Effect of temporal variation, gender and size on cuticle polyphenol oxidase activity in deep water rose shrimp (Parapenaeus longirostris).

Seasonal changes and physiological factors related to sex, size and spawning period may alter Polyphenoloxidase (PPO) activity in crustacean decapods. Given the undesirable effects that the enzyme has on the marketability of shrimps, a study was performed on the cuticles of the valuable deep-water rose shrimp. Monthly measurements of PPO activity in cuticles of juvenile and adult males and females were recorded for one year, along with sea-surface temperature (SST) and photoperiod. PPO activity was highest during late summer (August and September) and was lowest between February and March. The rate of enzyme activity in males was double that of females, when corrected for time period. Juvenile shrimp had the highest enzyme activity. Under the conditions tested, our results support that PPO assessing should take into account the sex and size as a factor potentially biasing in tissue enzyme distributions.