COMMUNICATIONS (continue)

NATIONAL FOOD PRODUCTION AND FEEDING TECHNIQUES IN THE REPUBLIC OF CROATIA

Miro Kraljevic
Croatia

Total world catch, according to the Bulletin of Fishery Statistics (GFCM-FAO) increased from 19.6 to 90 million mt. between 1948 and 1986. from 1986 to 1992 2 million tons were caught from the Mediterranean and Black Sea. Total catch will increase to 130 million mt by the end of this century.

Unfortunately, there are no available data for Croatian total catch during 80-ies. Total Croatian catch had been and integral part of the total catch of ex Yugoslavia unitil 1988. The coastal line of the Adriatic Sea belongs almost to Croatia (Coastal Croatia belt is 1987 km in addition to the 4 024 km island coastal line and exactly 1 233 island out of which 66 inhabited). More of 86% of the total catch of ex Ygoslavia belonged to Croatia. Since 1988 Croatian total catch (marine) has been presented separately (Morsko Ribarstvo, 1993) but it has not yet been included in the Bulletin of fishery Statistic (GFCM-FAO).

In this study we are presenting some information on statistical relationship between natural total catch and controlled production (both marine and freshwater, fish and shells) of Croatia as well as total production of sea bass (Dicentrarchus labrax) and gilthead Sea bream (Sparus aurata) fingerlings from our marine hatcheries. Also some new information on food production and feeding techniques are given.

STATISTICS OF THE TOTAL CATCH AND CONTROLLED PRODUCTION IN CROATIA

Of the total Mediterranean catch (along with the Black Sea) the catch of Croatia in Adriatic Sea constitutes only 2.13% (1.8–2.4%), while Italian total catch in the Adriatic Sea is five times greater amounting to 10.5%. Total natural catch of Croatia and commercially important fish species (used in mariculture -sea bass, gilthead sea bream, common dentex etc.) account for not more than 0.5 (1985) to 4.6% (1989) of the total catch of the Mediterranean and Black Sea. Shells make up still a lower proportion of from 0.8 (1985) to 2.6% (1989) of the total Mediterranean catch.

A drop of the total catch (by 48%) and total production (by 20%) is quite normal since this is the year of the war in the Republic of Croatia which had been the victim of a terrible aggression. However, in 1992 war is still going on and has proceeded up to now, but the total catch (marine organisms) has shown a slight increase (for 23%) while controlled production has rapidly increased (for 41%) (war stopped in the coastal area). More than 1/3 of the Croatian territory is still occupied and under fierce artillery attacks so we have not got proper information about freshwater production and natural catch.

It is obvious that the natural total catch in sea water prevails over (from 91.3 to 9.3%) controlled production (from 2.7 to 8.7%), but controlled of fish (0.3–2%) and shell (0.1–5.5%) is showing a slight and steady increase. So it can be concluded that mariculture is in progress in Croatia. Freshwater total catch is insignificant (4.7–5.3%) with respect to controlled production which exceeds 95% (94.7–95.3), quite contrary to the situation in mariculture.

Average natural marine catch, when taking into account only the last decade, is about 35200 mt. Pelagic fish prevail, of which sardine Sardina pilchardus, mostly used in canning industry, make up 70%.

Table 1. Natural fish catch (marine and freshwater) and controlled production (fish and shell) in Croatia (Adriatic Sea, 1986–1992).

Table 2. Comparison between marine and freshwater control production (fish) from Croatia in percentage (%) for period 1986–1990.

* There are no reliable data of freshwater control production

Aquaculture production (marine and freshwater fish production) is leveling 15500 mt of which freshwater fish constitute more than 95%.

Sea bass (D. labrax) and gilthead sea bream (S. aurata) are the principal species of interest for the Mediterranean and consequently the Croatian mariculture.

Total controlled mariculture fingerling production in Croatian hatcheries is shown in Table 3.

Table 3. Total production of fingerling sea bass (D. labrax) and gilthead sea bream (S. aurata) in Croatian hatcheries

Production of juvenile sea bass (D. labrax ) and gilthead sea bream (S. aurata) shows a slight increase in production from 2.5 to 5.1 million in Croatian hatcheries (except 1992 - war). In Croatia sea bass production contributes about 82% of total marine production, while gilthead sea bream contribution is about 13%, red sea bream (Chrysophrys major) about 4% and sheep nose bream (Puntazzo puntazzo) 1% (in the inshore cages). On the total Mediterranean production of fingerling sea bass and gilthead sea bream in 1986–1990, Croatia constitutes, with a defined oscillations, from 6.8% to 41.4%. Some other species of potential interest for mariculture are sheep nose bream P. puntazzo, common dentex, salmon Oncorhynchus kisutch. Ongrowing period is usually about 18–20 months for sea bream and 24–27 months for sea bass and fish sizes reach 250g and 350 grams.

Controlled marine production is about 680 mt of fish and 1900 mt of shell in 1992.

In the total freshwater production european common carp (Ciprinus carpio) dominates (73.3– 81.4%), while some other species (grass carp, silver carp, trout and cat fish) are equally represented (see Table 4.).

Table 4. Dominant species in freshwater aquaculture production for the period 1987 to 1990 (in %)

The average yield of the carp in the ponds is 1152 kg/ha, while the highest yield is 1971 kg/ha. More than 99% of these species are red in semi intensive regime and less than 1.0% in cages in the intensive regime. Total production of trout (about 1000 mt) took place in concrete ponds under the intensive regime. Recent production of trout is 257 tons/ha. european catfish (140 mt) and salmo sp (100 mt in brackish waters) are reared in the intensive regime.

FOOD PRODUCTION AND FEEDING TECHNIQUES

Food requirements for marine and freshwater controlled production exceeds. Production in Croatia now is not greater than 1 500 mt/year. The needs are between 17 000 and 20 000 mt/year. It is obvious that more than 90% of food lacks and should be imported from western European fish food factories.

Most fish producers use foreign starters for fish fingerling (marine and freshwater) food. Marine fish, form the stage of fingerlings (5g) to table size (250–300 g) producers make use of more than 90% of imported food (Italy, France, Spain etc.) whereas freshwater fish producers (same size) make use of slightly more than 7% of foreign domestic food.

Before the war in Croatia there had been several fish food factories. Some of them are now in the area under occupation and some have been destroyed during war operations. Single factory left is “POLJOPRERADA” Zagreb. This factory mainly produces food for trout, european common carp, european cat fish, and recently smaller quantities of marine fish food, sea bass and salmo silver. Total annual production is shown in Table 5.

Table 5. Annual production of fish food in mt

Total production is used on domestic market. 50% of raw material for food production (fish meal herring, maize gluten, connectives for pellets, fodder meal, vitamins and minerals) are imported from Western Europe. The remainder (flour, tosted soya, fodder yeast, oil and packing materials) are provided by domestic production.

Enzyme activity in fish in directly affected by the temperature of the water. Since during fish rearing seasons (2–3 years) temperature of a marine environment oscillates from 7–26°C, and that of freshwater environment from 4–30°C (trout 8–16°C) temperature appears to be a crucial factor of optimum conversion rate. So conversion rate varies in marine fish from 1.5 to 4.1 (2.9 mean) and in freshwater fish from 1.3 to 3.3 (1.7–1.9 mean). Conversion factor is also affected by protein quantity (from 40–56%) in food as well as by the size of fish fingerlings throughout the rearing cycle and particularly by food water content (8–78%).

The factor of food conversion was considerably lower in the warmer part of the year (18–26°C) than in the colder part (7–18°C). It is quite common that the lowest value of condition factor in marine organisms is recorded in August and September from 1.5 to 2.2, while in freshwater organisms from 1.3 to 1.8, and the highest in February and March from 3.3–4.1 and from, respectively 2.2–3.3 in food containing less than 10% of water.

Food price is affected by the fact whether used for fingerling feeding or adult fish feeding. It is also different in different producers (ranging from 1.0 to 1.8 DEM per kg).

Marine fish in cage culture are fed manually. Manpower is still more reliable than automatic feeders. Food from automatic feeders fells all the time all the same place in the cage and only stranger and faster indivuduals can reach it. When thrown manually food may be spread throughout the cage and thus both bigger and smaller fish could reach it. Today mechanically driven feeders are coming into use (clock mecahnism continuously drives the food for 12 hours). They are in use for post-larval feeding until the juvenile stage in some of our bigger hatcheries (CENMAR - 4 and MARIMIRNA - 2 millions of fry).

In our fish farms common feeding regimes are used. Small fish (0.1–10 g) are fed 6 to 10 times a day, bigger fish (10–150g) 3 to 5 times a day and the biggest fish (150–300 g) 2 to 3 times a day. The number of daily meals depends on the cultured species (sea bass, gilthead sea bream, trout, carp, salmon etc.), rearing regime (semi intensive), season, water level in the food (pellet, 8– 12%; fresh fish meal 70–80%).

The earliest feeding in our hatcheries is similar to that in other hatcheries throughout the Mediterranean. Sea bass fertilised eggs are kept in dark until complete yolk-sac resorbtion. They are fed live food (newly hatched Artemia nauplii) and they are fed enriched metanauplii of Artemia by the sixtieth day when they pass to artificial food. Gilthead sea bream is fed same way, with the only exception that the first given food is F-type of rotifers Brachionus plicatillis, enriched by fatty acids (n-3 HUFA's).

NUTRITIONAL STATEMENT IN MALTA

S. Deguarra
Malta.

Present state of fish farming industry in Malta

Since the first production of farmed fish in Malta in 1990, production has scared and is now approaching, 1,000 metric tonnes annually (exceeding 9 M $). The species of fish presently being cultured are: gilthead sea bream, (sparus aurata.,) and sea bass (Dicentrarchus labrax). Fish produce is exported to Europe, mainly to Italy. When the commercial companies now licensed attain their target capacity, production is expected to reach 2,500 metric ton (27M $). Moreover, other applications are being processed, and there is scope for developing the industry up to 6,000 metric ton (60M $). Other projects in hand are for local food manufacture and the local production of juveniles.

The local food production for aquaculture is, as yet, nil, and all commercial feed requirement are imported from various countries, namely Spain, Holland, France and Italy.

Research in Malta

Research in Malta is carried out in the National Aquaculture Centre in Marsaxlokk which has the following of facilities:

1. Hatchery.
2. Experimental facilities.
3. Fattening facilities including sea cages in the bay below the fort and fattening tanks in the fort.
4. Laboratories.
5. Conference and Workshop facilities.

6. Library and Computer.

Research and investigations in various fields of aquaculture are carried out by Scientists (permanent staff and students)
interested in Pathology, nutrition, Reproduction… etc.

Nutritional experiments, already performed at the Centre are as follows:

1. Effects of feeding frequency, pellet size and stocking density on growth and feed conversion of or Ochromis spilurus (Gunther). Casser, M. (B. Sc. Thesis May 1991).

