In this study we aimed to analyze the effects of water temperature and diet on the length-weight rela- tionship and condition of juvenile Malabar blood snapper Lutjanus malabaricus over a 30-d experimental period. The...In this study we aimed to analyze the effects of water temperature and diet on the length-weight rela- tionship and condition of juvenile Malabar blood snapper Lutjanus malabaricus over a 30-d experimental period. The experiment was conducted in the laboratory using a flow-through-sea-water system. The fish were subjected to four different temperatures （22, 26, 30, and 34 ℃） and two diets （commercial pellet and natural shrimp）. Fish were fed twice daily. L. malabancus exhibited negative allometric growth （b〈3） at the beginning of the experiment （Day 0） at all temperatures and both diets except for 22 ℃ fed with shrimp, which showed isometric growth （b=3）. Conversely, at the end of the experiment （Day 30） fish showed isometric growth （b=3） at 30 ℃ fed with the pellet diet, indicating that the shape of the fish did not change with increasing weight and length, and a positive allometric growth （b〉3） at 30 ℃ fed with shrimp diet, which indicated that fish weight increases faster than their length. The rest of the temperatures represented negative allometric growth （b〈3） on both diet, meaning that fish became lighter with increasing size. The condition factors in the initial and final measurements were greater than 1, indicating the state of health of the fish, except for those fed on a pellet diet at 34 ℃. However, the best condition was obtained at 30 ℃ on both diets. Nev- ertheless, diets did not have a significant effect on growth and condition of juvenile L. malabaricus. The data obtained from this study suggested culturing L. malabaricus at 30 ℃ and feeding on the pellet or shrimp diet, which will optimize the overall production and condition of this commercially important fish species.展开更多
Several dams have been constructed in Ethiopia, East Africa to support electricity and/or irrigation. Fishes were introduced to some of these dams. Thus, the objective of this study was to assess the dynamics and cond...Several dams have been constructed in Ethiopia, East Africa to support electricity and/or irrigation. Fishes were introduced to some of these dams. Thus, the objective of this study was to assess the dynamics and condition factor of Oriochromis niloticus in Korir and Lailay Wukro Dams, Northern Ethiopias. The study was conducted by deploying two gill net, every month in the littoral and pelagic zones of the two dams from August 2011 to May 2012. A total of 524 O. niloticus, 278 from Lailay Wukro and 246 from Korir dams were collected. The monthly catch per unit effort （CPUE） showed significant variation among months, the highest catch was in May and the least was in January 2012 （P 〈 0.000）. Catches of fish encountered higher in the littoral （69.1%） than in the pelagic zones （30.9%） （P 〈 0.000）. The condition factor of O. niloticus in the two reservoirs remains high, in Korir 2.05 and in Lailay Wukro 1.65 （P 〈 0.000）. In these small tropical dams, O. niloticus mature as they are smaller in size （Ls0： TL average 22.5 cm）. The ratio of male to female was 1.3：1 （P 〈 0.016）. The two dams have favorable condition for high production of O. niloticus. This high potential for fish production in the dams may be sustainable if the local authorities set a regulation to control the illegal fishing activity.展开更多
Length-weight relationship(LWR),condition factor(k)of the black chin tilapia,Sarotherodon melanotheron(Rüppel,1852)from Forcados River estuary Nigeria was investigated.The fish were collected monthly from fisherm...Length-weight relationship(LWR),condition factor(k)of the black chin tilapia,Sarotherodon melanotheron(Rüppel,1852)from Forcados River estuary Nigeria was investigated.The fish were collected monthly from fishermen for a period of 24 months(between April 2012 and March 2014).699 specimens of the fish species were collected.The Length-weight relationship(LWR)of the fish was evaluated using the equation:W=a L^(b) while the condition factor of the fish was determined using the equation;K=100W L^(b).The standard length of sampled S.melanotheron ranged from 4.15 to 18.92 cm,total length 6.01 and 22.5 cm while the weight ranged from 7.85-286.71 g.The b value 2.1299 was less than 3 indicating that the growth pattern of the fish was allometric.The correlation co-efficient(r)value for S.melanotheron was 0.7528.The condition factor for the combined sexes fluctuated monthly.The length-weight relationships and condition factor of S.melanotheron in Forcados river estuary indicated that the fish were above average condition.展开更多
A study on the food and feeding habit of Chrysichthys nigrodigitatus （Lacepede） was conducted in River Niger within the region of Oshimili local government area of Delta State Nigeria. A total of 90 specimens were c...A study on the food and feeding habit of Chrysichthys nigrodigitatus （Lacepede） was conducted in River Niger within the region of Oshimili local government area of Delta State Nigeria. A total of 90 specimens were collected with the help of fishermen using gill net, cast net and traps. The fish samples were immediately taken to the laboratory for analysis. Morphometric characteristics such as weight, length, condition factor, egg weight, Gonado Somatic Index （GSI） and sex ratio were determined. The stomach content was analyzed using numerical method to determine the food content. The total length of the fish sampled ranged from 14.40-44.60 cm, while the standard length varied from 11.00 cm to 47.00 cm and the fish body weight ranged between 19.00 g to 503.20 g. Sex ratio 1 female to 1 male was observed. The mean condition factor for both male and female obtained was 1.67. Of all the 90 fishes sampled, none had empty gut representing 100%. The major food items were phytoplankton, plant part and Detritus. Out of 41 females sampled, only 17 had eggs and the eggs were matured at stage IV.展开更多
