Fish at Crater Lake
There weren’t any fish in Crater Lake before it was discovered by Europeans.
In 1888 William G. Steel, considered the founder of Crater Lake National Park, made the first recorded attempts to stock Crater Lake. National Park Service researchers believe that before that time, Crater Lake contained no fish. William Steel’s motive for stocking the lake was probably to improve the lake’s recreational value.
Around the turn of the century, a regular stocking program was begun. Stocking continued through the early part of the century until creel censuses showed that the fish were naturally reproducing. Six species were introduced to Crater Lake during this time. The last recorded stockings were silver salmon in 1937 and rainbow trout in 1941.
Later investigations revealed that the naturally reproducing silver salmon were actually kokanee salmon. Since kokanee were not intentionally introduced, researchers believe that one of the plantings of silver salmon fingerlings was actually kokanee. Of the six species introduced, two remain:
- Kokanee Salmon (Oncorhynchus nerka) are a dwarf, landlocked form of sockeye salmon. Kokanee are the most abundant species in the lake, estimated to have a population well into the hundreds of thousands. An average kokanee is about 8 inches long, but some grow to as long as 18 inches.
- Rainbow Trout (Oncorhynchus mykiss) are less abundant than the kokanee, but are typically larger. The largest documented rainbow trout from Crater Lake was a 6 1/2 pound, 26 inch long specimen caught by the park research team. Most rainbows average 10 to 14 inches.
Rainbow trout and kokanee salmon populations are stable in the lake. Researchers believe that this stability is due to each fish species eating different foods. Kokanee feed on zooplankton and rainbows feed on aquatic insects.
Fish in Park Streams
Although the lake is by far the park’s largest body of water, fish also inhabit many of the small streams within the park. These streams are generally not accessible because of the steep canyons in which they are found.
According to stocking records, two species, eastern brook and rainbow trout, were planted in park streams. However, a total of four species have been identified:
- Eastern Brook Trout (Salvelinus fontinalis) have been found in almost every park stream.
- Rainbow Trout (Oncorhynchus mykiss) were originally planted in large numbers throughout the park. Today, it appears that their numbers are few and scattered. They have been collected in recent years from Annie, Bybee, Castle, Munson, and Sun Creeks.
- German Brown Trout (Salmo trutta), in recent surveys, had one representative specimen found in Sand Creek above the falls, which appears to be a barrier preventing upstream migration. Researchers believe that this fish may be the remnant of an unrecorded or unauthorized planting.
- Bull Trout (Salvelinus confluentus) are understood to be the only native fish species found within the park. These less competitive fish are a candidate species under the Endangered Species Act, and are considered rare in the Southern Cascades. Programs to conserve this species are now being implemented.
