Japanese threadfin bream Nemipterus japonicus (Bloch, 1791) is among the most abundant and commercially important species in Pakistan. From the coast of Pakistan, four demersal trawl surveys in October-November 2009 and May-June, August, October and November in 2010 were carried out. The purpose of this study is to estimate the population dynamics and status of the stock of the N. japonicus from Pakistani waters based on the research trawl surveys from the research area. The data consist of n=784 length-weight pairs and n=7 530 length frequency with the maximum length and weight of 29 cm and 358 g respectively. The length frequency data were analyzed using ELEFAN method in FiSAT computer package. The parameters of length and weight relationship were b=2.778, a=0.032 and R²=0.973. The estimated von Bertalanffy growth function parameters were L_∞=30.45 cm, K=0.270 year^-1. Based on length-converted catch curve analysis the total mortality (Z) during this study was estimated at 0.960 year^-1. The natural mortality coefficient (M) was 0.74 year^-1 using Pauly's equation (the annual average sea surface temperature was 27℃), therefore, the fishing mortality coefficients (F) were 0.22 year^-1. The yield per recruit analysis indicated that when t_c was 2, F_max was estimated at 1.2 and F_0.1 at 1.1. When t_c was 1, F_max was estimated at 0.95 and F_0.1 at 0.8. Because current age at first capture is about 1 year and F_current was 0.22, F_current is smaller than F_0.1 and F_max, which indicated that the fishery is about in a safe condition. When using Gulland (1971) biological reference point, F_opt was equals to M (0.74). The current fishing mortality rate of 0.22 was smaller than the target biological reference point.

UV radiation is known to affect aquatic primary producers and their grazers. However, little has been documented on its effects on zooplankton grazing. In this study, the authors investigated the effects of photosynthetically active radiation (PAR, 400-700 nm), ultraviolet-A (UV-A, 320-400 nm) and ultraviolet-B (UV-B, 280-320 nm) radiation on grazing, mortality and lipids oxidation of the copepod Acartia pacifica collected from the Xiamen Bay. After 30 min of the exposures, the copepod was fed in darkness with the diatom Phaeodactylum tricornutum at two cell concentrations (2.5×10⁴ and 2.5×10⁵ cells/ml). At the low cell concentration, the individuals pre-exposed to PAR (218.0 W/m²)+UV-A (48.2 W/m²) or PAR+UV-A+UV-B (2.1 W/m²) showed suppressed clearance and grazing activities compared with those receiving PAR alone, by 22.7% and 17.1% for clearance and by 22.6% and 5.5% for grazing rates, respectively. However, the suppression on clearance and grazing became indistinctive at the high food concentration. Exposures to UV-A and UV-B led to increased lipid oxidation and higher mortality, furthermore, the mortality linearly increased with enhanced oxidation of lipid.

Long-term variations in population structure, growth, mortality, length at median sexual maturity, and exploitation rate of threadfin bream (Nemipterus virgatus) are reported based on bottom trawl survey data collected during 1960–2012 in the Beibu Gulf, South China Sea. Laboratory-based analyses were conducted on 16791 individuals collected quarterly in eight different sampling years. Average body length, estimated asymptotic length, and percentage of large individuals have decreased significantly with the growth of marine catch and fishing power, indicating individual miniaturization of this fish species. Estimated exploitation rates indicate that the N. virgatus stock in the Beibu Gulf was moderately exploited in 1960 and 1962 and overexploited after 1992. This stock was taking a good turn in status in 2012, with the lowest exploitation rate since 1992 and ceased downward trend in length indexes. These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of this commercial fish species. Biological characteristics of most commercial fish species have phenotypic plasticity and might change over years in response to fisheries management. Therefore, attentions should be paid on variations in fish biological characteristics, when evaluating the effectiveness of current measures to control the total catch for all fisheries.

There were two severe coral bleaching events at Ko Khang Khao, the inner Gulf of Thailand, occurred during the prolonged period of the elevated sea surface temperature (SST) in 2010 and low salinity as well as turbidity due to heavy flooding in 2011. The bleaching index (BI) and mortality index (MI) are calculated to compare the susceptibilities of coral species in the two bleaching events. The BI and MI vary significantly among the study sites and bleaching events. The most susceptible corals during both bleaching events are Acropora millepora, Pocillopora damicornis and Pavona decussate, while the most resistant species were Galaxea fascicularis, Fungia fungites, Pavona frondifera, Oulastrea crispate, and Symphyllia recta. The corals Favia favus, Goniopora columna, Platygyra pini, Symphyllia agaricia were relatively more tolerant to high SST but they are relatively more susceptible to low salinity. Coral bleaching is a phenomenon that the dissociation stress of the symbiotic relationship between zooxanthellae and their cnidarian host results in the reduction in photosynthetic pigment concentration. Among stressors, both prolonged exposure of high SST and low salinity, above and below their thresholds, respectively. The long-term resilience of coral communities at Ko Khang Khao and other coral communities close to the mouth of large rivers may depend on the frequency and duration of the exposure on the elevated SST due to atmospheric heating and low salinity due to river flooding.

