Abstract
Spatial differences in demographics and nutrition can result in variations in reproductive output and larval quality among marine subpopulations. We investigated how local differences in maternal provisioning influenced the quality and quantity of larvae in sea perch (Helicolenus percoides, Sebastidae), a long-lived, viviparous species, widely distributed around New Zealand, in order to determine how local differences in maternal provisioning influenced the quality and quantity of larvae. Subpopulations from Deep Cove within Fiordland, on the west coast, and the Otago shelf on the east coast of New Zealand's South Island were compared. We used fatty acid analysis of adult liver and gonad tissues to investigate potential spatial differences in maternal nutrition. Fatty acid analysis of larvae on the day of parturition, larval notochord length and oil globule volume on the day of parturition, change in length of cohorts of larvae and change in average size of the oil globule were used as proxies to establish differences in larval quality between the Deep Cove and Otago shelf subpopulations. Our results demonstrated a trade-off between fecundity and oil globule size, where sea perch from the Otago shelf were more fecund but provisioned their larvae with smaller oil globules than females from Deep Cove. We observed faster change in length and slower rates of change in size of the oil globule among cohorts of larvae produced by females from Deep Cove. The maternally provisioned concentrations of the key fatty acids docosahexaenoic acid (DHA) and arachidonic acid (ARA) were higher, and the eicosapentaenoic acid (EPA)/ARA ratio was lower among larvae produced by females from Deep Cove. The results indicated that potential visual and osmoregulatory advantages linked to these fatty acids are passed on to the offspring, necessary to survive in the low-light, low productivity environment of the inner fjords, characterised by high freshwater inputs. The results of the present study highlight the important link between the maternal environment and the quality and fitness of fish larvae.
•Fecundity varies between spatially distinct subpopulations of sea perch•Maternal provisioning determines larval success and survival•There is a trade-off between the size of larval oil globule and fecundity•Larvae withstand extreme fjordic environmental conditions via increased DHA and ARA