An appraisal of the cultivability of Nigerian palaemonid prawns

I. E. Marioghae

AFRICAN REGIONAL AQUACULTURE CENTRE, PORT HARCOURT, NIGERIA
CENTRE REGIONAL AFRICAIN D'AQUACULTURE, PORT HARCOURT, NIGERIA

UNITED NATION DEVELOPMENT PROGRAMME
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
NIGERIAN INSTITUTE FOR OCEANOGRAPHY AND MARINE RESEARCH
PROJECT RAF/82/009

February 1987

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ABSTRACT

Adult size, growth rate, fecundity, ability to breed in captivity, and good adaptability to common environmental factors such as dissolved oxygen, pH and salinity are used to assess the cultivability of Nigerian palaemonid prawns. Prawns of the sub-families Euryrhnchinae, Typhlocaridinae, Pontoniinae, and Demoscaridinae are either too small, too fragile or too stenohaline to be suitable for culture. Of prawns in the sub-family Palaemoninae, only two members of the genus Macrobrachium, M. vollenhovenii and M. macrobrachion are considered to be suitable for culture.

L'EVALUATION DE LA POSSIBILITE DE L'ELEVAGE
DES CREVETTES (PALAEMONIDES) NIGERIANNES

RESUME

La taille de l'adulte, le taux de croissance, la fecondité, la capacité de se reproduire en captivité, l'adaptation aux facteurs de l'environnement le plus commun tels que l'oxygène dissous, le pH et la salinité sont utilisés pour evaluer la possibilité de l'élevage des crevettes palaemonides nigériannes. Les crevettes de la sous-famille Euryrhnchinae, Typhlocaridinae, Pontoniinae et Demoscaridinae sont trop petits, trop fragiles ou très stenohalins pour convenir a l'élevage. Parmi les crevettes de la sous-famille de Palaemoninae, seul deux espèces du genre Macrobrachium, M. vollenhovenii et M. macrobrachion sont consideres propice a l'élevage.

INTRODUCTION

Prawn culture is a relatively recent phenomenon, when compared to fish culture. The widespread culture of palaemonid prawns is due mainly to the pioneering work of Ling (1962), and Ling and Merican (1961) on the giant freshwater prawn of South-East Asia - Macrobrachium rosenbergii (De Man 1879). Further research and actual culture trials by other workers notably Fujimura and Okamoto (1972), Kwon and Uno (1968 and 1969), Choudhury (1970, 1971a, 1971b, 1971c), Shokita (1970), Costello (1971), Sandifer and Smith (1975) etc. have gradually made prawn culture viable. Kelly quoted by Agnone (1976) estimated that a conversion ratio (feed/flesh) of 1 to ½ kilo for prawns was feasible as compared to 3 to ½ kilo for beef. Since prawns also command higher prices (per kilogram) in the market, prawn farming is fast developing into big business. Fish Farming International (1985) reported this trend in the Philippines; traditional milk fish farmers switching to prawn farming on grounds of better remuneration, and the government decision to go into large scale prawn farming. In Nigeria however, as indeed in most countries of the African region, palaemonid prawn culture has not been attempted on any serious scale. However, the potential is there, and this paper is an attempt to assess the possibilities, taking into account what is known of the biology of the various local species. The cultivability of Nigerian palaemonid prawns will be considered with regards to whether they have a good adult size, a fast growth rate, ability to breed in captivity, a good adaptation to common environmental factors such as dissolved oxygen, salinity, etc.

NIGERIAN PALAEMONIDS

The Family PALAEMONIDAE has five sub-families namely Euryrhnchinae, Typhlocaridinae, Pontoniinae, Palaemoninae and Demoscaridinae (Borradaile, 1915), resurrected by Powell (1977).

Euryrhnchinae:

The two known species Euryrhnchina edingtonae (Powell 1976) and Euryrhnchoides holthuisi (Powell 1976) are the only ones of this genus from the old world. Their adult size is small, and they are neither abundant nor widely distributed. In fact, only the former is from Nigeria while the latter is from Sierra Leone.

Typhlocaridinae:

This sub-family has only one genus which is not represented in Nigerian waters.

