Salmon are one of the types of fish that are called “anadromous.” This
refers to their life cycle: they are born in fresh water, migrate down rivers
into the ocean where they grow into adults, and then return to the fresh water
to spawn (reproduce). One mystery is how the salmon “remember” the river
of their birth, but these fish will predictably return to spawn in the place
where they were born. Another, more recent, mystery is “WHERE HAVE ALL THE SALMON GONE
?”
Seven species of salmon live in the north Pacific and habitually travel
up Canadian and U.S. rivers to spawn. Some sources cite evidence that these
fish species have existed for up to 400 million years. Salmon have a
delectable pink flesh and have been a favorite food fish for centuries. Major
commercial salmon fisheries have operated on the west coast, and these fish
are also highly prized by the “recreational” fishery. Throughout the last
century it has been noted that the numbers of Pacific salmon have been
declining. In recent decades this has been a great cause of concern and major
efforts have been made to “support” and “protect” these fish stocks. Fish
hatcheries have been used extensively in an effort to help increase the salmon
populations. Another obstacle for the salmon has been man’s use of the rivers
that they must travel. Pollution and dam-building seem to be the worst
human-caused problems faced by the fish in the rivers. “Clean river”
campaigns, the provision of “fish ladders” and the like have been part of
major attempts to restore the river habitat of the salmon to a more hospitable
state. These efforts appear to have been fairly successful.
Despite all “conservation and protection” efforts, the Pacific salmon
are rapidly and “unexpectedly” disappearing. These fish are very accessible
for scientific study during the time when they are in the rivers, and a fair
amount is known about them. All the literature that I read on salmon stocks
pointed to the same problem: “marine survival” is where they are failing. The
condition of the river habitat is not killing them, they just “fail to return”
from their time spent at sea. Great numbers of salmon “hatchlings” are set
free, and the wild ones are counted on their way downstream. These numbers
are used to predict how many “should” return...but they just are not coming
back as predicted...why not?
Unfortunately, during their time at sea, salmon have a habit of
travelling a fair distance away from the shore. That is where the ocean is
hungriest. All of the other offshore fish stocks are disappearing due to the
food shortage, and the salmon are affected in the same way. I cannot “prove”
starvation in the salmon stocks because I have been unable to find
weight-at-age data for any of them. (This I find a bit strange...considering the
great amount of resources that have been spent on studying these particular
fish...there are a lot of names for the different juvenile stages, but the adults
seem just to be categorized as “small” and “large,” which is not enough
information to make an assessment of their nutritional status.) Regardless,
and this is only speculation on my part, but my theory on the disappearing
Pacific salmon is that the phenomenon represents just one more part of a
bigger and more serious picture: the
STARVING MARINE ECOSYSTEM.
The disappearing Pacific salmon have been a source of great
controversy on the west coast. Canada and the U.S. have practically had a
“salmon war” as they fight over the remnants. Much has been written about
the salmon, including a recent book “Salmon Without Rivers: A History of
the Pacific Salmon Crisis” by Jim Lichatowich. I have not read it but have
seen excerpts and favorable reviews. It seems to very well document the
history of the Pacific salmon fishery, and the associated economics and
politics. A better insight into the cause of their disappearance, however,
would be entitled “Salmon Without Food.”
