3. RECOMMENDATIONS

The main arguments which at this stage influence judgement on the suitability of using Elat as an oyster culture station are outlined in section 2.2 but on the basis of current information it is believed that there may be major difficulties involved. If problems known to exist in connexion with the method of culture are to be solved then a considerable research and development programme is likely to be required. In addition, if further research confirms that the standing stock of phytoplankton is inadequate for oyster growth then this would present an insuperable obstacle to the development of oyster culture in Elat.

There are, however, major gaps in the information available on which to base a judgement and an initial one-year programme for 1972 has been suggested to OLRC. This should provide initial answers on the method of culture, obtaining stocks of juvenile oysters, and the productivity of the sea water. At the end of this one-year programme, sufficient information should become available for OLRC to make a more soundly-based assessment on whether it is advisable to proceed with oyster culture at Elat and, if so, the effort that will be required. It is recommended that OLRC should obtain the assistance of an experienced consultant in evaluating this data. Section 3.3 of this report outlines the probable scale of effort which may be required if the 1972 experiments produce encouraging results.

3.1 Staff and Equipment at Elat

Two staff are available for full-time oyster research during 1972 with some assistance from a third person; only the senior member of the team has had a biological training. After account is taken of military duties, annual and state holidays, each man is available for about nine working months per year. It is recommended that there should be two men continuously available during 1972.

In the consultant's opinion it is unwise to arrange a research programme in which a man is physically engaged on his studies for more than half his working time. The remaining time should be taken up with general investigation in the research field, correspondence and reading. It must be stressed that the volume of published work on oyster culture throughout the world is very considerable, and the team at Elat should allow adequate time to become familiar with this. The staff of five which OLRC has based in Elat are accommodated in two bays of a three bay laboratory. They are clearly very cramped for space and laboratory work of an advanced nature cannot be expected under these conditions. Equipment and apparatus belonging to the University is available, although its widespread use may involve some problems. The budget for oyster research at Elat for 1972 is IL 100 000; this is mainly earmarked for salaries and does not allow for administrative or accommodation expenses.

3.2 Research Programme

The central theme is the necessity to obtain information on the growth and fattening of oysters at Elat. If this is found to be satisfactory then many of the other difficulties can be overcome. This estimate of growth rate will not be easy to obtain because of the difficulty of obtaining any substantial quantity of young oysters for these experiments. The larger oysters, of unknown age, which can be collected in the inter-tidal zone, are probably stunted and will yield unreliable growth data. They are probably a satisfactory source of material for studies on fattening and the breeding cycle.

Growth in the field. In a number of places, juveniles which are probably less than one year old, can be found attached to rocks very low in the littoral zone. By measuring samples of these at monthly intervals, data on the growth of individuals can be accumulated. Oysters can be identified either by mapping or marking with numbers.

Collection of natural spatfall. Since the oysters are confined to the inter-tidal zone, attempts should be made to collect the natural spatfall in that zone. Collectors of plastic or asbestos coated with a lime mortar should be exposed in sheltered areas - which can be made artificially with woven wood fencing - and the spat obtained allowed to grow for several months until their identity is certain. They can then be stripped from the collectors and planted in trays for growth studies. This will provide information on:

1. season and intensity of natural settlement, and

2. region of best settlement.

It is possible to collect small numbers of young spat attached to barnacles on the oil jetties. These can be transferred without damage to sub-littoral trays.

Condition index. The regular measurement of condition index in both natural populations and those which have been transplanted to cages in the sub-littoral zone should be continued and extended to include estimates of gonad condition. Although the condition index is only partially related to growth rate, it provides information on the period of the year favourable to the production of good quality oysters. An attempt should be made to measure the growth of those population which have been transplanted into trays.

The research items listed will not only give data on growth rate but will also inevitably provide information on possible culture techniques: stability of submerged structures at Elat, fouling problems, mortality of oysters, and the seasonal arrival of predators.

Larval rearing. It has been suggested that some attempts should be made to rear oyster larvae at Elat as it would (a) provide a reference collection of small stages to aid identification, and (b) provide stocks of juveniles for growth experiments. This type of work is likely to take a good deal of time and the available laboratory facilities are hardly adequate. The consultant advises that the effort devoted to this item should be small.

It is possible that a rearing trial can be made at the Fisheries Experiment Station, Conway, U.K., where suitable facilities are in continuous operation. This experiment would provide reference material and, if sufficiently successful, might provide some material for growth studies at Elat. It has been arranged for a sample of oysters to be sent to Conway in January 1972.

