Náttúra og náttúrutilfeingi
Viðurskifti, sum ávirka útbreiðslu av lús kring alibrúk og á firðum.
(Factors influencing the distribution of pelagic sea lice at fish farm- and regional scale)
Gunnvør á Norði
Øystein Patursson, Ása Jacobsen, Eirikur Danielsen, Debes H. Christiansen, Moira Galbraith og Rasmus Skern
Stuðul úr Granskingargrunninum:
Sea lice have become the plague of the salmon farming industry in Europe and America, and available therapeutants have become less effective. Thus solutions to the sea lice problem have been sought in spatial planning of farms, and coordinated farming cycles with the aim of reducing the risk of infection.
A pre-quest for the success in reducing the infection pressure, is to understand the distribution and infection pattern of the pelagic stages of the sea lice. The regional distribution of sea lice has been investigated and modelled in e.g. Norway, while the farm scale distribution of pelagic sea lice has received little attention, albeit there are some studies showing retention and re-infection of sea lice within net cages.
In this study the distribution of pelagic sea lice of the two species Lepeophtheirus salmonis and Caligus elongates will be investigated at farm scale in relation to factors, which might influence the retention of larvae inside the cages. Factors being; bio-fouling of net cages, influence of artificial light treatments, and the current speed at the farming site. The regional distribution of larvae will likewise be investigated, as will the effect of the coordinated fallow period on the infection pressure.
We will also try to further develop a real time PCR method established by (McBeath et al. 2006), with the aim of detecting and quantifying L. salmonis and C. elongates sea lice in plankton samples. A method which will significantly reduce the manpower needed to investigate the distribution of sea lice.
The project has incresead the understandding of distribution and infection pressure of sea lice. With direct observations it has been shown, that salmon lice copepodids are dispersed with the currents in the upppermost watercolumn, where the currents are influenced by winds. On the other hand, results indicated that salmon lice nauplii possibly migrate vertically in the water column towards highest possible temperature, as this would decrease the duration of the nauplii stages and hence the risk of mortality. At fish farms nauplii dominate the planktonic stages of sea lice while copepodods are scarce. The nauplii density was highly dependent on the current speed at the farm. This knowledge is useful in the effort to mitigate the infection pressure of sea lice e.g in hydrodynamic models with the aim of understanding the infection pressure of salmon lice, and further in locating the farms relative to the infection pressure.
Scientific articles, books, thesis etc.
Norði G. á, Simonsen K., Danielsen E., Eliasen K., Mols-Mortensen A., Christiansen D., Steingrund P., Galbraith M., Patursson Ø. (2015) Abundance and distribution of planktonic Lepeophtheirus salmonis and Caligus elongatus in a fish farming region in the Faroe Islands. Aquaculture Environment Interactions 7: 15 – 27 DOI 10.3354/aei00134
Other results, such as unpublished articles, patents, computer systems, original models and new procedures
Norði G. á, Simonsen K., Patursson Ø. (in prep) High resolution measurements of planktonic sea lice at a fish farm. Manuscript in preperation