Penaeoid shrimp fisheries resources in the Zhujiang Estuary

INTRODUCTIONThe Zhujiang (Pearl River) Estuary (22°00′-22°45′N, 113°30′-114°00′E), created by the inflow of fresh water from various tributaries of the Zhujiang, is the largest estuarine system in the southern China with an area of about 2 300 km2 . Average depth of the water body is about

Variation of the coastal upwelling off South Java and their impact on local fishery resources

There is a vast upwelling area induced by the southeast monsoon in the waters off South Java,making the region an important fishing ground.Climate events can affect the variation of upwelling,but oceanographers have different understandings on the extent to which climate events control upwelling in this area,which leads to a lack of basis for studies on the evaluation and mechanisms of the variability of fishery resources in the region.The correlation between environmental parameters,including surface temperature(SST),chlorophyll-a(Chl-a)concentration,and climate event indices in South Java from 2003 to 2020 was analyzed.Results show that the Indian Ocean Dipole(IOD)has a greater influence on the interannual variability of upwelling intensity than ENSO.During the IOD,variations in equatorial latitudinal winds excite different types of Kelvin waves that anomalously deepen or shallow the thermocline,which is the main cause of anomalous variations in upwelling,independent of variations in the local wind field.A correlation between the interannual variability in upwelling and the annual catches was revealed,showing that climatic events indirectly affect fishery resources through upwelling effects.During positive IOD/El Niño periods,strong upwelling delivers more nutrients to the surface layer,which favors fish growth and reproduction,resulting in higher annual catches.A negative IOD/La Niña,on the other hand,leads to weaker upwelling and fewer nutrients into the surface waters.Fish tend to move in deeper waters,making traditional fishing methods less efficient and consequently lower annual catches.

Assessment and Perceived Impact of Coastal Resource Management (CRM) Programs in the Southern Part of Masbate Island, Philippines

Coastal Resource Management (CRM) are activities that achieve sustainable use and management of valuable resources in coastal areas. This study presents the perceived impact of the coastal resource management (CRM) interventions implemented by the Bureau of Fisheries and Aquatic Resources (BFAR) under the FishCORAL Project in the Municipality of Milagros, Masbate. The respondents are members of fisherfolk organizations, Bantay Dagat (BD), and community members. The CRM projects include mangrove planting, the establishment of marine protected area (MPA) markers, the construction of a watchtower, and the establishment of Bantay Dagat (BD). Respondents were convinced that the interventions affected their daily living, especially mangrove planting projects. Members of fisherfolk organizations carried out the project in Barangays Jamorawon, Magsalangi, and Tagbon. In terms of knowledge, attitude, and practices (KAP), these could be attributed to the respondent’s appreciation of the intervention, which contributed to the protection of the area from flood, storm surge, and tsunami, support for livelihood, the presence of marine animals (i.e., shrimp and crabs), and apprehension of illegal fishing activities. Destructive fishing, domestic waste, and natural calamities are some identified causes of aquatic ecosystem destruction. In terms of socioeconomic, respondents are provided additional income ranging from Php 1,500.00 - 2,000.00 per month, and fish stocks have also increased. The distribution of fishnets and Banca, livelihood, protection of marine resources, and commitment of legal authorities to enforce related fishery policies are among the CRM activities with a sound impact on the community.

A comparative study of spatial interpolation methods fordetermining fishery resources density in the Yellow Sea

Spatial interpolation is a common tool used in the study of fishery ecology, especially for the construction of ecosystem models. To develop an appropriate interpolation method of determining fishery resources density in the Yellow Sea, we tested four frequently used methods, including inverse distance weighted interpolation(IDW), global polynomial interpolation(GPI), local polynomial interpolation(LPI) and ordinary kriging(OK).A cross-validation diagnostic was used to analyze the efficacy of interpolation, and a visual examination was conducted to evaluate the spatial performance of the different methods. The results showed that the original data were not normally distributed. A log transformation was then used to make the data fit a normal distribution. During four survey periods, an exponential model was shown to be the best semivariogram model in August and October 2014, while data from January and May 2015 exhibited the pure nugget effect.Using a paired-samples t test, no significant differences(P>0.05) between predicted and observed data were found in all four of the interpolation methods during the four survey periods. Results of the cross-validation diagnostic demonstrated that OK performed the best in August 2014, while IDW performed better during the other three survey periods. The GPI and LPI methods had relatively poor interpolation results compared to IDW and OK. With respect to the spatial distribution, OK was balanced and was not as disconnected as IDW nor as overly smooth as GPI and LPI, although OK still produced a few 'bull's-eye' patterns in some areas.However, the degree of autocorrelation sometimes limits the application of OK. Thus, OK is highly recommended if data are spatially autocorrelated. With respect to feasibility and accuracy, we recommend IDW to be used as a routine interpolation method. IDW is more accurate than GPI and LPI and has a combination of desirable properties, such as easy accessibility and rapid processing.

