammalian CD209s,with a cytosolic tail at N-terminus,a transmembrane region and an extracellular part containing a neck region and a CRD at C-terminus.The extracellular region and the neck region of SsCD-209like can both form dimers,which is different with the tetramer in human homologue.This result demonstrates the multimerization of CD209 homologue in fish for the first time.The EPN motif,a functional motif participating in sugar binding and affinity determination,is conserved in the CRD of SsCD209like,which is consistent with the higher binding strength of this lectin to L-fucose,D-GlcNAc and D-mannose.The binding of SsCD209like to different bacteria strains and bacteria-derived pathogen associated molecular patterns(PAMPs)are also observed in a dose-dependent manner.Results in this study show the sequence and structure features of SsCD209like and demonstrate its binding properties as a pathogen recognition receptor,which promotes our understanding of CD209 homologues in fish and provides basis for more in-depth studies of this molecule in the future.

Expression profile of long non-coding RNAs in the intestine of black rockfish Sebastes schlegelii in response to Edwardsiella tarda infection

Long non-coding RNAs(lncRNAs)are a class of transcripts longer than 200 bp,which have been emerged as essential regulators in numerous biological processes.Black rockfish(Sebastes schlegelii)is an economic fish that widely cultured in the coastal areas of China,Japan,and South Korea.With the expansion of aquacultural scale,various pathogens have threatened its industry and reduced its economic values.It has been reported that lncRNA were involved in the immune response and metabolic pathway in teleost,while no study is available on identification and functional analysis of lncRNAs in black rockfish so far.Herein,this study was performed to identify lncRNAs in the intestine of black rockfish after Edwardsiella tarda infection.In our results,a total of 9311 lncRNAs were identified through highthroughput sequencing,and 102 lncRNAs were significantly regulated following challenge,which were predicted to target 3348 mRNAs.Results of Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analyses of the se target genes showed they were function in catalytic activity,hydrolase activity,defense response and peptidase activity,which involved in metabolic pathways and immune related pathways.In addition,47 lncRNAs and 8 differentially expressed mRNAs(DEmRNAs)showed co-expression at two or more infection time points with metabolism and immunity functions.Moreover,real-time quantitative PCR(qRT-PCR)was performed to verify the reliability of sequencing gene expression analysis results.This research laid the foundation for further investigation of the regulatory roles of lncRNAs in the intestinal immune response of black rockfish.

Identification and Pathogen Stimulation Patterns of Neuronal Nitric Oxide Synthase(nNOS)in Black Rockfish(Sebastes schlegelii)

Neuronal nitric oxide synthase(nNOS)was the producer of nitric oxide(NO)which played important gas messenger molecules in biological process.It also can take effect as immune regulation molecule in organism.Black rockfish(Sebastes schlegelii)is an important economic fish which were widely farmed in East Asia countries.Meanwhile,the pathogenic bacteria such as the Edwardsiella tarda and Vibrio anguillarum in seawater always brought serious obstacles to their healthy growth.In order to explore the expression pattern of n NOS gene under the pathogen stimulation and predict its immune function,the n NOS gene in black rockfish named Ssn NOS was identified.It was 3780 bp in length,located on chromosome 6,and contained 27 coding domain sequence(CDs).According to the phylogenetic analysis,the Ssn NOS showed closest relative to the counterpart gene of swamp eel(Monopterus albus).Meanwhile,analysis of Ssn NOS expression in various healthy tissues showed that Ssn NOS expression level was highest in healthy brain tissues,followed by intestinal tissues.In addition,Ssn NOS showed significant expression changes in response to stimulation by two pathogens.Particular in gill,the expression of Ssn NOS after pathogenic stimulation increased significantly.The Elisa analysis showed the Ssn NOS content in gills was much higher than that in other tissues at all time points.Moreover,the expression patterns of Ssn NOS in brain,intestine and kidney after stimulation by pathogens showed a distinct expression pattern which first down-regulated and then up-regulated.Therefore,the Ssn NOS may be an important signaling molecule for fish to respond rapidly in immune stimulation.