The current study examines the diet of Serranus scriba （Osteichtyes of the family Serranidae）. This species of fish was collected using gillnets at the sea near the village of Sigri which is located in the South-Wes...The current study examines the diet of Serranus scriba （Osteichtyes of the family Serranidae）. This species of fish was collected using gillnets at the sea near the village of Sigri which is located in the South-West side of the island of Lesvos. Based on the results, Serranus scriba is characterized as carnivorous with a preference in Decapods. Also, the GSI （Gonado Somatic Index）, HSI （Hepato Somatic Index） and CF （Condition Factor） index were calculated, with the estimation of numbers of females and males and separation of mature stages using the scale Nikolsky. Majority of the individuals of this species are females with a ratio of 88% versus male with 12%. And based on the calculation of indicators they are characterized quite mature, with good percentage of stored energy and good condition of healthiness. Moreover, it is concluded, based on the above analysis, in the area there was plenty of food for the individuals of this species in their breeding season （April-August breeding season）.展开更多
Anthropogenic activities have greatly affected water resources on a global scale where the world is experiencing water quality and resources issues. Heavy metal is a crucial group of pollutants that is toxic to the en...Anthropogenic activities have greatly affected water resources on a global scale where the world is experiencing water quality and resources issues. Heavy metal is a crucial group of pollutants that is toxic to the environment even at low concentrations due to its bioaccumulation and biomagnification capabilities in living organisms. The detrimental effects of heavy metals on living organisms are due to their bioaccumulation in the aquatic ecosystem. Cadmium may result in adverse health effects due to its high toxicity. The study is conducted to determine the cadmium exposure effects on the morphometric indices of Anabas testudineus which are the Scaling Coefficient (SC) and Condition Factor (K) of such species. Anabas testudineus is exposed to four different cadmium treatment groups namely the control group, cadmium treatment group of 0.005 mg/L, 0.010 mg/L, and 0.015 mg/L for 16 weeks. The findings of the study have reported inconsistent trends in the values of SC and a decrease in the value of K with increasing cadmium concentration. The trend for the average SC has shown an overall decrease in value while the pattern of the K value is inconsistent in each treatment group with exposure time. Collectively, no significant differences for SC and K of A. testudineus in different treatment groups as well as comparison between treatment groups with time exposure.展开更多
A study on seasonal abundance,morphometric and meristic data,growth pattern,condition fector,sex ratio and gonadosomatic index of Liza falcip-innis(Wlenciennes,1836)from the Ojo axis of Badagry creek,Nigeria was condu...A study on seasonal abundance,morphometric and meristic data,growth pattern,condition fector,sex ratio and gonadosomatic index of Liza falcip-innis(Wlenciennes,1836)from the Ojo axis of Badagry creek,Nigeria was conducted from May 2019 to March 2020.A total of 1012 species were randomly selected,having 499 females and 513 males.The length frequency analysis and length-weight relationships(LWR)were determined.Sex ratio was determined by Chi-square analysis.The results showed that morphometric data are:0.5-2.5 mm for ED,2.1-12 mm for HL,1.7-8.1 mm for HD,2.5-11.7 for BD,2.6-233.3 mm for TL and 9.23-1006 g for BW for the combined sexes.The slope(b)shows an allometric growth pattern.The intercept'a'and slope'b'of the LWR(LogW=a+bLogL)were Log W=15.39+0.34 LogL(r=0.54)for combined sexes,Log W=12.49+0.02 log L(r=0.38)for males and Log W=18.23+0.01 log L(r=0.16)for females.The length frequency distribution indicated that species were dominated by two year classes(Ages 1 and 2).Condition factors were generally low.The values ranged between 0.68-0.85 for combined sexes.The gonadosomatic index for female was highest in August,2019(17.77%)with Mean±SD of 2.88±0.75;which indicated the peak of spawning period in the study area.Sex ratio difference was significant(P<0.05).Sexual differences were significant;the females are phenotypically larger than the male.展开更多
