ChoflgqRgls iOURt8R Cty rt th6southwestern China,is fsmous for its peppery hotpot dishes．Spiciness of hot pot fills every cornerof the city,and引Ivisitors to Chongqingaretempted to taste this delicacy．Of all the hot...ChoflgqRgls iOURt8R Cty rt th6southwestern China,is fsmous for its peppery hotpot dishes．Spiciness of hot pot fills every cornerof the city,and引Ivisitors to Chongqingaretempted to taste this delicacy．Of all the hot potF6St8UFSRtS tri ChOOgqiDgl th6 bFSRd’Litt旧 SWSR’is th6 iOSt W6II krtOWrt．展开更多
Fishery-independent surveys can provide high-quality data and support fishery assessment and management.Optimization of sampling design is crucial to increase the quality of fishery surveys.Crab pots are important fis...Fishery-independent surveys can provide high-quality data and support fishery assessment and management.Optimization of sampling design is crucial to increase the quality of fishery surveys.Crab pots are important fishing gears used to catch crabs.We analyzed the impacts of sampling design of crab pots on the abundance of Portunus trituberculatus in the Changjiang(Yangtze)River estuary to the Hangzhou Bay and its adjacent waters in East China Sea.The crab pots were cylindrical,240 mm in height and 600 mm in diameter of the iron ring.Our sampling designs(including fixed-station sampling,simple random sampling,stratified fixed-station sampling,and stratified random sampling),three number of stations(9,16,and 24),and three numbers of crab pots(500,1000,and 3000)were simulated and compared with the“true”abundance that obtained from bottom trawl surveys in the study area in 2007.The scenarios with 16 stations were set in stratification as a control group for comparison with unstratified designs.Results show that simple random sampling can obtain more stable results than fixed-station sampling in the abundance estimation of P.trituberculatus.In addition,stratified sampling resulted in more accurate abundance than unstratified sampling.The accuracy of the simulated results improved with the increase of the number of stations.No remarkable differences in the results were found among the scenarios of different number of crab pots at each station.However,resource-intensive areas exerted great impacts on simulation results.Thus,prior information or pre-survey results about resource abundance and density distribution are necessary.This study may serve as a reference for future sampling designs of crab pots of P.trituberculatus and other species.展开更多
The effects of bark on komatsuna (Japanese spinach) and tomato were investigated by changing the nitrogen content of chemical fertilizers and bark mixing ratio. Mixing 25 and 50% of bark with soil improved komatsuna g...The effects of bark on komatsuna (Japanese spinach) and tomato were investigated by changing the nitrogen content of chemical fertilizers and bark mixing ratio. Mixing 25 and 50% of bark with soil improved komatsuna growth, and also exceeded the growth rates obtained by using chemical fertilizers. However, komatsuna could not grow in 100% bark alone, with excessive amounts of bark majorly inhibiting komatsuna growth. The aeration of bark also did not enhance komatsuna growth. The nitrogen content and bark-mixing ratio had a much lower impact on tomato growth compared to komatsuna. In comparison, aerated bark was more effective in enhancing tomato growth compared to komatsuna growth.展开更多
To stop the decline of swimming crab(Portunus trituberculatus)stocks in the East China Sea,escape vents on crab pots are urgently required to improve pot selectivity and enable release of sublegal-sized crabs.This stu...To stop the decline of swimming crab(Portunus trituberculatus)stocks in the East China Sea,escape vents on crab pots are urgently required to improve pot selectivity and enable release of sublegal-sized crabs.This study presents field comparative fishing experiments,which examined the effectiveness of different shapes and sizes of escape vents in crab pots for the release of swimming crabs.Two sizes each of rectangular,elliptic,and circular escape vents were tested.The results of comparative fishing experiments indicated that experimental pots with escape vents,regardless of their configuration,caught significantly fewer sublegal-sized crabs(<49 mm carapace length,or<116 mm carapace width)than unmodified control pots.Although legal-sized swimming crabs were also less caught,analysis of size selectivity showed that rectangular vents produced steeper selectivity curves than elliptic and circular escape vents.This indicates that rectangular vents may be more suitable and controllable when escape vents will become a requirement and their use will be enforced in fisheries.Underwater observations were conducted using GoPro cameras and LED lights during the first 2.5 h of the deployments(which usually lasted between 5 and 12 h).Video recordings of experimental pots equipped with rectangular or elliptic escape vents showed that swimming crabs trapped in the pots could detect the vents,and readily approached and passed through these.However,no significant difference was detected in the response behavior of swimming crabs between rectangular and elliptic vent pots when quantitative indicators,derived from video recordings,were compared.The effect of different vent shapes on the escape behavior of swimming crab gradually manifested as an increased soak time and by the onset of the escape of larger crabs.Future underwater observations should thus last the entire duration of pot soaking to study how crabs escape from the pots.展开更多
