Despite the increased recognition of the nutritional value of the Oyster mushroom, coupled with its ability to tolerate a wide range of climatic conditions, its production is still at infancy stage with low adoption r...Despite the increased recognition of the nutritional value of the Oyster mushroom, coupled with its ability to tolerate a wide range of climatic conditions, its production is still at infancy stage with low adoption rate in Kenya. The low uptake could be attributed to the cost of spawns or lack of skills for spawns preparations coupled with poor knowledge on oyster mushroom consumption benefits. The objective of this study was to optimize Pleurotus ostreatus (Oyster mushroom) spawns production. To achieve the objective, the spawns propagation was optimized by varying the temperature level, sterilization time and culture media concentration in order to establish the feasible levels which minimized the days of mycelium full development using central composite designs. Based on the study findings, 26.29<span style="white-space:nowrap;">˚</span>C, 17.36 minutes and 60.95 g/L of temperature level, sterilization time and culture media concentration levels respectively minimized the days to full coverage of mycelium in a petri dish. Central composite designs for controlling temperature, sterilization time and culture media concentration were recommended for spawns maximum production. A further research on multiple response optimizations aimed at achieving resistance to bacterial diseases and yield by varying the strain in the culture were recommended.展开更多
[Objective]Implementation of the Ten-Year Fishing Ban policy may alter fish diversity and niche characteristics of dominant species in spawning grounds within the National Nature Reserve for Rare and Endemic Fish in t...[Objective]Implementation of the Ten-Year Fishing Ban policy may alter fish diversity and niche characteristics of dominant species in spawning grounds within the National Nature Reserve for Rare and Endemic Fish in the Upper Yangtze River.This study initiated continuous monitoring of natural spawning habitats from February 2022 to assess these ecological changes.[Methods]Environmental DNA(eDNA)metabarcoding was employed to analyze fish species composition,biodiversity patterns,and niche parameters of dominant species.Water sampling followed the CEN/TS 19461 standard across five monitoring transects(ZT1-ZT5).[Results]The eDNA analysis detected 45 species of fish belonging to 38 genera,13 families,and 3 orders were detected through environmental DNA(eDNA)in this survey,including 10 species endemic to the upper reaches of the Yangtze River,such as Procypris rabaudi and Myxocyprinus asiaticus.The fish community was mainly composed of bottom-dwelling,settling ovum-producing,omnivorous fish.The variation ranges of the Chao1 index,ACE index,Shannon index,and Simpson index are 736~996,719~965,1.58~3.23,and 0.83~0.99,respectively,indicating that fish species in spawning sites are abundant and community distribution uniformity is high.All indexes are highest at ZT1 monitoring points.Cluster analysis showed that,at a certain similarity level,fish community types in spawning sites could be basically divided into two groups:ZT1,ZT3,and ZT5 clustered together,and ZT2 and ZT4 clustered together,indicating similar fish community habitats.There are 9 dominant fish species in typical deep pool habitats in the reserve,with niche widths(Bi)ranging from 1.13 to 3.87.The dominant fish species are broad and medium niche fish,such as Cyprinus carpio and Hemiculter tchangi,with the niche overlap index(Oik)of some dominant fish species reaching more than 0.95.This indicates fierce competition for resources among the fish in this spawning ground.[Conclusion]The Zhutuo spawning ground demonstrates high species richness with homogeneous community structure and intense resource competition.This study establishes an eDNA-based monitoring framework that enhances conventional survey method,providing critical baseline data for adaptive management under the fishing moratorium regime.展开更多
The red tilefish Branchiostegus japonicus is an economically important demersal fish species with high-quality.However,research on its reproductive biology and population structure characteristics is limited.To better...The red tilefish Branchiostegus japonicus is an economically important demersal fish species with high-quality.However,research on its reproductive biology and population structure characteristics is limited.To better understand the reproductive biological features of B.japonicus,a study was conducted on 461 individuals collected from the East China Sea(27°00′-31°00′N,122°30′-127°30′E)from March to December in 2021.This study analyzed the relationship between standard length and the body weight,and detected the sex ratio,length at first sexual maturity,reproductive period,fecundity,and spawning type of this species.The results revealed a power function relationship between body weight(W)and standard length(L)in the samples as the following regression equation:W=0.000014 L^(3.16)(R^(2)=0.956).The sex ratio was close to 1:1(χ^(2)=1.11,P>0.05),and the sex ratio exhibited significant differences according to different standard lengths.Using the logistic equation,we estimated that 50% of B.japonicus individuals had a standard length at sexual maturity of L_(50)=210 mm.By analyzing the monthly variation in the gonadal index and the proportion of each stage of ovarian development in each month,we assumed that the spawning period of B.japonicus occurred from May to November,and the peak spawning period occurred from June to October.The absolute fecundity was 51441±33232 eggs,the relative fecundity at the standard length was(210±117)eggs mm-1,and the relative fecundity relative to body weight was(184±89)eggs g^(-1).The distribution of the egg diameter of B.japonicus had only one obvious peak,indicating the spawning pattern of B.japonicus was once a year.This study updated and enriched the basic biological data of B.japonicus,which is beneficial for obtaining a better understanding of its population dynamics,and promoting the conservation and sustainable utilization of B.japonicus in East China Sea.展开更多
As China’s second longest river,the Yellow River(YR)carries a large volume of fresh water into the Bohai Sea with abundant nutrients and,thus,plays a crucial role in regulating the temperature and salinity near the Y...As China’s second longest river,the Yellow River(YR)carries a large volume of fresh water into the Bohai Sea with abundant nutrients and,thus,plays a crucial role in regulating the temperature and salinity near the YR Delta.In this study,using the runoff data and the Finite Volume Community Ocean Model,we simulated the salinity distribution near the YR Estuary for 2013-2022.We investigated the effect of the YR runoff on salinity dispersion and established the relationship between salinity distribution and the river’s runoff volume.Additionally,we analyzed the relationship between fish eggs and salinity distribution using fish egg da-ta.Findings indicated that the freshwater discharged from the YR converged into Laizhou Bay under the influence of tide.The sever-al years of simulation results(2013-2022)showed that the salinity field near the YR Estuary changed with the variations of river runoff entering the sea.Simultaneously,we found a positive correlation between the area of low-salinity zones(below 27)and the monthly average river runoff,and this relation could be expressed as Y_(s)=0.7457X_(r)+78.904.The characteristics of fish egg distribution revealed that fish eggs were primarily distributed in the areas characterized by salinity in the range of 25-29.展开更多
