Effects of 7,12-dimethylbenz(a)anthracene on growth and haematological parameters in Korean rockfish, Sebastes schlegeli (Hilgendorf)

The objectives of the present experiment were to determine the effects on growth factors and some haematological parameters in Korean rockfish, Sebastes schlegeil, after dietary 7,12‐dimethylbenz(a)anthracene (DMBA) exposure at 0.6, 1.2, 2.4 and 4.8 mg kg^?1 diet for 8 weeks. The specific growth rate of the fish exposed to DMBA (≥1.2 mg kg^?1) showed significantly lower performance than the control. Following 8 weeks of exposure, the DMBA‐exposed groups (2.4 and 4.8 mg kg^?1) had a significantly higher mean hepatosomatic index. Condition factor of the fish exposed to DMBA did not show any statistically significant deviation from the control (P>0.05), although the mean values were somewhat lower than those of the control group. Observations on haematological parameters indicated DMBA treatment induced a severe anaemia. Total protein, albumin and total cholesterol concentrations decreased following exposure to DMBA at 2.4 and 4.8 mg kg^?1. In contrast, serum bilirubin and blood urea nitrogen in fish exposed to DMBA increased. Significant decreases in serum electrolytes, chloride, phosphorus, magnesium and calcium, and osmolality were observed in all DMBA‐treatment groups. All DMBA‐treatment groups showed a significantly higher activity of lactate dehydrogenase and alkaline phosphatase. Serum transaminase activity after the highest level of 4.8 mg kg^?1 DMBA was significantly increased. The key finding from this study is that rockfish exposed to dietary DMBA at concentrations of 1.2 and 2.4 mg kg^?1 diet are likely to experience adverse impacts in growth and haematological property respectively.     

Responses of cypermethrin-induced stress in haematological parameters of Korean rockfish, Sebastes schlegeli (Hilgendorf)

An increasing number of synthetic pyrethroids are used as an environmental friendly substitute of organophosphate and organochlorine insecticides. Pesticide pollution in the coastal ecosystem of Korea is considered to be a cause of slow growth and prevalence of diseases in commercial fishes. Therefore, it is necessary to develop fast techniques to detect insecticide toxicities. In the present work the results of rapid and inexpensive laboratory experiments show the patho‐physiological alteration of blood parameters to sublethal concentration of pyrethroid insecticide (cypermethrin) in the commercially important Korean rockfish (Sebastes schlegeli). Cypermethrin‐exposed fish showed erythropenia, low haematocrit and haemoglobin content and hyperglycemia, especially for long‐term exposure at high concentrations. Cypermethrin caused increased levels of serum glutamic‐acid‐oxylacetic‐acid‐transaminase, glutamic‐acid‐pyruvic‐acid‐transaminase and alkaline phosphatase, concomitant with a decreased concentration of chloride ion and blood serum osmolality, indicating the disruptive activity of cypermethrin after 8 weeks exposure. Moreover, reduced level of serum total protein, albumin, cholesterol, lysozyme activity and significantly higher level of glucose, bilirubin and malondialdehyde were measured and attributed to an increased demand for energy by fish under stress to cope with detrimental conditions imposed by chronic exposure to the toxicant.     

Attractiveness of various protein sources to juvenile rockfish (Sebastes schlegeli,Hilgendorf 1880)

ABSTRACT

The attractiveness of various protein sources of 16 feed ingredients was determined in juvenile rockfish (Sebastes schlegeli) by using reinforced acrylic tank composed of three equally divided rectangular attracting chambers and an acclimatization chamber. Thirty fish were held in the acclimatization chamber at a time and tournament comparison of feed ingredients was applied to evaluate attractiveness. Jack mackerel (JM) (40.0%), sardine (SM) (33.3%), Pollack (PM) (40.0%), shrimp (SHM) (36.7%), mussel meal (40.0%) and oyster (43.3%) meals achieved the highest feeding attractiveness to rockfish in the 1^st through 6^th preliminary test, respectively. JM (40.0%), SHM (36.7%), squid meal (SQM) (33.3%), SM (40.3%), PM (40.0%) and PM (36.7%) achieved the highest feeding attractiveness to fish in the 7^th through 12^th preliminary test, respectively. Among the top five feed ingredients showing high attractiveness to rockfish, JM achieved higher attractiveness than PM and SHM in the 1^st trial. In the 2^nd trial, attractiveness of JM to rockfish was higher than SM and SQM. SM achieved higher attractiveness to rockfish than SQM, but not different from PM throughout the 30-min observation in the 3^rd trial. The strongest feeding attractant response of rockfish was observed in JM, followed by SM, SQM, PM, and SHM, in order among various feed ingredients.     

