116 
Fishery Bulletin 109(1) 
Table 1 
Number of fish sampled (total fish), and size range of Atlantic herring ( Clupea harengus) analyzed for differences in 
content by year, season, and age class. 
total lipid 
Year 
Total fish 
Size (cm) 
Summer 
Winter 
Age 1 
Age 2 
Age 3 
Age 4+ 
2005-2008 
889 
8.8-28.2 
731 
158 
87 
469 
188 
145 
2005 
113 
9.0-25.0 
113 
0 
2 
66 
37 
8 
2006 
330 
8.8-27.3 
292 
38 
56 
134 
84 
56 
2007 
334 
10.7-28.2 
214 
120 
26 
206 
37 
65 
2008 
112 
10.8-28.0 
112 
0 
3 
63 
30 
16 
Year 
Figure 2 
Size-corrected total lipid content in Atlantic herring (Clupea 
harengus ) by sampling year (sample sizes: 77 2005 : H3, 7i 2006 : 
330, n 2 oo 7 : 334’ and /i 2008 :112). Error bars represent stan- 
dard deviation; values inside bars graph are the yearly mean 
percent lipid. 
total lipid content on fork length revealed a signifi- 
cant positive relationship (t - ^ 0.147, P<0.001, Fig. 1). 
The ANCOVA of total lipid content revealed sig- 
nificant differences (PcO.001) in the length-cor- 
rected lipid content of fish between years (Fig. 2). 
Multiple comparison tests (Bonferroni, a=0.05) 
showed that the total lipid content of fish from 
2005 (6.15% ±2.61%, 72 = 113) was significantly 
lower than the total lipid content of fish from 2006, 
2007, and 2008 (P<0.001 for all comparisons), 
but fish from the latter three years were not dif- 
ferent from each other (8.60% ±2.61%, 72 = 330; 
9.10% ±3.82%, 72 = 334; and 9.81% ±3.75%), n= 112, 
respectively; P> 0.05). The ANCOVA of total lipid 
content by season was significant with summer 
fish having significantly more total lipid (9.54% 
±3.93%, n = 506) than winter fish (6.66% ±3.60%, 
71 = 158; P<0.001, Fig. 3). 
Fatty acid composition 
A total of 551 individual fish collected between 
2005 and 2008 were analyzed for trends in fatty 
acid composition (Table 2). The ANOSIM of all 
fish showed a significant difference in fatty acid 
signatures of fish by age (global r=0.131, P<0.01, 
Fig. 4A). Figure 4A shows that age-1 and age-4+ 
fish group separately from age-2 and age-3 fish, 
but the clearest differences are seen between age-1 
fish and all other age classes. The differences in 
the percent composition of these fatty acids by age 
can be seen in Table 3. For example, omega-3 and 
omega-6 fatty acids were significantly higher in 
concentration in age-1 fish than in age 2-4 fish 
(P<0.001, 25.88% ±6.42% and 20.73% ±3.57%, 
respectively), whereas long chain monounsaturated 
fatty acids (20:1 tz-11, 20:1/2-9, 20:171-7, 22:1ti- 11, 
22:1/7-9 and 22:l/i-7) were higher in concentra- 
tion in age 2-4 fish than in age-1 fish (P<0.001, 
30.96% ±9.83% and 37.82% ±10.72%, respectively). 
However, the SIMPER analysis also showed that 
no fatty acid contributed more than 6.56% to the 
dissimilarity between the fatty acid signatures of 
fish by age, indicating that the variation observed 
