Evaluation of egg incubation methods and larval feeding regimes for north American burbot

Incubation methods and larval feeding regimes were investigated for North American burbot Lota Iota maculosa over 2 years. Three upwelling incubators were tested: 6.0-L McDonald-type jars, 2.0-L pelagic egg jars, and 1.2-L Imhoff cones. Larvae were allocated to five feeding regimes in year I (trial 1) and three feeding regimes in year 2 (trial 2). In trial 1, a live diet (marine rotifers Brachionus plicatilis and brine shrimp Artemia spp.) was administered from 11 d posthatch (dph) until introduction of a commercial diet at 21, 3 1, or 41 dph; the fourth treatment applied the commercial diet exclusively starting at I I dph, and the fifth treatment used only the live diet. Trial 2 examined (1) exclusive use of live feed beginning at 16 dph; (2) use of live feed at 16-50 dph, which was combined with commercial feed at 31-50 dph, and use of only the commercial diet at 51-76 dph; and (3) use of the live diet at 16-50 dph, the addition of frozen brine shrimp at 31-50 dph, and use of the commercial diet at 51-76 dph. Approximate stocking densities for feeding trials were 25 larvae/L in trial I and 250 larvae/L in trial 2. Survival and total lengths (TLs) were measured at 52 dph in trial I and at 76 dph in trial 2. Incubation trials showed that Imhoff cones or pelagic egg jars significantly improved embryo survival relative to McDonald jars. Larvae fed a live diet for an extended time had significantly higher survival and TLs in both trials. Introduction of a commercial diet at 31 or 41 dph after live-diet feeding was successful. This study provides a basis for further development of burbot aquaculture.