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Drug resistance in sea lice: a threat to salmonid aquaculture: Trends in Parasitology

Drug resistance in sea lice: a threat to salmonid aquaculture: Trends in Parasitology | Aquaculture Directory | Scoop.it

New paper from Stian Mørch Aaen, Kari Olli Helgesen, Marit Jørgensen Bakke, Kiranpreet Kaur and Tor Einar Horsberg; Norwegian University of Life Sciences, School of Veterinary Science, Sea Lice Research Centre, Oslo, Norway Drug-resistant sea lice are emerging in several salmonid-producing countries.Of the five compound groups available, resistance has been reported towards three.Efforts are being put into investigating genetic markers, physiology and biochemistry.The sensitivity status of sea lice populations could thus be monitored more easily.

 

Sea lice are copepod ectoparasites with vast reproductive potential and affect a wide variety of fish species. The number of parasites causing morbidity is proportional to fish size. Natural low host density restricts massive parasite dispersal. However, expanded salmon farming has shifted the conditions in favor of the parasite. Salmon farms are often situated near wild salmonid migrating routes, with smolts being particularly vulnerable to sea lice infestation. In order to protect both farmed and wild salmonids passing or residing in the proximity of the farms, several measures are taken. Medicinal treatment of farmed fish has been the most predictable and efficacious, leading to extensive use of the available compounds. This has resulted in drug-resistant parasites occurring on farmed and possibly wild salmonids.


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John Bostock's curator insight, January 31, 2015 12:07 PM

Further useful insights into the problems of drug resistance when combating parasites

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Ocea, Bremnes Seashore team up for thermal, green sea-lice solution | Undercurrent News

Ocea, Bremnes Seashore team up for thermal, green sea-lice solution | Undercurrent News | Aquaculture Directory | Scoop.it

Norwegian salmon farmer Bremnes Seashore has teamed up with aquaculture equipment and solutions provider Ocea to jointly develop the latter’s environmental friendly delousing solution, reported Norwegian media

 

Under a newly signed deal, the two companies have agreed to together further develop Ocea’s Thermolicer, which Ocea is bringing for the first time to Norway, said iLaks.no.

 

As part of the deal, Ocea will also supply Bremnes Seashore a new 400 metric ton feeding fleet, a renovation of a feeding station and other equipment for a combined value of NOK 28 million.

 

Ocea has worked on Thermolicer, a thermal solution for delousing fish, since 2007. It has patented the technique, which is being applied commercially in Chile already. The technique is now ready for commercial use in Norway, said the company.

 

Thermolicer works by pumping the fish into a lukewarm water bath for under 30 seconds. The lice cannot withstand the sudden temperature change and dies. The fish is then released lice-free into the sea, while the lice is collected and destroyed.

 

The technique has yielded very good results in Chile, with very low mortality both right after the treatment and over a longer period, said Ocea’s Karl Petter Myklebust.

 

Together with Bremnes, the company wants to further develop the process, with a focus on increasing its capacity while maintaining the fish’s wellbeing.


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John Bostock's curator insight, June 12, 2014 11:43 AM

In the interest of balance - here's another very interesting approach for sea lice treatment

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The surveillance programme for resistance to chemotherapeutants in L. salmonis in Norway 2013

The surveillance programme for resistance to chemotherapeutants in L. salmonis in Norway 2013 | Aquaculture Directory | Scoop.it

Grøntvedt RN, Jansen PA, Horsberg TA, Helgesen K, Tarpai A. The surveillance programme for resistance to chemotherapeutants in L. salmonis in Norway 2013. Surveillance programmes for terrestrial and aquatic animals in Norway. Annual report 2013.Oslo: Norwegian Veterinary Institute 2014


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John Bostock's curator insight, April 10, 2014 9:48 AM

Useful work from the Norwegian Veterinary Institute

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Triploid and diploid Atlantic salmon show similar susceptibility to infection with salmon lice Lepeophtheirus salmonis - Frenzl - Pest Management Science - Wiley Online Library