Genome-wide characterization of mapk gene family in black rockfish Sebastes schlegelii and their expression patterns against Edwardsiella piscicida infection

Mitogen-activated protein kinases(MAPKs)play pivotal roles in response to environmental stresses and bacterial infections.Compared with those in the higher vertebrates,studies of mapk gene family are still limited in teleost.Identification,characterization,classification,and expression profiling of totally 15 mapk genes in black rockfish(Sebastes schlegelii)were conducted.Phylogenetic relationships show that these mapk genes could be divided into extracellular signal-regulated kinase(ERK),c-Jun N-terminal kinase(JNK),and p38 sub-families.In addition,gene structures,syntenic analysis,and selective pressure analysis are performed to confirm their annotations.Results of selective pressure analysis indicate that mapk1,mapk3,mapk7,mapk10,mapk11,and mapk12 underwent significantly-positive selections,while the others genes such as mapk4,mapk6,mapk15,mapk8a,mapk8b,mapk9,mapk13,mapk14a,and mapk14b were under purifying selections.Moreover,results of qRT-PCR indicate that mapk genes in 8 healthy tissues displayed different expression patterns.The expression patterns of several mapk genes including mapk12,mapk13,mapk14a,mapk14b,and mapk15 were significantly changed in mucosal tissues after Edwardsiella piscicida infection.This study demonstrates that mapk genes in black rockfish play vital prevention roles against bacterial infection,which not only helps us understand the structure and function of mapk genes in black rockfish,but also provides a reference to understand the role of mapk genes in teleost immune responses.

许氏平鲉(Sebastes schlegelii)TRAF基因的鉴定及其响应杀鱼爱德华氏菌侵染的表达模式研究

TRAF是机体内一种具有信息传导作用的胞内因子,承担多个受体家族的信号转导工作,在固有免疫以及获得性免疫方面都发挥出重要作用。TRAF作为一类胞内接头蛋白,对多条信号途径的活化具有一定的影响,包括细胞的增殖、生存、凋亡、炎症反应、免疫反应等。目前已有研究表明鱼类中的TRAF基因也发挥重要的免疫防疫作用。以许氏平鲉为研究对象,基于基因组和转录组的数据库,进行了许氏平鲉TRAF基因家族的系统鉴定。在许氏平鲉中共鉴定到9个TRAF基因,并对这些TRAF基因的长度和氨基酸个数进行了统计分析。同时,分析了这9个TRAF基因的结构特征。选取了包括许氏平鲉在内的6种鱼类进行了TRAF基因的共线性分析。结果显示,TRAF基因在硬骨鱼类中具有保守的共线性。通过系统发育分析,更好地解析了TRAF家族基因的进化关系,同时也证明了对其鉴定及命名的准确性。此外,还进行了TRAF家族基因的蛋白质相互作用网络预测以及表达模式分析。通过蛋白质相互作用的网络分析,得到TRAF基因与其互作蛋白的关联状况。在杀鱼爱德华氏菌侵染许氏平鲉后的不同时间点,探究TRAF基因在杀鱼爱德华氏菌刺激下的表达模式。定量结果显示,除TRAF4.1外,其他TRAF基因在感染后均存在不同程度的上调。综上所述,从分子水平上揭示了许氏平鲉TRAF家族基因的结构和功能,揭示了TRAF可能依赖的免疫通路,为进一步探究TRAF家族基因在许氏平鲉先天免疫过程中的作用奠定了基础。

斑石鲷(Oplegnathus punctatus)、云龙石斑鱼(Epinephelus moara♀×E.lanceolatus♂)、许氏平鮋(Sebastes schlegelii)游泳行为对比分析研究

水流是影响鱼类生存和繁衍的重要的环境因子之一,通过比较分析三种深远海适养鱼类斑石鲷(Oplegnathus punctatus)、云龙石斑鱼(Epinephelus moara♀×E.lanceolatus♂)和许氏平鮋(Sebastes schlegelii)的游泳行为变化规律,以期为深远海养殖科学放养和大型养殖设施精准选址提供理论依据和技术支撑。以同一规格[(250.00±14.00)g]的三种适养鱼类为研究对象,利用鱼类游泳行为检测装置,在(24.00±1.08)℃条件下,观察分析三种鱼类的摆尾频率(TBF)、摆尾幅度(TBA)、运动步长(SL)和摆尾时间百分比。结果发现,许氏平鮋的TBF最大,SL最小;云龙石斑鱼的TBA最小;斑石鲷的摆尾时间百分比最大;且三种鱼类的TBF和SL在1~5 BL/s流速下均存在显著性差异(P<0.05),1、3和5 BL/s流速下摆尾时间百分比和2~4 BL/s流速TBA存在显著性差异(P<0.05)。三种鱼类的TBF、TBA和SL同流速均呈显著的线性正相关关系(P<0.05),摆尾时间百分比均随着流速增加先升高再降低。斑石鲷和云龙石斑鱼在1~4 BL/s流速下的TBF、TBA、SL之间均存在显著相关性(P<0.05),许氏平鮋在3~4 BL/s流速下三种指标存在显著相关性(P<0.05);但三种鱼类的摆尾时间百分比与其他指标之间均没有显著的相关性。以上结果表明,三种鱼类伴随着流速增加,其游泳行为指标皆呈现显著规律性变化,许氏平鮋TBF、TBA和SL之间只在高流速呈现显著相关性,预示相较于斑石鲷和云龙石斑鱼,其采取了不同于其他两种鱼类的游泳行为策略来应对低流速的水流环境。