2. Growth Comparisons Of Juvenile gilthead Sea Bream (Sparus aurata.) fed diets containing different quality fishmeals. Dallimore, J. (M.Sc. Thesis June 1993)

3. Growth responses of two species of tilapia. Debono, L.D. (B. Sc. Thesis, May 1991)

4. The effect of initial larval density on Growth and swimbladder inflation in intensively reared lar val gilthead sea bream (Sparus aurata..) Spiteri, A. (B.Sc. Thesis, May 1993)

Other research activities in nutrition which have been performed just lately or are underway are:

1. Comparison of growth of Two species of tilapia, Oreochromis spilurus and red tilapia (Chitlata Variety from Thailand (Oreochromis mossambicus × Orecochromis niloticus ) fed at different rates. Deguara, S.

2. Comparison Of Growth Of Two Species Of Tilapia, Oreochromis spilurus And Red Tilapia (Chitlata Variety From Thailand (Oreochromis mossambicus × Oreochromis niloticus) At Three Different Salinities. Deguara S.

3. An investigation of the potential of the unicellular algae Rhinomonas reticulata Var. reticulata Novarino 1991 for feeding the rotifer Brachionus plicatilis for Use in a marine fish hatchery. Vassallo, A.

4. Preliminary trials on the potential Crowth of amberjack Seriola dumerili using formulated pellets. Deguara, S.

5. Growth of gilthead sea bream (Sparus aurata.) fed diets containing different sources of protein. Bekkevold, K.

6. Study on the continuous culture of Brachionus plicatilis. Spiteri, D.

A number of new species are being grown in captivity in the hope that research may be conducted for their potential use in aquaculture, namely the amberjack, Seriola dumerili, while bream, Diplodus sargus, and sheepshead bream, Puntazzo puntuzzo. Some work has also been done on the dolphin fish, Coryphaena hippurus.

FOOD PRODUCTION AND FEEDING TECHNIQUES IN AQUACULUTRE.

G. Anastasiades,
Cyprus

Introduction

Aquaculture is a new developing sector of fisheries in Cyprus. All aquaculture activities are based on the reproduction, larval rearing, fattening and marketing of the marine fish species Sparus auratus (guilthead sea bream) and Dicentrarchus labrax (sea-bass), and on an experimental basis Puntazzo puntazzo (Sharpsnout bream). Pagrus major (red seabream), Dentex dentex (common dentex), and Pagrus pagrus (common bream) as well as on the fresh water fish species Oncorhynchus mykiss (rainbow trout), coi carp (ornamental fish) and Acipencer sp. (sturgeon).

In addition to the Meneou Experimental Marine Aquaculture Station of the Department of Fisheries, three private commercial marine fish hatcheries, five marine fish fattening farms (one land based and four open sea cage farms) and one shrimp farm, operate in Cyprus. Besides, an Experimental freshwater Fishculture Station at Kalopanayiotis of the Department of Fisheries, six small private commercial land based trout farms, also operated in Cyprus, in 1993.

The total marine fish culture production for 1993, is expected to be about 200 tons table size fish (305 gr) and 6.000.000 fry of sea bream-sea bass, about 5.000.000 of the above fry is exported. The trout production is expected to be about 100 tons.

Food Production

The vast majority of the fish food used in aquaculture both marine and freshwater is imported from various European countries. In 1992, 380 tons dry fish food were imported, and 30 tons were produced locally. Imported food is received at regular intervals, to avoid spoilage. All fish farmers make efforts to store their food in cool places. Although there are several local animal food industries in Cyprus, only a very small quantity to fish food is produced due to its lower quality. The small quantity of fish food produced locally are mainly pellets of large diameter.

Lack of technology and suitable equipment make it impossible for Cyprus industries to produce the whole range of fish feeds (fry feeds, fingerling pellets, grower pellets etc). Most of the ingredients used (fish meal, soya bean meal, vitamins, minerals etc) are imported.

Small quantities of food enrichments and special diets are imported for use at the hatchery level. In addition, various kinds of live feeds are produced (algae, rotifers). In 1992, about 2.5 tons of Artemia salina cysts were imported for use in marine hatcheries.

A fish feed formula for trout nutrition was elaborated by the Department of Fisheries, using ingredients which are easily found in Cyprus. This diet is under use at the Experimental Freshwater Fish Culture Station at Kalopanayiotis. A small pelleting press, 10HP, one mixer and a grinding mill are used for the preparation of experimental diets. This diet consists of fish meal, full fat soya bean meal, wheat flour, vitamin premix trace elements, methionine and binder.

The chemical analysis of the diet has the following characteristics in %.

This diet gave a food conversion ratio 1.7:1.

On the other hand with this diet some problems are faced, such as stability of pellets. The pellets after dropping in the water brake up quickly. A relativaly large quantity of dust wich remains in the bags, causes various problems. Experiments were undertaken for the improvement of that formula by using some additives as binders. These are, bentonite, zeolite and potato starch. It was proved that potato starch as binder gave better results.

Feeding Techniques.

Feeding in the larval and nursery level of marine hatcheries is continuous and it is managed with the use of various types of automatic feeders. For per-fattening as well as for fattening of marine fish, feeding is done mainly by hand, two to three times a day for fattening and five to seven times for pre-fattening.

Concerning the nutrition of fish in freshwater land based farms, feeding is done mostly by hand, once or twice a day. In some cage units feeding is done by battery and/or solar operated feeders.

The increase of production of marine and fresh water fish culture, will encourage the local industries to introduce advanced methods and technology for the production of high quality fish food, at lower cost. I believe that our industries in the near future will be ready to produce balanced fish diets, of high quality, equal to that imported.

STATE AND ASSESSMENT OF BULGARIAN FISH RESOURCES

K.I. Yoro
Bulgaria

STATE AND ASSESSMENT OF FISH RESOURCES ALONG THE BULGARIAN BLACK SEA COAST

The specific hydrological and hydrochemical regime of the black sea is characterised by clear stratification with two main layers; superficial or productive one with oxygen presence down to depth of 140–160m and lower-from the depths cited above to the bottom (maximum depth - 2245m) with abundant hydrogen sulphide presence making the sea lifeless. It is a half closed continental basin with intensive anthropogenic influence during the last 20–25 years. Pollution of the black sea with phosphates, nitrates, pesticides, heavy metals, oil and oil products coming from the river flow (83 MLN T suspensions annually) and from coastal agglomerations, is well proved. As a result of pollution the processes of eutrophisation are quickly developing, and phytoplankton blooms and accumulation of organic substances on the bottom sediment and in the water take place. The negative phenomena mentioned above and the abundant ctenophore mnemiopsis mccradyi (introduced from the Northwest Atlantic by ballast ship water in the 1980) directly and indirectly influence the state of the fish resources and their dynamics.

The volumes of commercial catches give to a great extent an idea about the dynamics of fish populations. In Bulgarian black sea waters their volumes changed during the period 1959–1992 between 2.900 (1990) and 19800 (1981) T. Undoubtedly those numbers do not reflect correctly the fluctuations in the resource abundance as catches are directly dependant on the market as well as on the development of the fishing gears resp. On the tendancies in development of the fishing sector. A significant effect on the Bulgarian sea fishery had the implementation of pelagic trawls which increased in a short time, in the early 1970, the volume of the catches. Selling few fishing trawlers to foreign companies had a negative effect. In general the fleet was reduced from 20 units in 1988 to 9 units in 1992. Sprat (Sprattus sprattus) in the main dominant commercial (fish) species. It is of boreal origin, performing local migrations perpendicularly to the coast and has a comparatively short life cycle of 4–5 years. Most important are the first two age groups which usually include 90–92% of the total population abundance. As sprat spawns in the open sea in October march, eggs and larvad are less negatively influenced by mnemiopsis mccradyi which during, the same period forms a very low biomass. Sprat is mainly caught by trawls almost throughout the year and by trap nets - In April–June. Then, after the end of spawning, the species approaches the coast for feeding. The mean size of the sprat is 99–10CM (In length) and 5G (In weight). In the last 15 years a tendency appeared towards decline in the mean length. Sprat gives up to 95% of the Bularian black sea catches

The total biomass of the sprat undergoes annual fluctuations depending on the survival of the new generations and the size of the recruitment. The biomass is assessed by trawl survey and by analytical methods, mainly by virtual population analysis (VPA). As a result of instrument assessment in 1982 the sprat biomass in the west part of the black sea was as the range of 170–200 thousand T. Assessment along the bulgarian black sea coast was as follows (thousand):

1994 - 24
1985 - 69
1886 - 77
1987 - 21
1988 - 74
1990 - 27

The above figures, especially those for 1984 and 1987, are considered as underestimated.

Horse mackerel (Trachurus mediterraneus)

A Mediterranean species hibernating in the Southwest part of the black sea and the Bosphorus prestrait area. In spring (May) it migrates for feyding and reproduction towards the Northwest part of the black sea; the autumn migration towards hibernating areas takes place in September – October. The lifecycle is appr. 10–12 years though in the catches the first four age classes dominate. The average size depends on the volume of the recruitment and the dominating generations in the age composition generally range 11–15cm. It is caught by trawls and traps nets. The Bulgarian catches range from 35T (1968) to 2200T (1974) and include only a small part of the stock. A larger part of the catches is fished by Turkey (up to 65000T) (1979) and Russia (up to 22000T in 1972). The Romanian catches reach maximum of 2.200T. The assessments for utilisation of the species come close to the values of the optimum allowable yield corresponding to the total biomass of 100– 4000000T. Due to the seasonal character of the fishery (May – June and September – October) and peculiarities of the spring - autumn migration, Bulgaria utilises appr. 1–2% of that stock. During the last 5 years the catches sharply decreased because of the negative influence of Mnemiopsis mccradyi (T):

1988 - 1677
1989 - 1101
1990 - 164
1991 - 55 (estimated)
1992 - 55 (estimated)

Anchoyy (Engraulis encrasicholus)

A thermophilic, high abundant species, life-cycle 4–5 years and mean length - 11–13CM. It hibernates along the anadol coast and in spring (May) migrates towards the north regions of the black sea. A relative small share of the stock comes to the Bulgarian coast even in years of augmented stock. Stock assessments are usually given separately for the two halves of the black sea and are determined by the values obtained from experimental fishing with pelagic trawl (thousand T):

During the last 5–6 years the anchovy stock sharply decreased and almost lost its commercial significance. The causes are the negative influlence of Mnemiopsis mccradyi and the overfishing of the turkish fishery during hibernation.

Turbot (Scophthalmus maeoticus)

A carnivorous demersal species, comparatively long life cycle - 12–14 years, average length 55– 58CM, average weight appyr. 3.7 kg. It performs hibernating migrations perpendicular to the coast, down to 80–90M depth November) and reproductive migrations to depth 10–40M (May). The Bulgarian annual catches in the periods given below are as follows (T):

The total biomass of the stock (VPA) ranges between 430 tons (1977) and 1710 tons (1962). The recruitment of the stock begins to decline if the commercial stock fall below 300T. Such decrease was registered at the end of the 1980 and it was the reason for the 5-years fishing moratorium which had been put into effect by Bulgaria. Russia and Romania. The first two years of the moratorium (1989–1990) Indicated stock recovery, but an invasion of Turkish fishermen in Bulgarian territorial sea caused heavy damages to be hardly overcome. Determinations from bottom trawl survey in January 1992 indicated commercial biomass of 100T.

