The acute effect of cortisol implant on self-feeding activity of rainbow trout Oncorhynchus mykiss (Walbaum)     

T Lyytikäinen  & K Ruohonen 《Aquaculture Research》2001,32(6):503-505

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Comparison of traditional and environmental DNA survey methods for detecting rare and abundant freshwater fish     

Maxine P. Piggott  Samuel C. Banks  Ben T. Broadhurst  Christopher J. Fulton  Mark Lintermans 《水产资源保护:海洋与淡水生态系统》2021,31(1):173-184

1. Detecting rare species is often a necessity for conservation and management, yet challenging for many field survey methods. Environmental DNA (eDNA) is a highly promising solution that has been shown to outperform many established survey methods.
2. Macquarie perch (Macquaria australasica) is an endangered native species that has declined significantly in range and abundance. Detection of M. australasica was compared with an abundant alien fish species (Oncorhynchus mykiss) using eDNA and three conventional survey methods: gill nets, electrofishing and fyke nets.
3. eDNA occupancy estimates for both fish species were compared using four different models to investigate what effect these differences have on false positives and false negatives for the rare and common fish species. These models used unadjusted eDNA detections in water samples, eDNA detections that have been screened using a limit of detection method to remove potential false positives, eDNA data supplemented with a second survey method, or eDNA data augmented with sequencing of positive polymerase chain reaction replicates.
4. eDNA surveying as a single detection method was found to be more efficient and sensitive compared with each capture method separately and combined. Occupancy estimates for the common and rare species did not vary significantly between the four site occupancy-detection models, suggesting that supplementary data may not have as much effect on occupancy estimates compared with other approaches such as temporal or spatial sampling.
5. We conclude that eDNA outperforms the three established survey methods for both a rare and common freshwater fish species. Although there was no significant effect of augmenting eDNA survey methods with other survey data, additional data may improve confidence in detection, and provide confirmatory evidence for unexpected or new detections of a species.

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虹鳟营养需求的研究进展   总被引：3，自引：0，他引：3  

李志华  王军霞  谢松 《水产科学》2004,23(2):39-44

简要介绍了近年来国内外虹鳟的营养研究,包括蛋白质、脂肪、维生素、矿物质等方面,提出一些虹鳟养殖中的注意事项,为虹鳟养殖、饲料生产和科研开发提供参考。  相似文献   

Female-biased mortality rate and sexual size dimorphism of migratory masu salmon, Oncorhynchus masou   总被引：1，自引：0，他引：1  

T. Tamate  K. Maekawa 《Ecology of Freshwater Fish》2004,13(2):96-103

Abstract –  We examined whether mortality and growth during the migration phase (the lacustrine phase after smolting) differ between sexes in migratory (lake-run) masu salmon ( Oncorhynchus masou ) in a lacustrine population, northern Hokkaido, Japan. The sex ratio of 1+ smolts was more skewed to females than that of the returning adults in three annual cohorts examined, indicating that females have a higher mortality rate during the migration phase. Although there was no difference in smolt length between sexes, female adults were larger in body length than males of the same age: female-biased sexual size dimorphism (SSD) occurs. We suppose that breeding selection favouring a larger body size for females than for males in this population probably requires that females undertake more intensive foraging behaviour with its greater inherent risks but faster growth rates during the migration phase. It therefore seems to be likely that the selection is the ultimate cause of the female-biased mortality rate and SSD.  相似文献   

Effects of the extensive culture system as finishing production strategy on biometric and chemical parameters in rainbow trout     

Giovanni M Turchini  Tiziana Mentasti  Claudio Crocco  Tommaso Sala  Cesare Puzzi  Vittorio M. Moretti  & Franco Valfrè 《Aquaculture Research》2004,35(4):378-384

The effect of finishing extensive farming period, to reduce fat content and manipulate the fatty acid profile of fish muscle, was evaluated in rainbow trout. Fish were stocked in an artificial lake, in which fish were fed only on naturally available nutrients with no supply of artificial feed, for different lengths of time from 0 to 120 days. No weight loss was noted during the whole finishing period while total length increased from 228±7 to 269±3 mm and the condition factor decreased from 1.41±0.04 to 0.89±0.02. The total fat content of the fillets decreased considerably from 4.7±0.6% at the beginning to 2.4±0.4% and 0.7±0.2% after 45 and 120 days respectively. Fillet fatty acid composition was affected by the time of stocking in the extensive farm. In contrast to the reduction in C18:1n‐9, C18:2n‐6, total monounsaturated fatty acid and total n‐6 percent values, an increase in the C20:5n‐3, C22:6n‐3, total polyunsaturated fatty acid and total n‐3 percent values was observed. It was shown that while other finishing strategies for salmonids have some disadvantages, the extensive culture system seems to be a potentially useful tool for increasing the general quality of the end product.  相似文献   