Characterization of SOX3 Gene in an Ovoviviparous Teleost, Black Rockfish(Sebastes schlegeli)

Evolutionary evidence suggests that Sox3, a member of the high-mobility-group(HMG) family of transcription factors, is an ancestral precursor of Sry and is involved in sex determination similar to Sry. However, there is limited information regarding the SOX3 gene of the black rockfish(Sebastes schlegeli). In this study, we first isolated SOX3 gene from the gonads of S. schlegeli by homology cloning. The full-length of S. schlegeli SOX3(SsSOX3) c DNA was 1386 bp, comprising a 906-bp open reading frame, which encodes a peptide showing 93.6% and 93.9% homology with the Sox3 proteins of Epinephelus coioides and Oryzias latipe, respectively. Comparison of the cDNA sequence of the Ss SOX3 gene with the corresponding genomic DNA fragment revealed that the SsSOX3 gene consists of a single exon. Phylogenetic analysis demonstrated the evolutionary relationship of Ss SOX3 with other known SOXB1 genes in fish and tetrapods. The promoter region contains binding sites of several transcriptional factors that might participate in the regulation of Ss SOX3 expression. Quantitative real-time PCR analysis indicated that SsSOX3 was expressed in all the investigated larval developmental stages from 1 to 35 days after birth and the level of expression gradually decreased as the development proceeded. SsSOX3 exhibited sexually dimorphic expression in adult gonads, with high expression in the ovary but low expression in the testis. In situ hybridization revealed that SsSOX3 was strongly expressed in oocytes and follicular cells of ovaries but slightly expressed in germ cells of testicular tissues. Therefore, this study suggests that Ss SOX3 plays an important role in oogenesis and ovary differentiation in S. schlegeli.

A Microsatellite Genetic Linkage Map of Black Rockfish(Sebastes schlegeli)

Ovoviviparous black rockfish(Sebastes schlegeli) is an important marine fish species for aquaculture and fisheries in China. Genetic information of this species is scarce because of the lack of microsatellite markers. In this study, a large number of microsatellite markers of black rockfish were isolated by constructing microsatellite-enriched libraries. Female- and male-specific genetic linkage maps were constructed using 435 microsatellite markers genotyped in a full-sib family of the fish species. The female linkage map contained 140 microsatellite markers, in which 23 linkage groups had a total genetic length of 1334.1 c M and average inter-marker space of 13.3 c M. The male linkage map contained 156 microsatellite markers, in which 25 linkage groups had a total genetic length of 1359.6 c M and average inter-marker distance of 12.4 c M. The genome coverage of the female and male linkage maps was 68.6% and 69.3%, respectively. The female-to-male ratio of the recombination rate was approximately 1.07:1 in adjacent microsatellite markers. This paper presents the first genetic linkage map of microsatellites in black rockfish. The collection of polymorphic markers and sex-specific linkage maps of black rockfish could be useful for further investigations on parental assignment, population genetics, quantitative trait loci mapping, and marker-assisted selection in related breeding programs.

