758 
Fishery Bulletin 95(4), 1997 
100 
PWS 
St. Mathews Bay 
SEAK 
SO- 
SO - 
40- 
20 - 
iff 
I 
fMJ.184 Sitka 
■ 
111 
P-0.021 
P 
i ll 
Pi 
111 
81 
Age (years) 
Figure 7 
Mean (±SE) percent effective swimmers of larval Pacific herring by female 
parent age, site, and region in Alaska, 1995. Sample sizes are indicated in 
Figure 5. Overall P-value from ANOVAis listed above each graph. Significant 
differences were Sitka, ages 3 and 4 > age 7 (P=0.011). 
vation. Natural environmental conditions, however, 
can also cause a high degree of variability in herring 
recruitment (Stevenson, 1962; Anthony and Fogarty, 
1985). For example, the 1989 year class at Sitka also 
represented a small proportion of the spawning popu- 
lation in 1995 (<2%; ADF&G 16 ); therefore factors 
other than oil are important determinants of cohort 
size. 
Whether or not herring in PWS were ever repro- 
ductively impaired by the EVOS is unknown, but the 
time lapse between the spill and our study probably 
precluded any detection of reproductive impairment. 
16 ADF&G (Alaska Department of Fish and Game). 1995. Her- 
ring test fishery data. Commercial Fisheries Management 
and Development Division, 304 Lake St., Room 103, Sitka, AK 
99835. 
