May 8, 2015
Letters, Vancouver Sun, May 8, 2015
Re: Sea lice limit young salmon’s ability to get food, April 30
The statements in the headline for this article are not supported by the data in the featured scientific paper.
Diseases and parasites are natural and common in wild salmon, the same way all living organisms including plants, pets, and people can become sick or be stricken by disease for unknown reasons. External parasites commonly infest fish that are sick for other reasons; this is similar to a person whose immune system is weakened — they can be more susceptible to catching other illnesses. This study is incomplete because it did not test the fish for diseases known to affect B.C. sockeye salmon.
Imagine a human hospital study that compares daily food consumption of people wearing hospital gowns with people wearing stethoscopes (e.g., doctors). The study would consistently find less feeding in groups wearing the gowns (e.g., patients) than in doctors. However, it would be incorrect to conclude the gowns were the reason for the decreased food intake.
Likewise, it is also incorrect to conclude sea lice were the reason for the decreased feeding by the sockeye salmon. As in the hospital, the cause of decreased sockeye salmon feeding might be pre-existing disease.
GARY MARTY
Senior Fish Pathologist, BC Ministry of Agriculture