Standing stock of organic matter

It may be that suitable growth data will not be obtained due to the difficulties which may be experienced in obtaining suitable oysters, or possibly due to the inherently poor growth rate of the species studied. To guard against this some basic observations on the standing stock of organic material in the sea water at Elat should be made for comparison with the water in other areas known to be favourable to oyster culture. A satisfactory cover of this area of study can only be obtained by the cooperation of other groups within OLRC.

The simplest technique (for which equipment is available at Elat), is to estimate the total suspended organic matter and the chlorophyll content of samples of sea water. If the samples are graded by sieving through several sizes of mesh, information will be obtained on the proportion of the suspended organic matter in various size groups. The finer groups, amongst which the oyster finds its food, are of the greatest interest in this context. The analytical methods are described by Strickland and Parsons (1968).

If it can be arranged for chemical analyses to be made by the chemical laboratory of OLRC in Haifa, phosphate and nitrate analyses should be made of twice weekly samples of water taken from the vicinity of the oyster growth experiments.

A number of qualitative studies on the plankton at Elat has been made by the staff of the Sea Fisheries Laboratory. Discussion with Professor B. Kimor, the Director of this group, has shown that it may be possible to extend this to a quantitative basis during 1972, with the cooperation of the oyster team at Elat. The consultant suggested that quantitative samples should be collected by a portable petrol pump from the vicinity of the oyster culture experiments adjacent to the laboratory. The samples should be examined so as to give (1) data on the abundance of individual species, and (2) the dry weight and chlorophyll content of plankton collected by nets with meshes of various sizes.

3.3 Work after 1972

If the studies made in 1972 are sufficiently encouraging some predictions can be made on the scale of effort which is likely to be required if the project is to be brought to fruition in a reasonably short time. Decisions would have to be made on the species to be cultivated, the method of culture (including predator control) and the commercial outlets envisaged. The following sections outline the work required which will take at least one to three years to get under way, followed by two seasons of full study.

If the local oyster (Crassostrea cucullata) is found to be suitable, then either:

1. intensive efforts will have to be made to catch and harvest the maximum number of naturally occurring spat; this will need the services of two men full time;

   or

2. producing stock by hatchery methods. A small hatchery (about 60 m²) requires a staff of three people at least one of whom should have training overseas. A hatchery could also from the basis for supplying stock to other areas.

If the local species is not suitable for culture, then trials will have to be made with species which are not native to the Gulf of Aqaba. It is strongly recommended that such introductions should be through a hatchery. As a guide, a copy of the code of practice at present being considered by the International Council for the Exploration of the Sea (ICES) is attached (Appendix 1).

Cultivation involves rearing the spat, which may either be caught in the sea or obtained from a hatchery to market size. Studies must be made on methods of rearing, comparative value of different sites, growth rates, meat quality and the control of predation and fouling organisms. Three men with additional assistance will be required for construction work and during busy seasons.

Sanitary and quality control standards will be required in conjunction with assessments of the market requirements. Realistic estimates of the capital and running costs of commercial development should be made as the data obtained from the studies outlined above become available. A decision will be required on whether to sell oysters on the shell or in a processed form.

This programme envisages the employment of five or six men with some outside support for a period of three years. Appropriate secretarial and administrative support would also be required. The major land-based capital cost will be incurred if hatchery development is required. The capital costs of harvesting and cultivating are likely to be more modest.

3.4 Pearl Oysters

The other potentially promising bivalves in the area are species of pearl oysters. Some information on the culture of this group for mother-of-pearl is available for the Red Sea (see Reed 1966, FAO 1962). It is possible that moderate numbers of young specimens of one or more species can be obtained in the vicinity of Elat, and the consultant recommends that these should be used for simple growth experiments in 1972. Pearl oysters are only attached to the substrate by a byssus and therefore young specimens can be more readily moved for experimental purposes than is the case with the edible oyster. The collected specimens can be kept in the same submerged cages used for the edible oyster experiments and their shell growth rate observed by measuring at monthly intervals. This would provide information on two points:

1. further data on the suitability of the Elat area for the culture of bivalves;

2. an indication of whether pearl oysters are more suitable than edible oysters for cultivation at Elat.

Before more extensive work is contemplated some studies of the market requirements for (a) shell and (b) cultured pearls should be made. Note should be taken of the social framework within which this type of culture is an economic proposition elsewhere in the world.

Table 1

THE AVERAGE HOURS OF SUNSHINE AND SEA WATER TEMPERATURE AT ELAT
(Israel Meteorological Service)

Table 2

THE PERCENTAGE FREQUENCY OF WIND SPEED AND DIRECTION AT ELAT FOR THE PERIOD 1960–69
Taken every 3 hours
(Israel Meteorological Service)

Table 3

THE DISTRIBUTION OF THE DRY MEAT CONDITION INDEX IN 222 OYSTERS COLLECTED IN THE PERIOD MAY-NOVEMBER 1971