Optimum dietary protein and lipid levels for juvenile rockfish (Sebastes schlegeli,Hilgendorf 1880)

Optimum dietary protein and lipid levels for juvenile rockfish were determined. Eight hundred and ten juvenile fish averaging 3.22 g were randomly chosen and distributed into 27 flow‐through tanks of 50 L (30 fish per tank). Nine experimental diets were prepared according to a 3 × 3 factorial experimental design: three crude protein levels (45%, 50% and 55%) × three crude lipid levels (11%, 15% and 19%). Crude protein and crude lipid levels increased at the expense of dextrin and cellulose in the experimental diets. Survival of fish was not affected by either dietary protein or lipid level. Weight gain of fish was affected by dietary protein level, but not by dietary lipid level. Weight gain of fish fed the 50P‐15L (50% protein and 15% lipid) diet was higher than that of fish fed the 45% protein diets regardless of lipid level, but not different from that of fish fed the 50P‐11L (50% protein and 11% lipid), 50P‐19L (50% protein and 19% lipid), 55P‐11L (55% protein and 11% lipid), 55P‐15L (55% protein and 15% lipid) and 55P‐19L (55% protein and 19% lipid) diets. Feed consumption of fish was affected by dietary protein level, but not by dietary lipid levels. Feed efficiency ratio (FER) of fish was affected by dietary protein level, but not by dietary lipid level. Protein efficiency ratio (PER) of fish was affected by dietary protein level, but not by dietary lipid level. Nitrogen retention efficiency (NRE) of fish fed the 45P‐19L diet was higher than that of fish fed the 45P‐11L, 50P‐11L, 50P‐15L, 50P‐19L, 55P‐11L, 55P‐15L and 55P‐19L diets, but not different from that of fish fed the 45P‐15L diet. Moisture, crude protein and crude lipid contents of fish was affected by dietary protein and/or lipid level. Plasma triglyceride of fish was affected by dietary lipid level, but not by dietary protein level. In conclusion, optimum protein and lipid levels for growth and feed utilization (PER and NRE) for juvenile rockfish were 50% and 15%, and 45% and 19%, respectively, and the optimum dietary protein‐to‐energy ratio of 27.4 and 23.9 mg protein kJ^?1.     

Dietary methionine requirement for juvenile rockfish, Sebastes schlegeli

A 65‐day growth trial was conducted at 19.5 °C to determine the optimal dietary methionine for juvenile rockfish, Sebastes schlegeli. Semipurified diets were formulated to be isonitrogenous and isoenergetic. Fish meal was used as intact protein source and crystal amino acid was used as a part of dietary protein. Six experimental diets were formulated to contain 5.8, 10.8, 15.8, 20.8, 25.8 and 30.8 g kg⁻¹ dietary methionine. The results showed that dietary methionine significantly affected specific growth rate, weight gain, food conversion ratio, protein productive value (PPV), energy retention efficiency, carcass index and body composition. No significant difference was found in hepatosomatic index. The dietary methionine requirement for maximum growth was 13.7 g kg⁻¹ dry matter or 28.0 g kg⁻¹ of dietary protein when cystine content was 1.2 g kg⁻¹ dry matter.     