Black sea shad (Alosa pontica)

A bathypelagic anadromous fish, 7years life cycle, average size 24–26CM, Average weight appr. 220G. Living in the black sea. It enters the Danube for spawning (April – May). 3–4 age groups are dominating. The Bulgarian annual catches from the black sea are at the range of 6440T and are determined both by abundance fluctuations and hydro-meteorological conditions in April–May. The biomass of the species ranges between 1.8 – 11.000T (VPA). The main share of the catches is caught by Romania and Russia in the Danube mouth. In the last 5 years the stock declined, affected by the river pollution and hydroconstructive activity.

Pontic Whiting (Odontogadus meralngus euxinus)

A boreal demersal species, life-cycle 6–8 years, mean length appr. 16CM, mean weight 25–30G. It is important medium link between fauna larger predators. Partially exploited by fishery as there are no traditions in its marketing. In the last 10 years the catches reach 10– 12000T caught mainly by Russia and to a certain degree by Romania. In the 1980S the assessment of the stock for the whole basin is appr. 30–35000T; 3–4000T on the bulgarian shelf.

Piched dogfish (Squalus acanthias)

Lenght up to 150CM, weight 3–7kg, life-cycle up to 20 years. Annually up to 25–28 little dogfish are born. The catches are taken primarily by trawl and bottom long-lines. There is no basis for a real assessment of the stock though the catches in recent years increase influenced by the market demand: 3–4000T for the basin as a whole and appr. 100–200T for the Bulgarian shelf.

Gobies

The species are not dominant in the catches. Annual changes of the latter are as follows: 90–180 T (1940 – 1960) and 24–90 T (1961–1990)

These examples are related to substantial reduction of gobies populations in the coastal lakes. Until 1960 the catches in the Bourgas lake were at the range of 30–115T per year. Similar was the case of Varna lake influenced by pollution and salinity increase after the second canal between the sea the lake was built up.

In the sea, the dominant species are Neogobius melanostomus and Mesogobius batracnocephalus (local names strongil and lihnus) caught by commercial and recreational fishery. Appr, 80% of the sea catches (up to 30–40 T annually) include strongil, a species having a long reproductive cycle and portinated ejection of gametes. Since 1990 a prohibition for spring fishing of gobies (45 days during their reproductive season) has been put into force. Assessment of the stocks (21 species in Bulgarian aquatoria) has not been made. Recently, due to eutrophication then oxygen deficiency gobies stocks have been continuously diminishing.

Except the species described, important for the fishery are also mullets (Mugilidae), blue fish (Pomatomus saltatrix), Silverside smelt (Atherina mochon pontica) and other fish of secondary importance. Bonito (Sarda sarda) and mackerel (Scomber scombrus), of utmost significance in the early 1970S, today are already caught.

The generalised data demonstrate that since 1985 sprat has been the most important species for the Bulgarian fishery: up to 95% in the commercial catches. The Bulgarian catches include also horse mackerel, Black Sea shad (about 2.5–3.0%0 and other species. As a basis for comparison data for the species composition in the commercial fishery during the period 1931–1971 (period of “clean sea”) are given below /%/:

The differences are considerable and illustrate substantial changes in the composition of catches caused mainly by the eutrophication of the Black Sea.

Except the national legislation fishery is regulated by the International Commission for the Implementation of the Agreement for Fishery in the Black Sea where Bulgaria, Romania and the Black Sea, countries of ex USSR participate. Every tow years the commission holds its meeting.

There are no quota limitations but regulations for minimum allowable fish size for fishing of each commercial species, for catching at non-standard length, minimum mesh size etc. for the period 1 January 1989 – 31 December 1993 a moratorium over fishing of Turbot has been established. After the political changes in the East European countries, the function of the commission has been disturbed and it reflects mostly on the exchange of fishery and scientific information. At the moment Bulgaria is trying to re-establish the previous relations in order a new text of the Convention to be elaborated. Turkey has been continuously invited and is expected to join the commission.

Bulgaria takes measures to restrict the harmful effect of certain fishing activities on the fish resources and marine ecosystems in general. For the first time in 1991 a prohibition was put into force related to the use of bottom trawls. In previous years the latter caused irreversible damages not only to the fish stock but to the whole bottom ecocoenosis. In 1992 all types of trawl fishery were forbidden in the 3-mile coastal zone along the north part of the Bulgarian coast and in the 1-mile zone south from cape Emine. Authorities are expected to put into force other regulations for fishery, protection of fish resources and carrying out activities to compensate the decrease in fish stocks and stimulate development of mariculture. In general, the main issue for the protection and recovery of the Black sea fishery resources remains protection of the marine environment from further pollution and taking measures to improve the ecological state of the whole watershed basin.

STATE OF MARICULTURE AS LIVING RESOURCES

Along the Bulgarian black sea coast mariculture is still on their premature stage of development. The institute of fish resources, Varna, and the fisheries institute, Bourgas, elaborated and implemented (R & D) biotehnologies (2 options, with and without net sleeves) for cultivation and processing at sea and ashore of mussels (mytilus galloprovincialis). Two mussel farms were built by Sozopol (of IRP-25; annual production 200–300 live weight) and by messebar (of black sea fishing Co. LTD; annual capacity (also not reached) 300–400 T). Both farms are being exploited much less than their actual potential.

In the 1970S the fisheries Institute, Bourgas, experimented cage cultivation of steelhead trout Salmo gairdneri and kisutch Oncorhynchus kisutch by Sozopol.

In the experimental station, Pomorie the fisheries institute carried out R & D for hibernating (In a green house) and fattening (in the Pomorie lagoon; spring-autumn) of mullet fry (1+), catching of 1-year fish in autumn (annual harvest 10–20T; dominant species Mugil saliens and M. cephalus).

Also in the experimental station, Pomorie, trials were held to propagate black sea shrimps (Palaemon adspersus) and black sea flounder (Platychtys flesus). Phyto-and zooplankton were used for their nutrition.

In 1992, due to deficiency in state investments, research in Pomorie station was ceased.

Private companies are interested in commercial mussel culture development. Mussels (Mytilus galloprovincialis) are still the main species of interest to emerging farmers. In this respect bi-and polyculture with algae or fish are also tempting for R & D. Worth attention are also the combination traditional fishing (trap nets, recreational fishing) - mussel culture as well as establishment and exploitation of artificial reefs.

Private companies are also interested to cultivate commercially salmonid species such as Salmo salar, S. gairdneri and, O. kisutch. Though numerous problems such as financing, legal aspects (e.g. permission for sea concessions), environmental effects of the introduced species, risks of the introductions etc, are still under discussion and remain to be solved in practice.

Turbot (Scophthalmus maeoticus) is also of utmost interest as a potential candidate for cultivation related to its high marketing demand and damaged stocks.

In 1991 bulgaria joined MEDRAP Il (Mediterranean Regional Aquaculture Project) (UNDP/FAO). Main activities of the project are constitution of networks for information, training, research, aquaculture and environment. The fisheries institute, Bourgas, is the national Coordinator to MEDRAP. For the effective participation of Bulgaria in MEDRAP Il a number of organizational-technical and financial problems have to be solved.

Though the promising results achieved and expanding private mariculture initiatives aqua/mariculture development in Bulgaria is primarily influenced by the general social-economic development of the country in the context of the integrated coasted activities. Mariculture is a mean for recovery and augmentation of the fishery resources and a field for employment of the coastal population. With better utilisation of the fish processing capacities available and under-exploited today.

The mariculture facilities of Bulgaria established until now could be a stable, promising prerequisite for development of mariculture along the coast. The capacities and facilities of IRP-25 (ex Fisheries institute) include the following:

MUSSEL CULTURE FARM, SOZOPOL
(IRP-25 CO. LTD., Bourgas, Bulgaria; ex Fisheries Institute)

A marine farm for suspended mussel culture (Mutilus galloprovincialis), 2 miles from the shore, in the vicinity of town Sozopol (5000 inhabitants, by an island “long-line” systems for 5000 collectors (5 M long). Production cycle 9–10 months, harvesting season February – May.

Ashore - Farm buildings, a quay, laboratory rooms, utility buildings, water supply, electrification, heating installations. Personnel -4 persons (2 Biologists). 3 exploitation boats.

Production transported to Bourgas (35 km northward) for processing (canning and freezing; IGF). Shells used for chicken fodder.

Mariculture Experimentation Station, Pomorie
(IRP-25 CO. LTD., Bourgas, bulgaria; exfisheries institute)

Ashore 0.6 ha working area. Canal connecting the sea and the lagoon. The lagoon - 250 HA, depth 0.8–1.2 M.
Earth ponds depth - 0.8–1.0 M; 2 HA.

Open tanks: 45 PCS, 30–50 cubic M, depth 0.8–1.8 M (mountable)

Covered: Nursing tanks 67 pcs, 1.5–3.0 cubic M-Round and rectangular, incubating department; equipment for food: phyto-and zooplankton.

Laboratories: chemical, ichthiological, hydrobiological, ichthiopathological (not completely equipped).

Supplementary installations - water supply from the sea, lagoon and drilling. Salinity 15–30%O. Water temperatures max 26–27 C (outdoor), min O-(-1) C (outdoor, indoor 8–10 C.

Water purification installations.
Promorie - 30000 inhabitants, 20 Km northward from Bourgas.

Bourgas - District centre, 250000 inhabitants.

Dams, specialised fish farms and the Danube

Bularia has a comparatively scarce water resources area. Though regarding its territory the fresh water potential is considerable. Its cadastral area is appr. 700 MLN so M, 300 MLN SQM - the area of the artificial water basing with good conditions for commercial fish exploitation with natural and artificial breeding for industrial and recreational fishery. The area of the specialised fish farms is appr. 37 MLN SQM with ponds for artificial breeding and raising of fresh water fish. There are good conditions for semi-intensive fish farming in some dams - for artificial propagation of valuable fish species, raising, fattening and catching. In larger part of the dams proper fish species are places, the latter being of interest for the commercial fishery and for the specialised fish farms. They are still state companies or co. LTD. With state properly. Privatisation in fish culture sector is still pending decision. Larger is the share or the dams with no suitable conditions for commercial fishery with technical and technological gear applied. Those dams are used for recreational fishery and their fish resources are naturally reproduced. Only some of them are artificially bred from time to time.

The dams with fishing activities have various hydrographic, hydrochemical, hydrobiological and fish farming peculiarities. They vary in space area and volume and occupy different climatic zones. The forms of their fish exploitation differ respectively, too.

The share of the dams of than 5 MLN SQ M is the largest and they are classified as large dams -61.3% of the total dams area of the country. The average ones are those with area of 2–5 MLN SQ and their share is 9.5%. Small ones with and area less than 2 MLN SQ M-28.2% of the total dam area. Dams proper for intensive fishery activity cover 37.6% of the total dam area in the country. The remaining part of the dam potential is used for energy production, water supply, irrigation farming, commercial and recreational fishery and other activities, too. In 1989 taken as a basis related to complete and detailed information, as well as favourable prerequisites for commercial fishery available, 12455 T of fish was caught. The Danube catches added 360 T. Most important species in the catches are: CARP - 8011 T (64,36%), phytophagues (mainly Hypophthalmichthys molitrix - 2815 T (22,60%), trout - 1099T (8,82%) and other species - 530T (4,26%).

