Effects of Dietary Lipid Levels on Growth,Survival, and Molting of Yearling Narrow Clawed Crayfish,Astacus leptodactylus

The influence of dietary lipid level was evaluated on growth, survival, and molting of yearling narrow clawed crayfish, Astacus leptodactylus. Yearling crayfish were fed five isonitrogenous diets (35% protein), formulated to contain 4%, 7%, 10%, 13%, or 16% lipid. Crayfish (10.1 ± 1.6 g) were reared for 56 days in 60-L fiberglass tanks at 23 ± 1.7 °C, with flow-through water and continuous aeration. At the end of the trial, crayfish fed 13% lipid had the highest weight gain and specific growth rate, significantly different from crayfish fed 4% and 7% lipid (p < 0.05). Crayfish fed 13% lipid had a significantly higher survival rate (86.7%) than the animals fed 4% lipid (71%) (p < 0.05). Molting was not affected by lipid level (p > 0.05). We recommend 13% dietary lipid level for optimum growth and survival of Astacus leptodactylus in intensive cultivation.     

Growth and Survival of Juvenile Orconectes virilis and Orconectes immunis at Different Temperatures1

Culture of orconectid crayfishes in the midwestern USA offers the potential of contributing to a year-round supply of fresh product as summer/fall production would augment winterhpring production in the southern USA. However, relatively little basic biological information exists for this potential new aquaculture crop. In this study, the authors reared juvenile (third instar) Orconectes virilis and Orconectes immunis at either 10, 15, 20, 25 or 30 C and measured weight gain and survival over a 21 day period. Orconcctes immunis juveniles were larger than O. virilis at the third instar and gained weight more rapidly in this experimental system. Gains in weight and length for both species increased as temperature increased from 10 to 25 C. Both values were lower in crayfish reared at 30 C, though number of molts was the same in crayfish reared at 25 or 30 C. Thus, there appears to be a bioenergetic cost of rearing orconectid crayfishes in temperatures above 25 C. Further, incremental growth with successive molts was influenced by water temperature.     

Increased Densities Result in Reduced Weight Gain of Crayfish Orconectes virilis1

Three independent studies were conducted in which supplemental food was provided to juvenile Orconectes virilis reared at varying densities. One study was conducted in fiberglass tanks (densities of either 13, 27 or 54 individuals/m²) and two were conducted in outdoor pools (densities of either 2.5, 5, 10, 20 or 30 individuals/m²). Crayfish were offered a variety of foods ranging from a formulated diet to agricultural forages. Weight gain of crayfish fed a formulated diet and reared at varying densities was similar in the study conducted in tanks, but survival was significantly lower at the two highest densities (27 and 54/m²). Weight gain, survival and yield decreased as density increased in the studies conducted in outdoor pools. The highest weight gain and survival were at a density of 2.5/m². Wheat straw was used as the source of nutrients. Use of formulated diets did not result in rapid weight gain when crayfish were reared at higher densities.     

The Effects of Temperature, Age, and Acclimation to Salinity on the Survival of Farfantepenaeus paulensis Postlarvae

Abstract.— Salinity tolerance limits during the ontogenetic development of Farfantepenaeus paulensis postlarvae (PL) were determined at different temperatures. Initially, PL 10, 20, 30, 40, 60 and 80 maintained in 30 ppt (parts per thousand) salinity, 22‐25 C, were directly transferred to 15 combinations of salinity (2, 5, 10, 20 and 30 ppt) and temperature (15, 20 and 30 C) for 96 h. Irrespective of age or salinity, higher survival rates were registered at 25 C. PL 10 suffered high mortality, especially at low salinities combined with low (15 C) or high (30 C) temperatures. From PL 20 to PL 40, an increase in survival was observed in all combinations. For PL 60 and 80, tolerance to low salinity was reduced, suggesting that PL have a maximum age by which they are able to develop adaptability to low salinities. In general, the effect of temperature contributed more significantly to mortality in PL 10 and PL 30, but its influence decreased afterwards. From PL 40, salinity becomes the main factor determining mortality. In order to examine the effects of acclimation to salinity on the tolerance limits, a second set of experiments was performed with PL 5, 10, 15 and 25 acclimated to 2, 5, 10, 20 and 30 ppt, 25 C, over a 5‐d period. Postlarvae were then transferred to different salinity levels (2, 5, 10, 20 and 30 ppt) and kept for 96 h. High mortality of PL 10 occurred after direct transfer from high to intermediate/low salinity levels. Although the acclimation to salinity increased survival, it was still poor. An increase in the salinity tolerance was observed from PL 15 to 30, even with no acclimation. Results indicate that PL 10 do not have a fully developed osmoregulatory capacity to cope with low and/or abrupt changes of salinity. It is recommended that non‐acclimated PL 10 should only be released in environments with salinity at or above 20 ppt. If acclimation is carried out, PL may be released in salinities above 10 ppt. The release of PL 10 in salinities below 5 ppt may result in mortality rates of up to 70%. The best age for the release of non‐acclimated F. paulensis PL in environments with low and/ or wide fluctuations of salinity would he PL 15‐30.     

