Improving the percent hatch during artificial spawning of walleye (Sander vitreus) could save agencies substantial resources. Semen inclusion techniques used to artificially fertilize walleye eggs may have a subsequen...Improving the percent hatch during artificial spawning of walleye (Sander vitreus) could save agencies substantial resources. Semen inclusion techniques used to artificially fertilize walleye eggs may have a subsequent influence on the percent hatch. We compared walleye egg survival to the early embryo stage across four semen inclusion techniques used during fertilization to determine if one or more of the techniques would result in a higher percent hatch. Six mL of freshly collected (within 2 h) semen was presented to common pools of walleye eggs separated into 250 mL lots by either 1) pouring semen on top of the eggs before sperm activation, 2) placing 3 mL of semen below and above the eggs before sperm activation, 3) pouring 3 mL of semen on top of the eggs, activating sperm, and adding the remaining 3 mL of semen after 30 s, or 4) activating the sperm by adding semen to 1 L of water, mixing and pouring the solution on the eggs within 3 s. All treatments received 1 L of filtered lake water for sperm activation and fertilization. Mean egg survival was similar ranging from 49.5% to 56.7% among the four techniques and was not significantly different across methods. These results suggest that any of the semen inclusion techniques will likely provide a similar percent hatch for walleye eggs when 250 mL of eggs, 6 mL of semen, and 1 L of water are used during fertilization.展开更多
Fish skin collagen hydrolysates (FSCH) were prepared from walleye pollock (Theragra chalcogramrna) using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3...Fish skin collagen hydrolysates (FSCH) were prepared from walleye pollock (Theragra chalcogramrna) using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3%. FSCH was mainly composed of low-molecular-weight peptides and the relative proportion of 〈1000Da fraction was 70.6%. Free radical and oxygen species scavenging activities of FSCH were investigated in four model systems, including diphenylpicrylhy-drazyl radical (DPPH), superoxide anion radical, hydroxyl radical and hydrogen peroxide model, and compared with that of a native antioxidant, reduced glutathione (GSH). FSCH was also evaluated by water-absorbing and water-holding capacity. The results showed that FSCH was able to scavenge free radical and oxygen species significantly and to enhance water-absorbing and water-holding capacity remarkably. Therefore FSCH may have potential applications in the medicine and food industries.展开更多
Walleye (Sander vitreus) fingerling production can be enhanced when the pond substrate is altered from earthen soils to an exposed liner;however, few differences in water chemistry, prey densities, and food habits hav...Walleye (Sander vitreus) fingerling production can be enhanced when the pond substrate is altered from earthen soils to an exposed liner;however, few differences in water chemistry, prey densities, and food habits have been identified that could potentially explain this production difference. Lack of an explanation led to further comparison of walleye fingerling culture between substrate types during 2016. Two ponds of each type were stocked with 1- to 3-day-old walleye fry, but lined ponds received an additional 104,166 fry/ha and were stocked 1 or 2 days later than earthen ponds (May 10). Walleyes in lined ponds achieved a growth advantage on May 31 (+2.5 mm) and on June 6 (+3.3 mm), but lengths were not significantly different at harvest (June 15). Lined ponds increased walleye yield and number 1.8-fold while not reducing individual fish size at harvest compared to earthen ponds. Walleye food habits were generally similar between pond types with a greater number of zooplankton being consumed through June 6 followed by an increase in larval chironomid consumption at harvest (June 15). After May 30, lined ponds exhibited lower dissolved oxygen and higher ammonia-nitrogen concentrations even though earthen ponds received additional (157 kg/ha) alfalfa (Medicago sativa) meal fertilizer. Also, at this time pH declined abruptly and remained below 8.2 in lined ponds. Moreover, the enhanced production in lined ponds coincided with walleyes that exhibited an increased pelagic (δ13C) signature during the culture period (2‰ to 3.3‰ more negative). Efforts to improve production in earthen-substrate ponds should focus on increasing the pelagic signature of the food web through fertilization strategies which increase ammonia-nitrogen (≈0.3 mg/L) and decrease dissolved oxygen (≈6.5 mg/L) while maintaining a pH between 8.0 and 8.2 during the second half of the rearing interval.展开更多
