Cottus klamathensis macrops

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General Information
Common Name: 
Bigeye marbled sculpin

Conservation Status in California: Class 3, Near threatened (Moyle et al. 2011).
No immediate extinction risk exists for bigeye marbled sculpin. However, populations appear to be declining within their restricted range.

Life History: 

Life History: Bigeye marbled sculpin grow quickly, attaining 35% of their maximum length in their first year and live about five years (Daniels 1987). Growth occurs from spring to early autumn. Average sizes are 39 mm at the age of 1 year, 55 mm at 2 years, 62 mm at 3 years, 70 mm at 4 years, and 79 at 5 years. Although fish over 80 mm are rare, one specimen was recorded at 111 mm. Marbled sculpin attain sexual maturity after 2 years, during the winter (Moyle 2002). Spawning occurs from late February to March. Fecundity is low, with females producing 139-650 large eggs each. Adhesive eggs are deposited in clusters in nests under flat rocks. Eggs from different females may be present in the same nest. Nests are usually guarded by males (Daniels 1987). Embryos number from 826-2,200 per nest. Larvae measure 6-8 mm upon hatching, are benthic and likely rear close to their nests (Moyle 2002). Because bigeye marbled sculpin have low fecundity, mature late, and live relatively long, they are well-adapted to environments with relatively few fluctuations such as spring-fed rivers (Daniels 1987).

Habitat Requirements: 

Habitat Requirements: Bigeye marbled sculpin are well-adapted to large, clear, cool (


Distribution: The bigeye marbled sculpin is distributed throughout the middle reach of the Pit River system (Moyle and Daniels 1982). In this region, it is found in the main river below Britton Reservoir, in Britton Reservoir, Tunnel Reservoir, lower Hat Creek, Sucker Springs Creek, and Clark Creek. It is the dominant sculpin in the sections of Lower Hat Creek and Burney Creek just above Britton Reservoir. The bigeye marbled sculpin also is found in the lower reaches of streams flowing into reservoirs of the lower Pit River, the lower Pit River itself, and Fall River.

Abundance Trends: 

Trends in Abundance: Although the least abundant of the three sculpins endemic to the Pit River drainage, bigeye marbled sculpin are still common in much of their limited range (Moyle 2002). It co-occurs with the rough sculpin, Cottus asperrimus, which is listed by the state as a threatened species, although the rough sculpin probably is more abundant than the bigeye marbled sculpin. They also seem to be less abundant today in the Fall River than when Rutter (1908) first collected them there.


Identification: All subspecies of marbled sculpin (Cottus klamathensis) have large, dorsally flattened heads with two chin pores; large, fan-like pectoral fins with four elements; and small pelvic fins that are positioned ventrally between the pectorals (Moyle 2002). Marbled sculpin are distinguished from other Cottus species by having 7-8 dorsal fin spines, joined dorsal fins, an incomplete lateral line with 15-28 pores, and relatively smooth skin (Daniels and Moyle 1984). However, a few prickles can sometimes be found below the lateral line. They also lack palatine teeth and have only one preopercular spine. Fin ray counts are: 18-22 in the second dorsal fin, 13-15 in the anal fin, 14-16 in the pectoral fin, and 11-12 (principal rays) in the caudal fin (Moyle 2002). All other sculpin species in California possess a split dorsal fin and more than 7 dorsal spines. Marbled sculpin are generally green-hued with a dark circular spot at the posterior end of the dorsal fin and alternating dark and light spots on the pectoral fin rays. Fish from the Klamath are generally lighter and more marbled than those from the Pit River (Moyle 2002). Other marbled sculpin characteristics include a wide interorbital region, a wide head and blunt snout, a maxillary rarely extending beyond the anterior half of the eye, and unjoined preoperculer mandibular canals, but these characteristics are shared with one or more other species (Daniels and Moyle 1984). The subspecies C. klamathensis macrops is distinguished from other marbled sculpins by having few (if any) axillary prickles, a short preopercular spine (