Application of Central Composite Design to Optimize Spawns Propagation

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˚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.

Otolith microchemical evidence revealing multiple spawning site origination of the anadromous tapertail anchovy(Coilia nasus)in the Changjiang(Yangtze)River Estuary

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.

Water temperature induced interannual variation in spawning of Japanese Spanish mackerel Scomberomorus niphonius in the northern Yellow Sea

Japanese Spanish mackerel Scomberomorus niphonius is a pelagic,neritic species that occurs in the Yellow Sea in high commercial value.The spawning period of this fast-growing species is controlled by water temperature.Based on microstructural analysis of otoliths from 145 young-of-the-year(YoY)S.niphonius collected by trawl in 2017,2018,and 2020,and the temporal variation in the spawning period in the northern Yellow Sea,and its relationship to water temperature were examined.We found that the spawning lasted from late April to late June but differed in year:in 2017 it occurred from April 23 to June 1 and peaked in early May,in 2018 it extended later from May 7 to June 29,and in 2020 from May 6 to June 22 and peaked later from late May to mid-June.The highest temperature in 2017 corresponds with the earliest end of the spawning period and a lower growing degree-day(GDD,℃·day)of 383℃·day.In 2018,slower warming corresponds with a longer spawning period,and a GDD spawning period of 506℃·day.Rapid warming in late 2020 corresponds with a spawning peak,and a GDD spawning temperature of 448℃·day.Despite differences in spawning period,the water temperature when spawning commenced was 10-12℃.Therefore,water temperature is the major determinant of the spawning period,affecting both the starting and the ending of spawning.This study improved our understanding of the spawning dynamics and environmental adaptation of S.niphonius,and how these might change in environments subject to increased warming.

Climate-Related Variations in Autumn Cohort of Japanese Common Squid Todarodes pacificus

The Japanese common squid Todarodes pacificus is widely distributed in the Sea of Japan,the East China Sea and the Northwest Pacific Ocean,and is largely exploited by the Asia-Pacific countries.In this study,the impacts of regime shift of the Pacific Decadal Oscillation(PDO)during 1977-2015 on the autumn cohort of T.pacificus were assessed by examining the variations in vertical water temperatures at depths of 0 m(Temp_0 m),50 m(Temp_50 m)and 100 m(Temp_100 m)and the distribution pattern of preferred spawning ground(SSG).Spatial and temporal correlation analysis revealed that the PDO index exhibited a significantly negative relationship with vertical water temperatures at different depths and was negatively related to catch-per-unit-effort(CPUE)and stock biomass of T.pacificus.In addition,water temperatures in the specific three water layers were positively associated with CPUE.The PDO regime shift strongly affected the thermal condition and spawning ground of T.pacificus.Comparing to the negative PDO,the waters from the surface to the deep became cool in the positive PDO phase;correspondingly,the area of SSG largely contracted at different depths.Consequently,the CPUE and stock biomass of T.pacificus profoundly decreased.From the results it can be concluded that the PDO regime shift-driven changes in vertical thermal condition and SSG ranges can yield substantial impacts on T.pacificus abundance.

A spawning particle filter for defocused moving target detection in GNSS-based passive radar

Global Navigation Satellite System(GNSS)-based passive radar(GBPR)has been widely used in remote sensing applications.However,for moving target detection(MTD),the quadratic phase error(QPE)introduced by the non-cooperative target motion is usually difficult to be compensated,as the low power level of the GBPR echo signal renders the estimation of the Doppler rate less effective.Consequently,the moving target in GBPR image is usually defocused,which aggravates the difficulty of target detection even further.In this paper,a spawning particle filter(SPF)is proposed for defocused MTD.Firstly,the measurement model and the likelihood ratio function(LRF)of the defocused point-like target image are deduced.Then,a spawning particle set is generated for subsequent target detection,with reference to traditional particles in particle filter(PF)as their parent.After that,based on the PF estimator,the SPF algorithm and its sequential Monte Carlo(SMC)implementation are proposed with a novel amplitude estimation method to decrease the target state dimension.Finally,the effectiveness of the proposed SPF is demonstrated by numerical simulations and pre-liminary experimental results,showing that the target range and Doppler can be estimated accurately.

Walleye Egg Survival Was Unaffected by Four Semen Inclusion Techniques during Artificial Fertilization

Improving the percent hatch during artificial spawning of walleye (Sander vitreus) could save agencies substantial resources. Semen inclusion techniques used to artificially fertilize walleye eggs may have a subsequent influence on the percent hatch. We compared walleye egg survival to the early embryo stage across four semen inclusion techniques used during fertilization to determine if one or more of the techniques would result in a higher percent hatch. Six mL of freshly collected (within 2 h) semen was presented to common pools of walleye eggs separated into 250 mL lots by either 1) pouring semen on top of the eggs before sperm activation, 2) placing 3 mL of semen below and above the eggs before sperm activation, 3) pouring 3 mL of semen on top of the eggs, activating sperm, and adding the remaining 3 mL of semen after 30 s, or 4) activating the sperm by adding semen to 1 L of water, mixing and pouring the solution on the eggs within 3 s. All treatments received 1 L of filtered lake water for sperm activation and fertilization. Mean egg survival was similar ranging from 49.5% to 56.7% among the four techniques and was not significantly different across methods. These results suggest that any of the semen inclusion techniques will likely provide a similar percent hatch for walleye eggs when 250 mL of eggs, 6 mL of semen, and 1 L of water are used during fertilization.