Reduced walleye (Sander vitreus) fingerling production possibly related to nuisance filamentous green algae and overly stable water chemistry patterns is a concern in earthen-substrate ponds at Blue Dog State Fish Hat...Reduced walleye (Sander vitreus) fingerling production possibly related to nuisance filamentous green algae and overly stable water chemistry patterns is a concern in earthen-substrate ponds at Blue Dog State Fish Hatchery, South Dakota, USA. We describe the success of alfalfa (Medicago sativa) meal (AFM, n = 2), alfalfa meal plus soybean (Glycine max) meal (AFM + SBM, n = 1), and alfalfa meal plus liquid 28N:0P:0K (AFM + 28:0:0, n = 1) at achieving walleye production objectives (>104,000 walleye and 32 kilograms/hectare) as well as the occurrence of filamentous green algae and the associated patterns of ammonia-nitrogen, pH, and dissolved oxygen in earthen-substrate ponds. Walleye production objectives were only achieved when filamentous green algae were absent preceding harvest, which occurred in one pond that received AFM and in the pond that received AFM + 28:0:0. The presence of filamentous green algae preceding harvest was associated with higher dissolved oxygen and pH, whereas declines in these variables occurred when filamentous green algae were absent. Organic fertilizer alone exhibited low ammonia-nitrogen ( favorable patterns in water chemistry warrant future experimentation with alfalfa meal supplemented with 28:0:0 in earthen-substrate ponds at this hatchery.展开更多
Fry stocking density can affect harvest metrics for fingerling walleye (Stizostedion vitreum) reared in drainable ponds, but few studies have examined these relationships with the use of elevated walleye fry stocking ...Fry stocking density can affect harvest metrics for fingerling walleye (Stizostedion vitreum) reared in drainable ponds, but few studies have examined these relationships with the use of elevated walleye fry stocking densities in lined ponds. Correlation and regression analyses were used to assess how a three-fold change in walleye fry stocking density (234,375 to 703,125 per hectare) relates to harvest metrics and length of the culture period, as well as the tradeoff experienced between walleye size (grams) and harvest density in 0.32-hectare lined ponds over a nine-year period at Blue Dog State Fish Hatchery, South Dakota. As fry stocking density increased, so did harvest metrics for both number (r = 0.85, P < 0.01) and yield (r = 0.81, P < 0.01). Length of the culture period varied between 24 and 35 days and was negatively related to stocking density (r = -0.66, P The linear relationship between harvest density and yield was highly correlated (r = 0.95, P < 0.01) with highest values measuring 617,625 walleye and 173 kilograms per hectare. Harvest density explained 61% of the variation in walleye size (P 0.01) and exhibited a decreasing curvilinear relationship such that continued increases in harvest density resulted in smaller reductions in fish size. Increasing fry stocking density from 234,375 to 703,125 per hectare in lined ponds coincided with increased rearing efficiencies for number and yield, as well as a reduced culture period. Minimal reduction in walleye size occurred once harvest density exceeded 300,000 per hectare.展开更多
We report here arsenic speciation in 1643 freshwater fish samples,representing 14 common fish species from 53 waterbodies in Alberta,Canada.Arsenic species were extracted from fish muscle tissue.Arsenic species in the...We report here arsenic speciation in 1643 freshwater fish samples,representing 14 common fish species from 53 waterbodies in Alberta,Canada.Arsenic species were extracted from fish muscle tissue.Arsenic species in the extracts were separated using anion-exchange high-performance liquid chromatography(HPLC)and quantified using inductively coupled plasma mass spectrometry(ICPMS).The total arsenic concentrations in fish ranged from 2.8 to 1200μg/kg(in wet weight of sample)(mean 71±101μg/kg),which are all below the 2000μg/kg(wet weight)maximum allowable total arsenic in fish,recommended by the Ontario Ministry of the Environment.In 99.7%,or 1638 of all 1643 freshwater fish samples analyzed,arsenobetaine(AsB)was detectable,with concentrations higher than the method detection limit of 0.25μg/kg(wet weight).Dimethylarsinic acid(DMA)was detectable(concentration>0.25μg/kg)in 92.1%,or 1514 of the 1643 freshwater fish samples.Inorganic arsenate(iAsⅤ)was detectable(>0.25μg/kg)in 1119 fish(i.e.,68.1% of 1643 samples).Monomethylarsonic acid(MMA)was detectable(>0.25μg/kg)in 418 fish(25.4%of 1643 samples).The concentrations of arsenic species in the 1643 fish samples varied by as much as three orders of magnitude,ranging from below the method detection limit of 0.25μg/kg to the maximum concentrations of 380μg/kg for AsB,150μg/kg for DMA,70μg/kg for iAsⅤ,and 51μg/kg for MMA.AsB made up 46.1%±26.2% of total arsenic species.Arsenic speciation patterns varied between lake whitefish,northern pike,and walleye,the three most common types of fish analyzed.The relative proportion of DMA in northern pike was larger than in lake whitefish and walleye,and conversely,the relative proportion of iAsⅤ was lower in northern pike.Seven unknown arsenic species were detected,and their chromatographic retention time did not match with those of available arsenic standards.At least one unknown arsenic species was detected in 33.4%,or 549 of 1643 freshwater fish samples.The concentrations of unknown arsenic species were as high as 61μg/kg.Future research is necessary to identify unknown arsenic species and to determine contributing factors to the observed arsenic species patterns and concentrations.展开更多