In this study, the authors investigated the effects of residual chlorine on mortality, grazing and respiration of Labidocera euchaeta in laboratory. The grazing rate was evaluated by subtraction method of food concentration and respiration rate was measured using oxygen electrode. It was found that the lethal effect of residual chlorine on L. euchaeta increased with enhanced concentration and prolonged duration. The medium lethal concentration (LC₅₀) of chlorine for L. euchaeta in 24 h was about 0.58 mg/L and the safe concentration was about 0.21 mg/L. However, the grazing and respiration of L. euchaeta decreased by 32.6% and 18.9% when exposed to 0.2 mg/L residual chlorine for 4 h. It indicated that the physiological activities of zooplankton could be suppressed by the residual chlorine less than the safety concentration. Therefore, both survival and physiological activities of the organisms living in the thermal (nuclear) power plant discharging waters should be considered when carrying out the ecological risks assessment.

In this paper Cohort Analysis (VPA) with the data on catch in number by age and year is used to estimate independently fishing mortality, abundance and actual number of spawning stock of the Pacific herring in the Huanghai Sea.The results show that catch rate of the fishery is very high, and that the fishing mortality of the dominant age group aged 2-4 was 0.87-2.97 during the years 1971-1984.The size of year class has been decreased since 1982 although the variability for this species in the Huanghai Sea is frequent.This results in reducing the recruitment of the fishery, the abundance and the actual number of spawning stock.Therefore, an urgent management measure should be considered.
The magnitude of several sources of errors in Cohort Analysis (VPA) are examined, and the precision of the estimates is mainly dependent on an accurate natural mortality.

Dilution experiments were performed to examine the growth rate and grazing mortality rate of size-fractionated phytoplankton at three typical stations, inside and outside the bay, in the spring and summer of 2003 in the Jiaozhou Bay, China. In spring, the phytoplankton community structure was similar among the three stations, and was mainly composed of nanophytoplankton, such as, Skeletonema costatum and Cylindrotheca closterium. The structure became significantly different for the three stations in summer, when the dominant species at Stas A, B and C were Chaetoceros curvisetus, Pseudo-nitzschia delicatissima, C. affinis, C. debilis, Coscinodiscus oculus-iridis and Paralia sulcata respectively. Tintinnopsis beroidea and T. tsingtaoensis were the dominant species in spring, whereas the microzooplankton was apparently dominated by Strombidium sp. in summer. Pico-and nanophytoplankton had a relatively greater growth rate than microzooplankton both in spring and summer. The growth rate and grazing mortality rate were 0.18~0.44 and 0.12~1.47 d^-1 for the total phytoplankton and 0.20~0.55 and 0.21~0.37 d^-1 for nanophytoplankton in spring respectively. In summer,the growth rate and grazing mortality rate were 0.38~0.71 and 0.27~0.60 d^-1 for the total phytoplankton and 0.11~1.18 and 0.41~0.72d^-1 for nano-and microphytoplankton respectively. The carbon flux consumed by microzooplankton per day was 7.68~39.81 mg/m³ in spring and 12.03~138.22 mg/m³ in summer respectively. Microzooplankton ingested 17.56%~92.19% of the phytoplankton standing stocks and 31.77%~467.88% of the potential primary productivity in spring; in contrast, they ingested 34.60%~83.04% of the phytoplankton standing stocks and 71.28%~98.80% of the potential primary productivity in summer. Pico-and nanophytoplankton appeared to have relatively greater rates of growth and grazing mortality than microphytoplankton during the experimental period. The grazing rate of microzooplankton in summer was a little bit greater than that in spring because of the relatively higher incubation temperature and different dominant microzooplankton species. Microzooplankton preferred ingesting nanophytoplankton to microphytoplankton in spring, while they preferred ingesting picophytoplankton to nanophytoplankton and microphytoplankton in summer. Compared with the results of dilution experiments performed in various waters worldwide, the results are in the middle range.

