Chapter 3 - Natural Resources - Marine Corps Base Camp Pendleton

MCB Camp Pendleton, California
(those occurring south of San Francisco Bay) were formerly found in coastal drainages as
far south as the Santo Domingo River in northern Baja California.
Regional
Southern steelhead were formerly
found in streams and rivers of Los
Angeles, Orange, and San Diego
counties (McEwan & Jackson
1996). Steelhead were thought to be
extirpated from much of their
historic range in southern California
south of Malibu Creek until 1999.
Presently, the Southern California
Steelhead DPS distribution extends
from the Santa Maria River in San
Luis Obispo County, to at least San
Mateo Creek on Camp Pendleton.
MCBCP
The intermittent presence of
Oncorhynchus mykiss on Base is
noted until the mid to late 1940’s
after which their presence is
attributed to hatchery trout plants
on- and off-Base. The few sightings
post 1980 are likely a result of
Oncorhynchus mykiss straying from
other drainages. Whether planted
rainbow trout survived and became
steelhead can only be speculated
upon; since hatchery rainbow stocks
FIGURE 3-27. STEELHEAD LOCATIONS
came from various mixtures of
coastal steelhead their ability to
spawn with native trout is likely, and has been reportedly observed by the CDFG (USFWS
1998g). In 1997, the first reoccurrence of steelhead on Base was observed in San Mateo
Creek since 1993 (2 adults) and 1989 (some 38 cm trout) (NOAA 2000 & USFWS 1998g).
Information compiled by CDFG is limited, but suggests that native adult steelhead that
strayed from another watershed, entered San Mateo Creek and successfully spawned in
1997 (NOAA 2000). The juvenile progeny of those spawning adults were observed by
CDFG during their field investigations in the spring and summer of 1999; between 3 March
and 3 September 1999, 78 juvenile steelhead observations were made, and genetic testing
by the CDFG determined that the steelhead observed were native to the region (Southern
California ESU) and offspring of an andromous form (NOAA 2000). In 2000, the numbers
of steelhead observed declined from 3 adults and 17 juveniles observed in June, to only 1
juvenile seen in November (Hovey 2000a-f). In cooperation with NMFS and CDFG,
existing pools were monitored beginning in summer 2001 and throughout 2002 to
determine if O. mykiss were able to survive in San Mateo Creek (MCBCP 2003b). The
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