The present work studies water deterioration, fish survival and production as a result of effluents discharged directly without prior treatments into lake Qaroun at Fayoum governorate, Egypt. Lake Qaroun represents he...The present work studies water deterioration, fish survival and production as a result of effluents discharged directly without prior treatments into lake Qaroun at Fayoum governorate, Egypt. Lake Qaroun represents heavily polluted wild habitat for both studied fish species, Tilapia zillii and Solea aegyptiaca, the most abundant species. Results revealed deterioration in water quality (low dissolved oxygen but high ammonia, nitrite, copper, lead and cadmium) of Northeastern sector where El-Bats drain discharge its effluents without prior treatment followed by that of eastern sector at four km from the point of El-Bats discharge. Water salinity and dissolved oxygen values were in the following order: Western lake Qaroun sector > Eastern lake Qaroun sector > Northeastern lake Qaroun sector. However, Ammonia and nitrite readings were in the following order: Northeastern sector of Lake Qaroun is followed by the Eastern sector, then the Western sector. Moreover, results of the present field study revealed a decrease in fish production with the lowest condition factor and a deterioration in meat quality (an increase in muscle water content and ash but a decrease total protein and total lipids) in case of fish collected from the polluted sites along the lake (Northeastern and eastern sectors). However, fish collected from the unpolluted western sector of the lake showed condition factor and chemical muscle composition more or less similar to normal healthy fish.展开更多
The thermodynamic systems and dynamic model suitable for determining the nonlinear chemical fingerprints of samples were analyzed.The results indicated that the damp nonlinear chemical reactions in close systems away ...The thermodynamic systems and dynamic model suitable for determining the nonlinear chemical fingerprints of samples were analyzed.The results indicated that the damp nonlinear chemical reactions in close systems away from the equilibrium and open systems without the complementarity of the dissipation substances have important significance for the throng characterization and whole content analysis of chemical components in samples.Various factors influencing on nonlinear chemical fingerprint,such as reactant species and their concentrations,electrode types,temperature,stir rate,the sort,dosage and granularity of the sample,etc.were amply researched by a nonlinear chemistry reaction,namely,damp B-Z oscillation which used acetone and glucose as the main dissipative substances.In addition,the quantitative information on the whole of chemical components in samples and the traits and applications of the fingerprint were investigated.The method and its important conditions for determining nonlinear chemistry fingerprint used in distinguishing and evaluating complex samples were successfully put forward.展开更多
Labeo victorianus(Boulenger,1901)is one of the endemic fishes in Lake Victoria Basin(LVB)but is now threatened by multiple stressors caused by human activities.We investigated spatial and temporal variability in food ...Labeo victorianus(Boulenger,1901)is one of the endemic fishes in Lake Victoria Basin(LVB)but is now threatened by multiple stressors caused by human activities.We investigated spatial and temporal variability in food composition and condition of L.victorianus in influent rivers of Lake Victoria,Kenya.Sampling was done during the dry and wet seasons by electrofishing.Food composition analysis showed that L.victorianus is a benthophagus and omnivorous species whose diet is dominated by detritus,periphyton and insects.There were differences in food composition among rivers,with significant river X season interactions(PERMANOVA F=11.6,df=4,p=0.001),suggesting that the diet depended on prevailing environmental conditions.In turbid rivers,the diet was dominated by detritus while in less turbid rivers it was dominated by insects and periphyton.Sand and mud also formed a significant part of the diet,which was an indication of a limited occurrence of preferable food items.There were ontogenetic shifts in food composition(PERMANOVA F=4.6,df=3,p=0.001),but also with a spatial interaction(PERMANOVA F=5.6,df=7,p=0.001),further indicating the role of environmental conditions in determining the diet for different size classes.Interestingly,the fish condition did not differ among rivers.This study shows that turbidity and organic matter and nutrient loading determine the diet of L.victorianus in LVB rivers,and provides further justification for the maintenance of water quality as a conservation measure for threatened species.展开更多
The edible portion of Procambarus clarkii mainly consists of the abdominal muscles,highlighting the genetic enhancement of abdominal meat yield in breeding.To explore a selective breeding strategy for abdominal meat y...The edible portion of Procambarus clarkii mainly consists of the abdominal muscles,highlighting the genetic enhancement of abdominal meat yield in breeding.To explore a selective breeding strategy for abdominal meat yield,the correlation of morphological characteristics with abdominal meat yield based on five P.clarkii populations collected from its major production areas in China was analyzed and an optimal prediction model was constructed for predicting abdominal meat yield.With the analyses of P.clarkii morphological characteristics,Fulton's condition factor(K),which had a strong negative correlation(-0.800 in males and-0.705 in females)with abdominal meat yield and the advantage of not requiring the sacrifice of breeding candidates,was eventually selected as the morphological predictor.And the optimal prediction model constructed based on K value was a quadratic curve,with R^(2)values of 0.684 for males and 0.590 for females,and correlation coefficients of 0.827 and 0.768 between observed and predicted values for males and females,respectively.The results of the abdominal meat yield selective breeding experiment,utilizing the optimal prediction model,demonstrated that the breeding population exhibited favorable morphological variation as expected.These findings provide a morphology-based selection strategy for breeding the abdominal meat yield of P.clarkii.展开更多