In the Danube catches, the following species dominate: carps (Hypophthalmichthys molitrix), pick perch, Carassius carassius, Abramis brama., Scardinius erythrophathalmus, danube barbel, chub and other species. Catches of sheatfish and sturgeons decline. In the 1940s the Danube catches were several times bigger, also in the 1950 and in some years - over 1500 T. Several factors contribute to the sharp decline of the fish stock and catches: industrial and sewage pollution of the river, destruction of the swamps along the Danube (the latter having been a source for good catches and for natural fish reproduction (recruitment) of the fish stock of the river. A large part of the natural fish spawning areas were destroyed. The Commercial constructive activities along the coast, taking away sand and other material from the river bottom, disturb the natural migration routes, (especially the hydrotechnical devices along the river). Sturgeons (fam. Acipenseridae) migrating from the black sea for breeding in the Danube were heavily damaged. Also the black sea shad (Alosa pontica pontica) called karagyoz.

As a result of the socio-economic and political changes in the country after 1989 and the disurbances in agriculture, the production of fish for human consumption, fry and fingerlings has sharply decreased. Last year the fish production was 6–8000 T. Precise estimation cannot be given as the system for collecting statistical information is disturbed. On the other hand, production expenditures quickly increase (prices of fodder, electricity, water, pharmaceuticals etc), and fish on the market has less demand. There are certain factors such as the forms of property, and management of the fish ponds in restoration of private land ownership and transfer to market economy which raise difficulties in the processes of privatisation of the branch.

There is a serious decrease in production of fry and fingerlings of basic commercial fish species related for high laborious operations, risk factors (e.g. Water supply problem), quality demands, the heavy losses caused by the fish-eating bird phalacrocorax carbo with its much abundant population.

The present situation in the country does not create favourable prerequisites for building up new fish farms. Fish production would considerably increase if better utilisation of fish ponds and dam waters in established. Plans for development of existing water potential demonstrate the following:

1. The existing 37 MLN SQ M pond fish farms (average production 0.15–0.17 kg/M) could produce. 5.5–6.000 T and better management could give more than 0.20 kg/M.

2. Small and average dams (total area appr. 115 MLN SQ M; average production 0.075–0.085 kg/M) could give total fish production 8.5–10.000T.

3. Larger dams with an area 190 MLN SQ M can give average production 0.0065–0.0085 kg/M and 1250–1700T could be produced.

Along this line in, optimum conditions, the fresh water potential of the country could produce 15000–18000 T. Such quantities could satisfy consumers demand for fresh water fish and a share of it could be exported to the European market. The Bulgarian trout production is well appreciated in some European countries and can compete with its quality the fish quality in many other countries. The demand for carp is less; it is exported mainly to Greece where wild carps is under demand. To satisfy the need of fresh water farming production, 40–46 MLN PCS of fry and fingerlings are necessary. Those quantities could be obtained in the hatcheries and ponds of the country, also in the selected fish of the farms.

In some of the large dams fish cultivation in net cages could be carried out with a lot of machinery applied.

The quality of the pellet fodder remains one of the important issues of the fresh water fish production. The country does not produce fodder of the quality required, and the high prices of the imported food is also a barrier for the expansion of the commercial farming activities.

Home Rivers

The fish resources of the home rivers in Bulgaria are of interest to the recreational fishery. In some of them, the larger ones such as Maritza, Tundja, Iskar and kamchia commercial fishery was held in the last century up to the second world war. Fishing gave food to the coastal population, and now the fish resources are of no commercial significance anymore.

Trout takes the most important place in the fishery from the home rivers (Salmo trutta morpha fario, Salmo irideus). In occupies the "trout zone" of the rivers over 800 M above the sea level; over 28% average slope of the river bed. The determinations given below are obtained as a result of ichthiological survey in 26 rivers. The ichthiologic material is collected according to the methods described by Mahon et al. (1979), Penezak (1981), Penezak el al (1981, m 1982, 1984), Labon-Cervia and Penezak (1984), Zalewski (1983). The abundance is determined in accordance with the methods of zipin (1956, 1958), Seber and Le Cren (1967), Seber and Whole (1970). The biomass estimation is achieved with the application of the Mahon's et al formula (1978).

The bottom of the investigated rivers usually are covered with gravel and stones, their depth is appr. 10–40 CM and in the pools it reaches 60–80 CM. The river coast is covered with coniferous and mixed forest and bushes. In general there are no water plants.

The oxygen content in the water usually increases 9 MG/L, pH - 6.8–7.4, total hardness - 1.53–6.30 German degrees, oxydation - 1.8–2.5 MG/L. The mean annual temperature of the water is 4.8 C. With few exceptions trout is the sole species living in the rivers of that zone. In some of the rivers under investigation individual specimen from the montain barbel (Barbus meridionalis), leshanka (Phoxinus phoxinus ), glavoch (Cottus gobio) could be caught though their abundance is very law and does not influence the trout population. There is no industrial and sewage pollution in the trout zone or it is very neligible. The state of the stock depends primarily on the recreational fishery. The populations investigated in most of the rivers are natural and reproduce themselves. The influence of the artificial breeding is very small and it is felt mainly in some parts of the rivers. In many river sectors where the conditions for natural reproduction, conservation and recovery of the populations are good, threshold and pools are built up.

The abundance and biomass of the trout in the rivers permitted for recreational fishery are appr. 2 times less than in the prohibited ones. An indirect conclusion can be made about the potential of the fishery rivers that it is at least 2 times bigger and for their complete exploitation one cannot rely only on the natural reproduction. They have to be artificially cultivated to allow increase in the population abundance up to the optimum.

Except trout, many other native species live in he home rivers. Dominant are chub, mountain barbel, maritza barbel, krim barbel.

The abundance and the biomass of the fish population in some of the main Bulgarian rivers reflect the abundance and the biomass of the dominant fish species in the same rivers.

It has to be stressed that the river Zlatna panega is heavily polluted along the whole stream. River struma is contaminated in different parts of the stream; along 60KM there is no fish. River VIT; in the sector after Pleven, has 70km without fish. Such is river sredtzka in the sector after the town of grudovo (Sredetz).

As a conclusion to this report it should be pointed out that there is no complete, well defined and precise evidence about the present state of the fish resources of the fresh water basins and along the Bulgarian Black Sea coast. It is due to lack of systematic research about the state and dynamics of ichthofauna development as a resource. Much more systematic research is carried out by the institute of fish resources, varna (for the black sea), ex fisheries institute (now IRP)25 Co. LTD - on mariculture), institute of freshwater fish culture, plovdiv (mainly regarding fresh water commercial culture including state fish farms), certain centres for applied research within the council of hunters and fishermen (regarding water basins for recreational fishery, mainly rivers and dams).

Some scientific data are also available in the institute of zoology and the institute of oceanology (Bulgarian academy of sciences), the biological faculty of the university of Sofia though their research refers more to biological than resource (stock) aspects.

Main issue remains the lack of linkage and coordinating unit to harmonise the efforts of the numerous highly specialised and competent scientist, to stimulate and encourage their activities and generalise scientific results in the form of useful and applicable commercial conclusions and recommendations. Such necessity becomes more urgent as the state monopoly over fishing and fish culture caused heavy exploitation of the resources while the care for their protection, reproduction and recovery was not the same.

Though high values of pollution in most water basins of Bulgaria, the latter are source of large volumes of production having high nutritive, dietary and pharmaceutical value. the potential described above needs attention paid by the society and state to create favourable conditions for development, reproduction, recovery, augmentation and rational exploitation of the fisheries resources of Bulgaria.

FISH NUTRITION IN WARM WATER-PONDS

S. Nasser
Egypt

Fish farms in Egypt are classified according to the type of water (fresh, brackish and marine)

These fish farms are either governmental or private. The governmental are almost 4000 Faddan and the private farms are almost 27413 Faddan.

Most of these farms are using polyculture extensive system.

Fresh and brackish water farms are common. Species uses in this farms are Tilapia nilotica, aurea and galilaea carps (silver, common, grass and bighead), grey mullet (M. capita, M. cephalus and M. saliens), clarias, nile perch (Latus niloticus), bagras bayad and eels.

The production of these farms are Ton/Feddan in a governmental sector and from 200 – 250 kg/Faddan in a private sector

Marine farms are few. Then production is about 100–150 kg/Faddan. Species are seabass and sea-bram.

Private sector start in marine cages in Mediterranean sea.

Nutrition of fresh and brackish water pods depend on the following:

1. Abundance of natural feed, this can be achieved by:
   1. Organic fertilization (caw dung-chicken manure)

   2. Inorganic fertilization (superphosphate and amonium sulphate)

2. Supplementary feed:
   There is inverse relation between density of fish in ponds and growth rate, for that reason farmers decrease stock of fish in ponds to allow a suitable quantity of natural food for fish. So we can get the required market size, but in this case the return will be low.

In case of over stocked ponds by fish the natural food will be insufficient for fish growth and the crop will be under the marketable size there for we should add manufacture feed (supplementary feed) to get the desirable size of fish with suitable density

Supplementary feed has a percentage of crude protein ranges from 17–30%, fat ranges from 4–6% fiber not excess than 7% and energy ranges form 2000–2400 k calory /kg.

Local available materials are wheat bran/rice bran, soyabean, cotton sead meal and cornzeamays.

Imported products are fish meal and meat meal. This feed produce by spacial factory. The production are pellets from 25.5–5 mm diameter.

We make economic study on the price of ingredients and the cost of final product. So the cost of these feeds are range from 750 L.E. for 17% to 1000 L.E for 30%.

Governmental sector uses supplementary feed.

Private sector is traditional, so some of them use manufacture feed and the other use rice bran or wheat bran plus cotton seed the ratio 3 to 1.

Feed conversion depend on the management of farm, control of water quality and the abundance of natural food. So it is about 1.5 to 2.

There is one trial to add food promotion (Ascergen) to feed

Manufacture feed uses mainly in this cases:

1. When water and soil are poor in feed and the fertilization is not affected.
2. Culture in a flowing water.

3. 3- Intensive culture which need a big amount of water with high degree of purity

Fish nutrition is affected by:

Temperature.

Since the fish is poikilothermic animal (cold blood animal ) rise temp. increases the demand of fish to feed in the same time the lowering temp will decrease the demand.

Carp loses its appetite when temp. decreases to 10°C for tilapia, the best temp. is 24°C all this degree it can feed on 10% from its weight while its appetite is lost when temp. reaches 13°C.

The temp has a great effect on natural feed production in the watered pond.

pH:

Natural water and low alkaline water give a very high production than that of acid water. Ponds water which have pH ranges from 6.5 to 9 is suitable for fish growth.

While acid water has a harmful effect on fish lead to the decrease in the demand of fish to feed, and it is a very good conditions for consistence of parasites and diseases.

Oxygen:

The rate of nutrition is affected by decrease of oxygen in water; we found that Tilapia consumers a few quantities of food when the percentage of oxygen is decreases to 2 milligram/liter. The main reason affect to decrease of oxygen in ponds is the decomposition of the organic matter.

Crowding:

Fish crowding has an inverse effect on the nutrition as a result of mechanical impact between fish or the chemical effect resulting from the density of fish in water.

