In several Australian states, the claimed potential for shrinkage of rock lobsters during cooking is a problem for enforcement of rock lobster fisheries regulations based on a minimum legal size. In Tasmania. uncertainty about the potential for shrinkage of rock lobster (Jasus edwardsii) regularly prevents prosecution. We tested the potential for shrinkage of rock lobsters by cooking 21 animals under typical industry protocols. Cooking had no statistically detectable effect on carapace length.