The study aims to afford a deeper knowledge on reproductive biology of Mystus bleekeri from Surma River,Bangladesh in a multidisciplinary way.Though,the species is in demand as food and ornamental fish in Bangladesh b...The study aims to afford a deeper knowledge on reproductive biology of Mystus bleekeri from Surma River,Bangladesh in a multidisciplinary way.Though,the species is in demand as food and ornamental fish in Bangladesh but still now comprehensive details on reproductive biology of this species is scanty.Total 600 fish samples were derived from commercial catches from July 2018 to June 2019.Periodic differences in sex ratio,size distribution,condition factor(Kn),fecundity,gonadosomatic index and gonadal maturation cycle were assessed.The results showed 384(64%)female and 216(36%)male with an overall sex ratio of 1.77:1(female:male).Mean total length(TL)and body weight(BW)of all fish studied were 14.85±3.38 cm TL and 27.54±15.76 g,respectively.The Kn varied with length groups,the highest(1.45±0.23)and lowest(0.89±0.18)values obtained in 16.0-16.9 and 10.0-10.9 cm TL groups,respectively.The highest Kn was documented in October while the lowest was in January.Monthly GSI values showed two peaks in July and November for both the sexes.The fecundity was found to vary from 1120 to 14790 eggs with average value of 4968±3047 with 14.4-18.3 cm in TL and 19.97-34.7g in BW.The relationship of fecundity with TL and BW was F=1.385TL13.405,r^(2)=0.885 and F=5.201BW^(4.827),r^(2)=0.944.Partial behavior of spawning together with allochronic oocytes development has also been found through histology.The results of this study could be used for predicting the response of populations of fish in Surma River and/or other where to human interferences and environmental change.展开更多
Objective:To investigate biometrics of the Rhinomugil corsula(Hamilton,1822)(R.corsula),including length-weight relationships(LWRS),condition factors(Allometric,K_(A);Fulton's,K_(F);Relative,K_(R);Relative weight,...Objective:To investigate biometrics of the Rhinomugil corsula(Hamilton,1822)(R.corsula),including length-weight relationships(LWRS),condition factors(Allometric,K_(A);Fulton's,K_(F);Relative,K_(R);Relative weight,W_(R)),and sex ratio and length-frequency distributions in the Ganges(Padma River),Northwestern Bangladesh.Methods:Monthly sampling was conducted using traditional fishing gears during June to August 2012.Total length was measured to the nearest 0.01 cm using digital slide calipers,and total body weight was measured using an electronic balance with 0.01 g accuracy.The LWR was calculated using the expression:W=a×L_(b),where the W is the body weight,L is the total length,a and b are the parameters of the regression.Results:A total of 350 specimens ranging from 8.59-15.71 cm in total length and 9.57-32.59 g in body weight were analyzed during this study.The overall sex ratio was not significantly different from the expected value of 1:1(X^(2)=2.57,P>0.05),but there was significant difference in the length-frequency distributions between the sexes(P=0.03).The allometric coefficient b for the LWR indicated negative allometric growth(b=3.00)in males,female and combined sexes.Results further indicated that Kr was not significantly different between the sexes(P=0.57).However,the mean W_(R)of R.corsula showed significant differences from 100 for males(P=0.03)and females(P<0.001)in this study,indicating the imbalance habitat with food availability relative to the presence of predators.Conclusions:This study reported the first description of biometric relationships for R.corsula,which would be useful for the sustainable conservation of this rear fishery in Bangladesh and also neighboring countries.展开更多
Objective:To investigate some important aspects of the biology of Callinectes amnicola(C.amnicola)such as fecundity,carapace length-weight relationship,condition factor and carapace length frequency distribution from ...Objective:To investigate some important aspects of the biology of Callinectes amnicola(C.amnicola)such as fecundity,carapace length-weight relationship,condition factor and carapace length frequency distribution from the Cross River estuary,Nigeria.Methods:A total of one hundred and twenty ovigerous females of C.amnicola,freshly caught with basket traps,lift net trap,and gill net were collected from the catches of the artisanal fisheries in the study area between June 2012 and May 2013.Fecundity,carapace length-weight relationship,condition factor and carapace length frequency distribution were determined and analyzed following standard methods.Results:Fecundity(F)ranged between 73090 eggs for crab of carapace length 8.1 cm