低温胁迫对许氏平鲉补偿生长的影响

以体质量(60±10)g、体长(13±2)cm的许氏平(Sebastes schlegeli)为研究对象,在8.5℃水体中低温胁迫1周(T1组)、2周(T2组)、3周(T3组)后在20℃水体中恢复3周,研究其补偿生长。结果表明,低温胁迫后,T1、T2、T3组体质量、生长率均显著低于对照组(C1组,20℃);随低温胁迫时间的延长,鱼体脂肪含量逐渐降低,水分含量则逐渐增加,蛋白含量、能值与对照组差异不显著。经低温胁迫1周后,鱼体溶菌酶、SOD、CAT活力比对照组略有下降,但随胁迫时间的延长,3种酶活力均呈上升趋势。经4周恢复生长后,T1、T2组鱼体各项生化组分及免疫酶活力均恢复至对照组水平,而T3组的鱼体脂肪、水分含量及免疫酶活力与对照组仍有显著差异,T1、T2组实现了完全补偿生长,而T3组只实现了部分补偿生长。从摄食率、食物转化效率的变化曲线可知,经低温胁迫后许氏平的补偿生长效应主要是通过提高食物转化效率实现的。[中国水产科学,2006,13(4):566-572]     

Effects of dietary carbohydrate to lipid ratios on growth and body composition of juvenile and grower rockfish, Sebastes schlegeli

Two feeding trials were conducted to determine the optimal dietary carbohydrate to lipid (CHO:L) ratio for juvenile and grower rockfish. Triplicate groups of juvenile (initial mean weight 3.6 g) and duplicate groups of grower (initial mean weight 166 g) were fed the five isonitrogenous (51% CP) and isoenergetic (4.0 kcal g^?1) diets with the different CHO:L ratios (0.4–5.6 g:g) for 8 weeks respectively. The survival of juvenile and grower was above 93% and was not affected by the dietary CHO:L ratios. Weight gain of juvenile fed the diets with CHO:L ratios of 0.8 and 1.6 was significantly higher than that of the fish fed diets with CHO:L ratios of 2.8 and 5.6 (P<0.05). The feed efficiency and protein efficiency ratio of juvenile fed the diet with CHO:L ratio of 5.6 were the lowest among all groups (P<0.05). The daily feed intake of juvenile fed the diet with a CHO:L ratio of 5.6 was significantly higher than that of the other groups (P<0.05). The condition factors of juvenile fed the diets with CHO:L ratios of 0.8 and 1.6 were significantly higher than that of 5.6 (P<0.05). The crude lipid content of whole body, liver and viscera of juvenile decreased as the dietary CHO:L ratio increased, and the opposite was found for the moisture content. Weight gain, feed efficiency, daily feed intake, protein efficiency ratio and condition factor of grower were not affected by the dietary CHO:L ratio. Hepatosomatic and viscerasomatic indexes of grower were significantly influenced by dietary CHO:L ratio (P<0.05). Significant differences were observed in the lipid content of whole body and viscera of grower. Dietary CHO:L ratios significantly affected the major fatty acid composition of whole body in both juvenile and grower. The contents of 18:2n‐6 and 18:3n‐3 linearly decreased as the dietary CHO:L ratio increased, whereas the 20:4n‐6, 20:5n‐3 and 22:6n‐3 contents increased. Based on growth, feed efficiency and body composition, the optimal dietary CHO:L ratio was 1.6 for juvenile rockfish fed isonitrogenous (51% CP) and isoenergetic (4.0 kcal g^?1) diets, and starch could partially replace lipids in the diets with CHO:L ratios ranging from 0.4 to 5.6 for grower.     

Effect of enriched live feeds on survival and growth rates in larval Korean rockfish, Sebastes schlegeli Hilgendorf

High mortality frequently occurs in larval mass production of Korean rockfish, Sebastes schlegeli Hilgendorf. Nutritional deficiencies in live feeds, rotifers and Artemia nauplii, fed to larvae could be a reason. A series of experiments was carried out to evaluate the effect of nutritional enrichment of live feeds by ω‐yeast, Spirulina powder and Super Selco^TM on survival and growth rates in rockfish larvae. Preference of rockfish larvae for the live feeds was determined by analysis of stomach contents. In addition, the effect of green water produced by the use of Chlorella ellipsoidea and Spirulina powder on the growth performance of larvae was evaluated. Larvae fed rotifers nutritionally enriched with Super Selco showed significantly higher survival rates than those fed rotifers enriched with ω‐yeast. Larvae fed rotifers that were nutritionally enriched with both Super Selco and Spirulina together exhibited improved growth and survival rates. Larvae fed Artemia nauplii nutritionally enriched with Spirulina powder showed significantly higher survival than larvae fed Artemia nauplii without enrichment. When larvae were fed rotifers, Artemia nauplii or the mixture of rotifers and Artemia nauplii, the second and last group showed significantly higher survival than the first group. Fatty acid composition in live feeds was improved by enrichment of ω‐yeast and larvae fed this feed showed higher survival and growth rates compared with larvae fed non‐enriched feeds. No positive effect of green water in the tank produced with C. ellipsoidea or Spirulina powder was observed on survival and growth rates for larvae fed nutritionally enriched rotifers with Super Selco and Spirulina powder. However, when the larvae were fed Artemia nauplii that were nutritionally enriched with ω‐yeast and Spirulina powder, green water obtained by adding Spirulina powder to the tanks resulted in significantly higher growth rates of larvae than was obtained by adding C. ellipsoidea.     

