Salmon

Redwood National and State Parks (RNSP) contain within them portions of two rivers, the Smith River and Klamath River as well as Redwood Creek. And within these are some exceptional fish: the salmonids. This group of fish includes trout, and salmon, species that are anadromous meaning they spend a part of their lives in the rivers, and part in the ocean. There are seven species of salmonids that occur in the parks, four are common and three are not.

 

Salmonids Common to Redwood National and State Parks

 

Coho Salmon

Coho salmon (Oncorhynchus kisutch) are also known as silver salmon. Coho have a three year life cycle, with most juvenile fish entering the ocean at one year of age and returning two years later to spawn. Most adult coho return to the parks’ rivers where they were born between November and February, the timing of which is dependent at least partly on river flow. Coho spawn from November to January and occasionally into February and March, with peak runs in Redwood Creek in November and December. That makes fall and winter months the best time to see coho spawning in the parks. Good places to watch for them are from bridges over Prairie Creek and Lost Man Creek. The bright red backs of the males are hard to miss, especially if water levels are low. These fish grow to 28 inches (710 mm) and usually weigh between 7 and 11 lbs (3 to 5 kg) but may get as large as 36 lbs (16 kg). As spawning adults they develop hooked jaws.

Coho require clear, cold water for spawning, egg incubation, and rearing, in low gradient streams, and clean gravels at least the size of peas. Like other salmonids, females dig depressions in the streambed, called redds, in which eggs are deposited and buried. The newly hatched fish, called fry, move to shallow areas near streambanks where they feed on aquatic insect larvae. In preparation for their entry into the ocean, juvenile coho undergo physiological transformations known as smoltification to adapt to living in saltwater. These transformations include different swimming behavior, lower swimming stamina, and increased buoyancy that make the fish more likely to be passively transported by currents. While living in the ocean, coho remain close to the river where they were born. Coho typically spend two growing seasons in the ocean before returning to their birth streams to spawn as three year olds.

Coho salmon populations in RNSP rivers are substantially reduced from historic times. There are many reasons for this, but in Redwood Creek stream habitat quality has declined due to severe floods that moved large amounts of soil and other sediment from hillslopes that were logged before the land became a park; logging also removed streamside vegetation. The large amount of deposited sediment and higher water temperatures due to a lack of shade has made some streams no longer suitable habitat for coho. Because of the reduction in coho salmon, the species is currently listed as a threatened (hyperlink)) by the National Marine Fisheries Service in Redwood Creek and the Klamath and Smith Rivers.

 

Steelhead

Steelhead (Oncorhynchus mykiss), are unique among the RNSP salmonids in that there are two different life forms within the species. One form is anadromous, spending its juvenile life in freshwater streams and in the ocean as adults. The other form, known as Rainbow Trout, spends its entire life in freshwater, never entering the ocean. It is believed that only the anadromous or steelhead type occurs within RNSP.

Biologically, steelhead can be divided into two basic types based on the state of sexual maturity at the time of river entry and duration of spawning migration. The stream-maturing type, or summer steelhead, enters freshwater in a sexually immature condition and requires several months in freshwater to mature before spawning. The ocean-maturing type, or winter steelhead, enters freshwater sexually mature and spawns shortly after river entry. Summer steelhead enter streams from April through June in RNSP. They require cool, deep holding pools during summer and fall, prior to spawning, which takes place from late December through April.

Winter steelhead enter freshwater between November and April, migrate to spawning areas, and spawn from February through April. Unlike our local salmon that die after spawning, steelhead are capable of spawning in more than one year before death.

Steelhead require cool, clear streams with suitable gravel size, depth, and current velocity for spawning. These fish arrive at spawning grounds weeks or months before they spawn and are vulnerable to disturbance and predation. Cover, in the form of overhanging vegetation, undercut banks, submerged vegetation, submerged logs and rocks, floating debris, and deep pools are required to reduce disturbance and predation of spawning steelhead.

Spawning and rearing of juvenile steelhead generally take place in small, cold, moderate-gradient tributary streams of the larger rivers. Depending on water temperature, steelhead eggs may incubate for 1.5-4 months before hatching, generally between February and June. After two to three weeks, in late spring, the young fish (called alevins) absorb their yolk sacs and emerge from the streambed gravels as fry. At this time they begin actively feeding and inhabit shallow water along stream banks where they also establish and defend territories. Juveniles rear in freshwater for two years, then smolt and migrate to the ocean in spring and summer. Steelhead remain in the ocean for two or three years prior to returning to their streams of their birth to spawn as four or five year olds.