Prespawn mortality in adult spring Chinook salmon outplanted above barrier dams     

M. L. Keefer  G. A. Taylor  D. F. Garletts  G. A. Gauthier  T. M. Pierce  C. C. Caudill 《Ecology of Freshwater Fish》2010,19(3):361-372

Keefer ML, Taylor GA, Garletts DF, Gauthier GA, Pierce TM, Caudill CC. Prespawn mortality in adult spring Chinook salmon outplanted above barrier dams.
Ecology of Freshwater Fish 2010: 19: 361–372. © 2010 John Wiley & Sons A/S Abstract – Dams without fish passage facilities block access to much of the historic spawning habitat of spring Chinook salmon (Oncorhynchus tshawytscha) in Oregon’s Willamette River basin. Adult salmon are routinely outplanted above the dams to supplement natural production, but many die before spawning despite extensive suitable habitat. In 2004–2007, we examined prespawn mortality patterns using live detection and carcass recovery data for 242 radio‐tagged outplants. Total prespawn mortality was 48%, but variability was high, ranging from 0% to 93% for individual release groups. Prespawn mortality was strongly condition dependent, consistently higher for females than males and higher for early release groups. Across years, warm water temperature in the migration corridor and at the collection site was associated with sharply higher mortality. Results highlight a need for better evaluations of the effects of adult mortality on population reintroduction and recovery and relationships among prespawn mortality, dam‐related temperature change and salmon life history and behaviour.  相似文献   

The density dilemma: limitations on juvenile production in threatened salmon populations     

Annika W. Walters  Timothy Copeland  David A. Venditti 《Ecology of Freshwater Fish》2013,22(4):508-519

Density‐dependent processes have repeatedly been shown to have a central role in salmonid population dynamics, but are often assumed to be negligible for populations at low abundances relative to historical records. Density dependence has been observed in overall spring/summer Snake River Chinook salmon Oncorhynchus tshawytscha production, but it is not clear how patterns observed at the aggregate level relate to individual populations within the basin. We used a Bayesian hierarchical modelling approach to explore the degree of density dependence in juvenile production for nine Idaho populations. Our results indicate that density dependence is ubiquitous, although its strength varies between populations. We also investigated the processes driving the population‐level pattern and found density‐dependent growth and mortality present for both common life‐history strategies, but no evidence of density‐dependent movement. Overwinter mortality, spatial clustering of redds and limited resource availability were identified as potentially important limiting factors contributing to density dependence. The ubiquity of density dependence for these threatened populations is alarming as stability at present low abundance levels suggests recovery may be difficult without major changes. We conclude that density dependence at the population level is common and must be considered in demographic analysis and management.  相似文献   

The Economic Impact of the Trout,Oncorhynchus mykiss,Industry on Transylvania County,North Carolina     

《Journal Of Applied Aquaculture》2013,25(1-2):61-83

Abstract

The commercial culture of rainbow trout, Oncorhynchus mykiss, in Transylvania County, North Carolina, generated approximately $9 million in economic output in 2002. Commercial trout farming began in North Carolina more than 45 years ago. Twenty of the 57 commercial trout farms in production in North Carolina are located in Transylvania County, ranging in size from 1,135 to 204,300 kg annual production in 2002. North Carolina presently ranks second in the United States in commercial trout production, behind Idaho. The study shows that, in 2002, the trout industry generated about $9 million in economic output, created 201 jobs, and generated $3 and $0.9 million, respectively, as labor income and tax revenue in 2002. This is particularly important for Transylvania County where economic prosperity depends on locally available jobs and diversification of economic activities.  相似文献   

Allo-eudiploidy of the diploid cells in diploid-tetraploid mosaic hybrids between female rainbow trout Oncorhynchus mykiss and male amago salmon O. rhodurus     

Xuelian  ZHANG  Hiroshi  ONOZATO 《Fisheries Science》2004,70(5):924-926

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在循环养殖系统中不同溶氧量对虹鳟幼鱼代谢水平的影响   总被引：2，自引：0，他引：2       下载免费PDF全文

吴垠  张洪  赵慧慧  李韬 《上海海洋大学学报》2007,(5):437-442

在循环养殖系统中设置四种溶氧水平,分别为7.05、8.82、11.84和15.80 mg/L,其中8.82 mg/L为对照组,对虹鳟幼鱼（体长13.0-18.5 cm）的代谢水平及生长率进行了研究。结果表明,饲养30 d后7.05mg/L的低溶氧使虹鳟幼鱼耗氧率和排氨率下降,11.84和15.80 mg/L溶氧下饲养的鱼耗氧率明显增加,15.80 mg/L使鱼的排氨率显著高于对照组。并且11.84和15.80 mg/L组虹鳟幼鱼在24 h内都具有高的代谢水平。随着溶氧量提高,虹鳟幼鱼的增重率、特定生长率和饲料转化率均随之升高,表现出生长指标的明显变化。  相似文献