and total weight 34 g and 809450 eggs for crab of carapace length 16.1 cm and total weight 395 g with a mean of 311808.93±17693.94 eggs.There was a positive significant relationship between fecundity and carapace length,total weight and condition factor as follows:F=6839.7CL^(1.4403)(r^(2)=0.2145,P<0.05),F=15302TW^(0.5798)(r^(2)=0.4079,P<0.05),F=147255K^(0.2788)(r=0.2717,r^(2)=0.0738,P<0.05).A significant linear relationship between carapace length and weight of C.amnicola is given by the equation:Log W=2.0447LogL–0.1389(r^(2)=0.3357,P<0.05).The crab exhibited a negative allometric growth pattern(b=2.0447).Condition factor ranged between 21.48 to 104.95 with a mean value of 47.21±2.17.The carapace length frequency distribution showed a unimodal class size distribution.Conclusions:Findings of this study is crucial in assessing the population dynamics and development of management strategies of the the Blue crab,C.amnicola from the estuary such as mesh size regulation,fishing season and fishing ground regulation in the Cross River estuary.Also,findings of this study will be useful in evaluation of the aquaculture potential of the Blue crab C.amnicola,which is a valuable shell fish for the inhabitants estuary.展开更多
基金supported by the Ministry of Science Technology and Innovation Malaysia(MOSTI)(No.04-01-02-SF1208)
文摘In this study we aimed to analyze the effects of water temperature and diet on the length-weight rela- tionship and condition of juvenile Malabar blood snapper Lutjanus malabaricus over a 30-d experimental period. The experiment was conducted in the laboratory using a flow-through-sea-water system. The fish were subjected to four different temperatures （22, 26, 30, and 34 ℃） and two diets （commercial pellet and natural shrimp）. Fish were fed twice daily. L. malabancus exhibited negative allometric growth （b〈3） at the beginning of the experiment （Day 0） at all temperatures and both diets except for 22 ℃ fed with shrimp, which showed isometric growth （b=3）. Conversely, at the end of the experiment （Day 30） fish showed isometric growth （b=3） at 30 ℃ fed with the pellet diet, indicating that the shape of the fish did not change with increasing weight and length, and a positive allometric growth （b〉3） at 30 ℃ fed with shrimp diet, which indicated that fish weight increases faster than their length. The rest of the temperatures represented negative allometric growth （b〈3） on both diet, meaning that fish became lighter with increasing size. The condition factors in the initial and final measurements were greater than 1, indicating the state of health of the fish, except for those fed on a pellet diet at 34 ℃. However, the best condition was obtained at 30 ℃ on both diets. Nev- ertheless, diets did not have a significant effect on growth and condition of juvenile L. malabaricus. The data obtained from this study suggested culturing L. malabaricus at 30 ℃ and feeding on the pellet or shrimp diet, which will optimize the overall production and condition of this commercially important fish species.
文摘Several dams have been constructed in Ethiopia, East Africa to support electricity and/or irrigation. Fishes were introduced to some of these dams. Thus, the objective of this study was to assess the dynamics and condition factor of Oriochromis niloticus in Korir and Lailay Wukro Dams, Northern Ethiopias. The study was conducted by deploying two gill net, every month in the littoral and pelagic zones of the two dams from August 2011 to May 2012. A total of 524 O. niloticus, 278 from Lailay Wukro and 246 from Korir dams were collected. The monthly catch per unit effort （CPUE） showed significant variation among months, the highest catch was in May and the least was in January 2012 （P 〈 0.000）. Catches of fish encountered higher in the littoral （69.1%） than in the pelagic zones （30.9%） （P 〈 0.000）. The condition factor of O. niloticus in the two reservoirs remains high, in Korir 2.05 and in Lailay Wukro 1.65 （P 〈 0.000）. In these small tropical dams, O. niloticus mature as they are smaller in size （Ls0： TL average 22.5 cm）. The ratio of male to female was 1.3：1 （P 〈 0.016）. The two dams have favorable condition for high production of O. niloticus. This high potential for fish production in the dams may be sustainable if the local authorities set a regulation to control the illegal fishing activity.
文摘Length-weight relationship(LWR),condition factor(k)of the black chin tilapia,Sarotherodon melanotheron(Rüppel,1852)from Forcados River estuary Nigeria was investigated.The fish were collected monthly from fishermen for a period of 24 months(between April 2012 and March 2014).699 specimens of the fish species were collected.The Length-weight relationship(LWR)of the fish was evaluated using the equation:W=a L^(b) while the condition factor of the fish was determined using the equation;K=100W L^(b).The standard length of sampled S.melanotheron ranged from 4.15 to 18.92 cm,total length 6.01 and 22.5 cm while the weight ranged from 7.85-286.71 g.The b value 2.1299 was less than 3 indicating that the growth pattern of the fish was allometric.The correlation co-efficient(r)value for S.melanotheron was 0.7528.The condition factor for the combined sexes fluctuated monthly.The length-weight relationships and condition factor of S.melanotheron in Forcados river estuary indicated that the fish were above average condition.