The Effect of Different Dietary Energy Levels on Growth and Survival of Eyestalk Ablated and Intact Juvenile Lobsters Homarus americanus

When fed formulated diets containing 45% protein derived from the rock crab Cancer irroratus , wheat gluten, gelatin, lipids adjusted from 3–14% and carbohydrates adjusted from 5–24%, the average survival of bilaterally eyestalk ablated juvenile lobsters and intact controls were 91% and 99%, respectively over a 90-day experiment. Photopenad (13 light: 11 dark vs 3 light: 21 dark) did not have a significant effect on growth or survival of ablated or intact lobsters. The optimal digestible energy levels and protein/energy ratio for the greatest growth in both ablated and intact lobsters were 3.7 to 3.8 (kcal/g dry) and 0.12 [g protein/(kcal/g)], respectively. The best feed conversion ratios (0.97 and 1.40 diet given/weight gain) for ablated and intact lobsters were obtained with diets containing 3.83 kcal/g and 3.63 kcal/g diet, respectively. The present study also demonstrated that crab protein served as a good protein source for intact and ablated lobsters.     

温度对鱼类生存的影响

鱼类进化发展至今，分布在全世界各个水域中的鱼类形成了能够在不同水温环境条件下生存的各种类型：如温水性鱼类、广温性鱼类、冷水性鱼类／耐低温鱼类和暖水性鱼类／耐高温鱼类。水温的变化不仅导致鱼类的夏眠和冬眠，而且还影响鱼类的繁殖和水体溶氧量，是与鱼类循环系统和呼吸系统关系最为密切、并进而影响鱼类生存的重要环境因子之一。     

Preliminary Evaluation of Production Systems and Forages for Culture of Orconectes virilis, the Northern or Fantail Crayfish

Culture potential of Orconectes virilis , the northern or fantail crayfish, was evaluated in deep ponds and simulated shallow ponds during the summer and fall. Adult crayfish were stocked in the deep ponds in October and known numbers of juvenile crayfish were stocked in the shallow ponds in May. Triplicate groups of crayfish in each system were either not fed (negative control) or fed corn silage or wheat straw. Production in either system was not significantly different between treatments, but production in the shallow tanks (790 kg/ha) was almost double that observed in the deep ponds (401 kg/ha) and may have been due to different stocking strategies. Juvenile crayfish were generally of minimal marketable size at the end of one growing season. The shallow tanks were restocked in October and drained in March to evaluate overwinter survival in this type of system. Survival averaged 78.9% for both males and females, and most (97.1%) age 1 females were carrying eggs.     

Weight Gain and Survival of Juvenile Australian Crayfish Cherax quadricarinatus Fed Formulated Feeds

Abstract.— Weight gain and survival were examined in newly-hatched juvenile Australian crayfish Cherax quadricarinatus fed formulated crustacean feeds. Crayfish cultured using several Argent specialty feeds, including brine shrimp flakes, freeze-dried krill, powdered spirulina, and hatchfry encapsulon, exhibited high mortality (>90%) and little or no weight gain. After ten weeks of culture, crayfish fed AB crayfish feed (AB) exhibited the highest weight gain with nearly 100% survival. Weight gain of crayfish fed other formulated feeds, such as Zeigler post-larval feed (ZPL), Zeigler shrimp grower (ZSG), Burris Mill crayfish feed (BM), Rangen shrimp grower (RSG), and a formulated CNStacean feed (CRUS) were significantly lower. Survival of crayfish cultured using these feeds was also significantly lower, ranging from 40% (CRUS) to 72% (BM). Mortalities associated with these feeds occurred both during the intermolt period and during the molt. Recovered biomass was approximately half of that observed for crayfish cultured using AB feed, further indicating the inadequacy of these formulated feeds for use in crayfish cultures. These data suggest that many commercially available feeds do not provide the nutritional requirements for juvenile Australian crayfish.     

