John T. Ogle

Characterization of an Experimental Indoor Larval Production System for Red Snapper

Abstract Over the past several years, we have developed an experimental-scale rearing system for larval red snapper Lutjanus campechanus that combines extensive outdoor production of live-feed zooplankton with intensive larval fish rearing. The salient features of the system are (1) use of size-graded copepods as live feed; (2) culture in clear water; (3) three-phase water management consisting of an initial static water phase followed by a volume-doubling phase in which water is gradually added and, finally, a recirculation-biofiltration phase; (4) a lowered salinity of 25 g/L water; and (5) an indoor location at constant temperature under artificial light. A total of 19,835 juvenile red snapper were produced from 12 larval rearing tanks in three separate batches with an overall survival of 16.5%. Survival varied from 1% to 31% in individual larval rearing tanks. Water quality variables (oxygen, temperature, salinity, total and un-ionized ammonia, nitrite, nitrate, pH, and alkalinity) were not significan...

Increasing Production of Copepod Nauplii in a Brown-Water Zooplankton Culture with Supplemental Feeding and Increased Harvest Levels

Abstract Two experiments were performed to investigate increasing the number of copepod nauplii obtained from a brown-water zooplankton culture for feeding to larval red snapper Lutjanus campechanus. Brown-water zooplankton cultures rely on the regular exchange of (brown) estuarine water to nourish and harvest the copepods. The majority of copepods in both experiments were Acartia tonsa. The goal of the first experiment was to determine whether adding rice bran to a brown-water zooplankton culture would increase copepod density. Brown-water zooplankton cultures supplemented with rice bran had significantly higher naupliar densities than either brown-water zooplankton cultures without rice bran or zooplankton cultures supplemented with rice bran but without brown-water exchanges. Both the rice-bran-supplemented brown-water zooplankton culture and the rice bran zooplankton culture had higher copepodid densities than the brown-water zooplankton culture, but they were not different from each other. The goal o...

THE EFFECT OF FISH ON PHYTOPLANKTON GROWTH IN OUTDOOR TANKS

The presence of mullet in 4,000-liter tanks used for rearing bull innows (Fundulus grandis) was noted to promote and prolong algal blooms compared to tanks of bull minnows containing no mullet. In separate studies utilizing 4-liter cultures, algal concentrations were noted to be an average of 3 times as dense in containers with mullet as opposed to cultures with either no fish present or bull minnows present. Algal concentrations for all treatments were an average of 2 times denser for treatments that were fed as opposed to those that received no food.