Chilo suppressalis （Walker） is one of the important pests in rice produc-tion. ln this paper, the spawning condition of Chilo suppressalis on rice seedlings in Wuxue, Qichun, Chongyang and Xiaogan of Hubei Province ...Chilo suppressalis （Walker） is one of the important pests in rice produc-tion. ln this paper, the spawning condition of Chilo suppressalis on rice seedlings in Wuxue, Qichun, Chongyang and Xiaogan of Hubei Province was investigated, and the spawning habit of overwintering-generation Chilo suppressalis on rice seedlings was analyzed. The results showed the overwintering-generation Chilo suppressalis prefers to spawn on verdant rice leaf blades （face, upper part）. The investigation on spawning habit of Chilo suppressalis would provide a theoretical basis for the fore-casting and control of Chilo suppressalis.展开更多
[Objective] Aim to know the whole process of embryonic development of loach. [Method] DOM + LHRH-A2 was used to induce spawning of loach,then after fertilization,the embryos were cultured into freshwater water with te...[Objective] Aim to know the whole process of embryonic development of loach. [Method] DOM + LHRH-A2 was used to induce spawning of loach,then after fertilization,the embryos were cultured into freshwater water with temperature from 24 to 26 ℃ and pH from 7.0 to 7.5. The embryonic development of loach was observed and 27 concrete morphological characteristics and development time of loach from fertilized egg to newly hatched larval period were described in detail. [Result] The embryonic development of loach could be divided into cleavage stage,blastocyst stage,gastrula stage,neurula stage and organogenesis stage. The loach embryo from fertilized egg to out membrane period was 30 h 45 min in fresh water from 24 to 26 ℃ and pH from 7.0 to 7.5. [Conclusion] It provided important reference for studying artificial propagation and genetic breeding of loach.展开更多
Chinese sturgeon(Acipenser sinensis) is the flagship species of the Changjiang River.The migration route of this species is blocked by the first dam,the Gezhou Dam,and its reproduction is affected by the Three Gorges ...Chinese sturgeon(Acipenser sinensis) is the flagship species of the Changjiang River.The migration route of this species is blocked by the first dam,the Gezhou Dam,and its reproduction is affected by the Three Gorges Dam(TGD),one of the largest dams in the world.We studied the impact of the impoundment of the Three Gorges Reservoir(TGR) since 2003 on the spawning stock and the natural reproduction of the Chinese sturgeon by using our monitoring data from 1997 to 2013.Results indicate that TGR impoundment has delayed the first spawning dates of the fish from middle-late October to late November,decreased the amount of spawning activities from twice to only once each year,and significantly reduced egg production.In particular,the fish did not demonstrate any spawning activities in 2013.Therefore,TGR impoundment significantly affects the natural reproduction of the fish downstream of the TGD.The spawning stock size of the fish is also predicted to further decrease in the future,which will lead to a risk of population extinction.Ecological regulations must be imposed on decreasing the water temperature to 20℃before mid-October and increasing water discharge downstream of the TGD in October to induce spawning of the Chinese sturgeon.展开更多
In order to improve production and breed new broods of bay scallop Argopecten irradians irradians, different-colored orange, purple and white lines were established by two mating methods of self-fertilization and mass...In order to improve production and breed new broods of bay scallop Argopecten irradians irradians, different-colored orange, purple and white lines were established by two mating methods of self-fertilization and mass spawning at a commercial scallop hatchery in spring, 2002. And then larval growth and survival of different lines was compared to test whether there is a relationship between shell color and growth and survival at early developmental stage. Both growth and survival have no significant differences among different experimental larvae of self-fertilization or mass spawning. Results are as following in the order of orange, purple and white shell stock. For the self-fertilization, growth rates of larvae were 6.174, 6.412, and 6.599 μm/d, respectively. Survival rates of larvae at Day 3 were 74.41%, 76.86%, and 82.05%; Day 6 were 49.14%, 65.63%, and 52.79%; and Day 9 were 25.06%, 20.80%, and 26.47%, respectively. For the mass spawning, the growth rates were 7.836, 7.941, and 7.878 μm/d, respectively. Survival rates at Day 3 were 93.05%, 91.95%, and 92.50%; Day 6 were 79.17%, 78.05%, and 82.50%; and Day 9 were 34.72%, 36.67%, and 38.33%, respectively. The absence of any relationship between shell color and growth and survival at the larval stage may be resulted from their common genetic basis.展开更多
Breeding strategies of Acrossocheilus fasciatus were studied from 592 specimens collected monthly during May 2007 and April 2008 in the Puxi Stream of the Huangshan Mountain. Sex ratio of the studied population was 0....Breeding strategies of Acrossocheilus fasciatus were studied from 592 specimens collected monthly during May 2007 and April 2008 in the Puxi Stream of the Huangshan Mountain. Sex ratio of the studied population was 0.90 ： 1 （ ♀ ： ♂ ）, not significantly different from 1 ： 1. Both sexes reached their first sexual maturity at age 2 （the second calendar year of their birth）. Fifty percent of females and males reached maturity at a total length of 69.75 mm and 69.36 mm respectively, and the minimum total length was 61.54 mm and 58.96 mm, respectively. Based on the monthly changes in gonado-somatic index and egg- development process, the breeding season of the population was from May to August, with one obvious interval （in June） occurring in the breeding activity for the females. The nonsynchronous development of oocytes observed in mature ovaries indicated that A. fasciatus is a batch spawner. Absolute fecundity of A. fasciatus ranged from 308 to 2002 eggs with a mean of 857 eggs, increased significantly with total length, and was significantly different among three age groups. Relative fecundity ranged from 38.63 to 71.70 egg/g with a mean of 53.29 egg/g, and was not significantly different among the three age groups. It was suggested that these reproductive characteristics were adaptive strategies for A. fasciatus to acclimatize to lotic water where environmental factors were unstable but predictable [ Current Zoology 55 （5） ： 350 - 356, 2009].展开更多
