Appendix 6A
LATIN, SYRIAN AND FRENCH NAMES OF SPECIES OF INTEREST FOR AQUACULTURE

Appendix 6B
SUITABILITY OF TILAPIA FOR MARINE FISH FARMING

(from FAO, 1980¹)

1. CHARACTERISTICS OF SOME TILAPIA SPECIES

2. SUITABILITY OF TILAPIA SPECIES FOR MARINE RESEARCH (Peacock, 1979)

2.1 Species and site

The species tested during these experiments were the following:

Fingerlings were obtained at a weight ranging between 1 and 4 g. First, the acclimatization was gradual (5 % per day), in order to confirm salt water tolerance. Then, fingerlings were acclimated in bulk at 10 % and sometimes 20 % per day and transported to sea cages in batches of 100.

The site was Sharm Obhor, a deepwater creek 25 km north of Jeddah. The cages (holding 1 m³ of water) were hung from a 25 m² raft moored in 20 m depth within 1 km of the mouth of the creek.

Sea temperatures range from 25 to 31°C, averaging 26–27°C from January to May and 28–29°C for the rest of the year.

Fingerlings were fed on trout fry feed up to 50 g whence they graduated to carp feed.

2.2 On-growing Sarotherodon niloticus

A total of 1 500 4-mg fingerlings were imported from Kenya, but a problematic journey reduced the number to 100 which were released in a sea cage after acclimatization. At the third month, a non-identified disease became apparent.

¹ FAO, 1980 Saudi Arabian Funds-in-Trust, Report to the Government of the Kingdom of Saudi Arabia. Mariculture in Saudi Arabia: A feasibility analysis and a proposal for a development programme. A report prepared for the Hydroagricultural Development Project based on the work of O. Ledoux. Rome, FAO, FAO/UTFN/SAU/002/SAU (TF 117):88–91

At the fourth month, the males weighed 55 g, the females 20 g. At the fifth month, the cage ruptured.

2.3 On-growing Sarotherodon spilurus

Although fingerlings suffered the same difficult journey experienced by S. niloticus, they survived markedly better (20 % survival after shipment to marine cages and losses by escape through meshes).

On a first trial, about 100 Spilurus fingerlings were released in a net-lined 1 m³ cage. The growth average rate was 1.7 % per day, compared with the 2.9 % achieved in fresh water at Roobab Farm in Kenya with male tilapia. It was suspected that poor feeding was responsible for these results. The fishes weighed around 250 g after 8 months of growth. Mortality, at a rate of 4.7 % per month, was low.

A second trial used a batch of Jeddah-bred fish initially weighing 0.9 mg. During the first five months, the growth rate was 2.7 % per day, which is very satisfactory. Mortality was low again (5.8 % per month). The growth rate dropped markedly as the fish approached 100 g, and again poor feeding is believed to be responsible.

2.4 On-growing S. aureus

The following results showed that S. aureus is not to be considered for salt-water rearing:

• mortality after the flight bringing the fishes from Kenya

• extensive mortality during salt-water acclimatization

• sensibility to diseases

• failure to breed satisfactorily.

2.5 On-growing Tilapia zillii

T. zillii from lake Qarun in Egypt were the first tilapia species imported and these adapted well to sea-cages, although they were affected by disease in saltwater aquaria. This species grows more slowly than the three previously described, whilst favouring a cheaper vegetarian diet.

Other trials were initiated by importing fingerlings from Kenya. Two trials were followed by lethal results during salt-water acclimatization. T. zillii are the most common salt-water adapted species in the Near East, but it is apparent that the purely freshwater strain from Kenya lacks the tolerance of Egyptian T. zillii.

2.6 Conclusions

On-growing certain Tilapia species in full-strength seawater is evidently not only feasible, but apparently capable of achieving results at least comparable with those of freshwater techniques. Among the species tested, Sarotherodon spilurus stood out as demonstrating a survival and growth performance that matches the requirements of aquaculture, Admittedly, these trials were of limited duration, occurring over one year with few batches of fish. Other species should not be rejected at this stage.

A combination of aspects of saltwater tolerance, satisfactory breeding characteristics and ease of handling present a very strong case for selecting S. spilurus for marine tilapia farming (which looks very promising).

3. PRELIMINARY OBSERVATIONS OF SOME ASPECTS OF BREEDING THE AFRICAN CICHLID SAROTHERODON SPILURUS (Osborne, 1979)

At an average temperature of 30°C, female Sarotherodon spilurus were found to breed every 9–14 days if the eggs or yolk sac fry were removed from the buccal cavity for in vitro incubation. A breeding unit of 15 females and 2 males produced 64 319 eggs and fry from 82 broods in 50 days of breeding, 1.64 broods per day; 48 000 eggs, 11 155 yolk sacs and 5 164 fry were obtained from 54, 17 and 9 broods respectively, an average of 857 eggs or 656 yolk sac fry or 574 fry per brood. The production was obtained in an area of 8 m², out of which only 4 m² were used by the breeding population.

