Variation Laws and Influencing Factors of pH in Fishery Waters in Quzhou City

[Objectives] This study was conducted to strengthen the understanding of the variation laws of pH in fishery waters. [Methods]Based on the investigation data of pH, dissolved oxygen(Do), water temperature(T) and chlorophyll a(Chl. a) of the fishery waters in Quzhou City from 2017 to 2020, the seasonal variation characteristics and influencing factors of pH in the fishery waters were analyzed and discussed. [Results] The pH of the fishery waters in Quzhou City was in the range of 6.40-11.3, and was characterized by the highest seasonal variation in spring and the lowest in winter. The correlation analysis showed that water temperature and pH were significantly positively correlated in spring and summer(P<0.05), and the photosynthesis of phytoplankton was the main reason that affected the pH of water bodies in spring and summer. There was a negative correlation between water temperature and pH in winter, and the pH in the natural waters had a significant negative correlation with water temperature(P<0.05). The balance of carbonate system in the water bodies was the main reason that affected the pH of water in winter. The level of water eutrophication(Chl. a) affected the pH of fishery waters to a certain extent. When Chl. a<10 μg/L, there was a significant positive correlation between the pH of fishery waters and Chl. a(P<0.05). Various environmental factors had different effects on the pH of different types of fishery waters. The stepwise regression analysis showed that the pH of natural waters was mainly affected by Chl. a, and the pH of aquaculture waters was mainly affected by water temperature and dissolved oxygen. [Conclusions]This study provides certain theoretical support for actual production management.

Study on Regulating Effects of "Aquatic Environment Protection Oriented Fishery" on Water Environment of Qiaodun Reservoir

In order to evaluate the regulating effect of ＂ aquatic environment protection oriented fishery＂ on aquatic ecosystem,the water quality,plankton community structure,biomass,diversity index,eutrophication index and ecosystem maturity evaluated with Ecopath model were compared from 2010 to 2012 in Qiaodun Reservoir of Zhejiang Province. It was indicated that the water quality had been improved obviously. The water transparency maximally increased by 130%,while TP,TN and CODCrwere reduced. The density and biomass of the plankton were decreased,so was the ratio of Cynobacteria in phytoplankton community. The Shannon-Weaver index was increased; the trophic level was decreased; the ecosystem maturity was improved. By all accounts,the ＂ aquatic environment protection oriented fishery＂ had positive effects on maintaining the balance of reservoir ecosystem and ensuring the safety of drinking water.

Significant decline of water pollution associated with inland fishery across China

Water pollution seriously threatens the sustainable development of fisheries in China.To inform effective pollution control policies,a comprehensive understanding of the fishery environment status is needed.However,nationwide data on the temporal changes of major pollutants in the fishery waters of China are scarce.This study collected data on the major water pollutants,including total nitrogen,total phosphorus,heavy metals,and total petroleum hydrocarbons(TPHs),from 2003 to 2017 to evaluate dynamic changes in the inland fishery water environment across China.We discovered that the levels of four heavy metals(Cu,Zn,Pb,and Cd)and TPH decreased during the 15-year period,corresponding to the reduced national discharge of pollution sources from 2003 to 2015.However,nitrogen and phosphorus levels in the inland fishery waters showed no significant changes during this period.A comparative analysis of water quality in different periods indicated that these improvements were highly associated with effective measures for water pollution control in China.In addition,the decline in pollution was consistent among the three regions of China(north,west,and southeast)from 2003 to 2017,while southeast China exhibited the weakest pollution mitigation among the three regions.These findings suggest that the inland fishery water quality improved during 2003–2017,but still faced eutrophication risk.

China’s policies and practice on combatting IUU in distant water fisheries

China’s distant water fisheries(DWF)have made considerable progress since its entering into this industry in the 1980s.Though great efforts have been made to combat illegal,unregulated and unreported(IUU)fishing activities,there are still repeated IUU cases reported or documented by regional fisheries bodies and coastal countries.This article starts with an introduction to the latest development in China’s policies and practices in the past three decades,followed by an attempt to explore the reasons behind this haunting IUU problem.It is found that lack of concrete regulatory measures,ineffective policy implementation,and insufficient supervision and control are the main impediments to eliminate the on-going IUU problem.Therefore,the authors suggest fishery authorities in China have stronger willingness and determination to impose stricter supervision and control on DWF industry,but at the same time,gives more concern to fishermen by offering training courses to raise their awareness of law compliance and mitigate motivations to commit infraction.Only in such way would China promote healthy and sustainable development of DWF,and become a responsible major fishing nation as it aims to be.