Effects of Salinity on Hatching and Post-Hatch Survival of the Australian Red Claw Crayfish Cherax quadricarinatus

Hatching rate and post-hatch survival of Australian red claw crayfish Cherax quadricarinatus decreased with an increase in seawater salinity. An LC₅₀ of approximately 11 g/L was determined for juvenile survival in seawater through 15 d. Sodium chloride salinity levels as low as 1 g/L killed all crayfish within 15 d. Tolerance of young red claw to higher levels of seawater salinity than sodium chloride salinity may he due to the concentration of other ions in seawater.     

底泥对不同规格克氏原螯虾存活的影响

在大型(80cm×52cm×25cm)及小型水族箱(45cm×35cm×20cm)底部平摊1kg和8.5kg底泥(干质量),分别放养小规格[刚离开母体,(4.23±0.258)mg]、中规格(2.69±0.410)g、大规格(7.55±0.415)g 3个规格克氏原螯虾幼虾,密度分别为每箱30、18、6尾,以不加底泥为对照,每个处理5个重复。在水温18~25℃下常规投喂饲养5~6周,并测试了克氏原螯虾生长、存活、耐低氧和高温能力以及底泥对水体中溶氧量的影响。结果表明,底泥组小(7.82%/d)、中(0.90%/d)、大(0.92%/d)3个规格幼虾的特定生长率分别极显著(P0.01)以及显著(P0.05)高于对照组(5.56%/d,0.20%/d,0.59%/d)。底泥组小规格幼虾死亡率(12%)显著低于对照组(17.3%)(P0.05);耐高温时间极显著大于对照组(P0.01);其他组间差异不显著(P0.05)。3种规格幼虾底泥组窒息时间均极显著大于对照组(P0.01)。底泥使水中溶氧量显著降低。     

Effect of Culture Temperature on Growth, Survival, and Biochemical Composition of Yellow Perch Perca fiavescens

Juvenile yellow perch Perca fiavescens were evaluated under controlled conditions in tanks for 13 wk to determine the effect of temperature on growth to advanced sizes under intensive culture conditions. Yellow perch weighing 6.6 ± 1.5 g were stocked into nine 4,755-L tanks at 131 fish/m³ (625 perch/tank). There were three replicate tanks per temperature (20, 24, and 28 C). Perch were fed to apparent satiation twice daily using a 45% crude protein diet with 16% crude fat. After 93 d the perch in the 24 C treatment were significantly larger ( P < 0.05) than those in the 20 C and 28 C treatments, which were not significantly different (P < 0.05) from each other. Yellow perch raised at 28 C had significantly higher ( P < 0.05) feed conversion ratios and significantly lower ( P < 0.05) survival and net protein utilization than perch raised at 20 C or 24 C. Whole body moisture was significantly higher in ( P < 0.05) yellow perch raised at 20 C which also had significantly higher levels of arachidonic acid (20:4 n-6) and docosohexaenoic acid (22:6 n-3). The ratio of palmitic acid (16:0) and palmitoleic acid (16:1 n-6) had a positive correlation ( P < 0.05) with culture temperature. These data indicate that 24 C may be an optimum temperature for yellow perch. At 20 C survival and feed conversion are good but growth rates are reduced. Temperatures near 28 C appear sufficient to represent chronic stress conditions.     

Effect of Water Temperature on Growth, Survival, and Biochemical Composition of Largemouth Bass Micropterus salmoides