USE OF RAW MATERIAL AND PROCESSING TECHNOLOGY

A. G. J. Tacon
FAO

1. INTRODUCTION

Aquaculture is playing an increasingly important role in world fishery production, and in 1990 contributed 10% of total landed fish, 15.6% of total landed crustaceans, 37.3% of total landed molluscs, and 73.5% of total landed aquatic plants, with a total value of US $ 26.5 billion (Table 1) Figure I shows the growth of world fish and shellfish aquaculture production between 1984 and 1990 and Table 2 and Figure 2 summarises world aquacuture production in 1990 by major culture group. An analysis of the data presented will show that finfish and crustacean aquaculture production increased by 96% from 4,656,000 metric tonnes (mt) between 1984 and 1990, representing an average annual growth rate of 16% per year. However, it should also be stated that the growth of the aquaculture sector has reduced somewhat since the mind eighties, with a modest increase of 8.0% and 6.1% reported between 1989 and 1990 for total fish and crustacean aquaculture production, respectively (Table 1). The annual production of the major cultivated fish and shrimp species between 1984 and 1990 is shown in Table 3. Warmwater freshwater fish species currently dominate finfish aquaculture production (Table 2, Figure 3), with freshwater cyprinids constituting 59.2% of he total weight of all farmed fish and occupying the top four positions of the top ten most cultivated fish and shrimp species in the world (Figure 4–6).

As with all other forms of animal production, the growth and production of farmed fish or shrimp is dependent upon the dietary intake of food containing 40 or more essential dietary nutrients, either in the form of endogenously produced live food organisms or exogenously supplied artificially compounded diets. It follows therefore that if aquaculture production, and in particular finfish and crustacean production, is to maintain its current growth rate into the next decade then corresponding inputs of fertilizer and aquafeed will also have to be provided.

On a nuturitional basis it is important to note that the top five most produced fish species in 1990 (lie. silver carp Hypophthalmichthys molitrix, common carp Cyprinus carpio, grass carp Ctenopharyngodon idella, bighead carp Hypophthalmichthys nobilis and milkfish Chanos chanos) have omniyorous or herbivorous feeding habits (ie. phytoplankton filter feeder, general benthos feeder, macrophytic feeder, zooplankton filter feeder, respectively) and are produced within semi-intensive and or extensive pond-based farming systems. The dietary nutrient requirements of these fish species is currently met largely through the consumption of live food organisms produced within the water body in which they are cultured. By contrast, the production of carnivorous fish species (ie. coldwater species rainbow trout Oncorhynchus mykiss, Atlantic salmon Salmo salar; warmwater species yellowtail Seriola quinqueradiata, eel Anguilla japonica, red sea bream Spurus major) is presently almost entirely dependent upon the external provision of an artificially compounded diet or aquafeed; carnivorous fish species representing about 13% of total finish production and generally being reared within intensive clear-water farming systems (ie. raceways, tanks and floating net cages).

For the purpose of this paper an aquafeed is defined as a diet in pellet, ball or mash form composed of one or more feed ingredients. Estimates for global aquafeed production vary widely; reported values ranging from 2.23 million mt (1988; New 1991), 2.96 million mt (1990; Chamberlain, 1992), 4.0 million mt (1988; Meggison, 1990) to as high as 18.3 million mt (1993; Anon, 1993). New (1991) has classified aquafeed production in 1988 according to dietary fish or shrimp feeding habit as 58% for carnivorous fish species (ie. trout, salmon, yellowtail, catfishes, eels), 19% for non-carnivorous fish species (lie. carp, tilpia, milkfish) and 23% for crustaceans (ie. omnivorous marine shrimp species). Similar estimates on a species basis have also been made for aquafeed production in 1990 by Chamberlain (1992) and these are summarised in Table 4. On the basis of an average aquafeed cost of US $ 500/ml it is estimated that the value of total global aquafeed production in 1990 was between 1.5 and 2 billion US dollars. Projections for aquafeed production by the year 2000 have been made by one same authors and vary from 3.5 million mt (a 58% increase from 1988; New, 1991a), 4.6 million mt (a 56% increase from 1990; Chamberlain, 1992) to 6.6 million mt (a 65% increase from 1988; Meggison, 1990)

Since aquafeeds generally represent the largest single cost item of most semi-intensive and intensive farming operations (food and feeding normally accounting between 30 and 60% of total farm production costs; Chong, 1992), it follows therefore that the selection of feed ingredients for use an aquafeed will play a major role in dictating its ultimate nutritional and economic success or not for a farmed fish or shrimp (Tacon, 1992). The aim of this paper is to review the use of processed feed ingredients within aquafeeds for warmwater finfish and to highlight current trends and future prospects. Processed feed ingredients are used here to include all animal and plant food items which have been physically processed prior to feeding either by drying, fermenting, composting, grinding, pelleting or by mixing with other food items into a compound diet. The use of feed ingredients within aquafeeds for cold water fish species and crustaceans will not be dealt with here as this has been reviewed in Tacon and Jackson (1985) and Tacon and Akiyama (1993), respectively.

2. INGREDIENT NOMENCLATURE, CLASSIFICATION AND COMPOSITION

Feed ingredients are usually named, classified and coded according to the "International Feed Vocabulary" of Harris (1980). The International Feed Vocabulary is designed to give a comprehensive name to each feed/feed ingredient as concisely as possible and so avoiding unnecessary confusion in ingredient identification. Using the above vocabulary over 18,000 feeds have been recorded and given International Feed Descriptions. Each feed/feed ingredient name is written in linear form and compiled using descriptors taken from one or more of six facets:

Facet 1 - Origin consisting of scientific name (genus, species, variety) and common name (generic name, breed or kind, strain or chemical formula)
Facet 2 - Part feed to animals as affected by process (es) (ie. actual part of the parent material fed)
Facet 3 - Process (es) and treatment (s) to which the part has been subjected
Facet 4 - Stage of maturity or development
Facet 5 - Cutting (applicable to forages)
Facet 6 - Grade (official grades with guarantees).

Feeds/ feed ingredients can also be further classified into one of eight classes depending on their proximate chemical composition and intended dietary use, namely:

• Class 1 - Dry forages and roughages, including hay, straw, fodder (aerial part) stover, bulls, and other products with more than 18% crude fibre (ie. rice bran, seed coasts, pods etc.)

• Class 2 - Pasture, range plants, and forages fed green, including all forage feeds either not cut (including feeds cured on the stem) or cut and fed fresh

• Class 3 - Silages, including only ensiled forages (ie. maize, alfalfa, grass etc.) and excluding ensiled fish, grain roots and tubers

• Class 4 - Energy feeds, including products with less than 20% protein (dry basis) and less than 18% crude fibre (ie. grain, mill by-products)

• Class 5 - Protein supplements, including products containing 20% or more protein (dry basis) from animal origin (including ensiles products) as well as oil meals, gluten etc.

• Class 6 - Mineral supplements

• Class 7 - Vitamin supplements, including ensiled yeast

• Class 8 - Additives, including antibiotics, colouring materials, flavours, hormones and medicants.

Finally, a six-digit “International Feed Number”(IFN) is assigned to each feed/feed ingredient description to facilitate identification and computer handing; the first digit of the IFN denoting the Class Number of the feed/feed ingredient (IFN examples are shown in Table 5). For information concerning the Feed Name Description, IFN and chemical composition of individual feed ingredient sources commonly used in animal feeds (including aquafeeds) within the region see the Arab and Middle East Tables of Feed Composition (Kearl et al. 1979). Table 6 and 7 shows the average proximate and amino acid composition of feed ingredients commonly used within aquafeeds for warmwater fish species. For additional information concerning the description and composition of other less common feed ingredients used within aquafeeds see Tacon (1987).

Despite the simplicity of the above nomenclature and feed reporting scheme the large majority of published data concerning feed ingredient usage within aquafeeds more often than not fail to give full ingredient names and descriptions, including FIN, proximate chemical composition, and ingredient particle size prior to mixing or feeding. For example, listing an ingredient within aquafeed formulation just as 'fish meal' or 'soybean meal' is totally meaningless as there are literally scores of different types and grades of fish meal and to a lesser extent of soybean meal, depending upon the species and origin of the raw fish or bean and processing method employed. Clearly, full ingredient descriptions and nutrient composition data must be given if any meaningful conclusions are to be drawn from the results of dietary feeding trials. For a recent review of this important subject area see Greenfield and Southgate (1992).

3. FEED INGREDIENT SOURCES - FISH & FISHERY PRODUCTS - BY

3.1 Fish meal and fish oil

Approximately 30% of the total world fish and shellfish catch of 85.1 million tonnes was reduced into fish meal and fish oil in 1990 for use in animal feeds; total meal production decreasing by 8.7% to 6.3 million tonnes and fish oil production decreasing by 14.7% to 1.4 million tonnes from the previous year (Table 8). On a global basis the production of fish meal and fish oil has remained relatively constant since 1984, oscillating between 6.1 and 6.9 million tonnes and 1.4 and 1.7 million tonnes, respectively. However, it is important to note that only 51.2% and 52.7% of total fish meal and fish oil production was available for export in 1990; the value of the exports exceeding 1.4 and 0.2 billion OS dollars, respectively Table 9 shows the top twenty fish meal producing countries in 1990 and indicates the reported percentage of their production which was exported. It is particularly interesting to not that despite the fact that fish meal production in Thailand increased from 222,558 mt in 1984 to 264,700 mt in 1990 the proportion of fish meal exported has decreased from 58.1% in 1984 to 5.8% in 1990 (FAO,1992b). To a large extent this decrease in exports has been due to the increased consumption of local fish meals by the rapidly growing aquaculture and poultry sector in Thailand. For example, aquaculture production of the giant tiger prawn (Penaeus monodon) has increased from 170 mt in 1984 to 77,500 mt in 1990(FAO, 1992), and recently to 163,000 mt in 1992 (Anon.,1993).

It is estimated that between 816 and 873 thousand tonnes of fish meal and between 190 and 205 thousand tonnes of fish oil was used in aquafeeds in 1990 (Chamberlain, 1992; Pike, 1991; Table 4) or the equivalent of 13 to 15% of the total world supply of fish oil (Figure 7). As expected, the major consumers of fish meal and fish oil are the carnivorous fish species (i.e. salmon, trout, eel, yellowtail, sea bream), followed by marine shrimp and omnivorous freshwater fish species (Figures 8–10). For example, 93.2% of the fish meal used in aquafeeds in 1992 was consumed by carnivorous fish species, and only 6.8% consumed by omnivorous fish species (Figure 10). It should be pointed out that the estimates of fish and fish oil usage are based on the ‘educated guesses’ of review authors concerning the levels of these two key ingredients within the different fish and shrimp feed lines produced by commercial aquafeed manufacturers and as such should only be used as a rough guideline rather than an actual reported statistic. For example, the latest estimates suggest that 840 and 1078 thousand tonnes of fish meal were used within aquafeeds in 1991 and 1992, respectively (Springate & Gallimore, 1992; I.H. Pike, personal communication). According to Chamberlain (1992) fish meal usage within aquafeeds is expected to increase by 50% from about 0.8 million tonnes in 1990 to 1.2 million tonnes in the year 2000, and fish oil usage by 77% from 0.2 to 0.36 million tonnes by the year 2000 (Table 4). Assuming that fish and crustacean aquaculture production will continue to increase at a modest rate of 5% per year and that global fish meal and fish oil production levels will remain at their present levels by the end the decade, this would mean that by the year 2000 about 20% of the total world supply of fish meal and fish oil would be consumed within aquafeeds (Chamberlain, 1992; New, 1991b; Wijkstrom & New, 1989; I.H. Pike, personal communication).

