Modeling the effects of sequential rearing on the potential production of controlled environment fish-culture systems

Abstract

The production potential of an aquaculture system can be achieved only if the feed carrying capacity (kilograms per day) of the system is maintained at the maximum acceptable rate throughout the rearing period. Continuous production of fish through successive stocking and harvesting provides a higher mean feeding rate than conventional batch culture methods. Algorithms were developed to optimize sequential fish production given the feed carrying capacity of the system, rearing period (RP), length of fish at stocking (L t = 0, growth rate (ΔL), feed conversion (FC), and mortality rate (Z). Algorithm use indicates that production per rearing period increases at a diminishing rate with the number (n) of stocking-harvesting intervals. For example, using rainbow trout ( Oncorhynchus mykiss), where RP = 270 d, L t = 0 = 7·6 cm; ΔL = 0·0.086 cm/d, FC = 1·8, and Z = 0·0, the increase in production over than predicted with the batch method (n = 1) for selected values of n was as follows: 44% (n = 2), 65% (n = 3), 87% (n = 5), 98% (n = 7), 104% (n = 9), and 110% (n = 12). Improvements in production with n > 1 diminish with a greater L t = 0 or Z, buth increase with RP or ΔL. Sequential rearing can substantially reduce the water flow required to achieve a chosen production goal.