Assessing the Fishery Resource Status of China’s Coastal Waters Using Surplus Production Models

Surplus production models(SPMs)are among the simplest and most widely used fishery stock assessment models.The catch-effort data analysis(CEDA)and a surplus production model incorporating covariates(ASPIC)are softwares for analyzing fishery catch and fishing effort data using nonequilibrium SPMs.In China Fishery Statistical Yearbook,annual fishery production and fishing effort data of the Yellow Sea,Bohai Sea,East China Sea,and South China Sea have been published from 1979 till present.Using its catch and fishing effort data from 1980 to 2018,we apply the CEDA and ASPIC to evaluate fishery resources in Chinese coastal waters.The results show that the total maximum sustainable yield(MSY)estimate of the four China seas is 10.05-10.83 million tons,approximately equal to the marine fishery catch(10.44 million tons)reported in 2018.It can be concluded that China’s coastal fishery resources are currently fully exploited and must be protected with a precautionary approach.Both softwares produced similar results;however,the CEDA had a much higher R2 value(above 0.9)than ASPIC(about 0.2),indicating that CEDA can better fit the data and therefore is more suitable for analyzing the fishery resources in the coastal waters of China.

An Evaluation of Artificial Fish Nest for Assessment Enhancement Effects of Fishery Resources of in Xiangjiang River

Artificial fish nests are set in Lukou section and Hengyang section of Xiangjiang River from March 20 to May 10, 2019. The structure of artificial fish nest is bamboo frame, with the size of 2.5 m × 5.0 m × 4 and a unit frame area of 60 m2. A total of 58,201 eggs were collected by 24 monitoring times, of which 30,441 were from Lukou and 27,760 from Hengyang. 3831 fish eggs identify 8 fish species using morphological or molecular biological methods. The results showed that the number of eggs peaked from the 8th day to the 24th day after the nest entered the water, and then decreased rapidly. There was significant negative correlation between egg number in per m2 fish nest and days of fish nest (P < 0.01). The economic benefits of artificial fish nests were RMB 11.81 million. The artificial fish nest can not only increase the population of fish, but also has significant economic benefits.

Studies on Classification of Recreational Fishery Resources and Evaluation on its Development

Recreational fishery is the combination of traditional fishery and modern leisure activities.Development of recreational fishery resources must be based on related resources,but the present research on recreational fishery is mainly confined to the development of leisure projects,the definition of connotation and scope of recreational fishery resources is rather vague,and there is no precise classification and evaluation system.According to the resources attributes,resources functions,and tourism resources classification,investigation and evaluation standard,recreational fishery resources include a number of different types.Expert Scoring Method and Analytic Hierarchy Process can be used to determine the evaluation factors of recreational fishery resources and their weights,and then make comprehensive evaluation on recreational fishery resources of different regions and types,so as to improve the scientific nature of recreational fishery development.

Seasonal Variations in Fishery Resources in Shenzhen Sea Area

Seasonal variations and causes for these were elaborated for fishery resources in Shenzhen sea area,to provide scientific basis for sustainable utilization and management of fishery resources in typical fisheries of South China Sea coasts. Based on the data of fishery resources collected through trawl surveys in Egong Bay fisheries area,Shenzhen,from August( autumn) and December( winter) of 2012 to March(spring) and May(summer) of 2013,seasonal variation of nekton species composition,stock density,dominant species composition,size spectra and biodiversity were studied. Results showed that there were 113 species of nekton in Shenzhen sea area,which belonged to 78 genus,50 families,14 orders and 3 classes. The number of species was the largest in summer(61 species) and smallest in autumn(53 species). In spring and winter,there was 56 species. The stock density and individual density of nekton were the minimum in summer(5950. 20 kg/km2 and 356. 45 ind/km2,respectively),whereas the percentage of fish stock density and individual density were the highest in summer(51. 99%and 42. 19%). The seasonal variations of size spectra indicated that fishing intensity was the highest in autumn,and was the lowest in summer. Additionally,biodiversity index presented significant seasonal variations,including Shannon-Wiener diversity index( H '),Margalef richness index( D') and Pielou evenness index( J'),with the same trend as summer > spring > autumn > winter. In conclusion,there are clear seasonal variations in the nekton species,biomass and structure in Egong Bay fisheries area in Shenzhen. Due to the difference in fishing intensity in different seasons( low intensity in summer and high intensity in autumn),community structure and function in summer are more stable than that in autumn and winter. Particularly,with the increase in the fishing intensity in autumn,k selection species will be replaced by r selection species.