Fish meal and fish oil currently occupy the unique position of being essential dietary feed ingredients for all industrially-produced aquafeeds for carnivorous fish, and to a lesser extent, omnivorous fish and shrimp species. Dietary fish meal inclusion levels usually range from as low as 4–5% within production diets for channel catfish (Ictalurus punctatus) to as high as 75% within larval diets for marine finfish and eel or turbot (Scophalmus maximus) production diets (Chamberlain,1992; Pike, 1991; Springate & Gallimore, 1992; Tacon, 1988; Table 4 & 10). Similarly, dietary fish oil supplementation levels range from as little 1–2% within production diets for omnivorous fish species to as much as 15–20% within expanded (ie.extruded) salmon diets (Chamberlain, 1992; Pike, 1990; Table 4).

The fact that fish meal and fish oil play such an important and central role within aquafeeds for carnivorous fish species is perhaps not surprising since the natural diet of these species in the wild is normally based on the consumption of fish or shellfish products. On a purely nutritional basis it has been repeatedly shown within dietary feeding trials that the best food or feed ingredient ( in terms of reported palatability, growth and food conversion efficiency) to feed a carnivorous fish species is another food fish (such as ‘trash fish’) or fish meal; the nutritional composition (ie. amino acid and fatty acid profile) of food fish and high quality fish meals approximating almost exactly to the known dietary nutrient requirements of the farmed species (Tacon & Cowey, 1985). For example, ‘trash fish’ based feeding regimes are still the most successful and economically preferred feeding method employed by the majority of marine fish cage farmers in South-East Asia for the on growing of carnivorous fish species (ie. grouper Epinephelus sp., Plectropomus sp., snapper Lutjanus sp, and seabass Lates clacarifer) and even herbiorous fish species (ie. rabbitifish Siganus canaliculatus) sp. and wild caught seed (Singh, 1991; Tacon et al. 1990,1991). In fact it is interesting to note that modern-day salmonid aquafeeds are mimicking more and more natural composition of food fish; European salmon production diets being almost entirely based on the use of high quality fish meals and fish oil, having a high dietary protein and lipid content, a low carbohydrate and fibre content, and consequently being highly digestible and therefore ultimately environmentally less pollution in nature.

As mentioned previously, a wide variety of fish meals are available on the market place, ranging from low quality high-temeratue dried fish meals produced from spoiled fish processing waste to high grade low-temperature dried fish meals produced from fresh whole fish. For example, Table 8 shows the major types of fish meal produced from whole fish by species source. It can be seen that at present over 94% of world fish meal production is from small oily pelagic fish species such as mackerel, pilchard, anchoveta, capelin and menhaden, and only a small proportion is produced from non-oily white-fish species such as cod and hake. From a nutritional and economic standpoint, the quality and value of a fish meal for use within an aquafeed will depend upon the condition of the raw material used and method of manufacture and storage employed, including : the origin and species of fish used; the freshness of the raw material used; processing method employed (in particular the drying temperature and exposure time), milling and storage method employed (in particular particle size, antioxidant addition, length and method of storage), and last but not least, the chemical composition of the final product (in particular the moisture content, protein and amino acid content, lipid and fatty acid content, lipid oxidative status, protein digestibility, ash and salt content, total volatile nitrogen content (TVN, including ammonia, dimethylamine and trimethylamine), and non-volatile biogenic amine content (including cadaverine, putrescine, histamine and tyramine). In general it has been found that meals possessing the highest nutritional value and eliciting the greatest growth response in carnivorous fish (ie.salmonids) are those which have been processed from fresh whole oily fish species and dried at low-temperatures (for review see FAO, 1986; Hardy & Masumoto, 1990; Pike, 1991 a; Springate & Gallimore, 1992,1992a). For example, Table 11 shows the influence of the freshness of the raw material on the TVN and non-volatile amine content of herring type fish meals. Examples of recommended specification for fish meal and fish oil used within salmon aquafeeds in North America include, fish meal: crude protein>68%, crude lipid<10%, ash<12%, salt<3%, ammonia-N<0.2%, moisture <10%, liquid antioxidant 250–500 mg/kg, particle size <0.25 mm, and preferably steam dried, and fish oil: moisture <1%, nitrogen <1%, free fatty acids<3%, proxide value <5 meq/kg and anisidine value <10 ( or totox <20, where totox = 2 × PV + AV) and antioxidant addition 250–500 mg/kg (Hardy & Masumoto, 1991).

The nutritional merits of fish meal and fish oil for farmed fish are many and can be summarised as follows:

• fish meal is highly palatable for farmed fish;

• fish meal is an excellent source of high quality protein and has an essential amino acid (EAA) profile which approximates almost exactly to the known dietary EAA requirements of farmed fish. In contrast to other commercially available feed ingredients fish meal can therefore be used as the sole source of dietary protein (therefore simplifying the dietary formulation) with no additional requirement for supplementation with synthetic amino acids;

• fish meal is an excellent source of digestible energy for farmed fish, and in the case of fish meals produced from oily-fish has an essential fatty acid (EFA) profile which approximates almost exactly to the known dietary EFA requirements of carnivorous fish species;

• fish meal is a good source of essential minerals and trace element, including calcium, phosphorus, magnesium, iodine, zinc manganese, selenium and trivalent chromium;

• fish meal is a good source of essential vitamins, including choline, vitamin B 12, inositol, vitamin A, vitamin D3 and to a lesser extent niacin, thiamine, riboflavin, pyridoxine, pantothenic acid, biotin and Vitamin E;

• fish oil is highly palatable for farmed fish;

• fish oil is an excellent source of polyunsaturated fatty acids of the linolenic family (n-3 series), and in particular of the dietary essential highly unsaturated fatty acids eicosapentaenoic acid (20;5 n-3) and docosahexaenoic acid (22:6 n-3) required by highly carnivorous marine fish species;

• fish oil is an excellent source of digestible energy;

• fish oil is a rich source of phospholipids and available phosphorus; and

• fish oil is a rish source of essential vitamins, including vitamin A, vitamin D3, choline, inositol and to a lesser extent vitamin E.

In view of the above qualities it is perhaps not surprising that Chamberlain (1992) has described fish meal as 'the single most critical ingredient in aquaculture feeds'. However, as a concluding note it must be stated that fish meal and fish oil are expensive and finite commodities which are also both competitively purchased by the larger and more valuable livestock production sector. For example, in 1990 over 86% of the world supply of fish meal was consumed within compound feeds for poultry, pigs and ruminants (Figure 7); the total production of compound animal feeds in 1993 is anticipated to exceed 610 million tonnes (32% poultry, 31% pigs, 17% dairy cattle, 11% beef cattle, 3% aquaculture feeds, 6% others) and have a total value in excess of US $ 55 billion (Anon, 1993a).

3.2 Other fishery by-product meals

In addition to the use of fish meals, there are also a limited number of by-product meals arising from the fishing and fish processing industry which have been successfully used within aquafeeds for warmwater fish, including:

Fish silage and fish protein hydrolysates (AQUACOP et al.1989; Bigucras-Serrano & Lapie, 1992; Boonyaratpalin, 1982; Bouchez, & Azzi, 1991 ; Goncalves et al.1989 ; Hardy, 1991; Hardy et benitez, al. 1983; Hole & Oines, 1991; Hossain et al. 1992; Ochumba, Manyala & Achuku, 1988; Wee, Kerdchuen & Edwards, 1986; Wilson, Freeman & Poe, 1984; Wood, Capper & Nicolaides, 1985; Yone et al. 1986, 1986a);

Shrimp head meal (Pandalus spp., Peneus spp., process residue, meal, IFN 5-04-226; AQUACOP et al. 1989; Barratt & Montano, 1986 ; Carver, Akiyama & Dominy, 1988 ; Lim, 1991; Meyers, 1986; Ornum, 1992; Robinette & Dearing, 1978; Shetty & Nandeesha, 1988; Toledo, Ortiz & Gonzalez, 1986);

Krill meal (Euphausia pacifica, whole meal, IFN 5-16-423; Allahpichay & Shimizu, 1984, 1984a; Budzinski, Bykowski & Dutkiewicz, 1985; Lou & Chen, 1980; Lukowicz, 1979; Watanabe, et al. 1991, 1991a, 1992); and

Squid meal ans squid oil (Todarodis spp., IIIex spp., IFN 5-04-671; AQUACOP et al. 1989; Boonyaratpalin, 1991; Chen & Liao, 1991; Kreuzer, 1989; Roh, 1992; Pascual & Hertrampf, 1992; Tacon et al. 1991; Watanabe et al. 1991a).

Although the market availability of the above fishery products is usually limited they all share similar properties to fish meal in that they are highly palatable (often used dietary feeding attractants) and have a well balanced EAA (with the possible exception of tryptophan deficiency within fish silage) and EFA profile for farmed fish. Table 10 shows the reported dietary inclusion levels of some of these feed ingredients within warmwater fish feeds.

4. FEED INGREDIENT - TERRESTRIAL SOURCES ANIMAL BY - PRODUCTS

4.1 Invertebrate animal by-product meals

Although very localised, a few processed invertebrate by-product meals have been successfully used within aquafeeds for warmwater fish species, including:

Silkworm pupae meal (Bombyx mori, IFN 5-11-787; Habib, Hassan & Akand, 1992; Hossain, Islam & Alim, 1991; Hossain et al. 1992; Nandeesha et al. 1989, 1990; Pezzato et al. 1984; Shetty & Nandeesha, 1988; Shyama & Keshavanath, 1991); and

Earthworm meal (Eudrilus eugeniae, Nandeesha et al. 1988).

4.2 Vertebrate animal by-product meals

After fishery products, terrestrial vertebrate by-product meals usually constitute the second major source of animal protein within aquafeeds for warmwater fish species, including;

Blood meal (spray dried, IFN 5-00-381; Davies et al, 1989; Diskson, 1987; Fagbenro, 1992; Gallagher & Degani, 1988; Habib, Hassan & Akand, 1992; Hossain et al. 1992; Mohanty & Swamy, 1986; Mohsen & Lovell, 1990; Otubusin, 1987; Tacon et al. 1983);

Liver meal (IFN 5-00-389; Arai, 1991; Charlon & Bergot, 1984; Dabrowski, Bardega & Przedwojski, 1983; Foscarini, 1988);

Meat meal (rendered, IFN 5-00-385; Pongmaneerat wetanzbé, 1991; Satoh, 1991);

Meat and bone meal (rendered, IFN 5-00-388; Cruz 1992; Davies et al. 1989; Mohsen & Lovell, 1990; Pezzato et al. 1984. Pongmaneerat & Watanabe, 1991; Suprayitno & Widagdo, 1989; Tacon et al. 1983);

Poultry by-product meal (rendered, IFN 5-03-798; Gallagher & Degani, 1988; Habib, Hasan & Akand, 1992; Hanley, 1987; Hasan, 1991; Hasan, Alam & Islam, 1989; Kissil, 1991; Viola, Lahav & Arieli, 1992; Voss & Nellen, 1985; Voss, 1988);
Poultry feather meal (hydrolysed, IFN 5-03-795; Ajuzie & Appelbaum 1993; Davies et al. 199/89; Meske, Meyer-Burgdorff & Guenther, 1990; Tacon et al. 1983; Voss & Nellen 1985; Voss, 1988);

Poultry manure (dehydrated, IFN 5-14-015; Davies Anuta, 1992; Kerns & Roelofs, 1977; Kumar & Singh, 1984; Shetty & Nandeesha, 1988); and
Miscellaneous (tannery hide fleshings meal - Kandasami & Raj, 1990; meal - Orengo et al. 1991; blood meal/rumen contents meal - Reece et al, 1975; chicken spleen/blood - Ajuzie & Applelbaum, 1993).