文摘A study on the food and feeding habit of Chrysichthys nigrodigitatus （Lacepede） was conducted in River Niger within the region of Oshimili local government area of Delta State Nigeria. A total of 90 specimens were collected with the help of fishermen using gill net, cast net and traps. The fish samples were immediately taken to the laboratory for analysis. Morphometric characteristics such as weight, length, condition factor, egg weight, Gonado Somatic Index （GSI） and sex ratio were determined. The stomach content was analyzed using numerical method to determine the food content. The total length of the fish sampled ranged from 14.40-44.60 cm, while the standard length varied from 11.00 cm to 47.00 cm and the fish body weight ranged between 19.00 g to 503.20 g. Sex ratio 1 female to 1 male was observed. The mean condition factor for both male and female obtained was 1.67. Of all the 90 fishes sampled, none had empty gut representing 100%. The major food items were phytoplankton, plant part and Detritus. Out of 41 females sampled, only 17 had eggs and the eggs were matured at stage IV.
文摘The current study examines the diet of Serranus scriba （Osteichtyes of the family Serranidae）. This species of fish was collected using gillnets at the sea near the village of Sigri which is located in the South-West side of the island of Lesvos. Based on the results, Serranus scriba is characterized as carnivorous with a preference in Decapods. Also, the GSI （Gonado Somatic Index）, HSI （Hepato Somatic Index） and CF （Condition Factor） index were calculated, with the estimation of numbers of females and males and separation of mature stages using the scale Nikolsky. Majority of the individuals of this species are females with a ratio of 88% versus male with 12%. And based on the calculation of indicators they are characterized quite mature, with good percentage of stored energy and good condition of healthiness. Moreover, it is concluded, based on the above analysis, in the area there was plenty of food for the individuals of this species in their breeding season （April-August breeding season）.
文摘Anthropogenic activities have greatly affected water resources on a global scale where the world is experiencing water quality and resources issues. Heavy metal is a crucial group of pollutants that is toxic to the environment even at low concentrations due to its bioaccumulation and biomagnification capabilities in living organisms. The detrimental effects of heavy metals on living organisms are due to their bioaccumulation in the aquatic ecosystem. Cadmium may result in adverse health effects due to its high toxicity. The study is conducted to determine the cadmium exposure effects on the morphometric indices of Anabas testudineus which are the Scaling Coefficient (SC) and Condition Factor (K) of such species. Anabas testudineus is exposed to four different cadmium treatment groups namely the control group, cadmium treatment group of 0.005 mg/L, 0.010 mg/L, and 0.015 mg/L for 16 weeks. The findings of the study have reported inconsistent trends in the values of SC and a decrease in the value of K with increasing cadmium concentration. The trend for the average SC has shown an overall decrease in value while the pattern of the K value is inconsistent in each treatment group with exposure time. Collectively, no significant differences for SC and K of A. testudineus in different treatment groups as well as comparison between treatment groups with time exposure.
文摘A study on seasonal abundance,morphometric and meristic data,growth pattern,condition fector,sex ratio and gonadosomatic index of Liza falcip-innis(Wlenciennes,1836)from the Ojo axis of Badagry creek,Nigeria was conducted from May 2019 to March 2020.A total of 1012 species were randomly selected,having 499 females and 513 males.The length frequency analysis and length-weight relationships(LWR)were determined.Sex ratio was determined by Chi-square analysis.The results showed that morphometric data are:0.5-2.5 mm for ED,2.1-12 mm for HL,1.7-8.1 mm for HD,2.5-11.7 for BD,2.6-233.3 mm for TL and 9.23-1006 g for BW for the combined sexes.The slope(b)shows an allometric growth pattern.The intercept'a'and slope'b'of the LWR(LogW=a+bLogL)were Log W=15.39+0.34 LogL(r=0.54)for combined sexes,Log W=12.49+0.02 log L(r=0.38)for males and Log W=18.23+0.01 log L(r=0.16)for females.The length frequency distribution indicated that species were dominated by two year classes(Ages 1 and 2).Condition factors were generally low.The values ranged between 0.68-0.85 for combined sexes.The gonadosomatic index for female was highest in August,2019(17.77%)with Mean±SD of 2.88±0.75;which indicated the peak of spawning period in the study area.Sex ratio difference was significant(P<0.05).Sexual differences were significant;the females are phenotypically larger than the male.
