Page 3 - bell1978fishes

1978 FISHES OF SANTA CLARA RIVER 3

and San Francisquito Canyon. Arrastre Canyon and Santa Paula Creek were examined

briefly, but no collections were made. The original purpose of the sampling program

was to determine the distribution of threespine stickleback (Gasterosteus aculeatus)

phenotypes. This species favors areas of low velocity flow so most collections were

made in backwaters, side streams, pools and mainstream margins. Samples are thus

biased against those species preferring rapidly flowing water. For this reason, esti-

mates of abundance, which may be misleading were not made, and the absence of

a species from a sample should be interpreted with caution.

Collecting stations were selected for accessability and the presence of suitable

habitat for Gasterosteus. The position of stations was determined in the field using

local landmarks, and they were recorded on U.S.G.S. 7.5 minute series (topographic)

maps. The distance of collection stations from the mouth in the Santa Clara River and

from the confluence with the Santa Clara River in tributaries was determined by step-

ping off that distance on the topographic maps using dividers set at 0.1 km. Stream

'
gradient was determined by stepping off the distance between one or two contour lines

up and downstream of the station with dividers set for 500 or 200 feet. Because of

irregularities in stream course, the distance from the mouth or confluence tends to be

a slight underestimate and the gradient a slight overestimate using this method.

Surface temperature and velocity were measured where the majority of fishes

was collected at each station. Thermometers were calibrated to within 0.5 C of the

freezing and boiling point of distilled water. Water temperature tended to vary with

the air temperature. Water velocity was determined by measuring the time required

for a vial partially filled with water (so only a comer protruded above the surface) to

drift 5 m. Water depth, stream width, amount of vegetation, bottom composition and

water color were typical of the habitat, but collecting frequently extended across a

heterogeneous segment of stream.

1
Fishes were collected with a 10 foot (3.048 m) , /s inch (3.175 mm) mesh knitted

nylon seine. The collecting effort usually varied inversely with the abundance of Gas-

terosteus. Specimens were fixed in 10% formalin and transferred to 50o/o isopropyl

alcohol 4 to 10 days after collection. Eddy (1957), Kimsey and Fisk (1960), Robins

and Miller (1957) and Smith (1966) were useful for identification. The current sci-

entific and common names were verified in Baily ( 1970). All collections were de-

posited in the fish collection of the Natural History Museum of Los Angeles County

(LACM). These are station 1, LACM 34071 , station 2 to 44, LACM 34198 to 34240

respectively, station 45, LACM 35228, and station 46, LACM 34241. LACM 35227

also came from station 31 and LACM 35648 w.as collected near station 30. Additional

specimens from the California Academy of Sciences Fish Collection (CAS) were ex-

amined to verify early collection records (CAS 20283, CAS 20284 and CAS Acc.

No. X:30).

I attempted to determine whether species presently occuring in or previously re-

ported from the Santa Clara River system were native or introduced. This is a rela-

tively simple task for species known to be introduced from distant sources, but those

native to southern California present a problem. One must depend on historical rec-

ords, distribution patterns, the original presence of appropriate habitats and the exis-

tence of dispersal routes for entry into the system. Only negative historical data can