TR: Monster Steelhead

Yuji Sakuma wrote:

Hello JR,

Hey, Yuji.

I am not sure that I understand the reasons for your opposition to trying to
restore disappearing natural runs with hatchery fish. These days, I
understand that hatchery stock, in order to maintain the purity of the gene
pool for a given river, is produced using eggs and milt from wild fish
returning to that river .

Sometimes yes, sometimes no, but even in cases where it is, if hatchery
fish breed with wild fish, the genetic structure of the population of
so-called "wild" fish changes over time.

From what I hear, hatchery fish do have a higher
early mortality than stream bred fish because despite having the same genes,
they will be less well adapted to wild conditions initially. However, if
they do manage to survive say, a year, it seems to me that they should be
the same in every way as stream-bred fish of the same age. Am I missing
something here?

At some point, it is useful to think less about the adaptation of
individual fish and more about the fitness of populations of fish to the
entire range of environmental conditions they face throughout their life
history.
Very many eggs, alevins and fingerlings do not survive the particular
conditions of hatchery life before the fish are released into the wild.
Those that do are, pretty much by definition, those that were "better
adapted" (for whatever mix of reasons) to those artificial hatchery
conditions, just as the population of smolts bred in the wild that
manage to survive to smoltification are those better adapted to whatever
conditions happened to exist where they were bred.

From that point forward, these two groups of fish (hatchery-bred and
stream-bred) are going to face pretty much the same environmental
conditions during migration to and from the sea. Some will survive,
some won't. Those from a hatchery, *if* the brood stock was truly,
entirely wild, would in theory be no more or less adapted to these
later, post-release environmental conditions than fish bred in the wild.

But, and this is a big BUT, if hatchery-bred fish are allowed to breed
with wild fish, this presumptive source of truly wild brood stock
inevitably changes over time. Over time, the genetic structure of the
population of *wild* fish is increasingly influenced by genes from fish
better adapted, in their early life history, to a hatchery environment
rather than a wild environment. Over time, the population as a whole
becomes increasingly one that is better adapted, in its early life
stages, to hatchery ponds and less well adapted to the quite different
conditions of natural redds and shoreline shallows that eggs, alevins
and young fingerlings develop in.

In addition, over time, the genetic structure of the population--for
what should be obvious reasons--will become one decreasingly contributed
to by the offspring of those individual breeding adults better adapted
(for whatever mix of reasons) to the rigors of finding suitable breeding
grounds and then building and/or defending their redds. Over time, the
so-called "wild" brood stock, even if the effort is made to take
breeding adults from the wild, becomes less and less "wild" in its
overall composition. Over time, the population as a whole becomes
increasingly domesticated, increasingly dependent on the intervention of
humans in a significant portion of its life cycle.

Sure, I too would like to see steelhead runs restored by
returning the environment to what it was a couple of centuries ago but let's
face it, that's not going to happen.

I think this "either/or" idea, the idea that maintenance or restoration
of habitats conducive to wild fish can only mean "returning the
environment to what it was a couple of centuries ago" is a straw man.
If the survival of wild fish comes to depend entirely on massive
influxes of hatchery fish as the sole counterpoint to dozens of other
factors destroying wild habitats (which is the direction current
policies tend toward), then wild steelhead and Pacific salmon are simply
doomed.

JR