Download or read book Management Strategies to Control Sexual Maturation in Sea reared Atlantic Salmon Salmo Salar L written by Eric Leclercq and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Pre-harvest sexual maturation in farmed Atlantic salmon, Salmo salar, remains a key biological bottleneck compromising biomass and financial output, production predictability, environmental respect, stock welfare and the overall sustainability of the on-growing industry. The management practices currently in place are not optimized and events of high maturation rate are still sporadically observed. From an ecological perspective, the escape of reproductively competent, domesticated Atlantic salmon constitutes a threat to the integrity of wild stocks. The forecasted expansion of the Scottish salmon industry compels the need for a comprehensive and more reliable control of sexual maturation. The general aim of this research project was to optimize the current management strategy (windows of light-manipulation and quality grading) and test alternative practices (lighting-technologies, selective harvest and triploidization) in the control of pre-harvest sexual maturation within the Atlantic salmon on-growing industry. In that end, a number of trials were performed using stock reared in sea-cages on a full commercial-scale or in tanks on an experimental scale. The results of this project are organized around three experimental chapters dealing consecutively with body-size dimorphism, grading and harvest quality; light manipulations and triploidy. In each chapter, two original manuscripts either published or in review are included. In addition to these experimental results, a literature review chapter composed of two review papers on the photoperiodic synchronization and developmental regulation of maturation in salmonids and on morphological skin colour changes in teleosts (published) are presented. In the first experimental chapters, we aimed at investigating the possibility of detecting and selectively harvesting a high proportion of sexually recruited fish before flesh quality deterioration. Results clearly showed that body-size dimorphisms between maturity cohorts at the end of the anabolic window of reproduction (June/July) are strong and standard predictors of maturation among related populations with the same freshwater history. Dimorphism can therefore be modelled to easily and accurately estimate maturation rate in a number of discrete rearing-units. If required, a high proportion of sexually recruited fish can be selectively harvested as superior quality product while leaving the immature fish for further on-growing. This provides an alternative to visual grilse grading that is not feasible in large-scale aquaculture systems, prevents downgrading and increases production predictability as compared to emergency harvests. Furthermore, our results showed immature males grow faster than immature females which should be further investigated to fully determine gender specific performances and nutritional requirements. Weight-grading performed earlier in the cycle affects the sex-ratio within individual pens and in turn apparent performance. This work also revealed that Atlantic salmon can exhibit significant variations in skin colouration resembling the onset of nuptial display but that are not related to sexual recruitment and do not correlate with reduced flesh quality. This originates from a lack of purine (silver) pigments which was also identified, to a larger extent, as characteristic of the nuptial display. This suggests a degree of desmoltification in these histologically immature fish. The instrumental colouration of the altered phenotype was shown to be improved towards a more silver-like appearance by direct ice-contact. This knowledge could facilitate post-harvest quality grading towards the most appropriate market channel and increase product acceptance and attractiveness. The second experimental chapter investigated the possibility of improving photoperiodic manipulation used to suppress early maturation, currently applied for 6-months during the second winter at sea using wide-spectrum, high-intensity lighting systems. Our results showed that the window of continuous artificial-light (LL) exposure can be reduced to 4-months following its onset in early January without compromising its efficiency in suppressing pre-harvest maturation. In addition, alternative lighting technologies were also highly potent at suppressing sexual maturation. The mean-irradiance (intensity) generated within a commercial sea-cage was inversely proportional to the suppression of nocturnal plasma melatonin (light perception hormone) and negatively correlates with the maturation rate within the commercial sea-pen. Threshold levels of light-intensity required to achieve optimal (total) suppression of sexual maturation are suggested. Alternative, narrow band-width lighting-technologies (cold cathode and light-emitting diodes) present an array of technical, practical, economic and welfare benefits comparing to the system currently in use. Clear improvements of the photoperiod-manipulation strategy were demonstrated and these would reduce economic and environmental costs but also potential impacts on animal welfare. The third experimental chapter showed the strong potential of sterile-triploid Atlantic salmon stocks both in freshwater and seawater. Triploid out-of-season smolts were produced for the first time using a classical accelerated "square-wave" photoperiod. Triploidization affected the smoltification pattern but had no detrimental effects on freshwater and early seawater performances under both a S0+ and S1 regime. This illustrates the need to adapt the timing of seawater transfer for successfully producing triploid Atlantic salmon post-smolts. Following one year of seawater rearing, the prevalence of external deformities was higher in triploids but remained within acceptable levels. Importantly, the incidence of vertebral deformities and ocular cataract was higher in triploids possibly due to their specific requirements. It is suggested that tailoring the diet to the nutritional requirements of triploids holds strong potential for remediation. This must be addressed if the use of sterile-triploid stock is to become a commercial reality. The present research project provides means to optimize the maturation management strategy within the Atlantic salmon on-growing industry through light-manipulation, maturation detection and selective harvest, and quality grading. Proposed improvements have the potential to increase biomass and financial output, production predictability, environmental respect and animal welfare and will allow standardization of the overall control of pre-harvest sexual maturation. Their implementation provides a comprehensive strategy likely to favour a sustainable expansion of the Atlantic salmon industry. From a longer term perspective, the rearing of sterile-triploid stocks is promising and should be actively investigated to isolate domesticated strains from their wild conspecifics. This would also eliminate the need for on-growers to deploy a maturation management strategy that that might still affect stock welfare and remains, despite the strong improvements demonstrated, not 100% reliable, costly, technical and protracted.