A large incubator, with an incubation capacity of 10 000 eggs has been designed. Hatch rates over 90 percent were obtained by using this apparatus.

Prophylactic use of formalin at the rate of 1:25 000 a.i. prevented fungus growth on the eggs and contributed to the high hatch rates obtained.

Yolk-sac fry were successfully incubated in shallow, unaerated dishes, at stocking densities up to 1 000 fry/litre. Survival rates were over 95 percent.

4. SOME ASPECTS OF THE SALINITY TOLERANCES AND SUBSEQUENT GROWTH OF THREE TILAPIA SPECIES: SAROTHERODON AUREUS, S. SPILURUS AND T. ZILLII (Osborne, 1979)

4.1 Methods

Salinity shocks (10, 20, 30 or 40 per mille) were applied to:

• one or two day old S. spilurus eggs
• yolk-sac fry (4–5 days after spawning)

Acclimatization to various salinities has been tested with various procedures (ranging from gradual acclimatization to 40 per mille sea-water over 4 days to direct transfer to seawater) with:

• newly emerged fry
• juveniles (1–3 g)
• adults (over 50 g)

Growths of S. spilurus in three different salinities (2 per mille, 20 per mille, 40 per mille) were tested.

4.2 Results and conclusions

Although eggs survived abrupt transfer to higher salinities, hatchability was reduced as salinity increased, from 95.7 percent at 2 per mille, to 86.3 percent at 10 per mille, 72.2 percent at 20 per mille, 48.2 percent at 30 per mille and 29.2 percent at 40 per mille.

No yolk-sac larvae survived beyond day 5 at salinities higher than 20 per mille. In 2 and 10 per mille, 99 percent of yolk sac fry that successfully hatched survived to day 7.

Survival of fry during acclimatization is dependent on the first salinity change. At a day 1 salinity of 10 per mille, survival was uniformly over 98 percent, even if subsequently transferred abruptly from 10 to 40 per mille. Survival reduced to 66 percent, 1.3 percent and 0 percent for a day 1 salinity of 20, 30 and 40 per mille respectively.

It is recommended that the fastest acclimatization procedure be used for fry, i.e., 2–10–40 per mille in two days. There is no apparent benefit from slow, gradual acclimatization.

Juvenile S. spilurus exhibit the same tolerances and survivals as fry.

Growth and survival in brackish or full-strength seawater are higher than that found in freshwater. A growth coefficient of 2.49 percent/day (length) in 2 per mille and 3.12 and 3.09 percent/day in 20 to 40 per mille respectively, was found.

There was no significant difference in growth rates in 20 or 40 per mille.

The race of T. zillii imported from Kenya appears unable to tolerate full strength seawater. However, a population of T. zillii which differs morphologically has been noted. This population lives at salinities of 1–3 per mille and has a reduced salinity tolerance in marked contrast to populations found in Lake Qarun, Egypt.

S. aureus appears unsuitable for culture in full-strength seawater. The possibility of a disease with this stock cannot, however, be ruled out entirely. It has been, therefore, recommended that further trials be carried out with this species.

Appendix 7
TENTATIVE APPRAISAL OF A POND-CULTURE FARM

1. Purpose of Analysis

The purpose of looking into the costs and earnings of potential pond culture is to form an opinion as to whether or not pond culture has a possibility of becoming economically attractive as a commercial activity.

2. Management Scheme

Recent developments in southeast Asia and the Middle East indicate that semi-intensive culture of mullets in saltwater ponds may be commercially viable. Mullet production of 3 t/ha/year is reported, from 30 g to 500 g (Mugil capito) or 1 500 g (Mugil cephalus) in a two-year production cycle. Calculations will be made for two different farm sizes: 8 and 50 hectares.

The farm has two types of ponds, all about 2 ha in size. Fry is harvested from the wild and raised for 9 months in fry rearing ponds until a weight of 30 g, then transferred to production ponds for growth to market size.

Pumping station is calculated for a water change every 3 months.

3. Inputs

Excavation accounts for the major part of pond construction costs. Therefore, the costs of pond construction do not decrease markedly with the increase in size of the farm (assuming, as we have done, that the size of individual ponds remains about the same).

Because of the considerable investment, depreciation and interest occupy between 25 and 30 percent of annual cost for a farm under full operation.

Amongst the recurrent costs, feed (40%) and salaries account for the greater part.

4. Output

The production of 3 t of mullets per hectare (of production pond) per year, uses a feed consisting of 25–30% of proteins.

