Determining the optimum feed duration of Artemia nauplii to maximize hybrid striped bass larval growth in cool-water culture conditions

Authors: Fuller, Adam

Submitted to: Journal of Applied Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2020
Publication Date: 12/14/2020
Citation: Fuller, S.A. 2022. Determining the optimum feed duration of Artemia nauplii to maximize hybrid striped bass larval growth in cool-water culture conditions. Journal of Applied Aquaculture. 34(2):267-278. https://doi.org/10.1080/10454438.2020.1841059.
DOI: https://doi.org/10.1080/10454438.2020.1841059

Interpretive Summary: Hybrid striped bass (HSB) represent a valuable sector of the U.S. aquaculture industry. One factor limiting the growth of the HSB industry is the lack of refined methods to rear larvae in tanks with minimal time spent on live feeds while maximizing growth and survival. Though HSB tank culture research has mainly focused on the temperature range of 20–32 deg C meant to maximize growth, little information exists regarding growth and survival of HSB larvae reared at temperatures below 20 deg C, a water temperature commonly encountered by year-round tank producers during winter months. Therefore, the goals of this study were to determine the earliest time HSB larvae could be weaned to a commercial dry diet after consumption of Artemia nauplii, a type of live zooplankton, fed between eight and 28 days at coolwater (18 deg C) culture temperatures to compare growth and survival of the resulting larvae. There was no difference in survival in HSB larvae based on how many days they were fed the live food but there was a range in survival (12.9-64.1%) with an average across all the feeding treatments of 31.2. At the end of the study, the larvae that were fed the live feed the shortest amount of time were statistically shorter than those fed the live feed the longest (8 days – 12.00mm vs 28 days – 16.03mm). The same relationship existed with larval body depth, with larvae feeding on live feed longer having deeper bodies than those larvae feeding on live feeds for a shorter period of time. The present study demonstrates that maximizing the time HSB larvae are fed live feed (Artemia) before the addition of dry commercial diet results in significantly larger larvae at the conclusion of the larval feeding period under these culture conditions.

Technical Abstract: Hybrid striped bass (HSB) Morone chrysops x M. saxatilis represent a valuable sector of the U.S. aquaculture industry. One factor limiting the growth of the HSB industry is the lack of refined methods to rear larvae in tanks with minimal time spent on live feeds while maximizing growth and survival. Four-day-old HSB larvae were stocked into a recirculating aquaculture system maintained at 18 deg C to mimic coolwater culture temperatures experienced by year-round producers to determine the earliest time HSB larvae could be weaned from Artemia to a commercial starter diet. After an initial 8-day rotifer feeding period where all treatments were fed three times daily with rotifers (60 rotifers/mL/tank/d), designated replicated treatments were progressively weaned from Artemia (12 Artemia/mL/tank/d) onto salmon starter (3.0 g/tank/d) for eight to 28-days in 4-day increments. Survival of larvae by the end of the experiment ranged from 12.9-64.1% and averaged 31.2 +/- 12.6% and there was no significant difference among treatments. At the end of the study, length of larvae ranged from 9.05-19.06mm and averaged 14.19 +/- 1.92mm and body depth of larvae ranged from 1.52-4.35mm and averaged 2.71 +/- 0.56mm. Total length and body depth of larvae varied significantly based on the number of days fed Artemia (P<0.0001), with both traits increasing with the number of days fed Artemia. The present study demonstrates that maximizing the time HSB larvae are fed Artemia before the addition of dry commercial diet results in significantly larger larvae at the conclusion of the larval feeding period under these culture conditions.