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An epidemiological study of cataracts in seawater farmed Atlantic salmon Salmo salar.

https://arctichealth.org/en/permalink/ahliterature50807
Source
Dis Aquat Organ. 2001 Aug 2;45(3):229-36
Publication Type
Article
Date
Aug-2-2001
Author
C. Ersdal
P J Midtlyng
J. Jarp
Author Affiliation
National Veterinary Institute, Oslo, Norway.
Source
Dis Aquat Organ. 2001 Aug 2;45(3):229-36
Date
Aug-2-2001
Language
English
Publication Type
Article
Keywords
Animals
Body Weight
Cataract - epidemiology - pathology - veterinary
Cross-Sectional Studies
Fish Diseases - epidemiology - pathology
Fisheries
Norway - epidemiology
Otoscopes - veterinary
Prevalence
Questionnaires
Research Support, Non-U.S. Gov't
Salmo salar
Seasons
Seawater
Abstract
Cataracts in farmed Atlantic salmon have been known for many years, but the aetiology and importance of the disease have not been clarified. A cross-sectional field study of 51 cages of Atlantic salmon at 49 randomly selected sea sites was performed during the summer of 1998. The target population was spring and autumn entry groups of the 1997 generation salmon. Approximately 15 fish from each cage, altogether 777 fish, were autopsied by the same person. Each eye of the fish was scored for cataracts on a scale from 0 to 4 using an otoscope lamp with magnification. The weight and length of each fish were measured. The prevalence of cataracts was 83 % and 79% in spring entry groups and autumn entry groups, respectively. The overall mean cataract index (mean score of both eyes) was 1.23, being significantly higher in the spring entry groups (1.36) than the autumn entry groups (0.85). The final results in the spring entry groups showed that the fish groups with higher weight at sea transfer also had a higher cataract index at inspection. The risk of development of cataracts varied significantly among the offspring from the 5 strains represented in the study. Fish from sites located in 2 counties in the southern part of Norway had a significantly higher cataract index than fish farmed in the northernmost county in the study. For the autumn entry groups none of the explanatory variables was significant. In the spring entry groups a significant negative relationship was observed between the cataract score and the weight of the fish at the time of inspection (Pearson's r = -0.17), while the corresponding correlation for the autumn released groups was r = -0.10. Among the spring entry groups the average weight of the fish with the highest cataract score was estimated to about a third of the weight of the fish with no visible cataracts.
PubMed ID
11558732 View in PubMed
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Critical assessment of regulatory standards and tests for fish vaccines.

https://arctichealth.org/en/permalink/ahliterature57374
Source
Dev Biol (Basel). 2005;121:219-26
Publication Type
Article
Date
2005
Author
P J Midtlyng
Author Affiliation
Centre for Veterinary Contract Research and Commercial Services, Ltd. (VESO), Oslo, Norway. paul.midtlyng@veso.no
Source
Dev Biol (Basel). 2005;121:219-26
Date
2005
Language
English
Publication Type
Article
Keywords
Animals
Aquaculture - methods - standards
Drug Administration Routes - veterinary
Europe
Fishes
Government Regulation
Mortality
Sample Size
Time Factors
Vaccination - methods - trends - veterinary
Vaccines - standards
Abstract
Within the European Economic Area (EU member states plus Norway, Iceland and Liechtenstein), veterinary vaccines must comply with EU regulations and relevant monographs of the European Pharmacopoeia. Since 1996, three European monographs specific for fish have been adopted; concerning oil-adjuvanted, injectable vaccine for salmonids against furunculosis, as well as bacterins against classical vibriosis (Listonella anguillarum) or cold-water vibriosis (Vibrio salmonicida) in salmonids. The regulatory requirements laid down in these monographs include the use of seronegative fish for in vivo safety testing; conduct of vaccination trials in which experimental challenge is administered by injection, and minimum relative protection to be achieved at a given level of control mortality. Several aspects of these requirements are being questioned. This concerns the relevance of injection challenge methods as opposed to waterborne challenge; the validity of relative protection assessed at 60 % control mortality (RPS6) as compared to protection calculated at the endpoint of mortality (RPSendpoint), and poor test power due to low numbers of fish per treatment group. There is a strong need for future efforts to refine the methods for documentation and testing of fish vaccines, and to assure their suitability for the intended purpose.
PubMed ID
15962484 View in PubMed
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Light scattering in normal and cataractous lenses of farmed Atlantic salmon (Salmo salar): a slit lamp and Scheimpflug photographic study.

https://arctichealth.org/en/permalink/ahliterature50804
Source
Ophthalmic Res. 2001 Sep-Oct;33(5):264-70
Publication Type
Article
Author
A. Wegener
H. Laser
M H Ahrend
O. Breck
E. Bjerkås
C. Glöckner
P J Midtlyng
W. Breipohl
Author Affiliation
Department of Experimental Ophthalmology, Rheinische Friedrich Wilhelm University, Bonn, Germany. a.wegener@uni-bonn.de
Source
Ophthalmic Res. 2001 Sep-Oct;33(5):264-70
Language
English
Publication Type
Article
Keywords
Animals
Cataract - classification - diagnosis - epidemiology
Fisheries
Lens, Crystalline - pathology
Light
Norway
Photography - methods
Research Support, Non-U.S. Gov't
Salmo salar
Scattering, Radiation
Abstract
To investigate normal light scattering and cataract formation, the anterior eye segments of farmed Atlantic salmon (Salmo salar) reared in fresh water and sea water were documented in vivo for the first time with a Topcon SL-45 Scheimpflug camera. A total of 40 fish from the fresh-water-rearing period, obtained from 2 groups of identical age but showing a different growth rate, and 24 fish from the sea-water-rearing period, sampled from 2 groups with identical age but being fed different food brands, were included in this study. The fish were anaesthetized before examination. Due to the naturally wide pupil, no mydriatic compound was applied. All fish were removed from the water for photography, which was performed for each eye in 0 degrees = vertical slit position. Images were recorded on Kodak Tmax 400 black-and-white film. Microdensitometric image analysis of all negatives was performed using a Joyce-Loebl online microdensitometer. In spite of the virtual absence of an anterior chamber gap between cornea and lens and very little light scattering in the normal fish lens, a small number of distinct layers could be reproducibly identified in the lens. While there was little abnormal light scattering which could point to cataract development in young fish from the fresh water period, the evaluation of the lenses from the 2 sea water groups showed the presence of specific forms of cataract especially in the cortical and supranuclear layers. There were significant differences between the groups fed different food brands at the sea water site. In conclusion, Scheimpflug photography proved to be applicable to eye research in fish in vivo. It is suggested that this method should be employed for reproducible documentation as an extension to slit lamp monitoring in experimental research to reveal causative factors for cataracts in farmed fish.
PubMed ID
11586059 View in PubMed
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