Triploid and diploid Atlantic salmon show similar susceptibility to infection with salmon lice Lepeophtheirus salmonis - Frenzl - Pest Management Science - Wiley Online Library | Aquaculture Directory | Scoop.it

Sea lice infection is the most expensive disease factor for Atlantic salmon sea-cage farming. For triploid salmon to be accepted as a commercial possibility, investigation of susceptibility of triploid salmon to sea lice infection is a fundamental milestone. The susceptibility of diploid and triploid salmon to infection with Lepeophtheirus salmonis was examined in a tank trial in Scotland, a tank trial in Norway and a cage trial in Scotland.Results

Following a single infection challenge, results indicated a significant correlation between fish size and the number of attached sea lice. Triploid fish were larger than diploids at the smolt stage. In the tank trials, no difference was found between infection levels on diploids and triploids after a single infection challenge. The tank trial in Scotland continued with a second infection challenge of the same fish, which also showed no infection differences between ploidies. A borderline correlation between first infection and re-infection intensity was found for PIT-tagged diploid salmon examined after each challenge. No significant difference in louse infection between diploid and triploid salmon (~2 kg) was found in the cage trial undertaken under commercial conditions.

Conclusion

This study concludes that triploid Atlantic salmon are not more susceptible to sea louse infection than diploid fish.


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Updated information on a "new disease" in rainbow trout - Norwegian Veterinary Institute

Updated information on a "new disease" in rainbow trout - Norwegian Veterinary Institute | Aquaculture Directory | Scoop.it

In late August 2013 the Norwegian Veterinary Institute (NVI) received the first case of diseased rainbow trout from a hatchery. The signs of disease were unusual for fish at this age. The second and third cases were submitted to the NVI during October and primo November. The most recent hatchery affected by this disease was recorded in January 2014. Diseased fish were sized from 30 – 100 g. One hatchery reported high mortality in some pens. The other affected sites reported moderate mortalities.  


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John Bostock's curator insight, July 3, 2014 9:33 AM

Information on an emerging disease issue in Norway

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Do anti-parasitic medicines used in aquaculture pose a risk to the Norwegian aquatic environment? - Environmental Science & Technology (ACS Publications)

Do anti-parasitic medicines used in aquaculture pose a risk to the Norwegian aquatic environment? - Environmental Science & Technology (ACS Publications) | Aquaculture Directory | Scoop.it

Aquaculture production is an important industry in many countries and there has been a growth in the use of medicines to ensure the health and cost effectiveness of the industry. This study focussed in the inputs of sea lice medication to the marine environment. Diflubenzuron, teflubenzuron, emamectin benzoate, cypermethrin and deltamethrin were measured in water, sediment and biota samples in the vicinity of 5 aquaculture locations along the Norwegian coast. Deltamethrin and cypermethrin were not detected above the limits of detection in any samples. Diflubenzuron, teflubenzuron and emamectin benzoate were detected, and the data was compared the UK Environmental Quality Standards. The concentrations of emamectin benzoate detected in sediments exceed the environmental quality standard (EQS) on 5 occasions in this study. The EQS for teflubenzuron in sediment was exceeded in 67% of the samples and exceeded for diflubenzuron in 40% of the water samples collected. A crude assessment of the levels detected in the shrimp collected from one location and the levels at which chronic effects are seen in shrimp would suggest that there is a potential risk to shrimp. It would also be reasonable to extrapolate this to any species that undergoes moulting during its life cycle.


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John Bostock's curator insight, June 7, 2014 4:44 PM

The significance of these findings will no doubt be disputed, but substantial use of pesticides in the marine environment is not desirable. It was good therefore to see the innovations from Aqua Pharma  in treatment delivery and control.at the recent Aquaculture UK exhibition. 

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New Vaccine Concept Wins Innovation Award

New Vaccine Concept Wins Innovation Award | Aquaculture Directory | Scoop.it
NORWAY - A homing fish vaccine developed at the Norwegian National Veterinary Institute and University of Oslo has received the Innovation Award at the marine innovation conference in Bergen.

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