The Weyerhaeuser Company, which got into the salmon ''ranching'' business here in 1972 and established a shrimp farm in Brazil in 1980, has had mixed results. The shrimp operation has been shut down. But the timber products company has been so successful with salmon that experts from many countries have come to Oregon to study the aquaculture venture.
Here, and in Coos Bay, Ore., where there are duplicate facilities, salmon have been returning this fall to the brood ponds in numbers that have gone as high as 4,000 a day.
About midway in November some 90,000 salmon had ''come home'' from the Pacific Ocean. With the ending of the run around Dec. 1, the count will have topped 100,000. The daily count tapers off as the run reaches its end.
Weyerhaeuser's salmon ranching is carried on by a subsidiary, Oregon Aqua Foods, under the direction of operations manager Norman Moe, who is happiest about the fact that this year, for the first time, the operation will be self-sufficient in eggs for hatchery purposes.
''We will take from our own brook salmon (salmon that were released as smolts by Oregon Aqua Foods) 30 million coho eggs for fertilization and that means that we will be releasing 20 million coho smolts into the ocean in 1982,'' Mr. Moe said.
These eggs come from some 11,000 female coho, each of which yields up to 3, 000 eggs.
Discussing overall operations, Moe said that this year's return of coho was above expectations. ''We had looked for a return of 1 percent on the 7,500,000 smolts released in 1980, or about 75,000 salmon.''
Also, because 1980 smolts were ''top quality'' the returning adult coho are of excellent quality and generally in the 6- to 10-pound range.
One of the things that has attracted the attention of foreign experts is Oregon Aqua Foods' use of warm water to raise smolts to release size at the hatchery in Springfield, Ore. The hatchery is adjacent to a company paperboard plant that is a continuous source of warm water for the smolt pens. Because of this warm water, smolts achieve a growth in seven to eight months equal to 16 to 18 months' growth in the normal way. As a result, salmon released in 1980 and which returned this fall were the size of two- and three-year-old salmon.
Because they are larger when released, the warm-water-raised smolts are better able to resist the dangers of the ocean.
Under Oregon State regulations, Oregon Aqua Foods may release each year 20 million each of coho and chinook salmon smolts, and 40 million chum, but only chinook and coho have been released thus far.
About 300 chinook salmon have returned this fall, having been released three to five years ago, normally returning after two to three years at sea. However, chinook eggs are scarce and Oregon has put the company and other private hatcheries low on the list to obtain eggs from state hatcheries.
Chum eggs also are a scarcity, Moe noted, adding that chum salmon smolts released in 1979 should begin to return as four year olds in 1983 when ''we hope enough come back so we can establish a brood stock for chum.'' The smolts released in 1979 were from eggs bought in Russia in 1978. But no more are coming from that source because of the political climate.
Oregon is the only West Coast state which permits private investment and hatchery operations for profit.
One recent foreign visitor to the salmon operations - from Norway - was Thor Mowinckel, founder of A-S Mowi Norwegian Salmon, which raises salmon in Bergen under fully controlled conditions in which the smolts are not released but are raised to 6- to 10-pound size in captivity. The firm is a subsidiary of Norske-Hydro, Norway's largest corporation.
Other foreign guests in 1981 have been visitors from New Zealand, Iceland, Chile, and Japan. Oregon Aqua Foods, Moe says, is now giving thought to Iceland as a possible site for a salmon ranching effort similar to what is being done in Oregon.
Bumble Bee Company here is shipping Oregon Aqua Foods salmon fresh to United States dealers. It is trying to build up foreign markets for frozen salmon from Oregon Aqua Foods, although there are no plans to market salmon under the Weyerhaeuser name.
The magazine Food Processing says of harvested salmon such as those of Weyerhaeuser that the ''quality . . . is high because they are bright, fresh, and undamaged by boat landing, storage and transportation. They come right out of the ocean into iced boxes for immediate distribution.''
On the other hand, the magazine said, ''salmon that survive upstream journeys to spawn are wasted. They become too spent and scarred for use as human food, and are too dispersed to be economically harvested as animal food or fertilizer.''
William A. Feldt, aquaculture manager for Weyerhaeuser, said that the Brazilian shrimp venture had been closed permanently. But, he added, ''A number of things were learned that will be helpful when another try is made'' in order to capitalize on the technology that was developed. He did not give any indication of where or when that would be.
The closure was the result of ''a number of problems'' at the shrimp farm site at Macapa in Amapa Territory. The initial investment was between $4 million and $6 million and Feldt said the shutdown resulted in the ''loss of several hundred thousands of dollars.''