An activity test to evaluate
larval competency in spiny lobsters (Jasus edwardsii) from wild and
captive ovigerous broodstock held under different environmental conditions
G.G. Smith, A.J. Ritar, G.A. Dunstan-2003
Aquaculture, 218(1-4):293-307
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 ppt, 15 ppt, 35 ppt, 55 ppt and 60 ppt) 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 ppt 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.
(School
of Aquaculture, Tasmanian Aquaculture and Fisheries Institute, University of
Tasmania, GPO Box 1214, Launceston, Tasmania 7250, Australia,
e-mail: Greg.Smith@dpiwe.tas.gov.au)