许氏平鲉的网箱养殖试验

对许氏平鲉(Sebastes schlegeli Hilgendorf)的网箱养殖试验从网箱的设计工艺到网箱养殖管理进行了详细的论述。对许氏平鱼自在网箱养殖条件下的摄食、生长特点、死亡规律、病害特征及病害防治方法，以及许氏平鲉在越冬过程中的耐低温能力作了较系统总结，为许氏平鲉的规模养殖生产提供了参考依据。     

许氏平鲉的生物学特征及其人工养殖

本文综述了许氏平鲉的生态特征,摄食与生长、繁殖习性等生物学特征。介绍了亲鱼选择、人工培育及病害防治技术。     

Effect of dietary taurine levels on the conjugated bile acid composition and growth of juvenile Korean rockfish Sebastes schlegeli (Hilgendorf)

This study was conducted to investigate the effects of different taurine levels on the conjugated bile acid composition and growth of juvenile rockfish. Five taurine level diets were made by the supplementation of taurine (0%, 0.5%, 1.0%, 1.5% and 2.0%) to a basal diet. Fish meal washed with 70% ethanol to exclude taurine was used for the sole protein source. Feeding experiments were accomplished at 15°C using juvenile fish (initial BW: 13.5 g). Fish were fed the experimental diets for 4 months. At the end of experiments, fish were weighed and stored at ?80°C for analysis of free amino acids and conjugated bile acids contents. The growth performance and feed efficiency of Korean rockfish were improved by taurine supplementation in the experimental diets. The taurine contents of the whole body increased with the increase in the taurine supplementation. The primary conjugated bile acids in gall bladder were taurocholic acid (83.5–165.6 mg mL^?1) and taurochenodeoxycholic acid (6.3–20.0 mg mL^?1). Total bile acids increased with increases in dietary taurine. Taurocholic acid content was more than 95% of the total conjugated bile acids. This indicates that taurine is the sole amino acid to make conjugated bile acid in Korean rockfish. Dietary taurine levels improved the conjugated bile acid composition in juvenile Korean rockfish.     

Long-term evaluation of extruded diets compared with raw fish moist diet for growing Korean rockfish, Sebastes schlegeli (Hilgendorf)

A long‐term experiment was conducted in sea cages to compare three experimental extruded pellet (EP) diets with a raw fish moist pellet (MP) diet for Korean rockfish, Sebastes schlegeli (Hilgendorf). White fishmeal (WFM), soybean meal (SM) and fishmeal analogue (BAIFA‐M?)‐based experimental EP diets were formulated to be isonitrogenous and isocaloric with 50% crude protein (CP) with available energy of 16.7 kJ g^?1 diet. An MP diet made of 80% frozen horse mackerel + 20% commercial binder meal was also included in the experiment. The proportions of the major protein ingredients in three experimental EP diets were as follows: WFM diet, 100% WFM; SM diet, 70% WFM + 30% SM; BAIFA‐M? diet, 70% WFM + 30% BAIFA‐M?. The experiment was divided into three periods according to fish size: period I, initial weight of 20.2 ± 3.6 g (mean ± SD); period II, initial weight of 57.6 ± 4.7 g (mean ± SD); period III, initial weight of 96.3 ± 6.9 g (mean ± SD). There were no significant differences in weight gain, feed efficiency ratio, thermal‐unit growth coefficient, specific growth rate, haemoglobin, or haematocrit among fish that were fed the four diets during all three periods. However, fish that were fed the MP diet had a lower survival rate than the fish that were fed the other three EP diets for all periods. These results strongly suggest that EP diets could be developed to replace MP diet for the grow‐out stage of production of Korean rockfish without adverse effects on growth performance.     

