Nichol: Annual and between-sex variability of Pleuronectes asper 
551 
+ Standard station a Exploratory tow ♦ Beam-trawl tow 
Figure 2 
Geographic location of exploratory (1988-91) and beam-trawl tows (1995) made inshore of 
the standard AFSC survey stations. 
for each tow. All fish within the path of the trawl 
were assumed captured. Male and female catch rates 
at each station were calculated as follows: 
CPUE, = CPUE ■ ( Weight Proportion of ith sex ) = 
CPUE 
n 
(l) 
where CPUE = 
CPUE / = 
n = 
n i = 
L = 
L = 
l 
a = 
b = 
catch per unit of effort (kg/hectare) 
of all yellowfin sole at a station; 
catch per unit of effort (kg/hectare) 
of the ith sex; 
total number of fish; 
number of fish of the ith sex; 
total length (cm) of the jth fish, 
males and females included; 
total length (cm) of the jth fish and 
ith sex; 
0.007441; and 
3.130. 
Constants a and b were calculated with nonlinear 
regression (nlin procedure; SAS Institute, 1989) with 
the equation: W = aL b (n=796, r 2 =0.99), where 
W=individual yellowfin sole weights (g) measured 
during the 1987 standard AFSC survey. Prior to es- 
timating a and 6, a test comparing the length- weight 
relations between males and females was performed. 
A test of the null hypothesis of no difference between 
male and female linear log( length )-log( weight) re- 
vealed no significant difference in either slopes 
(analysis of covariance; F- 2.46; df=l,792; P- 0.12) or 
intercepts (F=2.05; df=l,793; P=0.15). Sexes were there- 
fore combined to estimate constants a and b above. 
Annual yellowfin sole “survey biomass” was esti- 
mated as: 
n 
Biomass = ^^[CPUE k ■ A k ^j , (2) 
k=i 
where CPUE k = the mean of station CPUE values 
(Eq. 1) within the &th stratum (Fig. 
1); and 
A k - the area (hectares ) of the Mh stratum. 
Proportions of males (no. males/no. both sexes) at 
each station were averaged across stations by depth 
