Some more reading.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3675643/If you donot want to read it all here is the conclusion.
Salmon lice are natural parasites on salmonids in the sea water with a circumpolar distribution in the northern Hemisphere. The populations in the Atlantic and Pacific oceans are genetically distinct. Intensive salmon farming has improved the conditions for the growth and transmission of the parasites compared with natural conditions. Gene flow among populations appears high and most likely results from association with highly migratory hosts. There are distinct differences in the susceptibility to salmon lice infections among salmonid fish species.
Salmon recreational fishery, commercial fishery (sea fishery) and aquaculture have different stakeholders, practices, traditions and management objectives and strategies (Liu, Olaussen & Skonhoft 2011). Sea lice have clearly impacted wild salmon and trout fisheries without compensating for the imposed negative external costs. The quantitative estimates of these impacts show large variations. Further research is needed in order to understand the mechanisms and processes. The density of farms in an area has a clear effect on the levels of sea lice at individual farms within that area.
Since the start of large-scale salmon farming in the 1970s, control of salmon lice has been based mainly on chemotherapy. This has been effective and simple to use, but also creates unwanted environmental effects, occupational hazards and drug resistance problems. During the last few years, there has been a trend towards a more integrated management approach with synchronized treatments, biological control (cleaner fish), immunological interference (immunostimulants), mechanical de-lousing systems, selective breeding for louse-resistant salmon and regulatory approaches (zones with synchronized production and fallowing).
Sea lice resistance to chemotherapeutants is a serious concern. In Norway, Scotland, Ireland and eastern Canada, the number of salmon in farms greatly exceeds the number of wild salmon. Thus, the main sources of re-infestation are the farms themselves, where regular parasite treatments place constant selection pressure on resistance development. New chemicals may only be valuable for a limited period of time. Management practices with a variety of methods will be necessary to keep the sea lice under control in salmon farms.
Two published studies tested vaccine candidate antigens against salmon lice, which resulted in a reduced infection rate (Grayson et al. 1995; Carpio et al. 2011). For parasites like salmon lice that do not proliferate on or in the host, a vaccine will primarily reduce infection pressure. Salmon lice create problems for both the salmon farming industry and, under certain conditions, wild salmonids. A vaccine will probably not be adequate as a stand-alone treatment, but it would be a valuable element in the hierarchy of salmon lice prevention methods.
For the foreseeable future, salmon lice will continue to be a serious problem for the salmon farming industry and a threat to their environmental credibility. Salmon farmers invest in expensive sea lice monitoring and treatment programmes. The key to a sustainable production is to integrate several management practices. This will require a substantial increase in research in areas such as new pharmaceuticals, mechanical lice removal, vaccines and immunostimulants, selective breeding for increased resistance, effective aquaculture production and use of cleaner fish, and the development of coastal hydrographic models to estimate transmission dynamics and to support farm siting decisions and coordinated management.
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Topic: Get your facts straight? (Read 1689711 times)