As part of the pond area is used for grow-out of fingerlings, the effective yield is about 5/ha of pond area every two years.

5. Returns

The revenue generated, under different assumptions of prices at the farm-gate, is shown at the bottom of Table 5. Comparing gross revenue and costs it appears that this type of corporate fish culture, for the local market, could be commercially possible in Syria.

The price of £S 12/kg at the farm-gate, may be considered the equivalent of a freshwater fish price (Tilapia). At present, a £S 15/kg price is a minimum production price from fisheries.

Table 1

POND CONSTRUCTION AND ASSOCIATED INVESTMENT

Table 2

COST OF CONSTRUCTION OF A 2 HA POND

DYKES CONSTRUCTION

Table 3

PUMPING REQUIREMENTS (50 ha)

Water depth : 1,5 m - total water volume : 1,5×500 000 = 750 000 m³

4 water change per year : 3 000 000 m³/year

Pumping capacity : 1 m³/s = 3 600 m³/h - 75 HP Yearly pumping hours needed

Fuel needed : 835 × 75 × 0,15 = 9400 1

Table 4

SEMI-INTENSIVE FISH CULTURE

REQUIREMENT AND COSTS OF PERSONNEL

Table 5

COST OF OPERATION AND INCOME

(2 YEARS)

Appendix 8
APPRAISAL OF CORPORATE SCALE, INTENSIVE SEA-BASS FARMING

1. Management Scheme

Recent developments in the Mediterranean region indicate that intensive culture of sea-bass (Baghran), in certain settings may be commercially viable. Such a culture is analysed in this Appendix. Calculations will be made for two different farm sizes: 50 t and 300 t/year.

The farm has two types of raceways (25 × 2 m and 75 × 4 m), in order to grow the fish from fry (2 g) to fingerlings (30 g), then from fingerlings to commercial size (330 g). Fry will come from a hatchery, included or not in the farm. Feed will contain about 45% of protein and conversion index will be 1:2.5. Water change will vary from 1 l/sec for 100 kg of fish (commercial production) to 2 l/sec for 100 kg of fish (fingerlings production). Density will be 15 to 20 kg/m³.

2. Inputs

Concrete for raceways construction, and pumping station implementation accounts for the major part of farm construction costs. Therefore, the costs of raceways construction do not decrease markedly with the increase in size of the farm (assuming, as we have done, that the size of individual raceways remains about the same. The costs of pumping station implementation, on the contrary, does not increase with the increase in size of the waterpumping capacity. Depreciation and interest occupy between 20 and 25 percent of annual costs for a farm under full operation. Amongst the recurrent annual costs, fry and feed account for the greater part; energy and salaries are the two other main components. Two hypotheses are presented for each farm; a first hypothesis, with a higher rate of mortality, and a lower conversion index: this hypothesis could be used for the first 2 or 3 years of production. The second hypothesis corresponds to a well managed farm.

3. Outputs and Revenues

The farms are calculated for a production of 50 t/year and 300 t/year; costs of production vary between £S 25 and 36/kg. Sea-bass is considered as a first category fish, and £S 40–50/kg price could be obtained either on local market or on neighbouring countries markets. Comparing such prices and production costs, it appears that intensive marine fish farming could be now commercially possible in Syria. In addition, we should point out that the above analysis was carried out under unfavourable assumptions: cost of feed should be lower (£S 2.5/kg); cost of energy could be reduced by using diesel engine for pumps, etc.

RACEWAYS CONSTRUCTION AND ASSOCIATED INVESTMENTS

PRODUCTION SCHEME OF SEA-BASS (DICENTRARCHUS LABRAX)

IN THE MEDITERRANEAN

INTENSIVE MARINE FISH FARMING

REQUIREMENTS AND COSTS OF PERSONNEL

REQUIREMENTS AND COSTS OF FINGERLINGS
50 T FISH - FARM

Costs : H 1 : 313 500 × 1,5 = 470 250
H 2 : 260 500 × 1,5 = 390 750

REQUIREMENTS AND COSTS OF FINGERLINGS

300 T FISH - FARM

Costs : H 1 : 1 882 000 × 1,2 = 2258 400
H 2 : 1 562 500 × 1,2 = 2258 400

ANNUAL RUNNING COSTS FOR A PRODUCTION
OF 50 T PER YEAR

ANNUAL RUNNING COSTS FOR A PRODUCTION OF
300 T PER YEAR

COMPARAISON BETWEEN INTENSIVE FISH FARMING, MARINE FISHERIES
AND CHICKEN PRODUCTION

( 1 ) Marine aquaculture : S.P. 35/kg
Marine fisheries : S.P. 13/kg
Chicken (alive) : S.P. 6.7/kg