488 
Fishery Bulletin 95(3), 1 997 
eigenvalues greater than 1.0, cumulatively account- 
ing for only 66% of the variation, leading us to con- 
clude that the structure of the environmental data 
was not simple. 
Discussion 
The periodic nature of seasonal changes in some en- 
vironmental variables and in reproduction of the dif- 
Table 3 
Spearman correlation coefficients between proportional residuals for species’ densities and various environmental variables: 
amplitude = tidal amplitude; pressure = barometric pressure; current = flood tide current; hours = hours after sunset; spring tide 
= spring tide (versus neap tide); temperature = water temperature; wind velocity = average daily wind speed. Bt=B. tyrannus, 
Lr =L. rhomboides, L x=L. xanthurus , Mu=M. undulatus, Mc=M. cephalus , Pa=P. albigutta, Pd=P. dentatus, P1=P lethostigma. 
*=P< 0.05. **=P<0.01. ***=P<0.001. 
Variable 
Bt 
Lr 
Lx 
Mu 
Me 
Pa 
Pd 
PI 
Amplitude 
0 40 *** 
0.19* 
0.12 
0.08 
-0.24 
- 0.02 
0.20 
0.08 
Pressure 
0.11 
-0.09 
0.04 
0.03 
-0.24 
-0.08 
- 0.02 
- 0 . 20 * 
Current 
0 29 *** 
0 . 22 * 
0.06 
0.14 
- 0.11 
0.15 
0.10 
0 . 20 * 
Hours 
0.19* 
0.30*** 
0.30** 
0.43*** 
0.01 
0.24** 
0.17 
0 . 22 * 
Salinity 
0.06 
0.01 
- 0 . 20 * 
- 0.11 
-0.08 
-0.18* 
0.14 
-0.19* 
Spring tide 
-0.26** 
0.04 
- 0 . 22 * 
-0.24** 
- 0.00 
0.00 
-0.19 
0.09 
Temperature 
-0.07 
-0.24** 
-0.05 
-0.06 
0.18 
0.02 
0.08 
0.00 
Turbidity 
-0.28*** 
-0.42*** 
-0.32*** 
-0.29*** 
0.10 
-0.19* 
0.03 
-0.17 
Wind velocity 
0.14 
0.28* 
0 . 22 * 
0.06 
0.31* 
0.11 
0.16 
0.15 
(Sample size) 
133 
116 
102 
133 
61 
138 
91 
125 