The application of stereo-video technology for the assessment on population change of black rockfish Sebastes schlegeli in a vessel reef area in Haizhou Bay,China

The assessment of population structure and abundance of fish assemblages associated with artificial reefs(ARs) is an important aspect of AR management.In the present study,we used a DiveOperated Stereo Video(stereo-DOV) technique to assess the population structure and abundance of Sebastes schlegeli associated with two metallic,and three wooden,vessel reefs in Haizhou Bay during 2012 and2013.The study used video systems to obtain length measurements and estimates of abundance.The size composition of S.schlegeli differed among reefs and individuals around vessel reefs were all adults,with total lengths(TL) of >20 cm.Juvenile fish were encountered by divers in a rocky area near the island away from the vessel reefs.The largest individual S.schlegeli(with the highest TL) among five reefs were found around a metallic vessel reef in both 2012 and 2013.TL of S.schlegeli from all reefs increased by an average of 3.2 cm(P<0.05) from 2012 to 2013,with an estimated mean weight increase of 250.4 g(P<0.05).The video survey also indicated a decrease in the biomass of schools near two metallic vessels between the years.Stereo-video technology was found to be suitable for rockfish surveys around the reefs.

Histological Observation of Germ Cell Development and Discovery of Spermatophores in Ovoviviparous Black Rockfish(Sebastes schlegeli Hilgendorf) in Reproductive Season

Black rockfish(Sebastes schlegeli) is an important species for culture; however, its reproductive characteristics have not been fully documented. In this study, we investigated the morphology and developmental process of germ cells in this ovoviviparous rockfish in reproductive season(October 2011–November 2012) with histological methods. We found that the gonad of mature fish showed notable seasonal changes in developmental characteristics and morphological structure. The sperm cells matured during a period lasting from October to December, significantly earlier than the oocytes did. A large number of spermatozoa and other cells occurred in testis at different developmental stages. Vitellogenesis in oocytes began in October, and gestation appeared in April next year. Spermatophores were discovered for the first time in Sebastes, which assembled in testis, main sperm duct, oviduct and genital tract, as well as ovarian cavity in October and April. These organs may serve either as production or hiding places for spermatophores and spermatozoa which were stored and transported in form of spermatophores. Testicular degeneration started from the distal part of testis in April, with spermatophores assembled in degenerating testis and waiting for transportation. The copulation probably lasted for a long period, during which the spermatozoa were discharged in batches as spermatophores. These spermatophores were coated with sticky materials secreted from the interstitial areas of testis and the main sperm duct, then transported into ovary.

Cloning and Expression Analysis of vasa During the Reproductive Cycle of Korean Rockfish, Sebastes schlegeli

Vasa, which is a conserved member of the DEAD-box protein family, plays an indispensable role in primordial germ cell proliferation. However, the expression of vasa gene during the reproductive cycle in ovoviviparous fish has not been documented. In this study, the full-length sequence of vasa was obtained from the ovary of Korean rockfish (Sebastes schlegeli) using reverse transcription-PCR and rapid amplification of cDNA ends. The Vasa with a mature protein of 650 amino acids showed greatest homology (84%) with giant gourami (Osphronemus goramy) and Pacific bluefin tuna (Thunnus orientalis). The expression of vasa mRNA in Korean rockfish was detected in gonads only, suggesting its specific role in gonadal development. In addition, seasonal changes in the vasa expression levels were examined in gonads by quantitative real-time PCR. The vasa transcript levels in adult testis were found higher during spermatogenesis than during spermiation. The vasa transcript levels remained relatively high at the early ovary stage but declined during ovary maturation in adult female fish. These results suggest that the vasa gene play an important role in spermatogenesis and early oogenesis during the reproductive cycle of Korean rockfish.

Use of tetracycline hydrochloride and alizarin complexone for immersion marking black rockfish Sebastes schlegelii

We tested the utility of chemical marking techniques in the juvenile black rockfish Sebastes schlegelii. Juveniles(30–40 mm total length) were immersed in a range of tetracycline hydrochloride(TC) solutions at concentrations ranging from 300 to 500 mg/L, and alizarin complexone(ALC) solutions at concentrations ranging from 200 to 400 mg/L in filtered sea water(salinity of 30) for 24 h, respectively. Otoliths(sagittae, asteriscus), scales, fin rays(dorsal, pectoral, ventral, anal, and caudal fin rays), and fin spines(dorsal, ventral, and anal fin spines) were sampled and used to detect fl uorescent marks after a 60-day growth experiment. With the exception of 300 mg/L TC, acceptable marks were produced in the otoliths and fin spines by all concentrations of TC and ALC. In particular, we observed clearly visible marks in the sagittae, asteriscus, and fin spines under normal light at concentrations of 200–400 mg/L, 250–400 mg/L, and 250–400 mg/L ALC, respectively. Scales and fin rays had acceptable marks at much higher concentrations(≥350 mg/L TC, ≥250 mg/L ALC for scales and ≥350 mg/L TC, ≥300 mg/L ALC for fin rays). The best mark quality(i.e., acceptable marks were observed in all sampled structures after immersion marking) were obtained following immersion in TC at between 350–500 mg/L, and ALC between 300–400 mg/L. In addition, there was no significant difference in survival and growth of TC and ALC marked fish compared to their controls up to 60 days post-marking( P > 0.05).