气泡幕对许氏平鲉的阻拦效果研究

气泡幕可作为海洋牧场鱼群控制的技术手段之一。本研究通过改变气泡幕在水槽中的相对位置和试验许氏平鲉(Sebastes schlegeli)的密度来观察许氏平鲉的行为反应,运用了观察法、对照试验法和控制变量法探究了气泡幕对不同密度下的许氏平鲉的阻拦效果。结果显示:1)试验鱼20尾时,气泡幕的位置分别设置在矩形水槽长的1/4、1/2和3/4处(鱼的密度为12.52、6.26、4.17尾/m2),阻拦率分别达到了98.2%、88.4%和92.9%,阻拦效果明显。2)气泡幕设置在水槽长度方向的1/2处,试验鱼分别为5尾、10尾、15尾和20尾时,气泡幕阻拦率分别达到了100%、85.7%、100%和88.4%(鱼群密度分别为1.56、3.12、4.69、6.26尾/m2),阻拦效果良好。3)由于阻拦率较高,试验鱼群密度和阻拦效率没有明显的关系。本研究结果可为我国投放许氏平鲉的海洋牧场鱼群控制技术以及取水口拦鱼技术提供参考。     

Effects of dietary inclusion of yacon,ginger and blueberry on growth,body composition and challenge test of juvenile rockfish (Sebastes schlegeli) against Edwardsiella tarda

Effects of dietary inclusion of yacon, Polymnia sonchifolia (YC), ginger, Zingiber officinale (GG), and blueberry, Vaccinium ashei (BB), on growth, body composition and challenge test of rockfish against Edwardsiella tarda compared to ethoxyquin were investigated. Three hundred and sixty fish were randomly distributed into 12 flow‐through tanks. Four experimental diets were prepared: the control diet (Con) with 0.1 g/kg ethoxyquin, and YC, GG and BB diets. Each diet was assigned to triplicate tanks of fish and hand‐fed for 8 weeks. Externally normal fish after fourth and eighth weeks of feeding trial were infected with Edwardsiella tarda for challenge test. Weight gain and specific growth rate (SGR) of fish fed the YC diet were greater than those of fish fed all other diets. Feed efficiency, protein efficiency ratio and protein retention of fish fed the YC diet were higher than those of fish fed all other diets. In the both fourth and eighth weeks of infection trials, mortality of fish fed the Con diet was higher than that of fish fed all other diets. In conclusion, dietary inclusion of YC, GG and BB increased weight gain and SGR of fish. YC, GG and BB for 4 and 8 weeks lowered mortality of fish at occurrence of E. tarda.     

Effects of dietary macronutrient level and feeding frequency on growth and body composition of juvenile rockfish (Sebastes schlegeli)

An 8-week feeding experiment was conducted to investigate the effects of different dietary macronutrient level and feeding frequency on the growth, feed utilization, and body composition of juvenile rockfish. Triplicate groups of fish (body weight of 4.1 g) were fed the experimental diets containing either high levels of carbohydrate (HC, 35%), lipid (HL, 13%), or protein (HP, 55%) at different feeding frequencies (twice daily, once daily, and once every 2 days). Weight gain was affected by feeding frequency but not by dietary composition. Weight gain of fish fed the diets once every 2 days was significantly (P < 0.05) lower than that of other groups. Daily feed intake and energy intake were affected by both dietary composition and feeding frequency. Daily feed intake of fish fed the HC diet was significantly (P < 0.05) higher than that of fish fed the HL and HP diets at the same feeding frequency. Feed efficiency and protein efficiency ratio were affected by both dietary composition and feeding frequency and decreased with increasing feeding frequency in the same dietary composition. Feed efficiency and protein efficiency ratio of fish fed the HC diet were significantly (P < 0.05) lower than those of fish fed the HL diet at the same feeding frequency. Whole-body lipid content of fish fed the HL diet was significantly (P < 0.05) higher than that of fish fed the HC and HP diets at the same feeding frequency. These results indicate that an increase of dietary lipid level compared with dietary carbohydrate level may have the advantage of a protein-sparing effect at same feeding frequency, and a once-daily feeding regime is more effective than twice daily or one feeding every 2 days to improve growth performance of juvenile rockfish grown from 4 to 21 g.     

