Southern Rock Lobster (Jasus edwardsii) that are about to moult or have recently moulted have reduced market value due to higher mortality in live transport, higher cannibalism and lower meat recovery. Limiting the landing of softer shelled lobsters is desirable to maintain product quality. The effects of several factors on durometer readings were evaluated: sex, temperature (ambient plus elevated 3°C), location (from around the coast), and size (carapace length). Individuals were collected across two regions South Australia and Tasmania.

To test if the carapace length of lobsters changes during cooking, 21 legal-sized southern rock lobsters were collected in pots from Alum Cliffs, south-eastern Tasmania, Australia in October 1999 (42.95±S 147.35±E). The sample consisted of 7 female and 14 male lobsters ranging in carapace length from 106 mm to 153 mm (mean 120 mm). Each animal was abdominally tagged using individually marked t-bar tags (Hallprint T-bar anchor tag, TBA1; Hallprint Pty Ltd, 27 Jacobsen Crescent, Holden Hill, SA 5088, Australia). The carapace length of all lobsters were measured five times to the nearest 0.1 mm in a random manner, before and after processing. This repeated measurement of all specimens in random order was intended to evaluate measurement error. Processing was typical of that used commercially and involved killing the lobsters in fresh water before cooking in pre-boiling salted water for 12 minutes.