Although amphioxus is widespread in temperate and tropical seas,its population is diminishing be-cause of environmental pollution.To keep the population of this evolutionarily important animal fromdiminishing,study on...Although amphioxus is widespread in temperate and tropical seas,its population is diminishing be-cause of environmental pollution.To keep the population of this evolutionarily important animal fromdiminishing,study on its reproduction and development is necessary.The main findings in this study onthe spawning and fecundity of the amphioxus reared in laboratory and its larval development are as fol-lows.1.Water temperature markedly affected the spawning.It spawned only when water temperature reached 21℃.2.Spawning of the amphioxus in laboratory was markedly extended.Initially,the amphioxus spawned at about 7:00 PM,but spawning time was postponed as spawning days went on.3.The number of eggs produced by a female ranged from 1400 to 12800,average of 5800.This al-so represents the fecundity of the amphioxus because it shedded all eggs within the ovary at a time.4.During the first few months of life of the amphioxus,its growth rate changed seasonally.Thegrowth rate in summer and fall was greater than that展开更多
The Japanese common squid Todarodes pacificus is an economically important species with one year lifespan,which is significantly influenced by climatic and environmental variability. According to the fishery data of t...The Japanese common squid Todarodes pacificus is an economically important species with one year lifespan,which is significantly influenced by climatic and environmental variability. According to the fishery data of the winter cohort of T. pacificus from 2003 to 2012, as well as environmental data and the Oceanic Ni？o index（ONI,which was defined by the sea surface temperature（SST） anomaly in the Ni？o 3.4 region）, variations in the SST,chlorophyll a（Chl a） concentration, suitable spawning area（SSA） and sea surface height anomaly（SSHA） on the spawning ground of T. pacificus were examined under the El Ni？o and La Nina conditions. Their influences on squid abundance（defined by catch per unit effort, CPUE） were further assessed. The results showed that seasonal changes were found in SST, Chl a and SSA on the spawning ground of T. pacificus. Correlation analysis suggested that annual CPUE was significantly positively correlated with Chl a and SSA（p〈0.05）, but had insignificant relationship with SST（p〉0.05）. Moreover, the El Ni？o and La Ni？a events tended to dominate the changes of SSA and Chl a concentration in the key area between 25°–29°N and 122.5°–130.5°E, driving the variability of squid abundance. However, this influence varied with the intensity of each anomalous climatic event： the weak El Ni？o event occurred, the spawning ground was occupied by waters with enlarged SSA but with extremely low Chl a concentration, leading to low squid recruitment, the CPUE then decreased; the moderate intensity of El Ni？o event resulted in shrunk SSA but with high Chl a concentration on the spawning ground, the squid recruitment and CPUE increased; the moderate intensity of La Ni？a events yielded elevated SSA and high Chl a concentration on the spawning ground, the squid recruitment and CPUE dramatically increased. Our findings suggested that the ENSO events played crucial effects on the incubating and feeding conditions of the winter cohort of T. pacificus during the spawning season and ultimately affected its abundance.展开更多
The estuarine tapertail anchovy(Coilia nasus)is a high-value commercial fish.Estimating the spawning site or hatchery origin and habitat is essential for its conservation.This study aimed to determine the habitat use ...The estuarine tapertail anchovy(Coilia nasus)is a high-value commercial fish.Estimating the spawning site or hatchery origin and habitat is essential for its conservation.This study aimed to determine the habitat use and life history characteristics of C.nasus from the Changjiang River Estuary.We investigated the environmental signatures of strontium(Sr)and calcium(Ca)in the otoliths of the collected specimens using electron probe microanalysis;additionally,we examined their gonadal maturity stage.Our results indicate that the 31 adult C.nasus specimens used in this study could be classified into two types based on their otolith Sr:Ca concentration ratios and their gonadal maturity stage.The long freshwater early life history type(Type LF)had wider central region in the otolith with low Sr:Ca concentration ratios ranging from 1.24±0.62 to 1.92±0.78 and a bluish pattern of low Sr content level.These fish are of riverine origin and had a relatively long early life history in freshwater and low gonadal maturation when captured.The short freshwater early life history type(Type SF)had a shorter central region in the otolith with low Sr:Ca concentration ratios ranging from 1.35±0.5 to 2.82±0.97 and a correspondingly bluish pattern.These fish also had a relatively short-term early life history in freshwater and high gonadal maturation when captured.The results of the otolith microchemical analysis indicated that Type LF and Type SF originated in spawning/hatching sites far from and close to the estuary,respectively.The mature gonads of Type SF fish indicated that they may breed in areas close to the estuary,whereas the immature gonads of Type LF fish indicated that they may breed in areas far from the estuary.This study is the first to reveal that the Changjiang River Estuary contains stocks of anadromous C.nasus originating in different spawning sites during the same season.The estuarine habitat plays a critical role in the connectivity between freshwater recruitment and the marine resources available to adult spawners of this commercially valued species.From a conservation perspective,this study provides important information for identifying anadromous C.nasus stocks originating in different spawning sites in the Changjiang River Basin.展开更多
The reproductive biology of Schizopygopsis younghusbandi(Cyprinidae: Schizothoracinae) was studied by 719 individuals that collected from August 2008 to August 2009 in the middle reaches of Yarlung Tsangpo River, Chin...The reproductive biology of Schizopygopsis younghusbandi(Cyprinidae: Schizothoracinae) was studied by 719 individuals that collected from August 2008 to August 2009 in the middle reaches of Yarlung Tsangpo River, China. We coupled monthly variations of the gonadosomatic index(GSI), monthly proportions of the macroscopic maturity stages with size distribution of oocytes to evaluate spawning seasons. Taken as a set, these results indicated that S. younghusband i spawned from March to April with high degree of the spawning synchronicity. The standard lengths and the ages at 50% maturity for male were 222 mm and 4.4 year, and 308 mm and 7.0 year for female. In addition, the estimated mean fecundity and mean relative fecundity were 18682 and 57.8 eggs per g body weight. The fecundity of S. younghusbandi increased linearly with increasing of standard length and body weight. This study provides details about the S. younghusbandi reproduction suggesting that may be this species is vulnerable to exploitation in the middle reaches of Yarlung Tsangpo River.展开更多
