2012/720 Learning the practical aspects of using clay particles to improve bacterial management during marine larval culture, University of Miami, Experimental Marine Hatchery

By Robert Michael

High incidences of malformation and low level survival are common during Yellowtail Kingfish larviculture and it has been hypothesised that this is a result of excessive harmful bacterial loads within the culture tanks. The current rate of malformation and survival continues to impact heavily on the price of juvenile kingfish. There is a need therefore, to reduce the incidence of such malformations and increase the overall survival rate to reduce the cost of juvenile production and improve the quality and quantity of fish being put to sea.

The researcher Dr Michael, travelled to the University of Miami’s Experimental Marine Hatchery (UMEH) to work and train under the supervision of Professor Daniel Benetti and alongside his Masters student, Mr Zack Daugherty, the subject of whose thesis is the use of clay particles in larval rearing of Cobia. Over the past 12 months Mr Daugherty has been conducting preliminary trials on the best methods of handling and delivering clay particles to larval rearing tanks.

During the 30 day visit, Dr Michael was able to further develop these techniques with Mr Daugherty prior to conducting a 13 day replicated research trial that assessed the potential bacterial reducing properties of using clay during Cobia larval rearing compared with the standard green water method that uses concentrated nannochloropsis paste. Using clay particles to replace nannochloropsis paste during the green water phase of Cobia larval culture was recently investigated. The results clearly showed that using this media has the potential to greatly reduce bacterial loads within larval tanks and reduce costs associated with purchasing algal paste concentrates.