Table 10 shows the reported dietary inclusion levels of the major vertebrate by-product meals within practical fish feeds. With the possible exception of liver meal and meat meal, the utilization of most vertebrate by-prouct meals is usually limited by specific nutritional imbalances, including EAA imbalances (ie. blood meal, feather meal) and ash/mineral imbalances (meat and bone meal; Table 10). The dietary utilisation of most vertebrate by-product meals therefore requires careful formulation so as to obtain the desired overall nutrient profile within the finished aquafeed (ie. by mixing complementary feed ingredient sources).

5. FEED INGREDIENT SINGLE - SOURCES CELL PROTEINS (SCP)

For the purpose of this paper single cell protein (SCP) covers the use of unicellular and filamentous algae, fungi and bacteria in dried meal form. Examples of SCPs which have been used in aquafeeds for warmwater fish include:

Algal SCP (Spirulina maxima, Spiragyra maxima, Cladophora glomerata, Hydrodictyon reticulatum, Chlorella spp., Appler, 1985; Appler & Jauncey, 1983l; Atack Jauncey & Matty, 1979; Chow & Woo, 1990; Expo & Bender, 1989; Febregas & Herrero, 1986; Haniffa, Josemon & Ebenezer, 1992; Meske & Pfeffer, 1977; Nakagawa et al. 1985; Nematipour, Nakagawa & Ohya, 1990);

Fungal SCP (Candida spp., Saccharomyces spp., Torula spp, Kluyveromy spp., Ajuzie & Appelbaum, 1993; Appelbaum, 1979; Atack, Jauncey & Matty, 1979; Coutteau & Lavens, 1989; Heydarpour, 1987; Meske & Pfeffer, 1977; Metailler & Huelvan, 1991; Metailler, Cadena-Roa & Person-Le Ruyet, 1983; Omae, Susuki & Shimma, 1979; Pector et al. 1991; Roques & Dussert, 1991; Shcherbina et al. 1987; Shetty & Nandeesha, 1988; Winfree & Stiekney, 1984);

Bacterial SCP (Methanobacter spp., Pseudomonas spp., Micrococcus spp., Atach Jauncey & Matty, 1979; Davies & Wareham, 1988; Viola & Zohar, 1984; Voss & Nellen, 1985; Voss, 1988), and

Mixed SCP (Activated sludges derived from domestic sewage - Anwar et al. 1982; D'Souza & Dias, 1989; Kobayashi et al. 1969; activated sludges brewery waste - De Muylder et al. 1989; anaerobically digested swine manure - Watson, 1985).

By far the commonest source of SCP currently used within aquafeeds is yeast SCP, and in particular brewers and to a lesser extent torula yeast (IFN 7-05527, 7-05-534; Table 10). Used primarily as a good source of dietary protein and vitamins/carotenoid pigments, SCP hold particular promise for the future by virtue of their ability to be to be grown on a wide variety of substrates and waste streams, their ability to be grown within a limited land space with good control and often independently of climate, their ability to double their biomass a very short period of time, and ability to control their nutritional composition (within limits) through environmental and genetic manipulation. However, despite this positive outlook considerable further research is still required concerning the possible manipulation of the nutritional composition of SCP (ie. possible reduction of nucleic acid content, improved EAA and EFA profile; Rumsey Winfree & Hughes, 1992; Tacon & Jackson, 1985) and in the form of extended fish feeding trials from first feeding fry to market size before the true potential of SCP as a ‘fish meal replacer’ can be fully ascertained.

6. FEED INGREDIENT SOURCES - AQUATIC PLANTS

Although aquatic plants have long been used as a live food source for herbivorous fish species (Edwards, 1980, 1987; Gaigher, Porath & Granoth, 1984j; Hassan & Edwards, 1992; Tacon et al. 1990), their use as a dry processed ingredient within compound aquafeeds is more recent, and have included:

Seaweeds (Kelp meal IFN 4-08-073; Laminaria digitata, Undaria penatifida, Ascophyllum nodosum, Ulva pertusa; Nakagawa & Kasahara, 1986; Nakagawa et al. 1985; Satoh, Nagagawa & Kasahara, 1987; Yone, Furuichi & Urano, 1986);

Water hyacinth (Eichhornia crassipes - Hasan & Roy, 1992; Hasan, Moniruzzaman & Omar Farooque, 1990; Hutabarat, Syarani & Smith, 1986; Klinnavee, Tansakul & Promkuntong, 1990; Liang & Lovell, 1971; Nandeesha et al. 1991; Niamat & Jafri, 1984; Saint-Paul, Werder & Teixeira, 1981; composted material - Edwards, Kamal & Wee, 1985; Hutabarat, Syarani & Smith, 1986);

Coontail (Ceratophyllum demersum - Chiayvareesajja et al. 1988, 1989; Chiayvareesajja, Wongwit Tansakul, 1990; Klannavee, Tansakul & Promkuntong, 1990);

Aquatic fern (Azolla pinnata - Almazan et al. 1986; El-Sayed, 1992; Santiago et al. 1988);

Duckweed (Lemma minor - Devaraja, Krishna Rao & Keshavappa, 1981);

Water lettuce (Pistia stratiotes - Ray & Das 1992; Shivananda Murthy & Devaraj, 1991); and

Miscellaneous (Eleocharis ochrostachys - Klinnavee, Tansakul & Promkuntong, 1990; Salvinia spp. Mohanty & Swamy, 1986; Wolffia spp. - Cortez, 1987; Suprayitno & Widagdo, 1989a).

Like their terrestrial counterparts aquatic plants constitute a good source of dietary carbohydrate and energy for herbivorous/omnivorous fish species (for composition see Tacon, 1987), and have the added advantage of being able to be produced in association with the farmed fish species using the same water resources and/or farm effluents. In view of the major problems caused by aquaitic macrophyte infestations in many parts of the world (ie. the frequent clogging of rivers and lakes with floating aquatic macrophytes), clearly researche emphasis should be palced on the development of simple and cost effective harvesting/composting techniques so as to maximise the utilization of this hitherto largely underutilised resource by local fish farmers. Table 10 shows the reported dietary inclusion levels of selected aquatic plants within aquafeeds for warmwater fish.

7. FEED INGREDIENT SOURCES - OILSEEDS AND BY-PRODUTS

Plan oilseeds and their by-products usually constitute a major source of dietary protein within aquafeeds for warmwater omnivorous/herbiorous fish (for review see Akiyama, 1991 and Lim & Dominy, 1991) and iclude:
Coconut/copra meal (Cocus nucifera, mech.extr.meal IFN 5-01-572, solv. extr. meal 5-01-573; Campbell, 1985; Cumaranatunga & Thabrew, 1989; Gruz 1992; Guerrero, 1980; Jackson, Capper et Maty, 1982; Kamarudin, Kaliapau et Siraj, 1989; Superayitno & Widagdo, 1989);

Sesame seed meal (Seasamum orientalel S. radiatum, meal. extr. meal IFN 5-04-220, Hasan et al., 1991; Hossain & Jauncey, 1989, 1989a, 1990; Hossain et al. 1992; Kandasami & Raj, 1990);

Sunflower seed meal (Helianthus annus, dehulled mech. extr. meal IFN 5-04-738, dehulled solv. extr. meal IFN 5-04-739, hulled mech. extr. IFN 5-09-340; Dickson, 1987; jackson, Capper & Matty, 1982; Studentsova and Panasenko, 1990);

Cocoa pod/seed meal (Theobroma cacao, Fagbenro, 1988, 1992);

Linseed/flax meal (Linum usitatissimum, mech. extr. meal IFN 5-02-045, solv. extr. meal IFN 5-02-048, Hasan, Alam & Islam 1989, Hasan et al. 1991; Hossain & Jauncey, 1989, 1989a, 1990; Hossain et al; 1992);

Mustard seed meal; (Brassica spp., Capper, Wood and Jackson, 1982; Chatterjee & Konar, 1984; Hasan et al. 1991; Hossain & Janucey, 1989, 1989a; Hossain et al. 1992; Kandasmi & Raj, 1990);

Groundnut/peanut meal (Arachis hypogaea, mechanically extracted (mech.extr.) meal IFN 5-03-649, solvent extracted (solv. extr.) meal IFN 5-03-650; Campbell, 1985; Ding, 1991; Haniffa, Josemon & Ebenezer, 1992; Jackson, Capper & Matty, 1982; Luquet, 1991; Mohanty & Swamy, 1986; Nandeesha et al. 1989; Oduro-Boateng, 1986; Shivananda Murthy & Devaraj, 1991; Unprasert, 1989);

Rape seed meal (Brassica napus, B. campestris, mech. extr. meal IFN 5-03-870, solv. extr. meal IFN 5-03-871; Dabrowaski & Kozlowska, 1981; Dabrowski, Dabrowska & Kozlowska, 1981; Dabrowski, Krasnicki & Kozlowska, 1981; Dabrowski et al. 1982; Davies, Mc Connell & Bateson, 1990; Higgs et al. 1989; Jackson, Capper & Matty, 1982; Li et al. 1991);

Cotton seed meal (Gossypium spp., mech. extr. meal IFN 5-01-617, solv. extr. meal IFN 5-01-621, Dorsa et al. 1982; El-Sayed, 1990; Jackson, Capper & Matty, 1982; Lovell, 1980, 1982; Ofojekwu & Ejike, 1984; Robinson, 1991; Robinson & Brent, 1989; Robinson & Daniels, 1987; Robinson, Rawles & Stickney, 1984; Robinson et al. 1984, 1985); and

Soybean meal (Glycine max, heat processed seeds IFN 5-04-597, protein concentrate meal IFN 5-08-038, solv. ext. meal IFN 5-20-637, mech. extr. meal IFN 5-04-600, dehulled solv. extr. meal IFN 50-04-612; Ahmed & Dahril, 1989; Akiyama, 1988, 1991; Amerio et al; 1989, 1991; Balogun & Ologhobo, 1989; Cruz, 1992; Dabrowski & Kozak, 1979; Davies, Thomas & Bateson, 1989; Dickson, 1987; Ding, 1991; Haniffa, Josemon & Ebenezer, 1992; Hossain et al. 1992; Jackson, Capper & Matty, 1982; Kamarudin, Kaliapan & Siraj, 1989; Khan & Jafri, 1992; kim & Oh, 1985; Kim, Lee & Kang, 1984; Kissil, 1991; Lee, kang & Lee, 1991; Li et al. 1991; Lichatowich et al. 1984; Lim, 1991; Lim & Akiyama, 1992; Lim & Dominy, 1991; Lovell, 1991; Mazid et al. 1992; Millan, Ortega & Posada, 1989; Murai et al. 1986; Murai, Daozun & Ogata, 1989; Nandeesha et al. 1989; Reigh & Ellis, 1992; Shiau, Chuang & Sun, 1987: Shiau et al. 1988, 1989, 1990; Shimeno et al. 1992a; Tacon et al; 1983, 1990; Takii et al. 1989; Teshima & Kanazawa, 1988; Teshima, Kanazawa & Koshio, 1990; Viola & Arieli, 1983; Viola et al. 1981, 1982; Viola, Arieli & Zohar, 1988; Viola, Lahav & Arieli, 1992; Watanabe et al. 1992; Webster, Yancey & Tidwell, 1992; Webster et al. 1992; Wee & Shu, 1992; Wee & Shu, 1989; Wilson & Poe, 1985).