The effects of water temperature on growth rate, survival, and biochemical composition of juvenile largemouth bass Micropterus salmoides were evaluated under controlled conditions in tanks for 12 wk. Feed-trained juvenile largemouth (9.1 ± 1.9 g) were stocked into nine 3,610-L polyethylene tanks inside a greenhouse structure at 140 fish/m³ (500 fish/tank). Three treatment temperatures were evaluated (20, 26, and 32 C) with three replicates per treatment. Bass were fed to apparent satiation twice daily using a commercially available floating salmonid diet (45% crude protein and 16% lipid). After 97 d bass grown at 26 and 32 C had significantly higher ( P < 0.05) average weights, SGR, condition factor (K), and production rates (kg/m³) than those in the 20 C treatment. Bass in the 26 C treatment had significantly lower ( P 0.05) FCR and higher percent protein deposit (PPD) than bass raised at 20 and 32 C, which were not significantly different ( P >0.05). There were no significant differences ( P >0.05) in survival among treatments which averaged 97%, overall. Bass raised at 32 C had higher ( P 0.05) lipid levels in the liver than other treatments. Whole body amino acid concentrations were not significantly impacted ( P >0.05) by culture temperature. Largemouth bass raised at 26 C had significantly lower ( P 0.05) levels of stearic acid (18:0) and significantly higher ( P 0.05) levels of arachidonic acid (20:4 n-6) than bass raised at 20 or 32 C. Bass raised at 32 C had significantly higher ( P 0.05) levels of Linoleic acid (18:2 n-6), total saturates, and dienes than bass raised at 26 or 20 C. These data indicate that growth and feed conversion efficiency are reduced at 20 C. Growth is similar at 26 and 32 C, but feed and dietary protein are more efficiently utilized at 26 C.     

Effects of Temperature on Feeding Activity of the White River Crayfish Procambarus acutus acutus1

Feed consumption by white river crayfish Procambarus acutus acutus in a 56-d laboratory study increased at a linear rate with water temperature over a range of 5 to 25 C. Feed consumption changed as water temperatures were cycled from 20–8–20 C (0.5 C/d) over a 68-d period and was the highest at the initial 20 C level and the lowest at 8 C. As water temperature increased, feed consumption rate increased; however, consumption never reached the initial rate at 20 C. Crayfish fed 3% and 6% of body weight were significantly larger than animals fed at 1% of body weight after 8 wk. Feed conversion ratios increased significantly with feeding rate. Based on this laboratory study, white river crayfish feed most effectively when water temperature is ≥ 15 C and the feeding rate is 3% of body weight/d.     

温度对漠斑牙鲆幼鱼生长与存活的影响

本文根据温度实验,对漠斑牙鲆幼鱼的生长及存活的影响进行了探讨。结果表明：漠斑牙鲆幼鱼适宜生长温度范围为15—30℃,最适温度范围为18～27℃。在适宜温度下,漠斑牙鲆幼鱼生长快,存活率高。过高或过低的温度对幼鱼的生长发育均有一定的抑制作用。在生产上,当培育水体温度低于15℃时应进行人为加温,对促进幼鱼的生长发育与存活有积极意义。     

Growth and Survival of the Australian Red Claw Crayfish Cherax quadricarinatus at Three Densities in Earthen Ponds

Australian red claw crayfish Cherax quadricarinatus were cultured in nine 0.02-ha earthen ponds at densities of l/m², 3/m² and 5/m² for 158 d. Average weight at stocking was 3.2 g. All ponds were provided with a combination of hay and corn silage at a rate of 500 kg/ha per month and a commercial crayfish ration fed at 5%, decreasing to 2% of estimated biomass/d during the growing season. Overall survival rate was 72%, and did not differ among treatments. Final yields and average weights varied significantly with stocking density. Red claw averaged 67 g with an average pond yield of 475 kg/ha at l/m². At 3/m² and 5/m², red claw averaged 48 g and 38 g, respectively, and yielded 1,020 kg/ha and 1,422 kg/ha, respectively.     

The Effect of Temperature on First Feeding, Growth, and Survival of Larval Witch Flounder Glyptocephalus cynoglossus

Witch flounder Glyptocephalus cynoglossus has recently been identified as a candidate species for aquaculture in the northeastern United States and the Canadian Atlantic Provinces. This study investigated the optimal temperatures for witch flounder larval first feeding and for long term larval culture from hatching through metamorphosis. Maximum first feeding occurred between 15.0 and 16.2 C. Larvae did not survive beyond first feeding when reared at mean temperatures of 5.1, 10.4, or 19.5 C and were unable to initiate feeding at mean rearing temperatures below 6.0 C. At a rearing temperature of 15.0 C in 16-L tanks, mean larval survival to 60 days post hatch (dph) was 14.1%. Mean overall length-specific growth rate for larvae reared to 60 dph at 15.0 C was 3.5%/d and mean absolute growth was 0.62 mm/d. Subsequent larval growth at 15.6 C began to taper off towards 70 dph at the onset of weaning which overlapped with larval metamorphosis. Growth plateaued at 85 dph, followed by a rebound between 90 and 95 dph. Survival was 100% when weaning onto a dry, pelleted diet was initiated at 70 dph with a 10-d live diet co-feeding period. These results are favorable and encourage the further pursuit of commercial witch flounder culture.     

