Juvenile landlocked Chinook salmon (Oncorhynchus tshawytscha) (mean ± SD initial weight 2.6 ± 0.7 g, fork length 6.3 ± 0.5) were reared in three different water velocities [0.5, 1.5 and 3.0 body length/...Juvenile landlocked Chinook salmon (Oncorhynchus tshawytscha) (mean ± SD initial weight 2.6 ± 0.7 g, fork length 6.3 ± 0.5) were reared in three different water velocities [0.5, 1.5 and 3.0 body length/s (BL/s)] for four weeks to determine possible effects of water velocity on growth, condition, and survival. Fish were sampled for weight, fork length, condition factor, hepatosomatic index (HSI), viscerosomatic index (VSI), and fin erosion after four weeks of feeding to satiation. At the end of the feeding trial, the fish were handled and transported to simulate stocking, with survival observed over the following 10 d. Following four weeks of feeding, fish reared in 0.5 and 1.5 BL/s had the same growth and food conversion ratio, but fish reared at 3.0 BL/s had a significant reduction in both metrics. Furthermore, fish reared at 1.5 BL/s had a significantly higher condition factor than fish reared in other treatments. No significant differences were found for HSI, VSI, fin erosion, or survival. The results from this study indicate that a moderate velocity (1.5 BL/s), which is necessary for circular tanks to be self-cleaning, is not detrimental to fish growth or condition, but a faster water velocity (3.0 BL/s) negatively affects fish growth and food utilization.展开更多
Several treatment options have been developed to minimize the spread of zebra mussel Dreissena polymorphaveligers (larvae) during fish transportation. However, the effect of these treatments on the survival of newly-f...Several treatment options have been developed to minimize the spread of zebra mussel Dreissena polymorphaveligers (larvae) during fish transportation. However, the effect of these treatments on the survival of newly-fertilized salmonid eggs has not been evaluated. This study examined the survival of water-hardened landlocked fall Chinook salmon Oncorhynchus tshawytscha eggs after one of four different treatments: 1) Control (no chemicals), 2) 100 mg/L formalin for two hours, 3) 750 mg/L of potassium chloride for one hour followed by 20 mg/L formalin for two hours, and 4) 750 mg/L of potassium chloride for one hour followed by 20 mg/L formalin for three hours. The 100 mg/L formalin treatment produced complete egg mortality. Survival to hatch was not significantly different among the other three treatments. Based on these results, the use of 750 mg/L potassium chloride for one hour followed by 20 mg/L formalin for three hours is recommended when moving Chinook salmon eggs from waters potentially infested with zebra mussels to hatcheries for incubation.展开更多
Environmental enrichment has been shown to improve juvenile salmonid growth during hatchery rearing. This study examined the effects of vertically-suspended environmental enrichment starting seven days after feed trai...Environmental enrichment has been shown to improve juvenile salmonid growth during hatchery rearing. This study examined the effects of vertically-suspended environmental enrichment starting seven days after feed training and continuing for the next 32 days of landlocked fall Chinook salmon (</span><i><span style="font-family:Verdana;">Oncorhynchus tshawytscha</span></i><span style="font-family:Verdana;">) rearing. At the end of this experiment, final tank weights, gain, percent gain, and feed conversion ratio were all significantly improved in the tanks of salmon with environmental enrichment compared to barren tanks, with a nearly 25% improvement in feed conversion ratio. Individual salmon in tanks with environmental enrichment were significantly longer and weighed significantly more than salmon from tanks without enrichment. Specific growth rate was also significantly improved with the use of enrichment. The use of vertically-suspended environmental enrichment to improve growth and rearing efficiency is recommended during the initial rearing of landlocked fall Chinook salmon.展开更多
This experiment evaluated the use of an exercise routine and vertically-sus<span style="font-family:Verdana;">-<span style="font-family:;" "=""><span style="font-...This experiment evaluated the use of an exercise routine and vertically-sus<span style="font-family:Verdana;">-<span style="font-family:;" "=""><span style="font-family:Verdana;">pended structure during juvenile landlocked fall Chinook salmon (<span style="font-family:Verdana;">Oncor<span style="font-family:Verdana;">hynchus tshawytscha<span style="font-family:Verdana;">;<span style="font-family:;" "=""> <span style="font-family:Verdana;">mean ± SE, initial weight 1.47 ± 0.03 g, total length 56.4 ± 0.4 mm) rearing. Four treatments were used: 1<span style="font-family:Verdana;">)<span style="font-family:Verdana;"> no exercise routine nor vertically-suspended structure, 2<span style="font-family:Verdana;">)<span style="font-family:Verdana;"> exercise and structure, 3<span style="font-family:Verdana;">)<span style="font-family:Verdana;"> exercise and no structure, and 4<span style="font-family:Verdana;">)<span style="font-family:;" "=""><span style="font-family:Verdana;"> no exercise and structure. <span style="font-family:Verdana;">Water velocities in tanks without exercise were 12 cm/s, where-as the exercise routine consisted of seven days at 12 cm/s followed by seven days at 18 cm/s. The structure was an array consisting of four vertically-suspended aluminum angles. Total tank gain and percent gain were significantly greater after 50 