东海带鱼春、夏和秋季产卵群体的生殖周期特性与种群问题

东海带鱼有春、夏和秋季生殖之别,秋季并出现分群现象。带鱼第一个生殖周期与其出生季节相适应;从第二个生殖周期开始则消失了与出生季节的相应关系。根据种群结构的组成特性以及耳石相对生长的分析,从种群概念上阐明了不同季节出生的带鱼群体的相互关系。论证了春、夏和秋季产卵群体系为同一种群的不同生物学群。文中讨论了种下阶元的不同分化程度和位置:繁殖群(种群)——繁殖下群——生物学群。

罗源湾对虾产卵场调查

随着罗源湾沿岸对虾养殖面积的扩大,对海区对虾亲虾的需求量也不断地加大,这就导致大量捕捞亲虾,引起对虾资源的严重衰退。为了更好地保护和开发对虾资源,调查了连江、罗源及宁德三个县对虾育苗场在罗源湾收购对虾亲虾数量,同时,对虾部分亲虾进行体重、性比及成熟度的测量,从而了解该湾对虾亲虾资源量,此外,还访问有关水产单位和渔民捕虾数量及分布位置,并且结合罗源湾浮游动物调查样品分析资料,综合分析罗源湾对虾产卵场及对虾的来源,以便为今后对虾资源的保护和增殖放流提供参考,兹将调查结果和建议简述如下:

Impact of the Three Gorges Dam on the spawning stock and natural reproduction of Chinese sturgeon in the Changjiang River,China

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.

LABORATORY OBSERVATION ON SPAWNING,FECUNDITY AND LARVAL DEVELOPMENT OF AMPHIOXUS (BRANCHIOSTOMA BELCHERI TSINGTAUNESE)

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

Response of winter cohort abundance of Japanese common squid Todarodes pacificus to the ENSO events

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.

Transport and distribution of nutrients in anchovy spawning ground to the southern waters of Shandong Peninsula

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.

Cryopreservation of strip spawned sperm using programmable freezing technique in the blue mussel Mytilus galloprovincialis

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.

Reproductive characteristics of Psilorhynchus homaloptera Hora and Mukerji,1935 (Cyprinidae: Psilorhynchidae) in the lower Yarlung Zangbo River,Tibet

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.

Asian Horseshoe Crab Bycatch in Intertidal Zones of the Northern Beibu Gulf:Suggestions for Conservation Management

Bycatch poses a severe challenge to global fishery management.Although studies have focused on marine megafauna bycatch,research on relevant issues regarding invertebrates is limited,particularly for the threatened horseshoe crabs.In this study,the distribution of fishing gears and the bycatch intensity of Asian horseshoe crabs in the intertidal zones of the northern Beibu Gulf that harbors the most abundant juvenile Asian horseshoe crabs populations in China were evaluated.Seven intertidal nursery habitats for Tachypleus tridentatus and Carcinoscorpius rotundicauda were surveyed from May to July in 2021.A transect that crossed the tidal creeks and tidal flats between the high tide embankment/vegetation and low tide line of a given habitat was surveyed during the ebb tides.The type,number,and GPS of fishing gears were recorded when sighted,and the number and prosomal width of each horseshoe crab species were measured.Bycatch intensities differed among habitats,ranging from 0.3 to 18.4 and 1.2 to 22.7 individuals per kilometer of transect for T.tridentatus and C.rotundicauda,respectively.Among the three identified fishing gear types,ground cages and stick net sets caused a stronger bycatch pressure on these two species.Most T.tridentatus bycatch and C.rotundicauda bycatch were large individuals in late juvenile and adult stages.Therefore,the ground cages and stick net sets along/near the tidal creeks,mangrove fringe,and low tide line should be regulated and removed to ensure the functionality of the intertidal zone as the spawning corridor and nursery habitat of Asian horseshoe crabs.

Model for stock-recruitment dynamics of the Peruvian anchoveta (<i>Eugraulis ringens</i>) off Peru

This paper was aimed at re-examining the validity of the results from Cahuin et al. (Estuar. Coast. Shelf Sci. 84, 2009) and identifying a model to describe the stock-recruitment relationship of the Peruvian anchoveta (Eugraulis ringens). Regression analysis was used to determine if density-dependent effects were present. The analysis did not show the existence of any densitydependent effects. It is important to use environmental factors and take observational and process errors into account when attempting to identify density-dependent effects in fish populations. Sea surface temperature (SST) and Southern Oscillation Index (SOI) were used as independent variables to fit the recruitment dynamics of the anchoveta. Both SST and SOI were found to be significantly important parameters in structuring anchoveta dynamics according to Akaike Information Criterion (AIC) and R2 values. The results of this study do not correlate with the findings of Cahuin et al., (2009), where density-dependent effects and the presence of regimes were detected. In conclusion, the recruitment Rt is essentially determined in proportion to spawning stock biomass St, and then environmental factors in year t further change the recruitments. This mechanism is completely same with that for Japanese sardine proposed by Sakuramoto (The Open Fish. Sci. 5, 2012).

