Evaluation of Egg Incubation Methods and Larval Feeding Regimes for North American Burbot

Abstract

AbstractIncubation methods and larval feeding regimes were investigated for North American burbot Lota lota 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 1 (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, 31, or 41 dph; the fourth treatment applied the commercial diet exclusively starting at 11 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 1 and 250 larvae/L in trial 2. Survival and total lengths (TLs) were measured at 52 dph in trial 1 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.