days in the tanks of salmon subjected to the exercise routine and structure compared to the three other treatments. <span style="font-family:Verdana;">Gain and percent gain were also significantly greater in the tanks receiving<span style="font-family:Verdana;"> structure without exercise compared to tanks with exercise and no structure or tanks with neither exercise nor structure. Feed conversion ratio was signif<span style="font-family:Verdana;">icantly improved in the salmon tanks with structure and without exercise<span style="font-family:Verdana;"> com<span style="font-family:;" "=""><span style="font-family:Verdana;">pared to all other treatments. There were no significant differences for indi<span style="font-family:Verdana;">vidual fish weight, total length, specific growth rate, or condition factor<span style="font-family:Verdana;"> among any of the treatments at the end of the experiment. <span style="font-family:Verdana;">These results indicate that the use of both an exercise routine and vertically-suspended structure may be beneficial during the rearing of juvenile landlocked fall Chinook salmon.展开更多
Delayed fertilization of salmonid eggs can be a useful option to enhance the efficiency of artificial spawning operations. This experiment examined the fertility of landlocked fall Chinook salmon (Oncorhynchus tshawyt...Delayed fertilization of salmonid eggs can be a useful option to enhance the efficiency of artificial spawning operations. This experiment examined the fertility of landlocked fall Chinook salmon (Oncorhynchus tshawytscha) eggs stored for various times after removal from female broodstock. Fertilization occurred either immediately after spawning or the eggs were stored with oxygen at 11°C and fertilized at 4, 6, 8, 12, or 20 hours post-spawn. Survival to the eyed stage of egg development was significantly greater in the eggs fertilized immediately or after four, six, or eight hours of storage compared to those eggs stored for 12 or 20 hours prior to fertilization (P = 0.024). Survival to hatch was also significantly different (P = 0.018) and followed the same pattern. This study is the first to document the successful fertilization of landlocked fall Chinook salmon eggs after eight hours of storage.展开更多
During artificial spawning of salmonids, activated sperm is allowed to remain in contact with eggs for variable durations. This study examined multiple residence times (20, 40, 60, 90, or 120 seconds) for activated sp...During artificial spawning of salmonids, activated sperm is allowed to remain in contact with eggs for variable durations. This study examined multiple residence times (20, 40, 60, 90, or 120 seconds) for activated sperm on landlocked fall Chinook salmon (Oncorhynchus tshawytscha) eggs during spawning. There was no significant difference in egg survival to the eyed-stage of development or to hatch among any of the treatments, with a mean (SE) percent survival to the eyed stage of 63.9 (5.8). These results indicate that only relatively short residence times of activated milt on eggs during landlocked fall Chinook salmon spawning are needed to ensure egg survival, resulting in potentially substantial reductions in production-level spawning times and associated labor costs.展开更多
文摘Juvenile landlocked Chinook salmon (Oncorhynchus tshawytscha) (mean ± SD initial weight 2.6 ± 0.7 g, fork length 6.3 ± 0.5) were reared in three different water velocities [0.5, 1.5 and 3.0 body length/s (BL/s)] for four weeks to determine possible effects of water velocity on growth, condition, and survival. Fish were sampled for weight, fork length, condition factor, hepatosomatic index (HSI), viscerosomatic index (VSI), and fin erosion after four weeks of feeding to satiation. At the end of the feeding trial, the fish were handled and transported to simulate stocking, with survival observed over the following 10 d. Following four weeks of feeding, fish reared in 0.5 and 1.5 BL/s had the same growth and food conversion ratio, but fish reared at 3.0 BL/s had a significant reduction in both metrics. Furthermore, fish reared at 1.5 BL/s had a significantly higher condition factor than fish reared in other treatments. No significant differences were found for HSI, VSI, fin erosion, or survival. The results from this study indicate that a moderate velocity (1.5 BL/s), which is necessary for circular tanks to be self-cleaning, is not detrimental to fish growth or condition, but a faster water velocity (3.0 BL/s) negatively affects fish growth and food utilization.
文摘Several treatment options have been developed to minimize the spread of zebra mussel Dreissena polymorphaveligers (larvae) during fish transportation. However, the effect of these treatments on the survival of newly-fertilized salmonid eggs has not been evaluated. This study examined the survival of water-hardened landlocked fall Chinook salmon Oncorhynchus tshawytscha eggs after one of four different treatments: 1) Control (no chemicals), 2) 100 mg/L formalin for two hours, 3) 750 mg/L of potassium chloride for one hour followed by 20 mg/L formalin for two hours, and 4) 750 mg/L of potassium chloride for one hour followed by 20 mg/L formalin for three hours. The 100 mg/L formalin treatment produced complete egg mortality. Survival to hatch was not significantly different among the other three treatments. Based on these results, the use of 750 mg/L potassium chloride for one hour followed by 20 mg/L formalin for three hours is recommended when moving Chinook salmon eggs from waters potentially infested with zebra mussels to hatcheries for incubation.