Present Situation, Problems and Countermeasures of Fishery Resources Protection in Tibet

The present situation of fishery resources in Tibet was analyzed in the paper. The correspending conservation countermeasures aiming at various ecologi- cal and social problems of fishery resources in Tibet were put forward, including ex-situ conservation of some rare and endangered fishes, strengthening protection of gennplasm resources, establishing special and integrated nature reserves, and constituting environmental monitoring system for rare and special fish resources. Moreover, we should pay equal attention to economic development and environmental protection, strengthen propaganda and research, protect the existing habitat of rare and endangered species, and prevent invasion of Mien species, thereby ensuring sustainable development of fishery production.

Current Situation of Fish Resources in the Lower Reaches of the Songhua River

The Songhua River is one of the seven major rivers in China and an important river in Northeast China, with rich fish species and resources. Based on historical data, on-site visits and field investigation, this paper analyzed the changes of fish resources in the lower reaches of the main stream of the Songhua River, so as to understand the current situation of three grounds and one channel and resources of fishes. This study provides reference for fish conservation in the lower reaches.

The Research Development of Respiratory Metabolism for Living Beings of Fishery Resources

[Objective]To describe the research development of respiratory metabolism for living beings of fishery resources home and abroad so as to provide reference for fishery production and management. [Method]Investigate research methods of respiratory metabolism about fish,shrimp, crab,shells and other living beings and analyze factors affecting their oxygen consumption rates and ammonia excretion rates according to research results of respiratory metabolism for living beings of fishery resources home and abroad. [Result] Respiratory metabolism is one of the important contents of bioenergetics research,an important part of energy balance research. It reflects not only the physiological status of living beings,but al- so the influence of environment condition on their physiological activities. Factors affecting respiratory metabolism are divided into biological factors and non-biological factors. By researching factors such as weight,temperature,activities,circadian rhythm,ingestion,Oxygen partial pressure and so on,we can evaluate respiratory metabolism of living beings of fishery resources. [Conclusion]Investigating from the individual physiology and e- cology to group physiology and ecology,the research provides data support for enhancement and releasing of sea ranch.

Investigation and Protection of Fishery Resources in the Middle of Bohai Sea

In May and October 2017,12 stations were set up in the Central Bohai Sea for fishery resources investigation.The results show that there are many dominant species in this area,and the inshore fishery resources are higher than those in the open sea because of the abundant nutrients from land,the high density of zooplankton and the food of swimming animals.In order to effectively protect the fishery resources in the Central Bohai Sea,this paper puts forward some suggestions,such as strengthening the protection propaganda,scientific and reasonable fishing,and strengthening the management of marine environment.

Fish species diversity in the Huanghe Estuary

This paper lists 50 fish specs in the Huanghe Estuary, which belong to 9 orders, 22 families and 37 genera. The paper describes the seasonal distributions of these fish species and the succession of the important fish species during the past 50 a. The authors discuss the main factors that have resulted in the changes in fish species diversity and the fishery resources. These include the overexploitation of the fishery and the sharp reduction in the fresh water discharges from the Huanghe River.