文摘The present work studies water deterioration, fish survival and production as a result of effluents discharged directly without prior treatments into lake Qaroun at Fayoum governorate, Egypt. Lake Qaroun represents heavily polluted wild habitat for both studied fish species, Tilapia zillii and Solea aegyptiaca, the most abundant species. Results revealed deterioration in water quality (low dissolved oxygen but high ammonia, nitrite, copper, lead and cadmium) of Northeastern sector where El-Bats drain discharge its effluents without prior treatment followed by that of eastern sector at four km from the point of El-Bats discharge. Water salinity and dissolved oxygen values were in the following order: Western lake Qaroun sector > Eastern lake Qaroun sector > Northeastern lake Qaroun sector. However, Ammonia and nitrite readings were in the following order: Northeastern sector of Lake Qaroun is followed by the Eastern sector, then the Western sector. Moreover, results of the present field study revealed a decrease in fish production with the lowest condition factor and a deterioration in meat quality (an increase in muscle water content and ash but a decrease total protein and total lipids) in case of fish collected from the polluted sites along the lake (Northeastern and eastern sectors). However, fish collected from the unpolluted western sector of the lake showed condition factor and chemical muscle composition more or less similar to normal healthy fish.
基金supported by the National Key Technologies R & DProgram (2009GJD20033)the International Scientific and Technological Cooperation Project (2007DFA40680) from the Ministry of Scienceand Technology of China
文摘The thermodynamic systems and dynamic model suitable for determining the nonlinear chemical fingerprints of samples were analyzed.The results indicated that the damp nonlinear chemical reactions in close systems away from the equilibrium and open systems without the complementarity of the dissipation substances have important significance for the throng characterization and whole content analysis of chemical components in samples.Various factors influencing on nonlinear chemical fingerprint,such as reactant species and their concentrations,electrode types,temperature,stir rate,the sort,dosage and granularity of the sample,etc.were amply researched by a nonlinear chemistry reaction,namely,damp B-Z oscillation which used acetone and glucose as the main dissipative substances.In addition,the quantitative information on the whole of chemical components in samples and the traits and applications of the fingerprint were investigated.The method and its important conditions for determining nonlinear chemistry fingerprint used in distinguishing and evaluating complex samples were successfully put forward.
基金support was provided by the National Research Fund(NRF),Kenya through the KISS Project.
文摘Labeo victorianus(Boulenger,1901)is one of the endemic fishes in Lake Victoria Basin(LVB)but is now threatened by multiple stressors caused by human activities.We investigated spatial and temporal variability in food composition and condition of L.victorianus in influent rivers of Lake Victoria,Kenya.Sampling was done during the dry and wet seasons by electrofishing.Food composition analysis showed that L.victorianus is a benthophagus and omnivorous species whose diet is dominated by detritus,periphyton and insects.There were differences in food composition among rivers,with significant river X season interactions(PERMANOVA F=11.6,df=4,p=0.001),suggesting that the diet depended on prevailing environmental conditions.In turbid rivers,the diet was dominated by detritus while in less turbid rivers it was dominated by insects and periphyton.Sand and mud also formed a significant part of the diet,which was an indication of a limited occurrence of preferable food items.There were ontogenetic shifts in food composition(PERMANOVA F=4.6,df=3,p=0.001),but also with a spatial interaction(PERMANOVA F=5.6,df=7,p=0.001),further indicating the role of environmental conditions in determining the diet for different size classes.Interestingly,the fish condition did not differ among rivers.This study shows that turbidity and organic matter and nutrient loading determine the diet of L.victorianus in LVB rivers,and provides further justification for the maintenance of water quality as a conservation measure for threatened species.
基金supported by the Fishery Seed Industry Joint Breeding Program of Jiangxi Province,China(2023yyzygg-07),the Key Research and Development Program of Hubei Province,China(2021BBA232).
文摘The edible portion of Procambarus clarkii mainly consists of the abdominal muscles,highlighting the genetic enhancement of abdominal meat yield in breeding.To explore a selective breeding strategy for abdominal meat yield,the correlation of morphological characteristics with abdominal meat yield based on five P.clarkii populations collected from its major production areas in China was analyzed and an optimal prediction model was constructed for predicting abdominal meat yield.With the analyses of P.clarkii morphological characteristics,Fulton's condition factor(K),which had a strong negative correlation(-0.800 in males and-0.705 in females)with abdominal meat yield and the advantage of not requiring the sacrifice of breeding candidates,was eventually selected as the morphological predictor.And the optimal prediction model constructed based on K value was a quadratic curve,with R^(2)values of 0.684 for males and 0.590 for females,and correlation coefficients of 0.827 and 0.768 between observed and predicted values for males and females,respectively.The results of the abdominal meat yield selective breeding experiment,utilizing the optimal prediction model,demonstrated that the breeding population exhibited favorable morphological variation as expected.These findings provide a morphology-based selection strategy for breeding the abdominal meat yield of P.clarkii.
基金supported by Sylhet Agricultural University Research System(SAURES)Bangladesh through the research grant#SAU/Director(Research)-80/18/351(15).