文摘Environmental enrichment has been shown to improve juvenile salmonid growth during hatchery rearing. This study examined the effects of vertically-suspended environmental enrichment starting seven days after feed training and continuing for the next 32 days of landlocked fall Chinook salmon (</span><i><span style="font-family:Verdana;">Oncorhynchus tshawytscha</span></i><span style="font-family:Verdana;">) rearing. At the end of this experiment, final tank weights, gain, percent gain, and feed conversion ratio were all significantly improved in the tanks of salmon with environmental enrichment compared to barren tanks, with a nearly 25% improvement in feed conversion ratio. Individual salmon in tanks with environmental enrichment were significantly longer and weighed significantly more than salmon from tanks without enrichment. Specific growth rate was also significantly improved with the use of enrichment. The use of vertically-suspended environmental enrichment to improve growth and rearing efficiency is recommended during the initial rearing of landlocked fall Chinook salmon.
文摘This experiment evaluated the use of an exercise routine and vertically-sus<span style="font-family:Verdana;">-<span style="font-family:;" "=""><span style="font-family:Verdana;">pended structure during juvenile landlocked fall Chinook salmon (<span style="font-family:Verdana;">Oncor<span style="font-family:Verdana;">hynchus tshawytscha<span style="font-family:Verdana;">;<span style="font-family:;" "=""> <span style="font-family:Verdana;">mean ± SE, initial weight 1.47 ± 0.03 g, total length 56.4 ± 0.4 mm) rearing. Four treatments were used: 1<span style="font-family:Verdana;">)<span style="font-family:Verdana;"> no exercise routine nor vertically-suspended structure, 2<span style="font-family:Verdana;">)<span style="font-family:Verdana;"> exercise and structure, 3<span style="font-family:Verdana;">)<span style="font-family:Verdana;"> exercise and no structure, and 4<span style="font-family:Verdana;">)<span style="font-family:;" "=""><span style="font-family:Verdana;"> no exercise and structure. <span style="font-family:Verdana;">Water velocities in tanks without exercise were 12 cm/s, where-as the exercise routine consisted of seven days at 12 cm/s followed by seven days at 18 cm/s. The structure was an array consisting of four vertically-suspended aluminum angles. Total tank gain and percent gain were significantly greater after 50 days in the tanks of salmon subjected to the exercise routine and structure compared to the three other treatments. <span style="font-family:Verdana;">Gain and percent gain were also significantly greater in the tanks receiving<span style="font-family:Verdana;"> structure without exercise compared to tanks with exercise and no structure or tanks with neither exercise nor structure. Feed conversion ratio was signif<span style="font-family:Verdana;">icantly improved in the salmon tanks with structure and without exercise<span style="font-family:Verdana;"> com<span style="font-family:;" "=""><span style="font-family:Verdana;">pared to all other treatments. There were no significant differences for indi<span style="font-family:Verdana;">vidual fish weight, total length, specific growth rate, or condition factor<span style="font-family:Verdana;"> among any of the treatments at the end of the experiment. <span style="font-family:Verdana;">These results indicate that the use of both an exercise routine and vertically-suspended structure may be beneficial during the rearing of juvenile landlocked fall Chinook salmon.
文摘Delayed fertilization of salmonid eggs can be a useful option to enhance the efficiency of artificial spawning operations. This experiment examined the fertility of landlocked fall Chinook salmon (Oncorhynchus tshawytscha) eggs stored for various times after removal from female broodstock. Fertilization occurred either immediately after spawning or the eggs were stored with oxygen at 11°C and fertilized at 4, 6, 8, 12, or 20 hours post-spawn. Survival to the eyed stage of egg development was significantly greater in the eggs fertilized immediately or after four, six, or eight hours of storage compared to those eggs stored for 12 or 20 hours prior to fertilization (P = 0.024). Survival to hatch was also significantly different (P = 0.018) and followed the same pattern. This study is the first to document the successful fertilization of landlocked fall Chinook salmon eggs after eight hours of storage.
文摘During artificial spawning of salmonids, activated sperm is allowed to remain in contact with eggs for variable durations. This study examined multiple residence times (20, 40, 60, 90, or 120 seconds) for activated sperm on landlocked fall Chinook salmon (Oncorhynchus tshawytscha) eggs during spawning. There was no significant difference in egg survival to the eyed-stage of development or to hatch among any of the treatments, with a mean (SE) percent survival to the eyed stage of 63.9 (5.8). These results indicate that only relatively short residence times of activated milt on eggs during landlocked fall Chinook salmon spawning are needed to ensure egg survival, resulting in potentially substantial reductions in production-level spawning times and associated labor costs.