摘要Improving the percent hatch during artificial spawning of walleye (Sander vitreus) could save agencies substantial resources. Semen inclusion techniques used to artificially fertilize walleye eggs may have a subsequent influence on the percent hatch. We compared walleye egg survival to the early embryo stage across four semen inclusion techniques used during fertilization to determine if one or more of the techniques would result in a higher percent hatch. Six mL of freshly collected (within 2 h) semen was presented to common pools of walleye eggs separated into 250 mL lots by either 1) pouring semen on top of the eggs before sperm activation, 2) placing 3 mL of semen below and above the eggs before sperm activation, 3) pouring 3 mL of semen on top of the eggs, activating sperm, and adding the remaining 3 mL of semen after 30 s, or 4) activating the sperm by adding semen to 1 L of water, mixing and pouring the solution on the eggs within 3 s. All treatments received 1 L of filtered lake water for sperm activation and fertilization. Mean egg survival was similar ranging from 49.5% to 56.7% among the four techniques and was not significantly different across methods. These results suggest that any of the semen inclusion techniques will likely provide a similar percent hatch for walleye eggs when 250 mL of eggs, 6 mL of semen, and 1 L of water are used during fertilization.
基金supported by the High Technology Research and Development Program of China (No. 2006AA09Z438)the National Natural Science Foundation of China (No. 30871943).
摘要Fish skin collagen hydrolysates (FSCH) were prepared from walleye pollock (Theragra chalcogramrna) using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3%. FSCH was mainly composed of low-molecular-weight peptides and the relative proportion of 〈1000Da fraction was 70.6%. Free radical and oxygen species scavenging activities of FSCH were investigated in four model systems, including diphenylpicrylhy-drazyl radical (DPPH), superoxide anion radical, hydroxyl radical and hydrogen peroxide model, and compared with that of a native antioxidant, reduced glutathione (GSH). FSCH was also evaluated by water-absorbing and water-holding capacity. The results showed that FSCH was able to scavenge free radical and oxygen species significantly and to enhance water-absorbing and water-holding capacity remarkably. Therefore FSCH may have potential applications in the medicine and food industries.
摘要Walleye (Sander vitreus) fingerling production can be enhanced when the pond substrate is altered from earthen soils to an exposed liner;however, few differences in water chemistry, prey densities, and food habits have been identified that could potentially explain this production difference. Lack of an explanation led to further comparison of walleye fingerling culture between substrate types during 2016. Two ponds of each type were stocked with 1- to 3-day-old walleye fry, but lined ponds received an additional 104,166 fry/ha and were stocked 1 or 2 days later than earthen ponds (May 10). Walleyes in lined ponds achieved a growth advantage on May 31 (+2.5 mm) and on June 6 (+3.3 mm), but lengths were not significantly different at harvest (June 15). Lined ponds increased walleye yield and number 1.8-fold while not reducing individual fish size at harvest compared to earthen ponds. Walleye food habits were generally similar between pond types with a greater number of zooplankton being consumed through June 6 followed by an increase in larval chironomid consumption at harvest (June 15). After May 30, lined ponds exhibited lower dissolved oxygen and higher ammonia-nitrogen concentrations even though earthen ponds received additional (157 kg/ha) alfalfa (Medicago sativa) meal fertilizer. Also, at this time pH declined abruptly and remained below 8.2 in lined ponds. Moreover, the enhanced production in lined ponds coincided with walleyes that exhibited an increased pelagic (δ13C) signature during the culture period (2‰ to 3.3‰ more negative). Efforts to improve production in earthen-substrate ponds should focus on increasing the pelagic signature of the food web through fertilization strategies which increase ammonia-nitrogen (≈0.3 mg/L) and decrease dissolved oxygen (≈6.5 mg/L) while maintaining a pH between 8.0 and 8.2 during the second half of the rearing interval.