Spatio-temporal distribution of Konosirus punctatus spawning and nursing ground in the South Yellow Sea

In recent years,Konosirus punctatus has accounted for a large portion in catch composition and become important economic species in the South Yellow Sea.However,the distribution of K.punctatus early life stages is still poorly understood.In this study,generalized additive models with Tweedie distribution were used to analyze the relationships between K.punctatus ichthyoplankton and environmental factors(longitude and latitude,sea surface temperature(SST),sea surface salinity(SSS)and depth),and predict distribution K.punctatus spawning ground and nursing ground,based on samplings collected in 6 months during 2014–2017.The results showed that K.punctatus’spawning ground were mainly distributed in central and north study area(from 33.0°N to 37.0°N).By comparison,the nursing ground shifted southward,which were approximately located along central and south coast of study area(from 31.7°N to 35.5°N).The optimal models identified that suitable SST,SSS and depth for eggs were 19–26℃,25–30 and 9–23 m,respectively.The suitable SSS for larvae were 29–31.The K.punctatus spawning habit might have changed in the past decades,which was a response to increasing SST and fishing pressure.That needs to be proved in further study.The study provides references of conservation and exploitation for K.punctatus.

Effect of Intertidal Elevation at Tsuyazaki Cove,Fukuoka,Japan on Survival Rate of Horseshoe Crab Tachypleus tridentatus Eggs

Physical factors affecting the survival of Tachypleus tridentatus eggs were investigated by translocating their eggs between the high intertidal zone and the low intertidal zone of a known spawning site.The mean egg survival rates per day were highest in the mid intertidal zone(45.1%±25.4%)and the lowest in the low intertidal zone(13.3%±27.6%).Differences in the elevation,air exposure time,and water content of the spawning ground were significant factors determining the egg survival rates.Excessive or insufficient air exposure time resulted in inadequate water content at higher and lower intertidal zones and could reduce egg survival.On the other hand,moderate saturation and dehydration were repeated with each tidal movement in the mid intertidal zone.This dynamic is considered as one of the crucial factors for the survival of eggs and is considered optimal for spawning.Therefore,the protection of the mid intertidal zone is imperative for maximizing the egg survival rate in Tsuyazaki Cove where almost all suitable nesting sites have disappeared due to coastal development.By protecting these optimal sites for spawning and recovering other optimal sites on suitable beaches,a positive contribution can be made to future management and conservation.The study also suggests that translocating eggs from marginal to optimal spawning sites might be a recovery strategy for this globally endangered species.

Brown Trout Spawn Timing, Redd Locations, and Stream Characteristics in Spearfish Creek within Spearfish, South Dakota, USA

This study documented brown trout (Salmo trutta) spawning locations, redd construction timing, and associated environmental variables in an 850-m long mainstem section and a 400-m long diversion channel of Spearfish Creek within the city limits of Spearfish, South Dakota, USA in 2019. The first redds were observed on October 15, with no new redds observed after November 12. Redd construction peaked during the first week of November, when 23 redds were observed in the mainstem section and 50 in the diversion channel. Substrate size was significantly smaller, water temperatures significantly higher, and water velocities significantly greater in redd versus non-redd locations in both the mainstem reach and the diversion channel (P &#730;C), but significant, increase in water temperature from the rest of the channel locations. This is the first study to document redd locations in Spearfish Creek and will provide a baseline to evaluate future spawning activity, particularly as it may be affected by likely future anthropogenic changes potentially affecting the stream environment.

Key Technology for Liquid Spawn Production and Green and High-yield Cultivation of Pleurotus eryngii

[Objectives]Pleurotus eryngii is currently the second largest edible fungus variety cultivated in China,and it mainly adopts the bag cultivation mode.This study aims to effectively solve the problems of high cost of solid spawn,long spawn production cycle,low application level of green and high-yield cultivation technology and equipment,and unstable output and quality in the factory production process and to further promote industrial upgrading.[Methods]Since June,2018,a series of research and technical optimizations had been carried out by a technical research team consisting of personnels from Vegetable Office of Guannan County,Institute of Edible Fungi of Shanghai Academy of Agricultural Sciences and Jiangsu Xiangru Biotechnology Co.,Ltd.,around the production of liquid spawn,introduction of excellent varieties of P.eryngii,medium pretreatment,autoclaving,clean room inoculation,digital cultivation,harvesting,packaging,etc.[Results]The key technology of industrial production,liquid spawn production and green and high-yield cultivation of P.eryngii are summarized.[Conclusions]The economic benefit of liquid spawn of P.eryngii is extremely considerable compared with liquid spawns such as branch spawn.