Conservation Biology​​​ in the Boreal
HOW DOES NEWFOUNDLAND and LABRADOR COMPARE??​
Interactions between farmed and native fish
Species that are farmed are often kept in confined areas, compromising living conditions. With the animals being in such close proximity to one another, disease transmission is rapid.
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A parasite is often hosted by a fish farm but can spill out into the marine native populations, as their migratory patterns intersect with fish farms, or farmed fish escape their pens. A study done in British Columbia by Krkosek et al. (2004), revealed that even a single salmon farm can have a major impact on the sea lice, ​Lepeophtheirus salmonis​​.​ invasion on native populations.​
Results from this study suggest that the pressures of infection implemented by the farm are four times greater then the ambient pressures of the native salmon being infected by sea lice. This pressure can reach up to 73 times the order of magnitude if the farms are along the migratory routes. This is a huge risk if native population to come in contact with the parasite, being infected by the parasite decreases their fitness​ and may lead to death. The increase in lice infestations caused by the salmon farms, may be a limiting factor in the conservation of wild salmon stocks.
​ The exponential increase in fish farming has major ramifications, not only the rapid spread of sea lice through coastal waters, there are large numbers of salmon escaping pens and entering rivers, interacting with native populations throughout North America. This causes an increase in competition for space, mates and alters the food web dynamics. Making this a bigger concern is the genetic modification, through selective breeding that farmed fish undergo. Studies show that eggs from farmed fish are much smaller then those of native, a study in a norwegian river (Fleming et al., 2000) studying farmed Atlantic salmon, Salmo salar, in the north Atlantic showed that migratory patterns yield to be very similar between farmed and native fish, making the productivity of the native populations depressed by 30% because of resource competition.
While these studies took place in British Columbia and Norway these types of interactions are of concern in our own waters, here in Newfoundland and Labrador. In collaboration with Norway, Chile, United Kingdom, North American East Coast: Canada and the US, Australia, Iceland and Ireland, Memorial University was sponsor of a publication that outlined some major concerns of farmed fish, sea lice and interbreeding main concerns ​
This document explained that in these waters the wild salmon are interbreeding with farmed, causing a reduced lifetime and decreased fitness.
A study carried out in NL waters showed a sonically-tagged farm fish that escaped remained close to his cage site for up to two months, however interbreeding still may have occurred. As seen in the picture farmed and interbred fish can have deformities such as shortened gill covers, snout/jaw deformations and bud fin, this degrades the price of the fish at a market (Thorstad et al., 2008).
Inbreeding between native and farmed species.
Sea Lice Treatment
Canada is searching for ways to treat the reservoirs of sea lice residing on the farmed fish. The leading research is being done by DFO in Atlantic Canada. One is an anti-parasitic chemotherapeutant called SLICE®, they are now monitoring the effects it has in the tissues of the salmon and the environment (DFO,2011).
The other treatment is a hydrogen peroxide bath, to the right is a picture of a fish who​ had sea lice and underwent this treatment. It is thought that this treatment causes damage the dermis layer and the mucous coating over the fish, making it easier for sea lice to attach in the future (DFO,2011). While these treatments are not yet ideal, Canada is taking the first step forward in this research without using steroids.
FIsh treated with hydrogen peroxide for sea lice
Photo: M. Fast (UPEI)
Source: http://www.dfo-mpo.gc.ca/science/enviro/aquaculture/rd2011/aqua-eng.html
Sea Lice invested fish
Crowding in fish pens
Source: http://www.google.ca/search?hl=en&biw=1024&bih=593&q=aquaculture&bav=on.2,or.r_cp.r_qf.&bvm=bv.44697112,d.dmg&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&authuser=0&ei=JwJbUdShEtWl4AON-4HgBw
Fish with deformations caused by interbreeding
http://www.dfo-mpo.gc.ca/science/enviro/aquaculture/rd2011/aqua-eng.html
Fish pen
Source: google images