To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent （〉100 km）, we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and...To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent （〉100 km）, we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and archival tags on adult horseshoe crabs prior to their spawning season. We tagged and released 160 females and 60 males in 2004 and 217 females in 2005. The array covered approximately 140 km of shoreline. Recapture rates were 〉70% with multi-year recaptures. We categorized adult age by carapace wear. Older females tended to spawn earlier in the season and more frequently than young females, but those tendencies were more apparent in 2004 when spawning overall occurred earlier than in 2005 when spawning was delayed possibly due to decreased water temperatures. Timing of initial spawning within a year was correlated with water temperature. After adjusting for day of first spring tide, the day of In＇st spawning was 4 days earlier for every 1 degree （℃） rise in mean daily water temperature in May. Seventy nine % of spawning occurred during nighttime high tides. Fifty five % of spawning occurred within 3 d of a spring tide, which was slightly higher than the 47% expected if spawning was uniformly distributed regardless of tidal cycle. Within the same spawning season, males and females were observed spawning or intertidally resting at more than one beach separated by 〉5 kin. Between years, most （77%） did not return to spawn at the same beach. Probability of stranding was strongly age dependent for males and females with older adults experiencing higher stranding rates. Horseshoe crabs staging in the shallow waters east of the channel spawned exclusively along the eastern （N J） shoreline, but those staging west of the channel spawned throughout the bay. Overall, several insights emerged from the use of radio telemetry, which advances our understanding of horseshoe crab ecology and will be useful in conserving the Delaware Bay horseshoe crab population and habitats展开更多
The distribution of nutrients and the effect of side transport of nutrients on anchovy spawning ground to the southern waters of Shandong Peninsula are discussed based on the data collected in June 2000, May and June ...The distribution of nutrients and the effect of side transport of nutrients on anchovy spawning ground to the southern waters of Shandong Peninsula are discussed based on the data collected in June 2000, May and June 2001. The coastal current and upwelling are the main physical processes of nutrient transport to the southern waters of Shandong Peninsula. The concentrations of nutrients, Chl-a, the density of anchovy eggs, larva and juvenile fish increase obviously where they are greatly affected by these processes, while the contents of nutrients and Chl-a, the density of anchovy eggs, larva and juvenile fish decrease significantly where these processes diminish or disappear. The investigation suggest that the side transport of nutrients by Lubei (North Shandong) coastal current in the northern area causes the Chl-a content to be high and dense anchovy eggs, larva and juvenile fish to be dense in the coastal area of the Chengshan Cape. In the southern area, the riverine input from Subei irrigation ditch with high content of nutrients inshore and upwelling in the western edge of the Huanghai Sea Cold Water offshore should be responsible for high Chl-a concentration and dense anchovy eggs, larva and juvenile fish. It is possible that these processes of nutrient transport have controlled the anchovy spawning ground to the southern waters of Shandong Peninsula.展开更多
Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growt...Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50% sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size.展开更多
In this study, a programmable freezing technique has been developed for strip spawned sperm in the blue mussel, M ytilus galloprovincialis. The optimized key parameters include cooling rate, endpoint temperature, thaw...In this study, a programmable freezing technique has been developed for strip spawned sperm in the blue mussel, M ytilus galloprovincialis. The optimized key parameters include cooling rate, endpoint temperature, thawing temperature, sugar addition and sperm to oocyte ratio. The sperm quality was assessed by the fertilization rate or the integrity of sperm component and organelle. The highest post-thaw sperm fertilization rate was 91%, which was produced with sperm cryopreserved in 8% dimethyl sulfoxide at the cooling rate of-4°C/min from 2°C to-30°C before being plunged into liquid nitrogen for at least 12 h, thawed in a 20°C seawater bath and fertilized at sperm to egg ratio of 50 000:1. The addition of glucose, sucrose or trehalose to 8% dimethyl sulfoxide could not further improve fertilization rates. The fluorescent assessments showed that the post-thaw sperm plasma membrane integrity and acrosome integrity were significantly damaged in comparison with fresh sperm.展开更多
Psilorhynchus homaloptera mainly inhabits turbulent waters in the lower reach of the Yarlung Zangbo River,Tibet,China,and it is the only species of Psilorhynchus in China.However,many important aspects of its biology ...Psilorhynchus homaloptera mainly inhabits turbulent waters in the lower reach of the Yarlung Zangbo River,Tibet,China,and it is the only species of Psilorhynchus in China.However,many important aspects of its biology remain poorly documented,which hinders the conservation eff orts.Therefore,we studied its reproduction using 801 specimens from the Motuo sector of the lower Yarlung Zangbo River from December 2015 to November 2016.The sex ratio was 0.68꞉1(male꞉female)for the overall population.Females reached a larger total length and weight(134 mm and 18.6 g)than males did(113 mm and 12.2 g).Lengths at maturity were estimated 80.0 mm for males and 93.1 mm for females.Our analyses of gonad development and the size distribution of oocytes suggest that P.homaloptera is a single spawner with the peak spawning period between September and October.Furthermore,the estimated mean absolute fecundity was 557±204 eggs per fish,and mean relative fecundity was 50.9±10.9 eggs per g of female weight.The fecundity of P.homaloptera increased linearly with increasing total length,total weight,ovary weight,and age.This study on the reproductive biology of P.homaloptera demonstrates that the fish was in a vulnerable state due to the increasing anthropogenic activities in the lower Yarlung Zangbo River.展开更多
文摘Despite the increased recognition of the nutritional value of the Oyster mushroom, coupled with its ability to tolerate a wide range of climatic conditions, its production is still at infancy stage with low adoption rate in Kenya. The low uptake could be attributed to the cost of spawns or lack of skills for spawns preparations coupled with poor knowledge on oyster mushroom consumption benefits. The objective of this study was to optimize Pleurotus ostreatus (Oyster mushroom) spawns production. To achieve the objective, the spawns propagation was optimized by varying the temperature level, sterilization time and culture media concentration in order to establish the feasible levels which minimized the days of mycelium full development using central composite designs. Based on the study findings, 26.29<span style="white-space:nowrap;">˚</span>C, 17.36 minutes and 60.95 g/L of temperature level, sterilization time and culture media concentration levels respectively minimized the days to full coverage of mycelium in a petri dish. Central composite designs for controlling temperature, sterilization time and culture media concentration were recommended for spawns maximum production. A further research on multiple response optimizations aimed at achieving resistance to bacterial diseases and yield by varying the strain in the culture were recommended.
