Salmon Sense of Smell

It now seems to be generally accepted that salmon find their way back to their spawning grounds through their acute sense of smell. Just as each major city of the world has its own set of identifiable odors, each stream apparently has a unique set.

An illustration of just how acute is the salmon's ability to distinguish between different scents is given by C. Herb Williams writing in the November 1978 issue of Pacific Search. He cites experiments by Canadian scientists showing that salmon will slow or stop their migrations when certain human smells are present. A solution of one part human skin in 80 billion parts water dumped into a river caused salmon to stop migration for as long as a half hour.

The cause of the offensive smell is an amino acid called serine. It is found in the skin or hoofs of various animals, including dog, doer and sea lion. The amount of serine in human skin depends upon the sex, age and race of the individual. Women and children produce less serine than adult males. Blacks produce less serine than American Indians or Latins, and these groups have far less than the worst serine offender--the white adult male.

Williams' article notes that these differences in serine productivity can explain why some people have better luck at fishing than others, why the kid with a string on a stick may sometimes outfish his well outfitted father.

Perhaps one solution to the serine problem is the use of commercial scents. Another used by some fishermen is to rub their hands with anise oil; anise is an herb of the carrot family. Whether or not these balms really help may be a secret known only to the salmon.