





'■4^? 





14 



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FIGURE 2. — Sagittal sections of livers of anchovy larvae from ocean samples, showing the three grades based on intensity of the PAS 

 staining reaction. Darker shades represent PAS positive red material. Photomicrographs were taken and processed in the same way as 

 those in Figure 1. All were taken at 787 x . A. 6.2 mm larva, robust sample, graded High. B. 6.3 mm larva, emaciated sample, graded 

 Medium. C. 6.0 mm larva, emaciated sample, graded Low. D. 9.2 mm larva, robust sample, graded High. Whereas the first three are 

 from inshore samples, the fourth is from an offshore sample that produced the most intense staining reactions of all ocean samples. 



stained livers in the entire set of ocean specimens 



(Figure 2). 



Discussion 



This study was undertaken to determine 

 whether a histochemical test for glycogen in the 

 liver would indicate the occurrence of starvation 

 among northern anchovy larvae from the sea. The 

 results show that variation in glycogen concentra- 

 tion was lower, on the average, for larvae from sea 

 samples classified in a previous histological study 

 (O'Connell 1980) as generally emaciated, than 

 for larvae from samples classified as generally 

 robust. However, the difference was not as strong 

 as it was for larvae that were fed or starved in the 

 laboratory. 



Glycogen stored in the livers of fishes can be 

 severely reduced by sustained swimming activity 



810 



at moderate levels (Miller et al. 1959; Pritchard et 



al. 1971) or by starvation (Love 1974). It may also 



undergo some change relative to daily cycles of 



feeding and nonfeeding. There is no reason to 



believe that undue exercise was involved in the 



present case, and the data do not indicate a 



relation between glycogen rating and hour of 



capture. Starvation therefore seems the most 



likely explanation of the low levels shown 



by certain samples studied here, and this is 



supported by the relation of glycogen level to 



plankton volume, a not unreasonable index of food 



availability in the sea. For those sea samples 



characterized as emaciated and showing low liver 



glycogen reserves, the plankton volumes were 



among the lowest volumes obtained on the March 



1977 cruise (O'Connell 1980). These low plankton 



volumes can be assumed to represent reduced 



but not essentially nonexistent food, as does 



