3. broodstock

3.1 domesticated stock

A ten year research project undertaken by the CSIRO consortium in conjunction with The Australian Prawn Farmers Association to remove the barriers to domestication of Penaeus monodon (Fabricius) has resulted in major advances in the understanding of the reproductive biology and epidemiology of penaeid prawns (CSIRO, 2010).  Eight generations of selective breeding has substantially improved growth and survival rates (Preston et al., 2009).  The screening of animals for pathogenic viruses e.g. GAV, MoV and MBV using the molecular techniques , in situ hybridization (ISH) and polymerase chain reaction (PCR) assays has brought the industry to the forefront in obtaining specific pathogen fee (SPF) certification (Coman et al. 2009).  The choice of sampling tissue for RT-PCR tests is the pleopod exopodite.

2. marine algae

“Starter cultures” in 250 ml flasks of the microalgae species Chaetoceros muelleri (CS-176/6) and Skeletonema tropicum (CS-604/6) are obtained from the CSIRO National Algae Culture Collection in Hobart.  C.muelleri is predominantly a single celled diatom with a cell diameter of 8-10 microns (Kipp, 2010).  S.tropicum is a colony forming diatom of variable length with a cell diameter of 5.3-23 microns (Louisiana Universities Marine Consortium, 2009; Sarno et al, 2005).  The Algae Laboratory is fully equipped for axenic culture applications with autoclavable borosilicate glassware: volumetric flasks, pipettes, erlenmayer flasks, graduated cylinders and petri dishes.  Working stock solutions and primary stock solutions are routinely composed (Figure 14).  Sterilized seawater from the autoclave (Siltex) (Figure 15) is prepared in two litre flasks with culture medium F2. This medium is made up into stock solutions of the following chemicals:

Ø  Sodium/Potassium Nitrate

Ø  Sodium Di-Hydrogen Orthophosphate

Ø  Sodium Silicate

Ø  Ferric Chloride and Trace Elements

Ø  Ethylenediaminetetraacetic Acid Di-Sodium Salt (EDTA)

Ø  Stock Solution of Vitamins B6; B12 and Thiamine

Ø  (CSIRO Australian National Algal Collection, 2010)

MARINE PRAWN CULTURE 1. hygiene procedures

Hatchery hygiene is of major significance due to the risk of contamination of cultures from outside sources.  Strict hygiene protocols are necessary to maintain a pathogen-free, low risk rearing facility.

Biosecurity in the hatchery is maintained through an integrated management approach, and adhering to levels of quality in practice that provides the desired result. The biosecurity program encompasses these techniques:-

2. compressors

Two high pressure side channel blowers provide air throughout:-

(i)                  Bora (Sap 50) (Figure 12)

(ii)                Rietschle SKG 300 (Figure 13)

sterilising the water flow

Two, three phase Onga pumps (Model 142) bring water from the 40 tonne tanks into the hatchery system (Figure 6).  The Ultraviolet Steriliser (Ultra Pure Model 85k) provides treatment that leaves no residue in the seawater due to the use of light (Figure 7).  However it is the combination of methods that removes bacterially produced toxins, pesticides, heavy metals, etc.  Each of the production tanks have disinfected saltwater and freshwater on tap.

TECHNICAL SYSTEMS 1. pumping procedures

A 120 micron screened filter is positioned on the creek bank to allow input of seawater at salinity of 35 parts per thousand on the flood and ebb tides (Figure 1).  Pumping is avoided during heavy deluge or the presence of algal blooms in the creek (Figure 2). The three phase Onga Model OJ800 saltwater pump lies 4.4 metres at the base of a concrete well.  The pump lifts water to a subset of filters before flowing into the 350 tonne storage tank.  The subset consists of a 100 micron cartridge filter, then two sandfilters (Figure 3).  Liquid chlorine in the form of sodium hypochlorite is added to the raw water at 20 mg.L^-1 for sterilization purposes (Figure 4).  Chlorinated seawater is pumped from the settlement tank with the three phase Onga pump Model 112 and through a one micron cartridge filter to either of two 40 tonne temperature controlled tanks (Figure 5).

marine hatchery

The Marine Hatchery is situated on a 3,398 m² site, with a total building area of 732 m².  Access to a quality water supply from Cabbage Tree Creek is through an adjacent filtration and pumping system.   The desirable water conditions of the creek are due to its proximity to the mouth enabling a substantial turnover with oceanic influx, and an abbreviated catchment area which limits run-off from surrounding landbased activities.  Primary water storage is a 350 tonne fibreglass settlement tank which protracts into 2 x 40 tonne sterilisation and controlled temperature tanks.  The Hatchery has a fully equipped Larval Rearing and Nursery Section with total tankage of 185 tonne, Mass Algal Culture Room of 60 tonne capacity, and Finfish Production Unit of 25 tonne capacity. Ancillary areas include a functional laboratory, live feed preparation room and pump room.  Each section has overhead reticulated air and water systems, drainage system and water heating system.  A considerable amount of plant and equipment is incorporated as fixtures within the facility. The Hatchery is a specialist production edifice for marine prawns e.g. Tiger prawns, and finfish e.g. Barramundi, with a production cycle from spawning to market of 25 days for prawns and 45 days for finfish.

This is a blog if a detailed account of the operation of a site specific marine hatchery.

http://www.raywhiterural.com.au/