文摘[Objective]Implementation of the Ten-Year Fishing Ban policy may alter fish diversity and niche characteristics of dominant species in spawning grounds within the National Nature Reserve for Rare and Endemic Fish in the Upper Yangtze River.This study initiated continuous monitoring of natural spawning habitats from February 2022 to assess these ecological changes.[Methods]Environmental DNA(eDNA)metabarcoding was employed to analyze fish species composition,biodiversity patterns,and niche parameters of dominant species.Water sampling followed the CEN/TS 19461 standard across five monitoring transects(ZT1-ZT5).[Results]The eDNA analysis detected 45 species of fish belonging to 38 genera,13 families,and 3 orders were detected through environmental DNA(eDNA)in this survey,including 10 species endemic to the upper reaches of the Yangtze River,such as Procypris rabaudi and Myxocyprinus asiaticus.The fish community was mainly composed of bottom-dwelling,settling ovum-producing,omnivorous fish.The variation ranges of the Chao1 index,ACE index,Shannon index,and Simpson index are 736~996,719~965,1.58~3.23,and 0.83~0.99,respectively,indicating that fish species in spawning sites are abundant and community distribution uniformity is high.All indexes are highest at ZT1 monitoring points.Cluster analysis showed that,at a certain similarity level,fish community types in spawning sites could be basically divided into two groups:ZT1,ZT3,and ZT5 clustered together,and ZT2 and ZT4 clustered together,indicating similar fish community habitats.There are 9 dominant fish species in typical deep pool habitats in the reserve,with niche widths(Bi)ranging from 1.13 to 3.87.The dominant fish species are broad and medium niche fish,such as Cyprinus carpio and Hemiculter tchangi,with the niche overlap index(Oik)of some dominant fish species reaching more than 0.95.This indicates fierce competition for resources among the fish in this spawning ground.[Conclusion]The Zhutuo spawning ground demonstrates high species richness with homogeneous community structure and intense resource competition.This study establishes an eDNA-based monitoring framework that enhances conventional survey method,providing critical baseline data for adaptive management under the fishing moratorium regime.
基金funded by the Key Technology and System Exploration of Quota Fishing,Ministry of Agriculture and Rural Affairs,Fishery Management Fund Project(No.36,2017)the Zhejiang Fishery Resources Survey Special Project(No.HYS-CZ-202314)。
文摘The red tilefish Branchiostegus japonicus is an economically important demersal fish species with high-quality.However,research on its reproductive biology and population structure characteristics is limited.To better understand the reproductive biological features of B.japonicus,a study was conducted on 461 individuals collected from the East China Sea(27°00′-31°00′N,122°30′-127°30′E)from March to December in 2021.This study analyzed the relationship between standard length and the body weight,and detected the sex ratio,length at first sexual maturity,reproductive period,fecundity,and spawning type of this species.The results revealed a power function relationship between body weight(W)and standard length(L)in the samples as the following regression equation:W=0.000014 L^(3.16)(R^(2)=0.956).The sex ratio was close to 1:1(χ^(2)=1.11,P>0.05),and the sex ratio exhibited significant differences according to different standard lengths.Using the logistic equation,we estimated that 50% of B.japonicus individuals had a standard length at sexual maturity of L_(50)=210 mm.By analyzing the monthly variation in the gonadal index and the proportion of each stage of ovarian development in each month,we assumed that the spawning period of B.japonicus occurred from May to November,and the peak spawning period occurred from June to October.The absolute fecundity was 51441±33232 eggs,the relative fecundity at the standard length was(210±117)eggs mm-1,and the relative fecundity relative to body weight was(184±89)eggs g^(-1).The distribution of the egg diameter of B.japonicus had only one obvious peak,indicating the spawning pattern of B.japonicus was once a year.This study updated and enriched the basic biological data of B.japonicus,which is beneficial for obtaining a better understanding of its population dynamics,and promoting the conservation and sustainable utilization of B.japonicus in East China Sea.
基金supported by the Yantai City Science and Technology Innovation Development Plan Project(Nos.2023JCYJ097 and 2023JCYJ094)the Key Project of the National Natural Science Foundation of China(No.42330406).