文摘The study aims to afford a deeper knowledge on reproductive biology of Mystus bleekeri from Surma River,Bangladesh in a multidisciplinary way.Though,the species is in demand as food and ornamental fish in Bangladesh but still now comprehensive details on reproductive biology of this species is scanty.Total 600 fish samples were derived from commercial catches from July 2018 to June 2019.Periodic differences in sex ratio,size distribution,condition factor(Kn),fecundity,gonadosomatic index and gonadal maturation cycle were assessed.The results showed 384(64%)female and 216(36%)male with an overall sex ratio of 1.77:1(female:male).Mean total length(TL)and body weight(BW)of all fish studied were 14.85±3.38 cm TL and 27.54±15.76 g,respectively.The Kn varied with length groups,the highest(1.45±0.23)and lowest(0.89±0.18)values obtained in 16.0-16.9 and 10.0-10.9 cm TL groups,respectively.The highest Kn was documented in October while the lowest was in January.Monthly GSI values showed two peaks in July and November for both the sexes.The fecundity was found to vary from 1120 to 14790 eggs with average value of 4968±3047 with 14.4-18.3 cm in TL and 19.97-34.7g in BW.The relationship of fecundity with TL and BW was F=1.385TL13.405,r^(2)=0.885 and F=5.201BW^(4.827),r^(2)=0.944.Partial behavior of spawning together with allochronic oocytes development has also been found through histology.The results of this study could be used for predicting the response of populations of fish in Surma River and/or other where to human interferences and environmental change.
基金Supported by UGC(University Grants Commission),Banglades
文摘Objective:To investigate biometrics of the Rhinomugil corsula(Hamilton,1822)(R.corsula),including length-weight relationships(LWRS),condition factors(Allometric,K_(A);Fulton's,K_(F);Relative,K_(R);Relative weight,W_(R)),and sex ratio and length-frequency distributions in the Ganges(Padma River),Northwestern Bangladesh.Methods:Monthly sampling was conducted using traditional fishing gears during June to August 2012.Total length was measured to the nearest 0.01 cm using digital slide calipers,and total body weight was measured using an electronic balance with 0.01 g accuracy.The LWR was calculated using the expression:W=a×L_(b),where the W is the body weight,L is the total length,a and b are the parameters of the regression.Results:A total of 350 specimens ranging from 8.59-15.71 cm in total length and 9.57-32.59 g in body weight were analyzed during this study.The overall sex ratio was not significantly different from the expected value of 1:1(X^(2)=2.57,P>0.05),but there was significant difference in the length-frequency distributions between the sexes(P=0.03).The allometric coefficient b for the LWR indicated negative allometric growth(b=3.00)in males,female and combined sexes.Results further indicated that Kr was not significantly different between the sexes(P=0.57).However,the mean W_(R)of R.corsula showed significant differences from 100 for males(P=0.03)and females(P<0.001)in this study,indicating the imbalance habitat with food availability relative to the presence of predators.Conclusions:This study reported the first description of biometric relationships for R.corsula,which would be useful for the sustainable conservation of this rear fishery in Bangladesh and also neighboring countries.
文摘Objective:To investigate some important aspects of the biology of Callinectes amnicola(C.amnicola)such as fecundity,carapace length-weight relationship,condition factor and carapace length frequency distribution from the Cross River estuary,Nigeria.Methods:A total of one hundred and twenty ovigerous females of C.amnicola,freshly caught with basket traps,lift net trap,and gill net were collected from the catches of the artisanal fisheries in the study area between June 2012 and May 2013.Fecundity,carapace length-weight relationship,condition factor and carapace length frequency distribution were determined and analyzed following standard methods.Results:Fecundity(F)ranged between 73090 eggs for crab of carapace length 8.1 cm and total weight 34 g and 809450 eggs for crab of carapace length 16.1 cm and total weight 395 g with a mean of 311808.93±17693.94 eggs.There was a positive significant relationship between fecundity and carapace length,total weight and condition factor as follows:F=6839.7CL^(1.4403)(r^(2)=0.2145,P<0.05),F=15302TW^(0.5798)(r^(2)=0.4079,P<0.05),F=147255K^(0.2788)(r=0.2717,r^(2)=0.0738,P<0.05).A significant linear relationship between carapace length and weight of C.amnicola is given by the equation:Log W=2.0447LogL–0.1389(r^(2)=0.3357,P<0.05).The crab exhibited a negative allometric growth pattern(b=2.0447).Condition factor ranged between 21.48 to 104.95 with a mean value of 47.21±2.17.The carapace length frequency distribution showed a unimodal class size distribution.Conclusions:Findings of this study is crucial in assessing the population dynamics and development of management strategies of the the Blue crab,C.amnicola from the estuary such as mesh size regulation,fishing season and fishing ground regulation in the Cross River estuary.Also,findings of this study will be useful in evaluation of the aquaculture potential of the Blue crab C.amnicola,which is a valuable shell fish for the inhabitants estuary.
