Influence of diet on
broodstock lipid and fatty acid composition and larval competency in the
spiny lobster, Jasus edwardsii
G.G. Smith, A.J. Ritar, D. Johnston, G.A.
Dunstan-2004
Aquaculture, 233(1-4): 451-475
Abstract:
Adult spiny lobster females were starved for a 3-week
period then fed either a squid or beef-based diet for 5 months during
ovarian maturation to ascertain the pattern of lipid and fatty acid usage,
deposition and resilience to change in the digestive gland, ovary and tail
muscle. Phyllosoma larvae resulting from these broodstock and animals from
the wild were subject to an activity test (1 h exposure to temperature and
salinity stresses) to ascertain their competency at hatch. Larval competency
was validated with a period of culture. Prior to and during the feeding
period, broodstock lipid concentration was extremely high in the digestive
gland (66–74% of tissue dry weight [dw]), moderate in the ovary (38–43%
dw) and low in the tail muscle (5–8% dw). The lipid profiles of the
digestive gland, ovary and tail muscle were dominated by triacylglycerol
(TAG, 90%), polar lipid (PL)/triacylglycerol (52/43%) and polar lipid (90%),
respectively. The digestive gland lipid content was reduced by starvation
but increased by the end of the feeding period, suggesting this organ is
used as an energy (lipid) reservoir. By the completion of the study, the
fatty acid profile of the digestive gland closely resembled that of the
diet. By contrast, the concentration of lipids and fatty acids in the ovary
and tail muscle remained relatively stable independent of diet, although the
ovary size and lipid content increased concomitant with maturation.
Phyllosoma resulting from the broodstock dietary treatments and animals from
the wild had similar lipid class profiles; polar lipids and sterols
constituted over 98% of the total lipid. While their fatty acid profiles
were similar, phyllosoma from wild broodstock had a lower content of all
major fatty acids (except 20:4n-6) were larger, attained higher
survival (up to stage IV) and had lower inactivity counts (stress index).
During this study, the temperature and salinity parameters used in the
activity test were modified to improve the predictive capacity of the test.
(School of Aquaculture, Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, Locked Bag 1370, Launceston, Tasmania 7250, Australia, e-mail: ggsmith@utas.edu.au)