Some procedures must be developed for rapid sizing of fry, especially if wild fry are continued to be used. Animals collected are varied in size (0.2 – 0.6 g), of diverse genetic stock and exhibit notable differences in aggressiveness in terms of feeding behaviour. This imports an imbalance in the uniformity of feed consumption whereby smaller fry are unable to effectively compete for food in the holding facility. Evidence suggests that this has a direct effect on overall mortality and certainly affects food assumption efficiency. It appears that initial mortality may be more related to the system itself and animal competition rather than to the nutritional competition of the specific diet. Sizing of animals into two to three groups (i.e., <0.2 g, 0.2 – 4 g, and >0.4 g) should minimize feeding competition and allow a more uniform particle feeding system geared to animal ingestion features.
The pattern of water circulation in the culture vessel and orientation of animals to the food particles are of prime importance. In view of the superiority of circular tanks that have a water pattern permitting uniform distribution of food particles, there is a need to increase the number of such vessels for future work. Ratio of depth to circumference also is important, allowing transport of food particles at least several times around the tank with minimal sinking. Animals can be adapted to surface feeding, thus making a flake particle highly advantageous. As noted in the initial report, there is a need for additional experimental tanks along with an evaluation of the entire experimental capability of the Elat unit in terms of culture vessels required for current and projected programmes.
Recommendations were made in the initial report for the obtaining of urgently needed equipment at Elat. Such apparatus includes hammermill, Wiley Mill, forced-air drying oven, micro-pelleting apparatus, particle-sizing equipment and a drum dryer for preparation of flake formulations. These needs are outstanding and constitute top priority requirements. At this time, fry diet preparation and sizing is limited and is a serious restriction on the research capability of the unit.
The striking success of flake preparations as an early fry food further emphasizes the need for installation of such a unit at Elat. Presently, the experimental flexibility of Dr. Kissel in the area of diet development for young animals is limited due to these aforementioned equipment shortages. Furthermore, it is not possible to produce large volumes of diets for maintenance of fry populations for pond/cage stocking purposes. Any high protein commercial diet for this purpose must be imported and there is no assurance that such material will be optimal for the S. auratus fry. Optimization of any fry diet will require the equipment noted above.
There is a high priority need to establish an inventory of specialised feed commodities for preparation of experimental diets. Such items as protein concentrates, a variety of fish-based products (i.e., fish oil, solubles), pregelatinized starches (for particle binding) are unavailable at the Elat facility. Shortages of critical items are seriously affecting the experimental flexibility of the nutritional effort under Dr. Kissel's direction. Means must be developed to expedite shipment of such dietary ingredients into Israel. Legistics are still a serious problem and should be resolved at the IOLR headquarters in Haifa. For maximal efficiency, and to use the time of Elat personnel more effectively, ingredient information should be properly programmed and available for ready data retrieval. Use should be made of the recently accessioned Wang 2200-S computer at Elat for an ingredient programme geared toward commodity replacement, diet development, and least-cost formulation.
As mentioned in the previous report, technical assistance is urgently needed by Dr. Kissel in the area of nutrition and diet formulation. Such personnel will be required for the battery of analytical studies needed, such as rancidity testing of fish meal and oil preparations, effect of feed drying temperature on fatty acid composition, etc. At this time, limited personnel available does not allow such work, which must be considered as an essential component of the overall diet development programme. Budgetary considerations for this phase of the work should provide for a trained technician to assist Dr. kissil in his work.
The urgent need for a separate feed storage and diet preparation facility at Elat was stressed in the initial report. Proper storage of feeds is needed to avoid their breakdown under the existing high temperature conditions at the culture site. The problem is especially important in high fish meal/fish oil diets, whose breakdown can result in pathobiological conditions in the fish population. It was indicated that this requirement is now being met in terms of a projected storage processing facility to be built adjacent to the culture unit. Nevertheless, close attention must still be paid to in-situ temperature conditions in the unit if minimal use is made of air conditioning. The logistics of feed preparation must be analysed in terms of proper separation of storage area, pellet manufacturing section, and the portion of the unit intended for fabrication of experimental diets.
Cooperation with other culture/nutrition units is essential to avoid long delays due to logistics and procedural problems. Such cooperation already established with the CNEXO laboratory at Brest, France, is excellent in terms of benefits to the Elat effort. Plans should be made for on-going personnel exchange and training in both the spawning/hatchery area as well as in the diet formulation/nutrition programme. In the latter regard, Dr. Kissil should visit the CHEXO unit to participate in their excellent marine fish nutrition efforts.
