The marine fish production by aquaculture exceeded wild catch. However, marine fish aquaculture remains undeveloped in the United States despite high consumer demand for marine fish. On the other hand, it is predicted that wild fish populations will be overexploited, so the production necessary to satisfy the demand for fish derived from the increase in the world population will have to be provided by aquaculture. However, the limiting factor for marine aquaculture is the availability of juveniles to stock grow out facilities. To supply juveniles, we develop innovative semiautomatic intensive larval rearing technique to reduce space, labor and the final production cost per juvenile.
Red Drum (Sciaenops ocellatus) fertilized eggs were collected from natural spawn obtained from Whitney Lab broodstock. We follow the embryo develop and vitelline reserve before the larval rearing start. The egg incubation was done in a two 1.8 m³ tanks, maintaining a density of 100 larvae L⁻¹ in an flow through system. The rotifer were cultured using three 250 L tanks, maintaining densities of 800-1500 rotifers mL⁻¹, to produce up to 100 million rotifers daily, sufficient to sustain optimal larval feeding densities of 15-20 rotifers mL⁻¹. A single refrigerated unit maintains microalgae (Rotifer Diet™) at 4°C, continuously pumping this high-density feed to the rotifer tanks. After that, the rotifers were transferred directly from culture tanks to larval rearing tanks using peristaltic pumps. An average of 30 million of rotifers were moved to enrichment tanks (three units, each 75.7 L) to enhance their nutrient content. The Artemia was produced in three 132 L tanks, generating up to 35 million nauplii daily.
This system has demonstrated preliminary successful production runs, including 75,000, 95,000 and 130,000 pre-metamorphosed juveniles harvested after 23 days of hatch in each 1800, liters larval rearing culture tank. The temperature varied from 27 to 21 Celsius, oxygen average was 6 mg/L and pH of 7.9. The automation between tanks optimizes production efficiency. This new technology development increases larval survival and directly could benefits on-farm profitability as well as helps in sportfish and conservation efforts to reduce pressure on the natural stocks. This compact semiautomatic system provides a viable and sustainable pathway for future larval rearing aquaculture.