摘要Reduced walleye (Sander vitreus) fingerling production possibly related to nuisance filamentous green algae and overly stable water chemistry patterns is a concern in earthen-substrate ponds at Blue Dog State Fish Hatchery, South Dakota, USA. We describe the success of alfalfa (Medicago sativa) meal (AFM, n = 2), alfalfa meal plus soybean (Glycine max) meal (AFM + SBM, n = 1), and alfalfa meal plus liquid 28N:0P:0K (AFM + 28:0:0, n = 1) at achieving walleye production objectives (>104,000 walleye and 32 kilograms/hectare) as well as the occurrence of filamentous green algae and the associated patterns of ammonia-nitrogen, pH, and dissolved oxygen in earthen-substrate ponds. Walleye production objectives were only achieved when filamentous green algae were absent preceding harvest, which occurred in one pond that received AFM and in the pond that received AFM + 28:0:0. The presence of filamentous green algae preceding harvest was associated with higher dissolved oxygen and pH, whereas declines in these variables occurred when filamentous green algae were absent. Organic fertilizer alone exhibited low ammonia-nitrogen ( favorable patterns in water chemistry warrant future experimentation with alfalfa meal supplemented with 28:0:0 in earthen-substrate ponds at this hatchery.
摘要Fry stocking density can affect harvest metrics for fingerling walleye (Stizostedion vitreum) reared in drainable ponds, but few studies have examined these relationships with the use of elevated walleye fry stocking densities in lined ponds. Correlation and regression analyses were used to assess how a three-fold change in walleye fry stocking density (234,375 to 703,125 per hectare) relates to harvest metrics and length of the culture period, as well as the tradeoff experienced between walleye size (grams) and harvest density in 0.32-hectare lined ponds over a nine-year period at Blue Dog State Fish Hatchery, South Dakota. As fry stocking density increased, so did harvest metrics for both number (r = 0.85, P < 0.01) and yield (r = 0.81, P < 0.01). Length of the culture period varied between 24 and 35 days and was negatively related to stocking density (r = -0.66, P The linear relationship between harvest density and yield was highly correlated (r = 0.95, P < 0.01) with highest values measuring 617,625 walleye and 173 kilograms per hectare. Harvest density explained 61% of the variation in walleye size (P 0.01) and exhibited a decreasing curvilinear relationship such that continued increases in harvest density resulted in smaller reductions in fish size. Increasing fry stocking density from 234,375 to 703,125 per hectare in lined ponds coincided with increased rearing efficiencies for number and yield, as well as a reduced culture period. Minimal reduction in walleye size occurred once harvest density exceeded 300,000 per hectare.
基金supported by Alberta Health,Alberta Innovates,the Canada Research Chairs program,the Canadian Institutes of Health Research,and the Natural Sciences and Engineering Research Council of Canada.
摘要We report here arsenic speciation in 1643 freshwater fish samples,representing 14 common fish species from 53 waterbodies in Alberta,Canada.Arsenic species were extracted from fish muscle tissue.Arsenic species in the extracts were separated using anion-exchange high-performance liquid chromatography(HPLC)and quantified using inductively coupled plasma mass spectrometry(ICPMS).The total arsenic concentrations in fish ranged from 2.8 to 1200μg/kg(in wet weight of sample)(mean 71±101μg/kg),which are all below the 2000μg/kg(wet weight)maximum allowable total arsenic in fish,recommended by the Ontario Ministry of the Environment.In 99.7%,or 1638 of all 1643 freshwater fish samples analyzed,arsenobetaine(AsB)was detectable,with concentrations higher than the method detection limit of 0.25μg/kg(wet weight).Dimethylarsinic acid(DMA)was detectable(concentration>0.25μg/kg)in 92.1%,or 1514 of the 1643 freshwater fish samples.Inorganic arsenate(iAsⅤ)was detectable(>0.25μg/kg)in 1119 fish(i.e.,68.1% of 1643 samples).Monomethylarsonic acid(MMA)was detectable(>0.25μg/kg)in 418 fish(25.4%of 1643 samples).The concentrations of arsenic species in the 1643 fish samples varied by as much as three orders of magnitude,ranging from below the method detection limit of 0.25μg/kg to the maximum concentrations of 380μg/kg for AsB,150μg/kg for DMA,70μg/kg for iAsⅤ,and 51μg/kg for MMA.AsB made up 46.1%±26.2% of total arsenic species.Arsenic speciation patterns varied between lake whitefish,northern pike,and walleye,the three most common types of fish analyzed.The relative proportion of DMA in northern pike was larger than in lake whitefish and walleye,and conversely,the relative proportion of iAsⅤ was lower in northern pike.Seven unknown arsenic species were detected,and their chromatographic retention time did not match with those of available arsenic standards.At least one unknown arsenic species was detected in 33.4%,or 549 of 1643 freshwater fish samples.The concentrations of unknown arsenic species were as high as 61μg/kg.Future research is necessary to identify unknown arsenic species and to determine contributing factors to the observed arsenic species patterns and concentrations.