文摘As China’s second longest river,the Yellow River(YR)carries a large volume of fresh water into the Bohai Sea with abundant nutrients and,thus,plays a crucial role in regulating the temperature and salinity near the YR Delta.In this study,using the runoff data and the Finite Volume Community Ocean Model,we simulated the salinity distribution near the YR Estuary for 2013-2022.We investigated the effect of the YR runoff on salinity dispersion and established the relationship between salinity distribution and the river’s runoff volume.Additionally,we analyzed the relationship between fish eggs and salinity distribution using fish egg da-ta.Findings indicated that the freshwater discharged from the YR converged into Laizhou Bay under the influence of tide.The sever-al years of simulation results(2013-2022)showed that the salinity field near the YR Estuary changed with the variations of river runoff entering the sea.Simultaneously,we found a positive correlation between the area of low-salinity zones(below 27)and the monthly average river runoff,and this relation could be expressed as Y_(s)=0.7457X_(r)+78.904.The characteristics of fish egg distribution revealed that fish eggs were primarily distributed in the areas characterized by salinity in the range of 25-29.
基金Supported by National Five-year Science&Technology Support Program(2012BAD19B03)Special Scientific Research Fund of Agricultural Public Welfare Profession of China(201303017)~~
文摘Chilo suppressalis （Walker） is one of the important pests in rice produc-tion. ln this paper, the spawning condition of Chilo suppressalis on rice seedlings in Wuxue, Qichun, Chongyang and Xiaogan of Hubei Province was investigated, and the spawning habit of overwintering-generation Chilo suppressalis on rice seedlings was analyzed. The results showed the overwintering-generation Chilo suppressalis prefers to spawn on verdant rice leaf blades （face, upper part）. The investigation on spawning habit of Chilo suppressalis would provide a theoretical basis for the fore-casting and control of Chilo suppressalis.
文摘[Objective] Aim to know the whole process of embryonic development of loach. [Method] DOM + LHRH-A2 was used to induce spawning of loach,then after fertilization,the embryos were cultured into freshwater water with temperature from 24 to 26 ℃ and pH from 7.0 to 7.5. The embryonic development of loach was observed and 27 concrete morphological characteristics and development time of loach from fertilized egg to newly hatched larval period were described in detail. [Result] The embryonic development of loach could be divided into cleavage stage,blastocyst stage,gastrula stage,neurula stage and organogenesis stage. The loach embryo from fertilized egg to out membrane period was 30 h 45 min in fresh water from 24 to 26 ℃ and pH from 7.0 to 7.5. [Conclusion] It provided important reference for studying artificial propagation and genetic breeding of loach.
基金Supported by the Three Gorges Project Eco-Environmental Monitoring System(No.JJ[2015]-010)the National Natural Science Foundation of China(No.31201727)the China Three Gorges Corporation(No.0799533)
文摘Chinese sturgeon(Acipenser sinensis) is the flagship species of the Changjiang River.The migration route of this species is blocked by the first dam,the Gezhou Dam,and its reproduction is affected by the Three Gorges Dam(TGD),one of the largest dams in the world.We studied the impact of the impoundment of the Three Gorges Reservoir(TGR) since 2003 on the spawning stock and the natural reproduction of the Chinese sturgeon by using our monitoring data from 1997 to 2013.Results indicate that TGR impoundment has delayed the first spawning dates of the fish from middle-late October to late November,decreased the amount of spawning activities from twice to only once each year,and significantly reduced egg production.In particular,the fish did not demonstrate any spawning activities in 2013.Therefore,TGR impoundment significantly affects the natural reproduction of the fish downstream of the TGD.The spawning stock size of the fish is also predicted to further decrease in the future,which will lead to a risk of population extinction.Ecological regulations must be imposed on decreasing the water temperature to 20℃before mid-October and increasing water discharge downstream of the TGD in October to induce spawning of the Chinese sturgeon.
基金This work was financially supported by Project of Scientific Innova-tion, Chinese Academy of Sciences (ZKCX2-211).
文摘In order to improve production and breed new broods of bay scallop Argopecten irradians irradians, different-colored orange, purple and white lines were established by two mating methods of self-fertilization and mass spawning at a commercial scallop hatchery in spring, 2002. And then larval growth and survival of different lines was compared to test whether there is a relationship between shell color and growth and survival at early developmental stage. Both growth and survival have no significant differences among different experimental larvae of self-fertilization or mass spawning. Results are as following in the order of orange, purple and white shell stock. For the self-fertilization, growth rates of larvae were 6.174, 6.412, and 6.599 μm/d, respectively. Survival rates of larvae at Day 3 were 74.41%, 76.86%, and 82.05%; Day 6 were 49.14%, 65.63%, and 52.79%; and Day 9 were 25.06%, 20.80%, and 26.47%, respectively. For the mass spawning, the growth rates were 7.836, 7.941, and 7.878 μm/d, respectively. Survival rates at Day 3 were 93.05%, 91.95%, and 92.50%; Day 6 were 79.17%, 78.05%, and 82.50%; and Day 9 were 34.72%, 36.67%, and 38.33%, respectively. The absence of any relationship between shell color and growth and survival at the larval stage may be resulted from their common genetic basis.
基金by National Basic Research Program of China(2009CB119200)Anhui Provincial Natural Science Foundation(090413080)Natural Science Foundation of Anhui Education Bureau(KJ2009A110,KJ2008B211)
文摘Breeding strategies of Acrossocheilus fasciatus were studied from 592 specimens collected monthly during May 2007 and April 2008 in the Puxi Stream of the Huangshan Mountain. Sex ratio of the studied population was 0.90 ： 1 （ ♀ ： ♂ ）, not significantly different from 1 ： 1. Both sexes reached their first sexual maturity at age 2 （the second calendar year of their birth）. Fifty percent of females and males reached maturity at a total length of 69.75 mm and 69.36 mm respectively, and the minimum total length was 61.54 mm and 58.96 mm, respectively. Based on the monthly changes in gonado-somatic index and egg- development process, the breeding season of the population was from May to August, with one obvious interval （in June） occurring in the breeding activity for the females. The nonsynchronous development of oocytes observed in mature ovaries indicated that A. fasciatus is a batch spawner. Absolute fecundity of A. fasciatus ranged from 308 to 2002 eggs with a mean of 857 eggs, increased significantly with total length, and was significantly different among three age groups. Relative fecundity ranged from 38.63 to 71.70 egg/g with a mean of 53.29 egg/g, and was not significantly different among the three age groups. It was suggested that these reproductive characteristics were adaptive strategies for A. fasciatus to acclimatize to lotic water where environmental factors were unstable but predictable [ Current Zoology 55 （5） ： 350 - 356, 2009].
