Using digestive physiology to develop larval culture protocols for the Blackbanded Sunfish, a threatened centrarchid native to the United States.

Autor: Murray, Casey A., Lipscomb, Taylor N., Wood, Amy L., Tuckett, Quenton M., Patterson, Josh T., Watson, Craig A., DiMaggio, Matthew A.
Předmět:
Zdroj: North American Journal of Aquaculture; Apr2024, Vol. 86 Issue 2, p165-178, 14p
Abstrakt: Objective: The Blackbanded Sunfish Enneacanthus chaetodon is a small centrarchid that is endemic to slow‐moving waters from New Jersey to central Florida, United States. The distribution of this species has been increasingly fragmented, primarily due to habitat degradation. The development of larval culture protocols is essential to produce this species for the aquarium trade and for potential restoration efforts. To streamline the production process, larvae should be transitioned from live feeds to inert diets as early as possible without sacrificing larval growth or survival. Methods: A developmental trial was conducted to determine the timing of digestive tract maturation, which indicates the ability of larvae to better digest inert microdiets (MDs). Blackbanded Sunfish larvae were sampled 12 times from 2 days posthatch (dph; notochord length [mean ± SD] = 4.38 ± 0.22 mm) to 50 dph (total length [TL] = 9.89 ± 1.64 mm) for subsequent analysis of digestive enzyme activity (via microplate assays) and digestive system morphology (via histology). A dietetics trial was conducted to determine the most appropriate commercial MD for this species at early life stages by testing the efficacy of three different MDs against a reference diet of brine shrimp Artemia nauplii. Lastly, a weaning trial was conducted to determine the earliest time point at which MDs should be introduced during the larval period. Result: Blackbanded Sunfish larvae transitioned from agastric to gastric digestion at approximately 40 dph (7.95 ± 0.86 mm TL), as determined by the presence of gastric glands and pepsin activity. In the dietetics trial, certain MDs yielded higher survival than others; however, all diets performed equally when considering the TL of the larvae. In the weaning trial, the highest survival was found when larvae were fed Artemia nauplii exclusively or when an MD was introduced at 48 dph (10.62 ± 1.88 mm TL). Conclusion: Larval Blackbanded Sunfish may require up to 48 days of live feeds before introducing MDs but can be successfully transitioned to MDs after 48 dph without significantly affecting survival or growth. Impact statementThe Blackbanded Sunfish, a species with threatened populations throughout its endemic range, can be successfully aquacultured to aid in potential population restoration initiatives or to supply fish for the aquarium trade. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index