Comparison of oxygen consumption patterns between wild and cultured black rockfish Sebastes schlegeli

ABSTRACT:   To compare metabolic activity rhythms between wild and cultured black rockfish Sebastes schlegeli , we measured long-term oxygen consumption rates (OCR) using an automatic intermittent-flow respirometer under constant temperature and darkness. Oxygen consumption rates peaked among wild black rockfish at 12.4 h intervals, which corresponded to a circatidal rhythm. The wild fish were probably exhibiting responses that corresponded to tidal events in their natural environment. However, when captured wild black rockfish were kept under laboratory conditions (12 h light [L] : 12 h dark [D]) for 30 days, the OCR shifted to a circadian rhythm (24.1–24.9 h). The OCR of cultured black rockfish that had been reared in a tank for 9 months peaked at approximately 24 h intervals, corresponding to a circadian rhythm. The results of this study suggest that the differences in OCR patterns between wild and cultured fish were mainly due to differences in the environmental conditions between tidal and non-tidal habitats.     

The effect of the dietary substitution of fishmeal with tuna by‐product meal on growth,body composition,plasma chemistry and amino acid profiles of juvenile Korean rockfish (Sebastes schlegeli)

The effect of the substitution of fishmeal with tuna by‐product meal (TBM) in the diet of Korean rockfish on growth, body composition, plasma chemistry and amino acid profiles was determined. Nine experimental diets were prepared. The control (Con) diet consisted of 550 g kg^?1 fishmeal. The 10, 20, 30, 40, 60, 80 and 100 % fishmeal diets were substituted with tuna by‐product meal (TBM), referred to as the TBM10, TBM20, TBM30, TBM40, TBM60, TBM80 and TBM100 diets, respectively. Finally, the fishmeal and soybean meal was completely replaced with TBM in the diet TBM100‐S. There was no significant difference in weight gain and SGR of the fish that were fed the TBM40 and Con diets. The feed conversion ratio (FCR) of the fish that were fed the Con, TBM10, TBM20 and TBM30 diets was lower than that of the fish that were fed all of the other diets. The protein efficiency ratio (PER) of fish that were fed the TBM10, TBM20 and TBM300 diets was higher than that of fish that were fed the TBM40, TBM60, TBM80, TBM100 and TBM100‐S diets. It can be concluded that the substitution of fishmeal with up to 40 and 30 % TBM in the diet of juvenile Korean rockfish could be made without exerting a detrimental effect on their growth (SGR) and feed utilization (FCR and PER), respectively.     

摄食促进物质对许氏平鲉摄食和生长的影响 不同地理群体星突江鲽养殖子一代群体遗传多样性分析

以初始体重为49．83±．17g的许氏平鲇Sebastesschlegeli为实验对象,进行为期30d的摄食生长实验。共配制6种等氮等能饲料,其中5种饲料以鱼粉和豆粕为蛋白源（豆粕蛋白替代30％的鱼粉蛋白）配制出基础饲料,分别在基础饲料中不添加摄食促进物质和添加0．3％的商品诱食剂、二甲基-β-丙酸噻亭（DMPT）、甜菜碱和柠檬酸配制成5种豆粕替代饲料,其余1种为鱼粉不替代饲料作为对照组,研究摄食促进物质对许氏平鲇摄食和生长的影响。结果表明,当豆粕取代饲料中添加甜菜碱和柠檬酸时,许氏平铀的特定生长率、饲料效率、蛋白质效率以及肝脏、肠胰蛋白酶活力都显著高于不添加摄食促进物质组（P〈0．05）;当不添加摄食促进物质时,摄食率显著低于鱼粉不替代组（P〈O．05）;而添加DMPT、甜菜碱和柠檬酸时,摄食率与鱼粉不替代组比较没有显著差异（P〉0．05）;肝体指数都明显地低于鱼粉不替代组。结果表明,豆粕替代30％的鱼粉蛋白时,添加0．3％的甜菜碱或柠檬酸能够显著提高许氏平鲇幼鱼对饲料的摄食率和生长率。