Fate or independency: is batch-specific larval performance determined by egg traits? A case study in farmed pikeperch (Sander lucioperca)

Abstract

Fish embryos and larvae undoubtedly depend on maternal provisioning of essential egg components, such as fatty acids (FA), during early ontogeny. But which aspects and stages of batch-specific larval development are modulated by these inherent oocyte traits? This question is of major importance from an ecological, as well as from an aquacultural perspective. We examined the effects of batch-specific non-nuclear-genetic egg traits (fatty acid (FA) profiles, egg size, mtDNA fragmentation, cortisol content) already in unfertilized oocytes of pikeperch (Sander lucioperca) and studied their influence on survival (15 dph) and larval performance (length at hatch, stress resistance, first feeding, swim bladder inflation rate, yolk sac and lipid droplet size, growth in weight and length) after hatching under stable laboratory conditions (n = 12 batches). While larval survival and performance were independent of mtDNA fragmentation and cortisol levels, FA profiles affected specific larval traits. Especially, FA of the neutral fraction were positively correlated with larval size and growth (16:0, 18:0, 22:1n-9, total saturated FA), swim bladder inflation (arachidonic acid 20:4n-6, total FA), and early first feeding (16:0, 18:0, total saturated FA). Important FA of the polar fraction included 15:0 and 16:1n-7, which showed alternate effects on larval survival, first feeding, and growth (length). Furthermore, larval length at hatch was positively correlated with egg diameter. Other larval parameters (yolk sac and lipid droplet size and stress response) were not or only marginally affected by egg traits. Consequently, high oocyte FA deposition fuels fast rates of growth and development during early ontogeny. On the other hand, larvae develop independently of assumed disadvantageous properties (cortisol content, mtDNA damage). Knowledge of this relation allows for the improvement of aquaculture practice, as well as predicting recruitment success in the wild.