There are many indications that in the past the Sandy River hosted huge runs of Chinook salmon. Of the five species of Pacific salmon, Chinooks are the best equipped to exploit highly fluctual, glacial/volcanic watersheds like the Sandy River basin.

Chinook populations have to be pivotal to the overall fishery management
scheme in this river system. Spring Chinook are the largest spawning biomass
in the upper basin. Fall Chinook are the largest spawning biomass in the lower
main-stem. Therefore they are potentially the basis of the food chain for both
trout and steelhead.

Chinook spawn (eggs) and carcasses provide nutrients to the system, both
directly and indirectly. Chinook eggs are ravenously consumed by all sizes of
salmonids, cotids and minnows – whenever they are available. Salmon
carcasses are prey to all kinds of beneficial insects and plants, which are also
consumed by other species of fish, of many sizes.

Chinook fry are some of the earliest to emerge from the gravel (March-April).
This emergence provides an early spring meal for trout and steelhead
juveniles, which are two or more years older. Chinook fry are consumed by all
fish that are large enough to eat them.

John Peterson, who was a fishery tech for the Mt. Hood National Forest, was
in charge of the Still Creek fish trap. This trap is placed to capture
downstream migrating fish. Most of the fish that have been caught in this trap
are juvenile salmon, trout and steelhead. A small sample of each specie was
killed for scientific study. These studies included stomach autopsies. John
reported that most of the wild steelhead smolts had gorged on Chinook fry.

No doubt resident cutthroat and rainbow trout partake of this same feast.

Spring Chinook fry emerge January through March. Fall Chinook fry emerge
February through April. They are about 1 1/2 inches long when they become
free swimming. Many Chinook salmon rear in the stream for less than one
year before going to sea. Some start to out-migrate immediately upon
emerging from the gravel. Most are about 1 3/4 to 2 1/4 inches long when
they enter the salt. By comparison, the average out-migrating steelhead
smolts are usually 5 to 7 inches and may be more than 10 inches.

Chinook fry emergence is perfectly coordinated with the peak downstream
migration of juvenile steelhead. Juvenile steelhead consume large amounts of
Chinook fry on their way to the ocean. Chinook fry are larger food which
permit the steelhead juveniles to grow very quickly and enables them to
compete better in the ocean.

Since the Chinook and larger steelhead are out-migrating together, this
symbiotic relationship may continue for a while at sea. However, ocean
rearing Chinooks tend to feed at much greater depths than do steelhead and
the two populations are soon parted.

Since Chinooks out-migrate at a comparative small size, they probably don’t
compete much with other species for food or space while in the stream. They
are a wind-fall profit in the food chain department. Basin populations of every
other wild salmonid specie are probably highly dependent on very large
healthy populations of spawning and emerging Chinooks.

If we have more Chinooks we will probably have more of everything else.
Chinooks were the most abundant salmonid in the Columbia River basin. They
were also the most desirable salmonid for table fare. They were highly
exploited by indigenous populations of humans for thousands of years. They
were soon over exploited by the present civilization to the point of near
extinction.

This happened very early in our history. Records show that in 1877 there were
more than a thousand 1,200-foot long gill nets and many fish traps working
the Columbia River. All of the larger tributaries also had nets and traps. Most
of the Chinook runs were on the brink by 1885. This is long before we kept
records of wild fish populations.

I think that all of the west-slope rivers were much richer in all of their fish
runs before the Chinook populations were reduced. The catastrophic
reductions in Chinook runs probably brought a biological collapse to much of
the Columbia River basin, both east and west of the Cascades.

Sandy River Chinooks were some of the first to be heavily targeted by
commercial fishermen. The mouth of the Sandy is in close proximity to the
largest population area. Nets and fish wheels probably killed most of the
Sandy River Chinook runs before 1880.

A salmon hatchery was established on South Boulder Creek, a tributary to the
Salmon River in 1892. This hatchery was to supply Chinook eggs to bolster
the failing Clackamas River runs. Chinook eggs were taken from mid-July
through November. There were fair numbers of fish.

But what the hatchery people found at the mouth of South Boulder Creek in
1892 was probably no more than the remnant valleys, after the peak runs had
been cropped to extinction. Old records speak of July spawning Chinooks in
both the Sandy and Clackamas drainage’s. There is indication that in the first
two years of hatchery operation; peak-spawning activity was in mid to late
August. These upper river runs had severely declined by 1900. By 1906 the
runs were so poor that the hatchery was shut down.

(Next month, our fishing guide will explore the fate of the great Chinook, and
their return to prosperity.)