Influence of the gonadal cycle and food availability on postmortem changesin glycogen, adenosine triphosphate, hypoxanthine, and the 260/250 absorbance ratio in adductor muscles from scallop Aequipecten tehuelchus (D'Orbigny, 1846)

The influence of food availability and the reproductive cycle on the postmo rtem levels of glycogen, adenosine triphosphate (ATP), hypoxanthine, and th e 260/250 absorbance ratio in extracts of adductor muscles from scallop (Ae quipecten tehuelchus) was investigated. Phytoplankton production, measured as chlorophyll "a" concentration, was high in early autumn (March to April) and early spring (September to October). Food availability was low in wint er and summer, Specimens in good and poor biological condition, according t o the determination of chemical composition and energy content, were found in periods of high and low food availability, respectively. Glycogen and AT P levels were higher in muscles from specimens in better biological conditi on. The rate of decrease of both glycogen and ATP was not dependent on the biological condition. The values of the 260/250 absorbance ratio were highe r in extracts of cold-stored adductor muscle from scallops in better biolog ical condition. Irrespective of the biological condition hypoxanthine incre ased after 24 h in cold-stored muscles. Thereafter, the highest increments were observed in muscles from specimens in the best biological condition.