Effect of stocking rate on growing juvenile sunshine bass (Morone chrysops x M. saxatilis) in an outdoor biofloc production system

Authors: Green, Bartholomew - Bart; Rawles, Steven - Steve; Webster, Carl; McEntire, Matthew - Matt

Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2017
Publication Date: 12/14/2017
Citation: Green, B.W., Rawles, S.D., Webster, C.D., Mcentire, M.E. 2017. Effect of stocking rate on growing juvenile sunshine bass (Morone chrysops x M. saxatilis) in an outdoor biofloc production system. Journal of the World Aquaculture Society. https://doi:10.1111/jwas.12491.
DOI: https://doi.org/10.1111/jwas.12491

Interpretive Summary: The biofloc technology production system is a production system that intensifying management strategy used primarily for culturing tilapia and marine shrimp, both of which can consume the biofloc. Algae, micro-crustaceans, microbial grazers, and particulate organic matter comprise the biofloc, which can serve as natural food for fish and allows the protein content of prepared diets to be reduced without sacrificing growth. However, other fish, like the sunshine hybrid striped bass, can be grown in biofloc production systems because the biofloc serves as a biofilter that maintains water quality to ensure fast growth by the densely stocked and intensively fed fish. In this study we investigated how stocking different numbers of fish affected growth and production of advanced fingerling sunshine bass in an outdoor biofloc production system. At harvest 94 days after stocking, total fish production was not affected by the number of fish stocked and was higher than that of pond culture. Two distinct size groups of fish were observed at harvest: fish smaller than 115 mm long, denominated target fish, and fish longer than 115 mm long, denominated jumper fish. Jumper fish are undesirable in a population of sunshine bass because of their aggressive, domineering behavior towards smaller fish, which tends to reduce growth of smaller fish. We found that as the number of fish stocked initially into the culture unit increased, target fish increased linearly from 62% to 93% and jumpers decreased linearly from 38% to 7% of the population, respectively. Total suspended solids appeared to impede feed consumption. The outdoor biofloc technology production system offers potential for intensifying the production of advanced sunshine bass fingerlings. However, further research is needed to optimize stocking rates and solids management.

Technical Abstract: The biofloc technology production system is a production intensifying management strategy used primarily for culturing tilapia and penaeid shrimp, both of which can consume the biofloc. Other fish can be grown in biofloc technology production systems because the biofloc serves as a water quality management tool, metabolizing the ammonia excreted by the densely stocked and intensively fed fish. A dose-response study was conducted in an outdoor biofloc technology production to begin quantifying the stocking rate-production function system for sunshine bass (Morone chrysops x M. saxatilis) advanced fingerlings. Sunshine bass (2.9 ± 0.2 g/fish) were stocked into tanks at 50 to 250 fish/m2 in 50 fish/m2 increments. After 94 days, gross yields ranged from 1.4 to 3.1 kg/m3 and were independent of stocking rate. Harvested fish were separated into two size groups: smaller than 115 mm total length (target fish) and larger than 115 mm TL (jumper fish). In response to increased stocking rate, target fish increased linearly from 62% to 93% and jumpers decreased linearly from 38% to 7% of the population, respectively. Total suspended solids appeared to impede feed consumption. The outdoor biofloc technology production system offers potential for intensifying the production of advanced sunshine bass fingerlings. However, further research is needed to optimize stocking rates and solids management.