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Fishery Bulletin 107(2) 
of FA abundances. For example, in contrast to the quill- 
back rockfish embryos studied here, which showed the 
n-3 PUFAs 22:6n-3 and 20:5n-3 in greatest abundance, 
Tveiten et al. (2004) reported that of 16 FAs they inves- 
tigated in embryos of the spotted wolffish ( Anarhichas 
minor), 18:ln-9 was predominant. 
Caution must be used when attempting to apply 
condition indices based on FA amounts or proportions 
derived from other species. As lipids are broken down 
for use during development, the resulting FAs may be 
conserved as structural components of new tissues or 
metabolic compounds, modified into new FAs, or con- 
sumed as energy sources, and the timing and extent 
to which specific FAs are used varies considerably 
among species (reviewed in Tocher, 2003). In some 
marine fish, FAs appear to be utilized in a non-selec- 
tive fashion (e.g., in order of their abundance) while 
in others, some FAs have been preferentially retained. 
For example, retention of 20:4n-6 was found to occur 
in Murray cod ( Maccullochella peelii peelii ) and trout 
cod (Maccullochella macquariensis ; Gunasekera et al., 
1999), Senegalese sole (Solea senegalensis; Mourente 
and Vazquez, 1996), and spotted wolffish ( Anarhi- 
chas minor ; Tveiten et al., 2004); this PUFA was also 
used less rapidly than the total lipid for the rockfish 
embryos in this study. Greater retention of 20:5n-3 
has been reported in Atlantic halibut (Hippoglossus 
hippoglossus ; Ronnestad et al., 1995), but this did not 
occur for quillback rockfish here. Tveiten et al. (2004) 
found that spotted wolffish embryos had lower ratios 
of 20:4n-6 to 20:5n-3 than those generally deemed 
necessary for survival in other species. In spotted wolf- 
fish embryos, the proportion of 16:0 increased, while 
18:ln-9 decreased (Tveiten et al., 2004); for quillback 
rockfish, these FAs were used at the same rate as total 
FAs. This suggests that species differences must be 
considered in any assessment of the FA composition 
of developing fish. 
Saturated fatty acids and monounsaturated fatty acids 
The SFAs 16:0 and 18:0, and MUFAs that can be derived 
from them (e.g., 16:ln-7, 18:ln-9), are unlikely candidates 
for use as indicators of quillback rockfish nutritional or 
energetic status due to their relatively high abundances 
and the ability of all organisms to biosynthesize them. 
Any deficiencies in these FAs could be readily inferred 
from low total lipid levels. 
The MUFAs with high percentage mass losses were 
generally present in very low amounts and likely were 
not of high metabolic importance. For example, the 
MUFA 22:ln-ll, which is likely derived from calanoid 
copepods and transferred up through higher trophic 
levels in marine food chains (Saito and Kotani, 2000), 
was found to have the greatest rate of decrease in mass 
during larval development. However, its small initial 
mass and general absence from structural lipids in 
fish (Tocher, 2003) makes it likely to serve only as a 
minor energy source for developing quillback rockfish 
embryos. 
Polyunsaturated fatty acids 
The finding that 20:4n-6, which was the most abundant 
n-6 PUFA, was largely conserved seems consistent with 
its role as an important metabolic end product rather 
than a general energy source. As a precursor to the 
eicosanoids, a physiologically active and diverse group 
of hormone-like compounds, 20:4n-6 is believed to play 
a significant role in a variety of functions, including 
inducement of spawning, intercellular signaling, stress 
tolerance, immune response, inflammatory response, 
blood clotting, and is likely essential to normal growth 
and development (reviewed in Bell & Sargent, 2003; 
Tocher 2003). Several aquaculture studies have indi- 
cated that supplementing broodstock diets with 20:4n-6, 
within optimal concentration ranges or ratios to other 
FAs, results in improved egg and larval quality for a 
variety of marine fish species (reviewed in Bell & Sar- 
gent, 2003). Many marine fish seem to need 20:4n-6 in 
their diets and are unable to manufacture it from pre- j 
cursors (Mourente and Tocher, 1993; reviewed in Bell & 
Sargent, 2003); the levels of 20:4n-6 in embryos there- 
fore likely reflect the quality of maternal provisioning. 
While measuring the relative abundance of 20:4n-6 may 
be useful in assessing condition of quillback rockfish 
embryos, further investigation is needed to determine 
what levels of 20:4n-6 may be considered deficient, and 
what specific effects may arise from that deficiency. 
The PUFAs 20:5n-3 and 22:6n-3 were the most abun- 
dant FAs measured in quillback rockfish embryos and 
preparturition larvae, and decreased at approximately 
the same rate as total lipids. While 20:5n-3 and 22:6n- 
3 are important metabolic end products, they can also 
be consumed as major energy sources during the early 
life history of many marine fishes (reviewed in Toch- 
er, 2003). Due to their abundance and role as energy 
sources, the amounts of 20:5n-3 and 22:6n-3 in quill- 
back rockfish embryos are reflected in total lipid levels, 
and would not be informative as additional indicators 
of condition. 
The remaining PUFAs were used more quickly than 
the total lipid, were generally not very abundant, and 
are likely of limited importance. For example, 18:3n-3, 
an essential fatty acid derived from marine plants, can 
serve as a precursor to both 20:5n-3 and 22:6n-3 in 
some organisms, following a metabolic pathway that is 
similar across widely varying taxa (reviewed in Tocher, 
2003). However, the high abundances of 20:5n-3 and 
22:6n-3, in combination with the relatively low levels 
of 18:3n-3 (<1% total FA mass), suggest that they were 
being synthesized from 18:3n-3 to supplement the ma- 
ternally-provisioned amounts, it was only to a minor 
degree. Other research suggests that marine fish are 
largely incapable of synthesizing 20:5n-3 and 22:6n- 
3 from 18:3n-3 and they obtain these essential fatty 
acids from their diets (Tocher, 2003), in which case the 
embryos are likely using 18:3n-3 as a relatively small 
energy source. Similarly, 18:2n-6 may be of limited 
importance, as marine fish have limited ability to con- 
vert it to the metabolically-important PUFA 20:4n-6, 