文摘Although amphioxus is widespread in temperate and tropical seas,its population is diminishing be-cause of environmental pollution.To keep the population of this evolutionarily important animal fromdiminishing,study on its reproduction and development is necessary.The main findings in this study onthe spawning and fecundity of the amphioxus reared in laboratory and its larval development are as fol-lows.1.Water temperature markedly affected the spawning.It spawned only when water temperature reached 21℃.2.Spawning of the amphioxus in laboratory was markedly extended.Initially,the amphioxus spawned at about 7:00 PM,but spawning time was postponed as spawning days went on.3.The number of eggs produced by a female ranged from 1400 to 12800,average of 5800.This al-so represents the fecundity of the amphioxus because it shedded all eggs within the ovary at a time.4.During the first few months of life of the amphioxus,its growth rate changed seasonally.Thegrowth rate in summer and fall was greater than that
基金China Postdoctoral Science Foundation under contract No.2017M611612the National Key Technologies R&D Program of China under contract No.2013BAD13B01+2 种基金the Doctoral Startup Scientific Research Foundation of Shanghai Ocean University under contract No.A2-0203-17-100313the Open Fund for Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources under contract No.A1-0203-00-2009-5the Shanghai Universities First-Class Disciplines Project(Fisheries A)
文摘The Japanese common squid Todarodes pacificus is an economically important species with one year lifespan,which is significantly influenced by climatic and environmental variability. According to the fishery data of the winter cohort of T. pacificus from 2003 to 2012, as well as environmental data and the Oceanic Ni？o index（ONI,which was defined by the sea surface temperature（SST） anomaly in the Ni？o 3.4 region）, variations in the SST,chlorophyll a（Chl a） concentration, suitable spawning area（SSA） and sea surface height anomaly（SSHA） on the spawning ground of T. pacificus were examined under the El Ni？o and La Nina conditions. Their influences on squid abundance（defined by catch per unit effort, CPUE） were further assessed. The results showed that seasonal changes were found in SST, Chl a and SSA on the spawning ground of T. pacificus. Correlation analysis suggested that annual CPUE was significantly positively correlated with Chl a and SSA（p〈0.05）, but had insignificant relationship with SST（p〉0.05）. Moreover, the El Ni？o and La Ni？a events tended to dominate the changes of SSA and Chl a concentration in the key area between 25°–29°N and 122.5°–130.5°E, driving the variability of squid abundance. However, this influence varied with the intensity of each anomalous climatic event： the weak El Ni？o event occurred, the spawning ground was occupied by waters with enlarged SSA but with extremely low Chl a concentration, leading to low squid recruitment, the CPUE then decreased; the moderate intensity of El Ni？o event resulted in shrunk SSA but with high Chl a concentration on the spawning ground, the squid recruitment and CPUE increased; the moderate intensity of La Ni？a events yielded elevated SSA and high Chl a concentration on the spawning ground, the squid recruitment and CPUE dramatically increased. Our findings suggested that the ENSO events played crucial effects on the incubating and feeding conditions of the winter cohort of T. pacificus during the spawning season and ultimately affected its abundance.
基金The National Natural Science Foundation of China under contract No.31602159the Agricultural Finance Special Project under contract No.CJDC-2017-22the Scientific Research Foundation of Wuxi City for Returned Oversea Chinese Scholars under contract No.CZ2019231400.
文摘The estuarine tapertail anchovy(Coilia nasus)is a high-value commercial fish.Estimating the spawning site or hatchery origin and habitat is essential for its conservation.This study aimed to determine the habitat use and life history characteristics of C.nasus from the Changjiang River Estuary.We investigated the environmental signatures of strontium(Sr)and calcium(Ca)in the otoliths of the collected specimens using electron probe microanalysis;additionally,we examined their gonadal maturity stage.Our results indicate that the 31 adult C.nasus specimens used in this study could be classified into two types based on their otolith Sr:Ca concentration ratios and their gonadal maturity stage.The long freshwater early life history type(Type LF)had wider central region in the otolith with low Sr:Ca concentration ratios ranging from 1.24±0.62 to 1.92±0.78 and a bluish pattern of low Sr content level.These fish are of riverine origin and had a relatively long early life history in freshwater and low gonadal maturation when captured.The short freshwater early life history type(Type SF)had a shorter central region in the otolith with low Sr:Ca concentration ratios ranging from 1.35±0.5 to 2.82±0.97 and a correspondingly bluish pattern.These fish also had a relatively short-term early life history in freshwater and high gonadal maturation when captured.The results of the otolith microchemical analysis indicated that Type LF and Type SF originated in spawning/hatching sites far from and close to the estuary,respectively.The mature gonads of Type SF fish indicated that they may breed in areas close to the estuary,whereas the immature gonads of Type LF fish indicated that they may breed in areas far from the estuary.This study is the first to reveal that the Changjiang River Estuary contains stocks of anadromous C.nasus originating in different spawning sites during the same season.The estuarine habitat plays a critical role in the connectivity between freshwater recruitment and the marine resources available to adult spawners of this commercially valued species.From a conservation perspective,this study provides important information for identifying anadromous C.nasus stocks originating in different spawning sites in the Changjiang River Basin.
