the starvation treatment in the laboratory. This 

 difference might account for the greater propor- 

 tion of Medium ratings in the ocean samples, 

 robust as well as emaciated. In any event, a 

 moderate proportion of Medium glycogen ratings 

 for the ocean samples is not inconsistent with the 

 earlier histological assessments. The emaciated 

 samples, for example, contained only 60% larvae 

 showing histological signs of moderate to severe 

 emaciation or starvation (O'Connell 1980). 



The apparently higher level of liver glycogen 

 among larvae from offshore samples further indi- 

 cates that food availability is an important factor 

 governing liver glycogen reserves. The plankton 

 volumes for all offshore samples averaged con- 

 siderably higher than the plankton volumes for 

 inshore samples (O'Connell 1980). Moveover, 

 the particular offshore sample that produced the 

 larvae with the most intense PAS indications of 

 liver glycogen had the second highest plankton 

 volume of the entire 1977 cruise. 



The fact that the association of glycogen re- 

 serves and histological condition is evident for 

 only the smaller larvae from the sea might mean 

 that as larvae become larger, they can better 

 tolerate fluctuations in the plankton regime. 

 There was a hint of this also in the laboratory 

 results. Marine fish larvae in general select pro- 

 gressively larger prey and also a broader 

 size range of prey as they grow, and engraulids 

 tend to increase maximum prey size markedly 

 between 8 and 12 mm SL (Hunter in press). Thus a 

 reduction in any part of the crustacean plankton 

 community, but particularly among the smaller 

 organisms, could be detrimental primarily to the 

 smaller larvae. 



The PAS staining procedure appears, then, to be 

 capable of demonstrating the presence of star- 

 vation effects in a larval fish population. On 

 balance, it is a more readable indicator than the 

 comprehensive histological analysis, but it also 

 provides less information. The level of liver glyco- 

 gen reflects the status of only the first line of 

 energy reserve, whereas histological analysis, 

 with more varied indications, is more sensitive to 

 the extent of emaciation that has been sustained 

 by the larva. Perhaps both approaches can be 

 applied to the same larva, but if so, the histological 

 indications should be interpreted cautiously. 

 Our impression is that tissues of larvae can be 

 moderately distorted and degraded by the PAS 

 procedure regardless of feeding history or fixative. 

 On the other hand, the histochemical test might 



provide a sufficient characterization of the condi- 

 tion of larval fish samples for .some purposes, 

 especially if fixation is optimized for the preserva- 

 tion of glycogen. 



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