Steelhead are found in most small, high and low gradient tributaries to Redwood Creek. Spawners are able to leap above barriers, including some logjams, that might impede their larger salmon relatives. Productive steelhead habitat is characterized by complexity, primarily in the form of large and small in-stream wood. Steelhead require cold water in the range of 45º F (7° C) to 58º F (15° C). The steelhead population in Redwood Creek is substantially reduced from historic times. There are many reasons for this, but in Redwood Creek stream habitat quality has declined due to severe floods that moved large amounts of soil and other sediment from hillslopes that were logged before the land became a park; logging also removed streamside vegetation. The large amount of deposited sediment and higher water temperatures from a lack of shade has made some streams no longer suitable as habitat for steelhead. Because of the reduction in steelhead populations they are currently listed as a threatened species (hyperlink) in Redwood Creek by the National Marine Fisheries Service.

 

Chinook Salmon

Chinook (Oncorhynchus tshawytscha), also known as King Salmon, is the largest of the salmonids in RNSP streams measuring 24 to 36 inches (610 to 1,058 mm; but may be up to 58 inches (1,500 mm)) in length; they average 10 to 50 lbs (4.5 to 23 kg), but may reach 100 pounds (45 kg). Entry into freshwater streams and spawning are related to local water temperature and flow regimes, but typically begins in fall in the Klamath River and November in Redwood Creek. Adult fish return to spawn after three to six or more years in the ocean, although two year old male spawners (“jacks”) are commonly observed. These fish begin their upstream migration into Redwood Creek in fall when the sand bar that blocks the mouth breaks open as a result of winter rains. As stream flows increase, the estuary fills and breaches the sand bar. Chinook have spawned and died by the end of January.

Newly hatched fish, known as fry, seek out shallow areas with slow current and good cover, and begin feeding on small terrestrial and aquatic insects and aquatic crustaceans. The optimum water temperature range for Chinook fry is 50-55F° (10-13°C). In spring and early summer, Chinook fry migrate downstream to rear in the estuary before and after the mouth closes. Chinook enter the ocean in the fall when the mouth opens. Thus, the Redwood Creek estuary is very important rearing habitat for Chinook fry. If given the opportunity the juveniles will spend an extended period (to late summer) in the estuary before entering the ocean; there may be a survival advantage favorable to the fish that remain in the estuary and grow to a larger size before entering the ocean. The majority of Chinook juveniles enter the ocean during their first year of life.

The juvenile Chinook population in the Redwood Creek estuary has declined in recent years, as have the numbers of adult Chinook returning to spawn; this is likely related in part to the diminished condition of the Redwood Creek estuary.

Estuary fish rearing habitat was degraded when flood control levees that bisected and altered the historical configuration of the Redwood Creek estuary were constructed in 1968. The levees altered the physical and biological functions of the estuary and adjacent wetlands and confined the lower 3.4 mi (5.5 km) of Redwood Creek stream channel to a width of 300 ft (91 m). The flood control project reduced the amount of riparian vegetation and tree cover, reduced adjacent wetlands, altered valley drainage patterns, decreased the amount of instream woody debris, and caused decreased pool depths along lower Redwood Creek. Adjacent agricultural land uses cattle grazing on the flood plain have also contributed to habitat degradation of the estuary. Chinook salmon in Redwood Creek are currently listed as a threatened species by the National Marine Fisheries Service.

 

Coastal Cutthroat Trout

Cutthroat Trout (Oncorhynchus clarki) are the smallest of the salmonids in RNSP rivers and creeks, weighing in at just 0.5 to 3.2 oz (14 to 91 g), although cutthroat using the Redwood Creek estuary may be much larger, 21 oz (600 g). Like other salmonids, coastal cutthroats may have an anadromous, or ocean-going, life stage, however, like steelhead they also are capable of permanent residency in streams. It’s believed that the population of coastal cutthroat in Redwood Creek consists of residents that migrate to the estuary but not the ocean. Cutthroat are identified by the numerous dark spots on the back and sides and the red linear marks on the lower jaw which are responsible for this fish’s name.

Coastal cutthroats usually inhabit small to moderately large, clear, cold, well-oxygenated rivers and streams. Spawning occurs from December through June with peak spawning in February. The southern boundary of their range is the Eel River, just 50 miles south or RNSP.

 

Salmon Uncommon to Redwood National and State Parks

Various fish surveys take place each year in RNSP, mainly in the Redwood Creek watershed. These include summer steelhead snorkel surveys, spawning surveys, and juvenile fish distribution surveys. And nearly every year in association with these surveys fish species that are out of their normal range are detected.