An activity test to evaluate larval competency in spiny lobsters ( Jasus edwardsii) from wild and captive ovigerous broodstock held under different environmental conditions

Abstract

A short-term activity test was developed to ascertain the physiological condition of newly hatched phyllosoma larvae of the spiny lobster Jasus edwardsii at hatch. Results of the activity test were compared with growth and survival of larvae cultured at 18 °C for up to 42 days and phyllosoma fatty acid profiles at hatch. The stresses used in the activity test comprised combinations of temperature (18, 23 and 28 °C) and salinity (10‰, 15‰, 35‰, 55‰ and 60‰) applied to larvae for a 1-h period. Larvae exposed to the activity test were sourced from ovigerous captive and wild-caught broodstock held at 21, 17 °C or ambient temperature (9.5–13.5 °C) during embryonic development. Phyllosoma originating from the 21 and 17 °C embryonic development temperatures were smaller in body length during culture compared to larvae from ambient incubated wild-caught broodstock, while better larval survival was achieved in larvae from ambient incubated broodstock. A strong correlation was obtained between larval activity at 23 °C at 10‰ and survival of both unfed larvae cultured for 14 days (Stage I; r=0.8720, P=0.0000), and fed larvae cultured for 42 days (Stage IV; r=0.9054, P=0.0000). Elevated incubation temperature reduced the duration to hatch resulting in the quantitative sparing of a number of fatty acids. There was no correlation between activity test results and the presence of any individual or fatty acids groups. The results of this study demonstrate that it is possible to determine larval physiological condition using an activity test comprising temperature and salinity stresses, while additionally, it was noted that larval competency is compromised when elevated temperatures are used during embryonic development to reduce the duration to hatch.