基金Supported by the Finance Special Fund of Chinese Ministry of Agriculture(Fisheries Resources and Environment Survey in the Key Water Areas of Tibet)
文摘The reproductive biology of Schizopygopsis younghusbandi(Cyprinidae: Schizothoracinae) was studied by 719 individuals that collected from August 2008 to August 2009 in the middle reaches of Yarlung Tsangpo River, China. We coupled monthly variations of the gonadosomatic index(GSI), monthly proportions of the macroscopic maturity stages with size distribution of oocytes to evaluate spawning seasons. Taken as a set, these results indicated that S. younghusband i spawned from March to April with high degree of the spawning synchronicity. The standard lengths and the ages at 50% maturity for male were 222 mm and 4.4 year, and 308 mm and 7.0 year for female. In addition, the estimated mean fecundity and mean relative fecundity were 18682 and 57.8 eggs per g body weight. The fecundity of S. younghusbandi increased linearly with increasing of standard length and body weight. This study provides details about the S. younghusbandi reproduction suggesting that may be this species is vulnerable to exploitation in the middle reaches of Yarlung Tsangpo River.
基金Support Program, New Jersey Fish Game & Wildlife, and Delaware Department of Natural Resources and Environmental Control
文摘To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent （〉100 km）, we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and archival tags on adult horseshoe crabs prior to their spawning season. We tagged and released 160 females and 60 males in 2004 and 217 females in 2005. The array covered approximately 140 km of shoreline. Recapture rates were 〉70% with multi-year recaptures. We categorized adult age by carapace wear. Older females tended to spawn earlier in the season and more frequently than young females, but those tendencies were more apparent in 2004 when spawning overall occurred earlier than in 2005 when spawning was delayed possibly due to decreased water temperatures. Timing of initial spawning within a year was correlated with water temperature. After adjusting for day of first spring tide, the day of In＇st spawning was 4 days earlier for every 1 degree （℃） rise in mean daily water temperature in May. Seventy nine % of spawning occurred during nighttime high tides. Fifty five % of spawning occurred within 3 d of a spring tide, which was slightly higher than the 47% expected if spawning was uniformly distributed regardless of tidal cycle. Within the same spawning season, males and females were observed spawning or intertidally resting at more than one beach separated by 〉5 kin. Between years, most （77%） did not return to spawn at the same beach. Probability of stranding was strongly age dependent for males and females with older adults experiencing higher stranding rates. Horseshoe crabs staging in the shallow waters east of the channel spawned exclusively along the eastern （N J） shoreline, but those staging west of the channel spawned throughout the bay. Overall, several insights emerged from the use of radio telemetry, which advances our understanding of horseshoe crab ecology and will be useful in conserving the Delaware Bay horseshoe crab population and habitats
文摘The distribution of nutrients and the effect of side transport of nutrients on anchovy spawning ground to the southern waters of Shandong Peninsula are discussed based on the data collected in June 2000, May and June 2001. The coastal current and upwelling are the main physical processes of nutrient transport to the southern waters of Shandong Peninsula. The concentrations of nutrients, Chl-a, the density of anchovy eggs, larva and juvenile fish increase obviously where they are greatly affected by these processes, while the contents of nutrients and Chl-a, the density of anchovy eggs, larva and juvenile fish decrease significantly where these processes diminish or disappear. The investigation suggest that the side transport of nutrients by Lubei (North Shandong) coastal current in the northern area causes the Chl-a content to be high and dense anchovy eggs, larva and juvenile fish to be dense in the coastal area of the Chengshan Cape. In the southern area, the riverine input from Subei irrigation ditch with high content of nutrients inshore and upwelling in the western edge of the Huanghai Sea Cold Water offshore should be responsible for high Chl-a concentration and dense anchovy eggs, larva and juvenile fish. It is possible that these processes of nutrient transport have controlled the anchovy spawning ground to the southern waters of Shandong Peninsula.
基金supported by National Basic Research Program of China(2009CB119200)Natural Science Foundation of China(31172120)Anhui Provincial Natural Science Foundation(090413080)
文摘Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50% sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size.
基金Supported by the China Scholarship Council and South Australian Research and Development Institute(SARDI)
文摘In this study, a programmable freezing technique has been developed for strip spawned sperm in the blue mussel, M ytilus galloprovincialis. The optimized key parameters include cooling rate, endpoint temperature, thawing temperature, sugar addition and sperm to oocyte ratio. The sperm quality was assessed by the fertilization rate or the integrity of sperm component and organelle. The highest post-thaw sperm fertilization rate was 91%, which was produced with sperm cryopreserved in 8% dimethyl sulfoxide at the cooling rate of-4°C/min from 2°C to-30°C before being plunged into liquid nitrogen for at least 12 h, thawed in a 20°C seawater bath and fertilized at sperm to egg ratio of 50 000:1. The addition of glucose, sucrose or trehalose to 8% dimethyl sulfoxide could not further improve fertilization rates. The fluorescent assessments showed that the post-thaw sperm plasma membrane integrity and acrosome integrity were significantly damaged in comparison with fresh sperm.
基金Supported by the Powerchina Chengdu Engineering Corporation Limited。
文摘Psilorhynchus homaloptera mainly inhabits turbulent waters in the lower reach of the Yarlung Zangbo River,Tibet,China,and it is the only species of Psilorhynchus in China.However,many important aspects of its biology remain poorly documented,which hinders the conservation eff orts.Therefore,we studied its reproduction using 801 specimens from the Motuo sector of the lower Yarlung Zangbo River from December 2015 to November 2016.The sex ratio was 0.68꞉1(male꞉female)for the overall population.Females reached a larger total length and weight(134 mm and 18.6 g)than males did(113 mm and 12.2 g).Lengths at maturity were estimated 80.0 mm for males and 93.1 mm for females.Our analyses of gonad development and the size distribution of oocytes suggest that P.homaloptera is a single spawner with the peak spawning period between September and October.Furthermore,the estimated mean absolute fecundity was 557±204 eggs per fish,and mean relative fecundity was 50.9±10.9 eggs per g of female weight.The fecundity of P.homaloptera increased linearly with increasing total length,total weight,ovary weight,and age.This study on the reproductive biology of P.homaloptera demonstrates that the fish was in a vulnerable state due to the increasing anthropogenic activities in the lower Yarlung Zangbo River.
