Research Briefs Salmon genetics
Aquaculture Research Volume 42, Issue 9 Anaesthesia of Atlantic hali- but: Effect of pre-anaesthetic sedation, and importance of body weight and water tem- perature
The genetic identification of escaped farmed salmon to the farm of origin is possible
Inger Hilde Zahl, Anders Kiessling, Ole Bent Samu- elsen and Magne Kjerulf Hansen The effi cacy of the anaes- thetic agents benzocaine, met- acaine (MS-222), metomidate, 2-phenoxyethanol, quinaldine and isoeugenol was studied in Atlantic halibut. Fish with an average body weight of 33 g were anaesthetised at 8 °C and fi sh with an average body weight of 1243 g were anaesthetised at 8 and 15 °C. Agents were tested indi- vidually and as combination anaesthesia comprising pre- anaesthetic sedation, followed by anaesthesia. Induction and recovery times varied in relation to the body weight and water temperature. Large fi sh had longer induction times and shorter recovery times, and displayed reduced responsiveness to handling compared with small fi sh. A higher temperature resulted in shorter induction times, longer recovery times and increased responsiveness to handling. Lower dosages were used for all agents in combination anaesthesia. In small fi sh, this had no effect on the induction times but resulted in shorter recovery times and reduced responsive- ness to handling. In large fi sh, combination anaesthesia resulted in shorter induction times whereas no uniform trend in recovery times and no differences in responsiveness to handling were observed. Neither individual agents nor combinations blocked all refl ex reactions to external stimulation in all fi sh of any treatment group. MS-222 and benzocaine, used separately or in combination anaesthesia, were the most effective agents in reducing refl ex reactions.
Genetic differentiation Fish Farmer September/October 2011
among Atlantic salmon reared in sea-cages reveals a non-random distribution of genetic material from a breed- ing programme to commercial production
Kevin Alan Glover, Øys- tein Skaala, Anne Grete Eide Søvik and Tor Arne Helle
Seven samples, each consisting of approximately 50 Atlantic salmon, were collected from fi ve marine farms in Norway. These farms reported to rear fi sh originating from the same commercial breed; however, all samples followed a unique route of production from breeder to marine farm via egg, fry and smolt producers. A group of farmed escapees (n=50) were also captured. Following genotyping with 18 microsatellite loci, the global FST was 0.083, and pair-wise values were as high as 0.158. Four clusters, with varying degrees of genetic differentia- tion, were identifi ed among samples from the farms, and the source of the escapees was identifi ed successfully. It is suggested that the genetic differences observed among samples from the farms were created through the process of genetic drift, facilitated by parallel sub-strains, extensive within-strain selection and low to moderate numbers of adults contributing to batches of eggs. In conclusion, this study has demonstrated that genetic identifi cation of escaped Atlantic salmon, back to the farm of origin, may be possible even when farms rear fi sh reported to originate from a single breeder.
Aquaculture
Volume 315, Issues 1-2
Translocation of infectious pancreatic necrosis virus across the intestinal epithe- lium of Atlantic salmon Henrik Sundh , Sara Calabrese, Fredrik Jutfelt, Lars Niklasson, Rolf-Erik Olsen and Kristina Sundell Infectious pancreatic
48
necrosis virus (IPNV) is a viral disease that affl icts salmon aquaculture world- wide. Transmission of viral diseases may occur via the skin, gills or intestine but the main entry route for IPNV is not known. However, acute infl ammation of the intestinal mucosa is an early symptom in infected fi sh which sug- gest transmission through an oral route. The main aim of this study is to determine if IPNV can translocate across the intestinal epithelium. It also aims to investigate how acute and chronic IPNV exposure as well as stress af- fects the physiological barrier functions of the intestinal epithelium. Possible trans- location of IPNV across the intestinal mucosa as well as effects of virus on intestinal barrier function was meas- ured in vitro, using the Using chamber technique. IPNV was translocated across both proximal and distal segments of the intestine with a higher rate in distal compared to proximal intestine. The translocated virions caused cytopathic effects on cultured Chinook salmon embryo cells (CHSE-214), proving viability and high virulence. Intestinal barrier function was disturbed as assessed by increased permeability for 14 C-mannitol in the proxi- mal region after exposure to IPNV in vitro. The same pattern was observed after prolonged exposure to IPNV in vivo. Further, the intestine appeared to respond with an increased mucus secretion, as indicated through increased TER after prolonged IPNV exposure. No additional effects of cortisol implanta- tion on barrier function were observed. In conclusion, this study demonstrates that both proximal and distal intestine can be used by IPNV as a route of infection and that the intestinal barrier function is negatively affected by expo- sure to IPNV.
Cobia aquaculture in Viet- nam: Recent developments
www.fishfarmer-magazine.com
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