The pots discovered in Inner Mongolia and Hebei Province are huge with a maximum diameter of 9 m and a depth of 3.5 m, singular in shape,caused by weathering and wind erosion and have certain direction. They are a kin...The pots discovered in Inner Mongolia and Hebei Province are huge with a maximum diameter of 9 m and a depth of 3.5 m, singular in shape,caused by weathering and wind erosion and have certain direction. They are a kind of typical climatic geomorphology. This展开更多
An increase in the crab pot fishery in the East China Sea has caused great pressure on swimming crab Portunus trituberculatus resources.Thus,it is essential to implement suitable measures to release sublegal-sized cra...An increase in the crab pot fishery in the East China Sea has caused great pressure on swimming crab Portunus trituberculatus resources.Thus,it is essential to implement suitable measures to release sublegal-sized crabs to increase the number of recruits for legal-sized crabs.One of the measures considered is the installation of escape vents on crab pots.We tested crab pots with one and two escape vents and compared the catchability and size selectivity of these pots with control pots without an escape vent.Pots with one escape vent located on single side of the pot,top or bottom(SS),and another on both sides at top and bottom edges(BS)were tested in sea trial experiments following typical commercial fishing practice.The results show that both SS pots and BS pots caught significantly smaller number of sublegal-sized crabs(<116 mm carapace width,CW),but the difference in catch between the two types of crab pots is not significant.The 50%selective CWs(CW_(50))and the selective ranges(SRs)of both BS pots are slightly larger than those of SS pots.However,95%confidence intervals of CW_(50)s and SRs are overlapped,indicating that the discrepancy between them is small.Then,in a mixed effect model,the effect of locations of escape vents,taken as the fixed effect,on selectivity parameters and indexes was analyzed by hypothesis testing.The results show that null hypothesis of no effect of location of vents on size selectivity cannot be rejected,indicating that there is no significant difference in size selectivity between the two types of pots for P.trituberculatus.展开更多
Gillnets are the primary fishing gear used to catch Atlantic cod(Gadus morhua)in coastal areas of Newfoundland and Labrador but are known to catch non-target species and produce lower quality fish than live-catch meth...Gillnets are the primary fishing gear used to catch Atlantic cod(Gadus morhua)in coastal areas of Newfoundland and Labrador but are known to catch non-target species and produce lower quality fish than live-catch methods.The purpose of this study was to compare the catch efficiency of collapsible cod pots against gillnets near the Gilbert Bay Marine Protected Area(MPA),Labrador,where a reduction in by-catch is needed.Results showed that one cod pot caught half as much Atlantic cod as a gillnet,and pots had a relatively stable catch rate throughout the sampling period,whereas gillnets caught relatively few fish later in the sampling season.Moreover,nearly all fish sampled with pots were caught alive undamaged,whereas most gillnet-caught fish experienced damage or mortality.As a conservation measure pot-fishing would enable fishing within close proximity to the Gilbert Bay MPA and the live-release of visually distinguishable Gilbert Bay cod,thereby mitigating against the negative effects of commercial fishing on this protected Atlantic cod population.展开更多
文摘ChoflgqRgls iOURt8R Cty rt th6southwestern China,is fsmous for its peppery hotpot dishes．Spiciness of hot pot fills every cornerof the city,and引Ivisitors to Chongqingaretempted to taste this delicacy．Of all the hot potF6St8UFSRtS tri ChOOgqiDgl th6 bFSRd’Litt旧 SWSR’is th6 iOSt W6II krtOWrt．
基金Supported by the National Key Research and Development Program of China(No.2019YFD0901304)the Science and Technology Project of Zhoushan(No.2017C41012)。
文摘Fishery-independent surveys can provide high-quality data and support fishery assessment and management.Optimization of sampling design is crucial to increase the quality of fishery surveys.Crab pots are important fishing gears used to catch crabs.We analyzed the impacts of sampling design of crab pots on the abundance of Portunus trituberculatus in the Changjiang(Yangtze)River estuary to the Hangzhou Bay and its adjacent waters in East China Sea.The crab pots were cylindrical,240 mm in height and 600 mm in diameter of the iron ring.Our sampling designs(including fixed-station sampling,simple random sampling,stratified fixed-station sampling,and stratified random sampling),three number of stations(9,16,and 24),and three numbers of crab pots(500,1000,and 3000)were simulated and compared with the“true”abundance that obtained from bottom trawl surveys in the study area in 2007.The scenarios with 16 stations were set in stratification as a control group for comparison with unstratified designs.Results show that simple random sampling can obtain more stable results than fixed-station sampling in the abundance estimation of P.trituberculatus.In addition,stratified sampling resulted in more accurate abundance than unstratified sampling.The accuracy of the simulated results improved with the increase of the number of stations.No remarkable differences in the results were found among the scenarios of different number of crab pots at each station.However,resource-intensive areas exerted great impacts on simulation results.Thus,prior information or pre-survey results about resource abundance and density distribution are necessary.This study may serve as a reference for future sampling designs of crab pots of P.trituberculatus and other species.