Download or read book Sexual Maturation in Atlantic Salmon Salmo Salar L Aspects of Environmental and Hormonal Control written by Geir Lasse Taranger and published by . This book was released on 1993 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of Extended Day Length on Early Sexual Maturation and Growth in Atlantic Salmon Salmo Salar Reared in Sea Cages written by and published by . This book was released on 1992 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two year-classes of Atlantic salmon, represented by a line selected for growth performance and a control line in one year-class and an unselected control line from a similar gene pool in a second year-class, were reared in sea cages. The fish were used to evaluate the effects of extended day length, using artificial light from fluorescent tubes, on growth and sexual maturity as grilse (maturation after one sea-year).
Download or read book Sexual Maturation in Farmed Atlantic Salmon Salmo Salar written by Margarita Rivera and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sexual maturation of Atlantic salmon Salmo salar is a multifactorial process in which fish acquire somatic characteristics to reproduce. In salmon farming has been described a high variability in the trait age at maturation derived from wild reproductive strategies. Early maturation is a phenotype that generates serious economic repercussions on both, sea cage and on land-based aquaculture systems. In view of the challenges of this problem for the global salmon farming industry, it is essential to thoroughly understand the influencing factors of early and late maturation to find efficient alternatives for managing the phenomenon. This review briefly describes sexual maturation in S. salar, its variability in cultures, and the factors influencing the maturation age trait at the physiological, genetic and environmental levels. The control of early maturity through changes to the natural photoperiod and through the use of genetic markers are discussed.
Download or read book Fisheries Review written by and published by . This book was released on 1992 with total page 948 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sexual Maturation and Smoltification in Baltic Salmon Salmo Salar written by Ingemar Berglund and published by . This book was released on 1991 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Smoltification and Early Sexual Maturation in the Baltic Salmon Salmo Salar L written by Magnus Rydevik and published by . This book was released on 1989 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of Photoperiod on Growth and Maturation of Atlantic Salmon Salmo Salar in the Bay of Fundy written by P. R. Harmon and published by St. Andrews, N.B. : Department of Fisheries and Oceans. This book was released on 2003 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2001, a study on the effects of photoperiod on growth and early maturation was initiated on a commercial salmon farm in southwestern New Brunswick. Three cages (70-m diameter circles) had lights turned on November 21. A second set of three cages had lights turned on February 15, 2002. Lights were left on 24 h per day. All lights were turned off on May 31, 2002. Six unlit cages served as controls.
Download or read book Atlantic Salmon Ecology written by Øystein Aas and published by John Wiley & Sons. This book was released on 2010-10-18 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Atlantic salmon is one of the most prized and exploited species worldwide, being at the centre of a massive sports fishing industry and increasingly as the major farmed species in many countries worldwide. Atlantic Salmon Ecology is a landmark publication, both scientifically important and visually attractive. Comprehensively covering all major aspects of the relationship of the Atlantic salmon with its environment, chapters include details of migration and dispersal, reproduction, habitat requirements, feeding, growth rates, competition, predation, parasitsm, population dynamics, effects of landscape use, hydro power development, climate change, and exploitation. The book closes with a summary and look at possible future research directions. Backed by the Norwegian Research Council and with editors and contributors widely known and respected, Atlantic Salmon Ecology is an essential purchase for all those working with this species, including fisheries scientists and managers, fish biologists, ecologists, physiologists, environmental biologists and aquatic scientists, fish and wildlife department personnel and regulatory bodies. Libraries in all universities and research establishments where these subjects are studied and taught should have copies of this important publication. Comprehensive and up-to-date coverage of Atlantic Salmon Atlantic Salmon is one of the world's most commercially important species Backed by the Norwegian Research Council Experienced editor and internationally respected contributors
Download or read book Atlantic Salmon Brood Stock Management and Breeding Handbook written by Harold L. Kincaid and published by . This book was released on 1989 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Growth Respiration and Sexual Maturation of Juvenile Atlantic Salmon Salmo Salar L written by Robert Louis Blake and published by . This book was released on 1981 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Principles of Salmonid Culture written by W. Pennell and published by Elsevier. This book was released on 1996-10-11 with total page 1071 pages. Available in PDF, EPUB and Kindle. Book excerpt: As salmonids have been reared for more than a century in many countries, one might expect that principles are well established and provide a solid foundation for salmonid aquaculture. Indeed, some of the methods used today in salmonid rearing are nearly identical to those employed one hundred years ago. Areas of salmonid research today include nutrition, smolt and stress physiology, genetics and biotechnology.The purpose of this book is to provide a useful synthesis of the biology and culture of salmonid fishes. The important practices in salmonid culture as well as the theory behind them is described. This volume will be of interest to students, researchers, fisheries biologists and managers as well as practising aquaculturists.
Download or read book Parr smolt Transformation in Nonanadromous Atlantic Salmon Salmo Salar and Effects of Sexual Maturation on the Parr smolt Transformation in Male Anadromous Atlantic Salmon written by Timothy Peter Birt and published by . This book was released on 1985 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book State of Sexual Maturity of Atlantic Salmon Salmo Salar L Caught at Sea in Commercial Fisheries Off Newfoundland written by Conrad Mullins and published by . This book was released on 1995 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book State of Sexual Maturity of Atlantic Salmon Salmo Salar L Caught at Sea in Commercial Fisheries Off Newfoundland written by Conrad Mullins and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Precocious Sexual Maturation and Smolting in Baltic Salmon Salmo Salar L written by Hans Lundqvist and published by . This book was released on 1983 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Photoperiod Ration Sea Water and Sexual Maturation on Food Consumption and Growth of Atlantic Salmon Salmo Salar L written by Selina Marguerite Stead and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
