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SCORE

1.6

CRITICAL

McCloud River Redband Trout

Oncorhynchus mykiss stonei

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At a Glance

McCloud River Redband trout populations are very small, fragmented, and exist in limited and isolated habitat. Their status could change rapidly, particularly in relation to predicted climate change impacts such as reduced snowpack and precipitation increasingly falling as rain instead of snow.

Species characteristics

McCloud River Redband trout are similar in appearance to other Redbands, with yellow to orange bodies, dark oval parr marks on their sides, and white-tipped fins. The characteristic brick-red stripe on their sides is a defining feature, similar to that of the California Golden trout. Many, but not all, McCloud River Redbands have teeth on their tongues and an orange slash along the throat, characteristics more typically associated with Cutthroat trout.

Estimated numbers of McCloud River Redband trout in the past were highly variable and ranged from 53 to 1,100 per km (about 85 to 1,770 trout per mi.) throughout their range. According to a 2011 CDFW survey, the total population of McCloud River Redband trout was about 3,560 fish. During recent drought years, 1,597 trout were rescued from Sheepheaven, Swamp, Edson, and Moosehead creeks, likely leaving less than 1,250 fish over 80 mm (3 in.) in the wild.

Sheepheaven Creek is a small, spring-fed stream at an elevation of 1,433 m (nearly 4,600 ft.). Very cold, clear water trickles from volcanic soils between 10-13°C (50-55°F) year-round and runs a short distance before returning underground. Other McCloud River Redband trout streams are generally small, with riffles and small pools providing cover, especially if they contain fallen trees. McCloud River Redbands are small trout; the largest adults often measure less than 21 cm (about 8 in.). They can become territorial and even cannibalistic under some circumstances. Like most other Redband trout, they spawn in late spring from May to June.

Hybridization between Coastal Rainbow trout and Redband trout is a natural event. However, due to planting of Rainbow trout upstream of natural barriers such as waterfalls, hybridization has become a primary threat to McCloud River Redbands. While there are currently four, and possibly as many as six, isolated populations of McCloud River Redband trout, recent genetic analyses show that fish in Sheepheaven Creek are distinct from the others. A formal McCloud River Redbands Hatchery and Genetic Management Plan is forthcoming from CDFW.

Conservation Actions

Conservation Strategy

  • Work with the McCloud Redband Core Group to implement the 2014 Inland Redband Conservation Agreement to manage land uses in the McCloud River Basin.
  • Establish a McCloud River Redband trout refuge that contains all current Redband streams and suitable reaches of potential future habitat for translocations.
  • Use a captive broodstock program to protect the genetic integrity of McCloud River Redbands and facilitate CDFW’s 2013 Upper McCloud River Redband Trout Reintroduction Plan.
Photo: Michael Wier

Where to find McCloud River Redband Trout

McCloud River Redband trout once ranged throughout the mainstem McCloud River above Middle Falls and its tributaries, and perhaps the lower river and its tributaries as well. Potential habitat, including the upper McCloud River, encompasses about 98 km (about 61 mi.). Today, they persist only in four small (< 2 km, or 1.2 mi.) isolated streams upstream of the McCloud River’s Middle Falls that disappear underground into highly porous volcanic rock before connecting with the mainstem McCloud River downstream.

How This Species Scored

From Caltrout’s SOS II Report

METRICSCOREJUSTIFICATION
Area occupied1Four ‘core’ populations are clustered fairly close to each other and all are in Upper McCloud watershed, so are treated as one ‘watershed.’
Estimated adult abundance1Population prior to the 2012-2016 drought was likely somewhat less than 3,000 fish over 8 cm (3 in.), with each stream having 100-1,000 fish. In drought years, total numbers of fish of this size likely totaled less than 1,250 fish.
Intervention dependence2Drought necessitated rescue of several populations and relocation to holding facilities until natural conditions improved. Ongoing implementation and recent revision and expansion of a formal Conservation Strategy is critical for survival.
Environmental tolerance3It is likely they are fairly tolerant of high temperatures, as are other Redband trout, but water quality in their small streams has to be monitored during drought years.
Genetic risk1Hybridization risk with rainbow trout is high; small isolated populations result in genetic bottlenecks and inbreeding depression.
Climate change1Vulnerability is high in all streams because of small size and cumulative effects of a changing climate and drought.
Anthropogenic threats21 High and 4 Medium threats.
Average1.6LEVEL OF CONCERN: CRITICAL
Certainty: 4. Most published information is on Sheepheaven Creek population, though recently more studies have come from Edson, Moosehead, and Swamp creeks habitats.

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