Trinity River Ecology FAQ

Frequently Asked Questions (FAQ) on Trinity River Ecology

Please note that questions regarding flows are in the Flow FAQ while questions regarding features of TRRP rehabilitation sites are in the Rehabilitation FAQ.

What types of salmon are in the Trinity River?

The Trinity River has chinook and coho salmon, plus the closely related steelhead.  Chinook salmon can also be separated into spring and fall runs.  Fall-run chinook are the most numerous salmonid in the Trinity River, followed by steelhead.

What about brown trout?

While fun to fish, brown trout are not native to the Trinity River.  These beautiful trout are aggressive predators that may be detrimental to our native salmonid populations.

What is the difference between hatchery-produced salmon and naturally spawned salmon?

Hatchery salmon and steelhead  that spawn in natural areas are known to decrease spawning success and reduce production of young salmon. Hatchery salmon and steelhead are meant for harvest not to spawn in natural areas.  See our page on Hatchery Steelhead Straying and the suggested further reading.

What other factors may be causing current problems for salmon populations?

Variations in marine survival of salmon and subsequent returning adults often correspond with periods of alternating cold and warm ocean conditions.  For example, cold conditions are generally good for Chinook and coho salmon, whereas warm conditions are not. Useful information on these conditions can be found at http://www.nwfsc.noaa.gov/research/divisions/fed/oeip/a-ecinhome.cfm.

What other factors may have caused historic problems for salmon populations?

The first known impact on Trinity (and Klamath) River salmon came from canneries operating near the mouth of the Klamath River in the mid-1800′s. Unfortunately there is very poor documentation of the impact, but there are some stories that very few fish escaped these canneries and the river may have been dominated by spring-run chinook.

Subsequently, large-scale gold mining had a variety of effects.  Water was diverted from tributaries where steelhead and coho salmon spawned. medium-scale dams and diversions were regularly constructed to allow mining access to the river bed; extensive hydraulic mining kept the river muddy most of the time (see ‘Found a New Steelhead Stream‘); and dredge mining reformed the river channel, obliterating many floodplains.