Domestication of Wild Broodstock and Early Development of Pacific Cod (Gadus macrocephalus)

Abstract:

Pacific cod (Gadus macrocephalus) is a commercial potential species for marine fish aquaculture. The present study used a wild population of Gadus macrocephalus that was captured from the open sea of Weihai (Yellow Sea region). Under captivity, 49 wild individuals survived and acclimated to broodstock rearing conditions. Shortly, 15 batches of fertilized eggs were collected. Embryogenesis and early larval development of G. macrocephalus, including morphological features and development time, were described. G. macrocephalus spawned demersal and slightly adhesive eggs. Eggs were almost spherical and had no oil globules with diameter about 0.9–1.1 mm. The embryonic development of G. macrocephalus was divided into five stages, namely cleavage stage, blastula stage, gastrula stage, neurula stage as well as organogenesis stage. Embryos hatched out after 312 h 30 min in the sea water when the temperature was 9–10℃. The total length of newly hatched larva was (3.85±0.12) mm．Larva opened mouth at 6 days post hatching (dph) and started exogenous nutrition (first-feeding) stage. The yolk was completely absorbed at 8 dph. Primordial swimming bladder appeared at 6 dph and was filled with air at 16 dph. The first and second intestine physiological curvature formed at 12 dph and at 22 dph, respectively. This study provides the important baseline reference for broodstock management and larviculture of G. macrocephalus.