Transcriptome-Wide Identification and Validation of Reference Genes in Black Rockfish(Sebastes schlegelii)

The quantitative real-time reverse transcription PCR(qRT-PCR)is a widely used technique to analyze gene expression levels.Selecting a suitable reference gene is a crucial step to obtain an accurate result in qRT-PCR.However,most previous studies on fishes adopted reference genes that were commonly used in mammals without validation.In this study,we utilized 89 transcrip-tome datasets covering early developmental stages and different adult tissues,and carried out transcriptome-wide identification and validation of reference genes in Sebastes schlegelii.Finally,121 candidate reference genes were identified based on four criteria.Eight candidates(METAP2,BTF3L4,EIF5A1,TCTP,UBC,PAIRB,RAB10,and DLD)and four commonly used reference genes in mam-mals(TUBA,ACTB,GAPDH,RPL17)were selected for validation via qRT-PCR and four statistical analysis methods(delta-Ct,Best-Keeper,geNorm,and NormFinder).The results indicated that when the black rockfish are cultured in a general condition,the eight candidate reference genes are more stable than traditional reference genes in mammals,and RAB10,EIF5A1,PAIRB and BTF3L4 are the best reference genes in rockfish.This is the first study to conduct transcriptome-wide identification and validation of reference genes for quantitative RT-PCR in the black rockfish,and lay an important foundation for gene expression analysis in teleost.

Use of calcein and alizarin red S for immersion marking of black rockfish Sebastes schlegelii juveniles

Black rockfi sh Sebastes schlegelii juveniles(30–40 mm total length) were immersed in a range of calcein(CAL) solutions at concentrations ranging from 50 to 250 mg/L and alizarin red S(ARS) solutions at concentrations ranging from 100 to 500 mg/L in fi ltered seawater(salinity 30) for 24 h. Fluorescent marks were detected in otoliths(sagittae, asteriscus), scales, fi n rays(dorsal, pectoral, ventral, anal, and caudal fi n rays), and fi n spines(dorsal, ventral, and anal fi n spines) after a 60-d growth experiment. With the exception of 50–100 mg/L CAL, acceptable marks were produced in the otoliths and fi n spines by all concentrations of CAL and ARS. In particular, marks were clearly visible under normal light in the sagittae, asteriscus, and fi n spines of fi sh immersed in 200–500 mg/L, 300–500 mg/L, and 200–500 mg/L ARS, respectively. Scales and fi n rays had acceptable marks at much higher concentrations(≥50 mg/L CAL, ≥300 mg/L ARS for scales and ≥50 mg/L CAL, ≥200 mg/L ARS for fi n rays). The mark quality was highest(i.e., acceptable marks were observed in all sampled structures after immersion marking) in fi sh immersed in 150–250 mg/L CAL or 300–500 mg/L ARS. In addition, there was no signifi cant difference in survival and growth of marked fi sh compared with controls 60 d post-marking( P >0.05).

Feasibility of Partial Replacement of Fishmeal with Proteins from Different Sources in Diets of Korean Rockfish(Sebastes schlegeli)

An 8-week feeding experiment was conducted in an indoor recirculation seawater system to investigate the effects of partial replacement of dietary fishmeal with proteins from five sources on the growth performance and feed utilization of Sebastes schlegeli. Six isonitrogenous and isoenergetic diets were formulated using fishmeal(FM, the control) as sole protein source, or proteins from five sources including poultry by-product meal(PBM), meat and bone meal(MBM), soybean meal(SBM), cottonseed meal(CSM) and canola meal(CNM). Fifteen percent of the crude protein provided by fish meal was replaced, respectively. The results showed that the differences in specific growth rate(SGR) and survival rate(SR) among fish fed PBM, MBM, SBM, CSM and whole FM diets were not significant. However, SGR and SR of fish fed CNM diet was significantly lower than that of other treatments. Feeding rate, feed conversion, nutrient retention showed similar patterns to that of growth. Fish fed CSM and CNM showed significantly lower apparent digestibility coefficient(ADC) of dry matter and gross energy than those fed others while fish fed CNM showed lower ADC of crude protein than those fed others(P<0.05). These results suggested that it was feasible to substitute 15% dietary protein provided by fishmeal with PBM, MBM, SBM and CSM, respectively, but not with CNM as the replacement with CNM reduced fish growth and feed utilization.

