Changes in fish resources 5 years after implementation of the 10-year fishing ban in the Chishui River,the first river with a complete fishing ban in the Yangtze River Basin

Background To rehabilitate the depleted fish resources of the Yangtze River Basin,China,a 10-year fishing ban has been implemented.This national initiative has attracted worldwide attention.The present study aimed to explore the ecological process and recovery effectiveness of this complete fishing ban in the Chishui River,the first river where the fishing ban was enacted in the Yangtze River Basin.Changes in fish resources were analyzed based on investigations conducted 5 years before(2012–2016)and 5 years after(2017–2021)the implementation of the fish-ing ban in four reaches along the longitudinal gradient.Results A total of 140 fish species,including 127 native and 13 exotic species,were collected during the study period.The number of fish species as well as the diversity indices showed no significant temporal changes.However,11 native species that had disappeared for many years appeared again after the fishing ban.The occurrence rates of some key protected species,Procypris rabaudi,Acipenser dabryanus,Euchiloglanis davidi and Myxocyprinus asiaticus,increased after the fishing ban,while Coreius guichenoti,Percocypris pingi,Onychostoma angustistomata and Leptobotia rubrilabris showed no obvious recovery.The fish assemblage structure in nearly all reaches(except the headwater)showed significant temporal changes with an increase in the relative abundance of larger body-sized species.The population structure of most dominant species improved greatly with the mean standard length and the mean body weight as well as the proportion of larger-sized individuals clearly increasing.In addition,the density of fishes changed dramatically with the catch per unit effort(CPUE)increasing by 140–210%for different study reaches.Conclusions The present study confirmed that the complete fishing closure is an effective measure to facilitate fish resources recovery.These results provide valuable references for evaluating the effectiveness of the 10-year fishing ban policy in the entire Yangtze River.

Comparative Analysis of Metals in Seafood from Rio Doce Coastal Areas and Regional Fish Markets

On November 5, 2015, the Fundão Dam breached (the “Event”), releasing water, tailings, dam construction material, and debris to downstream watercourses. Over 20 million cubic meters of fine particles from the tailings, as well as scoured soil and sediments, reached the Rio Doce estuary and surrounding marine area 17 days later. Fishing was banned by the Federal Court of Espírito Santo in February 2016. The fishing ban area included the coastal area near the mouth of the Rio Doce and seaward to a depth of 25 meters, south to Barra do Riacho, and north to Degredo Beach. In June 2019, the Brazilian health agency, Anvisa, published a risk assessment for fish consumption which recommended daily consumption limits for fish of 200 grams for adults and 50 grams for children for both continental and coastal areas of the Rio Doce basin. Comparative analyses were performed between metal concentrations in marine fish and crustaceans collected in the banned fishing area to reference areas and commercialized seafood markets along the Brazilian coast. The results reveal that metals detected in seafood tissue collected in the fishing ban area are not significantly different than other reference areas or from commercially available seafood. This result indicates that elevated metal concentrations in seafood are a regional problem, unrelated to the Event. Higher concentrations of metals in fish in reference areas outside of the fishing ban area as well as in commercial seafood markets demonstrates that the risk management approach of a localized fishing ban is ineffective for reducing risk to the population related to seafood consumption. .