TABLE 5.— Number of Etheostoma squamiceps individuals 
ils, by habitat. Young were up to 1 year of age, adults over 1 
13 
per square meter collected at approximately 3-month inter- 
year. 
a EE 
Big Creek Sample 
Number of LE. squamiceps 
Ferguson Creek Sample 
Number of 2. squamiceps 
Be iicction Seated Per Square Meter in Collection Dees Per Square Meter in 
Date fected Slab Gravel Non-Slab Date Teotea Slab Slab Non-Slab 
Pools Riffles Pools Pools Riffles Pools 
I 
Adults 
July 1972 6 0.81 0.0 0.0 8 July 1972 3 0.0 0.58 0.0 
October 1972 9 0.73 0.63 0.05 20 October 1972 1 0.0 0.27 0.0 
January 1973 2 0.22 0.0 0.0 16 January 1973 5 0.04 0.63 0.0 
April 1973 4 0.54 0.0 0.0 30 April 1973 3 0.25 0.0 0.0 
MEAN 0.58 0.16 0.01 MEAN 0.07 0.37 0 
SD 0.26 0.32 0.03 SD On 0.29 
Young 
July 1972 10 0.40 0.60 0.0 8 July 1972 64 0.25 9.03 1.08 
October 1972 4 0.24 0.63 0.0 20 October 1972 30 0.0 8.07 0.0 
January 1973 7 0.77 0.0 0.0 16 January 1973 21 0.27 iLalat 0.39 
April 1973 11 1.48 0.0 0.0 30 April 1973 19 0.99 1.26 0.0 
MEAN 0.72 0.31 0 MEAN 0.38 4.87 (hay 
SD 0.55 0.36 SD 0.43 4.27 0.51 
reek, 72.1 percent were up to 1 year of age, 20.5 
rcent were over | year and up to 2 years, 6.7 
rcent were over 2 and up to 3 years, and 0.7 
reent were over 3 years. The very small number 
these darters over 3 years of age effectively dem- 
strates that 3+ is the maximum age of E. squami- 
ps (Table 6). 
A skewed sex ratio was found in each study 
pulation, both among the young [1.3 females to 
male in Big Creek (x? = 5.52; P<0.025), 1.7 to 1 
Ferguson Creek (x? = 20.64; P<0.005)] and 
1ong the total samples [1.3 to 1 in Big Creek (x? = 
02; P<0.005), 1.9 to 1 in Ferguson Creek (x? = 
01; P<0.005)]. The only year class in which males 
edominated was 3-4, indicating a greater longevity 
“males, 
The skewed sex ratios among young-of-the-year 
ottail darters suggest a genetic rather than a direct 
vironmental cause for the predominance of females. 
ie absence of spawning activities by all but the 
TABLE 6.— Distribution of sexes and year classes in 
nples of Etheostoma squamiceps collected between 6 Oc- 
er 1970 and 19 June 1973. 
a ————— eee 
——————$——— 
Sex Number by Year Class Total 
—1 ee 2+ 3+ 
nee ere ee ee a eee 
Big Creek 
fale 146 83 26 3 258 
"emale 189 125 29 0 343 
Total Sov) 208 55 3 601 
Ferguson Creek 
Tale 115 18 12 2 147 
‘emale 195 70 aly il 283 
Total 310 88 29 3 430 
large males (a small proportion of the population ) 
and the fact that several females may contribute to 
the nest of one male may have resulted in selection 
against a 50-50 sex ratio. 
Survival 
Relative survival values (Table 7) for each year 
of life were calculated for males, females, and total 
samples of E. squamiceps, using the data in Table 6. 
It was assumed that each age class was collected 
in proportion to its relative number in the population, 
that the population was neither increasing nor de- 
creasing, and that the number of fry entering the 
population each year was constant. 
Because approximately one-third of the sampling 
effort each month was expended in the slab pools, 
which constitute less than one-third of the habitat 
of Big Creek but in which adults tended to be con- 
centrated (Tables 1 and 4), the number of adults 
in Table 6 probably exaggerates their actual pro- 
portion in the population. Survival was therefore com- 
puted on the 1+ year class as well as the -1 year 
class (Table 7). 
The general shapes of survival curves for males, 
females, and total samples (Fig. 10) were similar to 
one another except for the Ferguson Creek male 1x' 
curve. The increasing steepness of the slope with 
age reflects the lower rate of survival for each age 
class. The unusual shape of the Ferguson Creek 
male Ix' curve is a result of the very low number of 
1+ males and is probably due to sampling error. 
The decrease in survival of E. squamiceps with 
each year of life demonstrates a tendency toward a 
life-span characteristic of the species (Deevey 1947: 
286). Very few individuals of either sex live longer 
than 3 years. The oldest E. squamiceps examined 
