Development of intensive copepod culture technology for Parvocalanus crassirostris: Optimizing adult density

Abstract

The use of copepod nauplii as live prey for first-feeding marine fish larvae is enabling the culture of many marine fish species with small, difficult to rear larvae. The small planktonic nauplii of the copepod Parvocalanus crassirostris is a particularly suitable first-feed due to its small size and ready acceptance by larvae of many species. This study details the relationship between stocking density and egg and nauplii production rates for P. crassirostris copepods, demonstrating a significant decline in culture production as system densities are increased. Fecundity decreased from 26 eggs female− 1 day− 1 at an adult density of 0.25 mL− 1 to less than 1 egg female− 1 day− 1 when operated at 8 adults mL− 1. Effects of increasing adult densities on nauplii survival, feed availability, and water quality were sequentially investigated as potential mechanisms for the apparent inverse relationship between adult density and fecundity, with little success. In contrast, increasing egg and nauplii harvest frequency yielded large improvements in egg and nauplii production, with small (1 L) scale cultures yielding over 40,000 eggs and nauplii per day when stocked at 4 adults mL− 1. A 1500 L pilot production system, designed to efficiently remove eggs and nauplii, generated a mean daily output of 18 million eggs and nauplii per cubic meter of culture volume under continuous operating conditions for a period of over one month.