Systematics of Prickly Sculpin, II — Krejsa 
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O=€ollection, but no fish; •=l»6 fish; • =7-18; •=19-36; W= 37-60; W=6l-90. 
f\ \ \ \ \ \l Intertidal Zone; IMSniOnnSI Spawning Zone; Spawning Season. 
Fig. 5. Monthly distribution of young-of-the-year Cottus asper within the Little Campbell River, 
taken from pooled biweekly samples representing results of 700 seine hauls. 
Data 
cate that natural spawning temperatures range 
from 8° to 13° C. Egg-rearing experiments at 
various temperatures resulted in complete mor- 
tality at 18° C, less than 50% survival at 15° 
C, and greater than 85% survival at 12° C. 
Control of lower temperatures was beyond the 
limitations of available equipment. 
The annual mean range of ambient tempera- 
tures experienced by inland populations of C. 
asper is twice as great as that experienced by 
coastal populations at the same latitude (Krejsa, 
1965:109). The monthly mean temperature 
range between northern and southern localities 
is from 8.8° to 19-5° C on the coast, and from 
9.6° to 29.6° C inland. A priori , one might 
expect that inland populations would experience 
a greater range of developmental temperatures 
than do coastal populations. Apparently, how- 
ever, they do not. When monthly mean temper- 
atures, representing inland and coastal localities 
encompassing the distributional range of C. 
asper, are plotted against latitude, the mean 
temperature differences between inland and 
coastal localities during the spawning period are 
almost negligible (Fig. 6). In fact, the empiri- 
cally determined, average spawning temperature 
range of 8° to 13° C (shaded bar, Fig. 6) can 
be followed as a thermal "wave” progressing 
through inland and coastal localities from the 
south in February, to the north in June. Ap- 
proximate spawning times, determined from 
examinations of gonadal condition in more than 
1,100 specimens from all latitudes, are in gen- 
eral agreement with this south-north progres- 
sion although the latitudinal range over which 
spawning occurs in March, April, and May is 
remarkably consistent (Fig. 6). 
Theoretically, inland forms have a shorter 
period of exposure to spawning temperatures 
of 8° to 13° C than do coastal forms (Fig. 6). 
This supposition has been borne out by field 
data from the two most frequently collected 
spawning sites, Squakum Lake and Little Camp- 
bell River. 
According to Figure 6, the inception of 
spawning in inland streams should lag behind 
that of coastal streams at similar latitudes. This 
is because upstream or inland areas remain 
colder for a longer period than do coastal areas. 
This is apparently true in the lower Fraser Val- 
ley. For example, the following localities are all 
within 15' of 49° N, and gravid females and/ 