The influence of main ecological and environmental factors on the energy budget of Schlegel＇ s black rockfish Sebastes schlegeli

In the Maidao Ecological Laboratory of the Huanghai Sea Fisheries Research Institute in 1998 ~ 2000, the continuous flow-through method was adopted to determine the energy budget components and models of Schlegel＇ s black rockfish under different ecological and environmental factors, such as temperature, food species, body mass and feeding level, etc. The body mass of test fish ranged from 21.2 to 224.5 g. The specific growth rate tended to invert ＂U＂ change with temperature increase. The ecological conversion efficiency showed the same trend as temperature and feeding level rise. Only the specific growth rate tended to decelerate the increment with the rise of feeding level. From the above quantitative relationships, the maximum and optimal growth temper- atures could be obtained as 17.5 and 16.2 ℃, and the maintenance feeding rate and optimum feeding rate as 0.8% and 4. 1% of the body mass. The specific growth rate and ecological conversion coefficient showed a decelerating decrease trend with body mass increment. The small-sized fish food was more advantageous to the feeding level increase in comparison with the small-sized shrimp food, which led to the increase of growth, metabolism and excretion, but had no significant influence on the ecological conversion coefficient. All of temperature, feeding level, body mass and food species can obviously change the energy budget models. The assigning rate of growth energy tended to change along the invert ＂U＂ curve with the increase of temperature and feeding level, and decrease with the body mass increase, but the assigning rates of metabolism energy and excretion energy were quite reverse. These relationships could be quantitatively described as quadratic or power function curve. If the above relationships proved true to other marine fish, the establishment of energy budget model of the same fish under different conditions can be largely simplified.

Preliminary Study on the Water Drag of Schlegel's Black Rockfish Sebastes schlegeli

Drag forces acting on Schlegel’s black rockfish Sebastes schlegeli were studied. A new drag force transducer was designed and used to measure the water drag on Schlegel’s black rockfish in a vertical recirculating flume tank. Fourteen individuals were investigated, yielding two mean drag coefficients referred to the cross sectional area and volume 2/3 respectively at water velocities ranging from 0.3 to 1.0 m s -1 . The drag coefficients can be used for estimating the drag forces acting on Sebastes schlegeli in water.

许氏平鲉幼鱼对人工鱼礁模型不同阴影情况的行为响应

阴影效应是影响人工鱼礁诱集效果的主要因素之一,为研究许氏平鲉(Sebastes schlegelii)对人工鱼礁不同阴影情况的行为响应,采用室内模拟实验方法,在实验水槽顶部固定光源,共设计3组实验:A组实验探究不同阴影面积的鱼礁模型对实验鱼的诱集效果;B组实验探究不放置鱼礁模型、悬挂不同开孔率顶板对实验鱼的诱集效果;C组实验探究阴影面积相同但开孔数量不同的鱼礁模型对实验鱼的诱集效果;对照组实验水槽中不放置鱼礁模型、不悬挂顶板。观察并记录许氏平鲉幼鱼(体长(5.06±0.09)cm,体质量(3.22±0.16)g)在水槽中的行为与分布特征。研究表明:3个实验组中许氏平鲉在鱼礁放置区域的出现率均显著高于对照组和其他区域;A组实验中,许氏平鲉在鱼礁放置区的平均出现率随着鱼礁阴影面积的增大而上升;B组实验中,许氏平鲉在顶板放置区的平均出现率显著高于对照组,但不同水平组之间差异不显著;C组实验中,开孔数为1时许氏平鲉在鱼礁放置区的平均出现率与开孔数为9时相近且高于开孔数为4和6时。研究结果表明,阴影面积越大的人工鱼礁对许氏平鲉的诱集效果越好,阴影面积相同时开孔数较多的人工鱼礁能够在提供良好庇护所的同时保证诱集效果。