Natural mortality rate (M) is one of the essential parameters in fishery stock assessment, however, the estimation of M is commonly rough and the changes of M due to natural and anthropogenic impacts have long been ignored. The simplification of M estimation and the influence of M variations on the assessment and management of fisheries stocks have been less well understood. This study evaluated the impacts of the changes in natural mortality of Spanish mackerel (Scomberomorus niphonius) on their management strategies with data-limited methods. We tested the performances of a variety of management procedures (MPs) with the variations of M in mackerel stock using diverse estimation methods. The results of management strategies evaluation showed that four management procedures DCAC, SPMSY, curE75 and minlenLopt1 were more robust to the changes of M than others; however, their performance were substantially influenced by the significant decrease of M from the 1970s to 2017. Relative population biomass (measure as the probability of B>0.5B_MSY) increased significantly with the decrease of M, whereas the possibility of overfishing showed remarkable variations across MPs. The decrease of M had minor effects on the long-term yield of curE75 and minlenLopt1, and reduced the fluctuation of yield (measure as the probability of AAVY<15%) for DCAC, SPMSY. In general, the different methods for M estimation showed minor effects on the performance of MPs, whereas the temporal changes of M showed substantial influences. Considering the fishery status of Spanish mackerel in China, we recommended that curE75 has the best trade-off between fishery resources exploitation and conservation, and we also proposed the potentials and issues in their implementations.

On the basis of the sequence and analysis of genome from the orange-spotted nervous necrosis virus (OGNNV), China strain, a pair of special primers were designed according to the nucleotide sequences of RNA2 from OGNNV.The major capsid protein (MCP)gene of OGNNV was cloned by means of reverse-transcriptase polymerase chain reaction (RT-PCR)and ligated into the pET32a expression plasmid.The MCP gene of OGNNV was 1 017 bases, encoded a protein of 338 amino acid with a molecular mass of 37.1 kDa.Recombinant protein with a molecular mass of 57.4 kDa was expressed in E.coli BL21 (DE3).Vaccine was prepared from the recombinant protein expressed in recombinant cells.The juvenile orange-spotted groupers (8 cm in average length) were immunized by intraperitoneal injection.Group A was challenged with infected tissue filtrates 25 d post-vaccination.The mortality in the vaccined group (A1, 30%) was a little higher than the unvaccined group (B2, 27.8%).Group B was challenged after three vaccine injections.The mortality in the vaccined group (B1, 16.7%) was lower than the unvaccined group (B2, 27.8%), And the relative percentage survival (RPS) value of vaccined group, compared with the unvaccined group, was 40%.The anti-recombinant protein sera with a 1:100 dilution were mixed with double volume of infected tissue filtrates and incubated at 4℃ for 12 h and then intramuscularly injected into the juvenile orange-spotted grouper.Treatment of infected tissue filtrates with anti-recombinant protein serum resulted in a significantly lower mortality of fish (Group C1, mortality of 18.18%), compared with the fish (Group C2, mortality of 40%) which received infected tissue filtrates treated with control serum.Results implied the potential use of the capsid protein in immunization against OGNNV.

The size-spectrum model has been considered a useful tool for understanding the structures of marine ecosystems and examining management implications for fisheries. Based on Chinese tuna longline observer data from the central and eastern tropical Pacific Ocean and published data, we developed and calibrated a multispecies size-spectrum model of twenty common and commercially important species in this area. We then use the model to project the status of the species from 2016 to 2050 under five constant-fishing-mortality management scenarios: (1) F=0; (2) F=F_recent, the average fishing mortality from 2013 to 2015; (3) F=0.5F_recent; (4) F=2F_recent and (5) F=3F_recent. Several ecological indicators were used to track the dynamics of the community structure under different levels of fishing, including the mean body weight, slope of community size spectra (Slope), and total biomass. The validation demonstrated that size-at-age data of nine main catch species between our model predictions and those empirical data from assessments by the Western and Central Pacific Fisheries Commission matched well, with the R²>0.9. The direct effect of fishing was the decreasing abundance of large-sized individuals. The mean body weight in the community decreased by ~1 500 g (21%) by 2050 when F doubled from F_recent to 2F_recent. The higher the fishing mortality, the steeper the Slope was. The projection also indicated that fishing impacts reflected by the total biomass did not increase proportionally with the increasing fishing mortality. The biomass of the main target tuna species was still abundant over the projection period under the recent fishing mortality, except Albacore tuna (Thunnus alalunga). For sharks and billfishes, their biomass remained at relatively higher levels only under the F=0 scenario. The results can serve as a scientific reference for alternative management strategies in the tropical Pacific Ocean.