The economic contribution of fish and fish trade in Bangladesh

Bangladesh possesses a large wetland area comprising diversified fisheries resources.Fish and fisheries are an integral part of Bangladesh and have earned its importance due to immense export and revenue potential.The objective of this study was to investigate the trend of fish production,export and import of Bangladesh during the last two decades.Several reviews of the literature were done,numerical data was obtained from the Ministry of Fisheries and Livestock(MoFL),Department of Fisheries(DOF),Bangladesh Bureau of Statistics(BBS).The results showed that fish production has increased in Bangladesh during the last two decades,starting from 17.81 lakh metric tons in 2000–01 and reaching up to 41.34 lakh metric tons in 2016–17.Due to the gradual decline in capture fishery,a significant percentage of total production comes from aquaculture.Hilsha(Tenualosa ilisha)is the largest single-species fishery in Bangladesh which makes the highest contribution to the country's total fish production.Exports of the fish commodity in terms of quantity and value has declined in recent years due to food quality and safety standards.This study has highlighted the contribution of fisheries production in Bangladesh and trade to the country's economy.By paying more attention to the fisheries sector,Bangladesh can boost up its economy.

Petroleum hydrocarbons and their effects on fishery species in the Bohai Sea, North China

Systematic studies on the changes in concentrations of petroleum hydrocarbons （PHs） and their effects on fishery species in the Bohai Sea during 1974–2004 are presented. Changes in PHs concentrations were closely related to Yellow River runoff. Concentrations of PHs accumulated in fish and shrimp increased by about 0.712 mg/kg dry weight when trophic level of fish and shrimps increased by 1. Attention should also be paid to the high PHs concentrations in mollusks along the coastal waters of the Bohai Sea. Average concentration of PHs in the adjacent coastal waters of Tianjin City during 1996–2005 decreased the population growth rates of fish, crustaceans and mollusks in the Bohai Sea by 2.58%, 6.59% and 2.33%, respectively. Therefore, PHs have significantly contributed to the decline in fisheries in the Bohai Sea, and they must be reduced to realize the sustainable fisheries.

Genetic population structure of red snapper(Lutjanus malabaricus)and orange-spotted grouper(Epinephelus coiodes)in Brunei and Sabah

The genetic population structure of red snapper Lutjanus malabaricus and orange-spotted grouper Epinepheluscoiodes in Brunei and Sabah was investigated using allozyme electrophoresis. Samples were collected from threesites in Brunei for E. coiodes and from three sites in Brunei and Sabah for L. malabaricus. A total of 22 loci and 16loci were scored, respectively. The index of fixation (FST) for the E. coiodes population was 0.176 but, in general, itlacked within-population structuring. The FST was particularly high between Brunei Bay/Jerudong and Brunei Bay/Kuala Belait, suggesting genetic subdivision on a small spatial scale. Isolation of Brunei Bay from the South ChinaSea may constrain the movement of adult fishes and larval dispersal, thereby reducing homogeneity amongsubpopulations. All variable loci for E. coiodes were in Hardy–Weinberg equilibrium except for MDH* and GTDHP*(P < 0.01), in which two subpopulations showed an excess of heterozygotes (P < 0.01). The study on the L.malabaricus population showed a heterozygote deficit of approximately 60% in variable loci (FIS, genetic variationwithin population = 0.45;P < 0.05);however, the mean observed heterozygosity for the population far exceeded L.malabaricus populations in Australia and Indonesia. A FST value of 0.076 revealed moderate genetic differentiationamong subpopulations of L. malabaricus. The genotypes were likely to be drawn from the same distribution inJerudong and Kuala Belait. This study infers that sustainable management of snapper and grouper resources inBrunei waters must take into account the presence of a single stock and two stocks, respectively.

An optimal management strategy for stochastic population dynamics of released Plecoglossus altivelis in rivers

Excessive predation pressure from the waterfowl Phalacrocorax carbo(Great Cormorant)on Plecoglossus altivelis(Ayu)has recently been a severe problem of river environment in Japan.Local fishery cooperatives are currently suffering from economic difficulties due to decrease of the fish catch of P.altivelis.Local fishery cooperatives and municipalities have been enthusiastically trying to develop countermeasures that can effectively reduce the predation pressure;however,their effectiveness and efficiency have not been systematically quantified well.This aim can be achieved with the help of an appropriate mathematical model.In this paper,based on a pure death process,a practical stochastic control model for population dynamics of released P.altivelis in river environment under predation pressure from P.carbo,harvesting by human,and environmental fluctuations is proposed.Finding an optimal management strategy ultimately reduces to solving a 2D Hamilton–Jacobi–Bellman equation,which is performed with a finite element scheme.Its application to a Japanese river environment successfully computes the optimal management strategy that is consistent with the reality.Numerical sensitivity analysis of the presented mathematical model is also performed for comprehension of dependence of the optimal strategy on the model parameters.