By John Gibson
I would like to comment on a column written by Trevor Taylor in The Telegram on May 21, related to the net pen rearing of Atlantic salmon.
I am surprised he did not at least read up on the subject before publishing his article, which is full of errors.
He gives the impression that salmon escapes should not be of concern, that sea lice are not really a problem and that disease is normal and therefore not a problem.
However, it must be pointed out that it has been shown that if salmon farming is permitted near wild salmon rivers, invariably the local natural stocks decline.
This has occurred in New Brunswick, Ireland, Scotland and Norway.
Salmon escapes are a major reason.
This may include attraction of extra fish predators, which increases pressure on the natural stocks, but mainly the problem arises when the escaped fish interbreed with natural stocks.
Wild salmon have been naturally selected for best fitness for the particular system, which includes the best growth rates and survival for that system, times of emigration and immigration, etc.
The farm fish, as Taylor points out, have been selected for best growth in farmed conditions. They are almost a different species.
Scientific studies in Ireland and Norway have shown significant declines in wild stocks where escaped aquacultured fish have interbred with the native stocks.
Sea lice also are also a very major problem. No one has suggested that the aquaculture industry invented sea lice.
However, when densely packed in pens, the sea lice proliferate, releasing masses of larvae and cause major mortalities of the outgoing smolt, of both sea trout and salmon.
This has been shown in scientific studies in Ireland and Norway, and more recently has been blamed as a major reason for the collapse of sockeye runs on the Fraser River in B.C.
The treatment of sea lice in pens in Nova Scotia recently resulted in mortalities in lobsters and of other crustaceans (sea lice are a crustacean).
Also, where any animal is kept in dense and confined conditions they are more likely to produce an epidemic, which has occurred with infectious salmon anemia in the salmon aquaculture industry.
Containments on land are the best solution, where fish would not be exposed to parasites or diseases.
Although I do not agree with all genetically modified organisms, I have to admit that I am in favour of the genetically fast-growing salmon, which was engineered at Memorial University.
They are sterile, and they have to be reared in landlocked containments. They are good to eat.
Since they are fast-growing, it would be more economical to rear these genetically modified salmon than it would be to have marine net pens, which have been shown to have negative effects on natural salmon stocks.
John Gibson is a former fisheries scientist.
He writes from St. John’s.