The possibility of a fish leaving a pen and entering a river with something that wasn't already present is spectacularly small
Disease interaction and pathogens exchange between wild and farmed fish populations with special reference to Norway
L.-H. Johansen a,⁎, I. Jensen a, H. Mikkelsen a, P.-A. Bjørn b,1, P.A. Jansen c, Ø. Bergh d,e
a Nofima, Pb 6122, N-9291 Tromsø, Norway
b Institute of Marine Research, PO Box 6404, N-9294 Tromsø, Norway
c National Veterinary Institute PO Box 750 Sentrum, N-0106 Oslo, Norway
d Institute of Marine Research, PO Box 1870 Nordnes, N-5817 Bergen, Norway
e University of Bergen, Department of Biology, PO Box 7803, N-5020 Bergen, Norway
Aquaculture 315 (2011) 167–186
⁎ Corresponding author. Tel.: +47 77629204.
E-mail address:
lill-heidi.johansen@nofima.no (L.-H. Johansen).
1 Present address.
0044-8486/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.aquaculture.2011.02.014
On ISA p.169:"
Out of 8 Atlantic salmon positive for IPNV in 2008, 7 were escaped farmed fish (based on scale analysis tests). In 2009 IPNV was isolated from two wild Atlantic salmon".
"
There is increasing evidence that IPNV may be transferred from farmed to wild fish through contact with discharges and products from IPNV-contaminated farms (Bucke et al., 1979; Hastein and Lindstad, 1991;McAllister and Bebak, 1997;McVicar et al., 1993; Mortensen, 1993; Sonstegard et al., 1972; Wallace et al., 2008)".
On VHS p.170: “
The infection may persist sub-clinically in rainbow trout, and reservoirs of infection are cultured or wild fish that are covert carriers. Virulent virus is shed with urine and ovarian fluids (Skall et al., 2005), and once the virus is established in a farmed stock the disease becomes enzootic because of the latent carrier fish.”
“
Genotyping of VHSV isolates from other clinical outbreaks in farmed turbot and rainbow trout in areas previously considered VHS free in Sweden and Finland indicates transfer of VHSV from wild to farmed fish (reviewed in Raynard et al., 2007; Skall et al., 2005). The most probable route of VHSV infection in farmed Atlantic salmon in North America was also through contact with wild fish (Raynard et al., 2007; Skall et al., 2005).”
On ISA p.171: “
Based on phylogenetic analysis it is claimed that ISAV has been transferred from wild to farmed fish at least three times since the start of salmon farming in the north Atlantic (Nylund, 2007; Nylund et al.,2003). There is no documented evidence that ISAV has been transferred from farmed to wild fish (Nylund, 2007). In the area of Troms County that has had annual outbreaks, ISAV was detected in some of the escaped farmed salmon caught in rivers in the area (Johansen et al.,2009b). Thus, there may be a potential for transmission from farmed to wild fish, but it is not known whether this has actually caused any impact on the wild fish populations.).”
On Aeromonas salmonicida subsp. Salmonicida (AKA furunculosis) p.171: “
Direct evidence for transmission from farmed to wild fish is scarce, but epizootological data suggest that such transmission takes place. Prior to the epizootic in Norway in 1991–1993 the disease was absent in Norway apart from one single outbreak several years before. The rapid spread to farms and natural water sources was associated with several factors such as escaped farmed fish and natural movement of wild fish in the sea (Johnsen and Jensen, 1994).”
On Flavobacterium psychrophilum(AKA bacterial cold water disease) p.171: “
F. psychrophilum has been found in wild fish used as brood stock, wild salmon close to fish farm, in several wild fish species with no clinical signs of disease and in the water environment of fish farms that are infected (Raynard et al., 2007)..”
On Renibacterium salmoninarum (AKA causative agent of bacterial kidney disease (BKD) p.172: “
As both horizontal and vertical transmission has been reported, there is a risk for transfer between wild and farmed species. Evidence for transfer has been found only in North American trout species in freshwater (Mitchum and Sherman, 1981; Mitchum et al., 1979).”
On Vibrio salmonicida (AKA cold water vibriosis) p.172: “
Cold water vibriosis is transmitted horizontally and an epizootological study based on plasmid profiles suggested transmission from farmed Atlantic salmon to wild-caught Atlantic cod and vice versa..”