As with any intensive livestock production, diseases and parasite infestation may lead to large scale losses causing financial loss.
Two types of sea lice Caligus and the larger Lepeophtheirus, recognised by their horse shoe shaped outer shell bite intensively farmed fish and damage the scales, cell tissue and mucous membrane.
This leads to a weakening of the fish’s immune system leaving it open to secondary infections and water accumulation in the tissue.
Hariolf Schmid (2003) suggests a method of solving this sea lice problem in fish farms by treating the whole school of fish with a semi-automatic injection device. This device involves directing the fish single file past an inoculation apparatus that weighs the fish and administers a correct dose to each fish.
An amazing invention! Details of the patent can be viewed here
Sea lice pose a huge health threat to both wild and farmed fish. Researchers have investigated the efficacy of a treatment for sea lice in wild sea trout.
Sea lice are important exoparasites of fish, both in the wild and in aquaculture.
These tiny crustaceans can lower the fitness of the fish and indirectly cause fatalities due to open lesions that prevent the fish from maintaining its osmotic, or salt/water balance. If infection rates are severe, the parasites can feed on the fish at higher than the growth rate. It follows then that developing stock are more prone to this distressing phenomenon due to their small size.
To investigate means of tackling this disease, wild sea trout were tagged with Passive Integrated Transponder tags (PIT tags). Fish are therefore identifiable and traceable using a tag scanner on recapture of the fish.
There were two groups, one treated with a prophylactic substance designed to control the parasite and the others untreated. The experiment took place in the north-west of Scotland.
It was discovered that the treatment had a significant effect on the condition factor of treated fish. Indices of condition indicated that the fish that received the prophylactic suffered less growth constraints whilst in open sea.
Possible subsequent effects on growth and survival to sexual maturity could have significant implications on stock conservation due to the direct relationship between fecundity and size in the female.
Control of this parasite is important, not only for farmed stocks, but also for wild stocks as farming situations are thought to act as sources of infection for this pest. Further research could well bring about more effective controls and superior management of our natural and farmed fish stocks.
More on this approach to sea lice control is available via this link.