Table 10 shows the reported dietary inclusion levels of various oilseed meals within warmwater fish fees. By far the most commonly used oilseed has been soybean meal. To a large extent this has been due to its ready market availability and cost, and its high nutritional value for most cultivated fish species; Soybean being a rich source of dietary protein and EAA (possessing one of the best amino acid profiles in the plant kingdom; Table 7), and a good source of EFA (linoleic and to a lesser extent linolenic acid) and the phospholipid) lecithin (the latter serving as and emulsifier as well as being a rich source of available choline, inositol and phosphorus). However, as with most other oilseeds and plant proteins, soybean does contain a variety of endogenous antinutritional factors which, unless destroyed or biologically inactivated during processing, can greatly reduce its feed value to farmed fish (for review see Akiyama & Tan 1991; Shimeno et al. 1992a; and Viola, Mokady & Arieli (1983). For example, Table 12 shows the quality standards for soybean products in the USA recommended by the National Soybean Processors Association. According to Akiyama (1988) a trypsin inhibitor level of 1–3 mg per gram soybean meal (trypsin inhibitor being one of the major anti-nutritional factors present in raw soybeans), which correlates to a urease activity value of 0.00 to 0.23 (Table 12; urease activity being a rapid chemical test used measuring the level of toasting/ processing of soybean meal and therefore protein quality), and a protein solubilily index value of 60–80 is considered to be ideal for processed soybean products intended for use within aquafeeds.

Finally, the ultimate success or not of a soybean or oilseed protein based diet will depend upon the supplementation of the oilseed with its corresponding limiting essential nutrients so as to obtain the desired final balanced aquafeed nutrient profile. For example, high dietary soybean inclusion levels usually require supplementation with methionine (Akiyama, 1998; Murai, Daozun & Ogata, 1989; Murai et al. 1986; Takii et al. 1989; Teshima, Kanazawa & Koshio, 1990; Viola et al. 1981), lysine (Viola, Mokady & Arieli, 1983; Viola, Lahav & Arieli, 1992; Viola et al. 1981, 1982; Webster et al. 1992), phosphorus (Akiyama, 1988; Kim & Oh, 1985; Viola, Arieli & Zohar, 1988) and energy (Akiyama, 1988). In this respect it is also important to note that fish species vary in their sensitivity to soybean quality (Lim & Akiyama, 1992) and response to dietary supplementation with crystalline free amino acids; Tilapia spp. obtaining little or no benefit from dietary supplementation with amino acids in free crystalline form (shiau, Chuang & Sun, 1987; Teshima & Kanazawa, 1988; Theshima, Kanazawa & Koshio, 1990).

8. FEED INGREDIENT SOURCES - GRAIN LEGUMES AND BY-PRODUCTS

Although grain legumes or pulses have not been widely used within aquafeeds, they represent a good source of dietary protein and energy, and have included:

Cowpea (Vigna catianq; Cumaranatunga & Thabrew, 1989; Cumarantunga & Mallika, 1991; De Silva, Keembiyahetty & Gunasekera, 1988; Oduro-Boateng, 1986);

Green gram/mung bean (Phaseolus aureus; De Silva & Gunasekera, 1989; De Silva, Keembiyahetty & Gunasekera, 1988);

Winged bean (Psophocarpus tetragonalobus, Hashim & Hoong, 1992);

Black gram (Phaseolus mungo; De Silva, Keembiyahetty & Gunasekera, 1988);

Jack/sword bean (Canavalia ensiformis; Martinez-Palacios et al. 1988);

Sesbania (Sesbania spp., Olvera et al. 1988, 1990);

Green pea meal (Phaseolus radiatus; Ahamed & Dahril, 1989; Studentsova & Panasenko, 1990);

Lupin seed meal (Lupinus spp., Robaina et al. 1991; Viola, Arieli & Zohar, 1988a);

Lead tree/lpil-lpil (Leucaena leucocephala leaf meal; Basa, 1989; Hasan, Moniruzzaman & Omar Farooque, 1990; Nandeesha et al. 1991; Pantastico, 1988; Pantastico & Baldia, 1980; Penaflorida, Pascual & Tabbu, 1992; Santiago et al. 1988; Wee & Wang, 1987).

Like the oilseeds, grain legumes contain a variety of endogenous anti-nutritional factors which require deactivation and/or extraction prior to usage within aquafeeds (for specific examples see Table 10).

9. FEED INGREDIENT SOURCES - CEREAL GRAIN AND BY - PRODUCTS

Cereal grains and their by-products usually constitute the major source of dietary carbothydrate and energy within aquafeeds for warmwater omnivorous and herbivorous fish species and include:

Barleyl (Hordeum spp., brewers grains IFN 5-02-141; Hanley, 1987; Pouomogne Rouger & Kaushik, 1992);

Corn/ maize (Zea mays, grain/flour IFN 4-02-935, gluten meal IFN 5-28-241, corn distillers grains with solubles IFN 5-28-236; Webster, Tidewell & Yancey, 1991; Webster et al. 1992).

Rice (Oryza sativa, bran IFN 4-03-928; Ahmad & Dahril, 1989; Basa, Cruz, 1992; Guerrero, 1980; Luquet, 1991; Shetty & Nandeesha, 1988; Suprayitno & Widagdo, 1989; Tacon et al. 1990; Unprasert, 1989;

Sorghum (Sorghum spp., grain/flour IFN 4-04-383, brewery waste meal; Oduro-Boateng, 1986; Oduro-Boateng & Bart-Plang, 1988; Viola & Arieli, 1983); and

Wheat (Triticum spp., grain/four IFN 4-05-268, middlings/pollard IFN 4-05-205, bran IFN 4-05-190, mill run IFN 4-05-206; Campbell, 1985; Ding, 1991; Hasan, Alam & Islam, 1989; Lie et al. 1991; Luquet, 1991; Satoh, 1991; Tacon et al. 1990; Viola & Arieli, 1983).

Table 10 shows the reported dietary inclusion levels of cereals and their by-products within warmwater fish feeds. By far the commonest cereal by-products used in warmwater aquafeeds for omnivorous/herbiovorous fish species has rice bran. To a large extent this has been due to its low cost and ready availability in most developing countries. As with most plant feedstuffs, cereal grains may also contain a variety of endogenous anti-nutritional factors (Table 10).

10. FEED INGREDIENT SOURCES . MISCELLANEOUS PLANT PRODUCTS

Although by no means complete, the following are examples of miscellaneous processed plant ingredients which have been used within warmwater fish feeds.

Cassava/tapioca (Manihot esculenta; tuber meal IFN 4-09-598, leaf meal;Ng & wee Viola, 1989; Arieli & Zohar, 1988a);

Alfalfa/clover (Trifolium spp., IFN 1-00-023; Jia & Yang, 1991;

Leaf protein concentrate (Crow, Toth & Olahm 1983;Ogino, Cowey & Chiou, 1978);

Coffee (Coffea spp., pulp dehydrated IFN 1-09-734; Bayne, Dunseth & Ramirios, 1976; Christensen, 1981);

11. FUTURE PROSPECTS AND CONCLUSION

The future prospects of feed ingredient selection and usage within aquafeeds for warmwater fish species can be viewed at two levels depending upon whether the intended aquafeed is formulated for carnivorous fish species or omnivorous/herbivorous fish species.

11.1 Feed ingredients for carnivorous fish species

In 1992, approximately 232 thousand tonnes of fish meal reported used within aquafeeds for warmwater carnivorous fish species (ie. eels, yellowtail, seabass, seabream etc.) or the equivalent of about 20% of the total fish meal consumed within fish and crustacean aquafeeds (Figure 10); fish meal constituting 50% or more of the aquafeed for these species (Table 4). Together with other marine based ingredients such as fish oil, fish protein concentrates, squid and shrimp meal, it is believed that fishery products probably make up about 70% of the total aquafeed of most warmwater carnivorous marine fish species. However, as mentioned previous;y, this is perhaps not surprising since the natural diet of these predatory fish species usually consists of live fish and shellfish. At present the use of high dietary levels of marine fishery products within aquafeeds has been due to their almost ideal nutritional composition and quality (ie. making the formulation of the aquafeed much simpler and easier), ready market availability throughout the year, and more importantly, because of the current high market (ie. retail) value of marine cultured fish species, which in turn makes the purchase and dietary use of the expensive feed ingredients by the aquafeed compounder and/or farmer economically possible.

Although fish meal and fishery by products will probably remain as the main source of dietary protein used within warmwater aquafeeds for carnivorous fish species by the end of the decade, it is anticipated that high quality fish meal replacers such as bacterial/fungal SCP and plant protein concentrates (priced just below that of high quality fish meals) will gradually gain prominence, and eventually reduce fish meal dietary inclusion levels within aquafeeds by about half to 25–30%. This trend will be evident in non-fishmeal producing countries than the traditional high fishmeal producing countries (Tabl 9).

11.2 Feed ingredients for omnivorous and herbivorous fish species

Although only 73 thousand tonnes of fish meal was reportedly used within aquafeeds for non-carnivorous warmwater fish species in 1992 (Figure 10), it is anticipated that by the end of the decade dietary fish meal inclusion levels will be reduced from a global average of 20–25% to about 5–10% within aquafeeds for intensive farming systems. It is generally believed that dietary fish meal reduction will be largely achieved through the increased utilization of plant oilseeds such blending of complementary ingredient sources or by direct nutrient supplementation.

Finally, it is important to mention the studies of Viola, Arieli & Zohar (1988) with hybrid tilapia (Oreocharomis niloticus × O. aureus and Webster et al. (1992) with channel catfish (Ictalurus punctatus which have shown that cost-effective practical aquafeeds can be produced without the use of fish meal with no resulting or apparent loss in fish growth. This will be particularly true for extensive and semi-intensive pond farming systems where fish, and in particular those filter-feeding fish species which feed low aquatic food chain (ie. such as the Chinese carps and Tilapia spp.), can obtain a large part of their dietary nutrient needs, from consumption of naturally available food organisms. At present almost all warmwater fish farms use a complete diet feeding strategy for their fish with no allowance provided within the formulated aquafeed given for natural food availability. Clearly, this situation will have to be remedied if the aquaculture sector is to reduce its dependance upon fish meal and farmers are to reduce feed and production costs and improve farm profitability.