文摘The effects of bark on komatsuna (Japanese spinach) and tomato were investigated by changing the nitrogen content of chemical fertilizers and bark mixing ratio. Mixing 25 and 50% of bark with soil improved komatsuna growth, and also exceeded the growth rates obtained by using chemical fertilizers. However, komatsuna could not grow in 100% bark alone, with excessive amounts of bark majorly inhibiting komatsuna growth. The aeration of bark also did not enhance komatsuna growth. The nitrogen content and bark-mixing ratio had a much lower impact on tomato growth compared to komatsuna. In comparison, aerated bark was more effective in enhancing tomato growth compared to komatsuna growth.
基金study was jointly funded by the National Natural Science Foundation of China(31001138)the National Key Research and Development Program of China(2020YFD0900803).
文摘To stop the decline of swimming crab(Portunus trituberculatus)stocks in the East China Sea,escape vents on crab pots are urgently required to improve pot selectivity and enable release of sublegal-sized crabs.This study presents field comparative fishing experiments,which examined the effectiveness of different shapes and sizes of escape vents in crab pots for the release of swimming crabs.Two sizes each of rectangular,elliptic,and circular escape vents were tested.The results of comparative fishing experiments indicated that experimental pots with escape vents,regardless of their configuration,caught significantly fewer sublegal-sized crabs(<49 mm carapace length,or<116 mm carapace width)than unmodified control pots.Although legal-sized swimming crabs were also less caught,analysis of size selectivity showed that rectangular vents produced steeper selectivity curves than elliptic and circular escape vents.This indicates that rectangular vents may be more suitable and controllable when escape vents will become a requirement and their use will be enforced in fisheries.Underwater observations were conducted using GoPro cameras and LED lights during the first 2.5 h of the deployments(which usually lasted between 5 and 12 h).Video recordings of experimental pots equipped with rectangular or elliptic escape vents showed that swimming crabs trapped in the pots could detect the vents,and readily approached and passed through these.However,no significant difference was detected in the response behavior of swimming crabs between rectangular and elliptic vent pots when quantitative indicators,derived from video recordings,were compared.The effect of different vent shapes on the escape behavior of swimming crab gradually manifested as an increased soak time and by the onset of the escape of larger crabs.Future underwater observations should thus last the entire duration of pot soaking to study how crabs escape from the pots.
文摘The pots discovered in Inner Mongolia and Hebei Province are huge with a maximum diameter of 9 m and a depth of 3.5 m, singular in shape,caused by weathering and wind erosion and have certain direction. They are a kind of typical climatic geomorphology. This
基金funded by National Natural Science Foundation of China(31001138)Special Fund for Agro-scientific Research in the Public Interest(201203018).
文摘An increase in the crab pot fishery in the East China Sea has caused great pressure on swimming crab Portunus trituberculatus resources.Thus,it is essential to implement suitable measures to release sublegal-sized crabs to increase the number of recruits for legal-sized crabs.One of the measures considered is the installation of escape vents on crab pots.We tested crab pots with one and two escape vents and compared the catchability and size selectivity of these pots with control pots without an escape vent.Pots with one escape vent located on single side of the pot,top or bottom(SS),and another on both sides at top and bottom edges(BS)were tested in sea trial experiments following typical commercial fishing practice.The results show that both SS pots and BS pots caught significantly smaller number of sublegal-sized crabs(<116 mm carapace width,CW),but the difference in catch between the two types of crab pots is not significant.The 50%selective CWs(CW_(50))and the selective ranges(SRs)of both BS pots are slightly larger than those of SS pots.However,95%confidence intervals of CW_(50)s and SRs are overlapped,indicating that the discrepancy between them is small.Then,in a mixed effect model,the effect of locations of escape vents,taken as the fixed effect,on selectivity parameters and indexes was analyzed by hypothesis testing.The results show that null hypothesis of no effect of location of vents on size selectivity cannot be rejected,indicating that there is no significant difference in size selectivity between the two types of pots for P.trituberculatus.
基金The study was funded by the Fisheries and Oceans Canada.
文摘Gillnets are the primary fishing gear used to catch Atlantic cod(Gadus morhua)in coastal areas of Newfoundland and Labrador but are known to catch non-target species and produce lower quality fish than live-catch methods.The purpose of this study was to compare the catch efficiency of collapsible cod pots against gillnets near the Gilbert Bay Marine Protected Area(MPA),Labrador,where a reduction in by-catch is needed.Results showed that one cod pot caught half as much Atlantic cod as a gillnet,and pots had a relatively stable catch rate throughout the sampling period,whereas gillnets caught relatively few fish later in the sampling season.Moreover,nearly all fish sampled with pots were caught alive undamaged,whereas most gillnet-caught fish experienced damage or mortality.As a conservation measure pot-fishing would enable fishing within close proximity to the Gilbert Bay MPA and the live-release of visually distinguishable Gilbert Bay cod,thereby mitigating against the negative effects of commercial fishing on this protected Atlantic cod population.