Effect on Growth, Survival, and Fatty Acid Composition of Australian Red Claw Crayfish Cherax quadricarinatus Fed Practical Diets With and Without Supplemental Lecithin and/or Cholesterol

Red claw crayfish Cherux quadricarinatus is one of more than a hundred species of Australian freshwater crayfish. However, because of its rapid growth rate, communal and non‐burrowing behavior, ease of spawning, wide temperature and dissolved oxygen tolerance, and no free‐swimming larval stages, red claw may be the best candidate among the Australian crayfishes for semi‐intensive or intensive aquaculture in the United States. The objective of the study was to examine the effects of growth, survival, and fatty acid composition of newly‐hatched red claw when fed four practical diets with or without lecithin and cholesterol. However, little is known of its nutritional requirements or practical diet formulations. An 8‐wk feeding trial was conducted in a recirculating system with newly‐hatched juvenile (mean individual weight, 0.2 g) red claw, each stocked in separate plastic mesh culture units containing their own individual water line. Water was recirculated through biological and mechanical filters. Practical diets were formulated to be isonitrogenous (40% protein) and isocaloric (4 kcal available enerpy/g of diet) and contained menhaden fish meal (25%), soybean meal (35%, except in Diet 4), and shrimp meal (10%, except in Diet 4) as protein sources. Diet 1 had 0.5% lecithin added and 1.0% cholesterol added: Diet 2 contained 0% lecithin and 1.0% cholesterol; Diet 3 contained 0.5% lecithin and 0% cholesterol: and Diet 4 contained 0% lecithin and 0% cholesterol. After 8 wk, juvenile red claw fed diets with 0% supplemental lecithin (Diets 2 and 4) had no significant difference (P >0.05) in final weight and percentage weight gain (5.6 g and 2626%. respectively) compared to red claw fed the control diet (Diet 1) containing 0.5% lecithin. Red claw fed a diet without added cholesterol (Diet 3) had significantly (P 0.05) lower final weight (3.6 g) and percentage weight gain (1,717%) compared to red claw fed the control diet (Diet 1). However, red claw fed Diet 4 (containing 0% added cholesterol and 0% added lecithin) showed no significant (P >0.05) difference in final weight (5.1 g) and percentage weight gain (2254%) compared to red claw fed all other diets. There was no significant difference (P >0.05) among all diets for specific growth rate (SGR) which averaged 5.38%/d. Percentage survival was not significantly different among all treatments and was 76% for red claw fed Diet 1, 64% (Diet 2), 56% (Diet 3), and 80% (Diet 4). These results indicate that red claw fed Diet 4 containing 25% menhaden fish meal, 44.5% soybean meal, 0.5% choline chloride, 2% cod liver oil and 1% corn oil may satisfy the lecithin and cholesterol requirements and that the addition of dietary lecithin and cholesterol may not be necessary for good growth and survival of small (0.2 g) juvenile red claw. This may allow for less expensive diet formulations for use by producers of red claw crayfish.     

亲缘关系对克氏原螯虾仔虾种内斗争的影响

将源于1、2、3、4尾雌虾的克氏原螯虾仔虾以4种方式混养,每个混养群体共有仔虾24尾,设3个重复。结果表明:亲缘关系对幼年螯虾种内斗争影响显著。随着仔虾来源的增多即亲缘关系复杂性的提高,螯虾的存活率总体呈下降趋势,而残虾率、体长变异系数、体长增长率总体上显著上升。     

温度对黄鳍东方鲀胚胎发育和仔鱼存活的影响

观察了不同温度条件下(20、23、26、29、32℃)黄鳍东方鲀受精卵的培育周期、孵化周期、孵化率和畸形率;并对黄鳍东方纯初孵仔鱼进行耐饥饿试验,测定其不投饵存活系数。试验结果表明,黄鳍东方纯受精卵孵化的适宜温度为20～26℃(最适温度为23℃);仔鱼生存的适宜温度为20～26℃(最适温度为23℃)。黄鳍东方鲀受精卵和仔鱼对温度这种环境因子的耐受范围基本相同。