Pontoniinae:

There are only two genera Palaemonella and Periclimenes. They are usually small prawns found in marine and polyhaline situations. They are therefore not suitable for culture.

Demoscaridinae:

There is only one genus and two species Demoscaris trispinosa (Aurivillius 1898) and D. bislineata (Powell 1977). Both are small freshwater prawns (maximum carapace length 7mm), too small for prawn culture.

Palaemoninae:

Local species of the Palaemoninae belong to four genera as set out in Table I.

Palaemon and Palaemonetes:

All the local species of the two genera - Palaemon maculatus, Palaemon elegans, Palaemon species ‘A’ (Powell 1982) and Palaemonetes africanus are small in size. Their maximum total lengths range from 30 – 50mm. This is a major disadvantage.

Table I Food, max. adult size, fecundity, and tolerance of salinity and low oxygen tension of Nigerian palaemonid prawns

* Maximum total length in the Niger Delta. In Europe, it is 60mm.
** Maximum total length in Nigeria. Values up to 120mm have been reported for Central Africa.

However they do possess other characters which (but for their small sizes) would have made excellent culture prawns. They are hardy, and can survive in situations where dissolved oxygen is less than 1 ppm. They thrive easily on available natural food. They breed throughout the year following a fornightly rhythm with individual peaks in different seasons of the year. This would have ensured a steady supply of seed to the fish farmer.

Nematopalaemon:

The only local member of this genus N. hastatus has much to discourage its culture. It is a rather specialised species. It is pelagic, and appears only in well aerated marine and polyhaline waters (Marioghae, 1980). It feeds almost exclusively on mysids and copepods, Marioghae (op cit.). Its maximum size 75mm (Holthuis 1980) is small. However, it breeds throughout the year, and the clutch size 700 – 2500 is good. Availability of seed would have posed no problem. The taste is excellent, and the growth to adulthood is about six months.

Macrobrachium:

All local members of this genus have fairly good adult size and would appear to be culturable.

M. vollenhovenii:

This is the largest of the local palaemonid prawns. With a maximum size at 182mm (Holthuis, 1980), this species is in the same size class as M. americanum (Bate, 1896), M. carcinus (Linnaeus, 1758) and M. malcolmsonii (H. Milne Edwards, 1844). It is a hardy prawn in many ways. It thrives in murky waters (white water rivers in the Nigerian context), and will survive in waters with dissolved oxygen as low as 1 ppm. Ville (1971), and Marioghae (1982) reported the capture of this species from waters with natural salinites at 27 ppt and 19 ppt respectively. Mwangi (1984) proved experimentally that the species can easily tolerate salinities ranging from freshwater to 22 ppt. It is therefore clear that the species may be cultivated without fear in a wide range of salinities. Mwangi (op cit.) also established experimentally that the species can tolerate pH values as low as 5. As pH values in well tended ponds rarely fall below 6, M. vollenhovenii appears to be quite safe in ponds. However, even if the water is badly fouled, this species (like many members of the genus) can climb out and does survive out of water for upwards of 12 minutes (Marioghae, 1982). This ability to climb however has its disadvantages, because the prawns could be exposed to predation by birds etc. in the process.

M. vollenhovenii is an omnivorous detritivore with preference for animal remains (Marioghae, 1982). Mwangi (1984) showed that this species preyed effectively against frog tadpoles, and the fry of Tilapia zilli and Oreochromis niloticus. Thus M. vollenhovenii could be used in polyculture for controlling overpopulation of tilapias. Its clutch size 12 – 45,000 is quite adequate, while its growth to adult size in eight to ten months is not too long. This period can probably be reduced under culture conditions. Morioghae (1982) noted that moulted prawns were not attacked and pointed out that this could be an asset in its culture. M. vollenhovenii is quite tasty, although the integument is rather thick. However, even that should pose no problems, since prawns are largely consumed without the integument. A kilogram of the prawns now costs about 4 - 5 head-on, (about $2 – $2.5). Remuneration to the farmer would therefore be adequate even in terms of the local market. Miller (1971) reported a fungal infection of the gills, although the incidence appeared to be small. However this may increase under culture conditions, especially under intensive culture. It should be watched for in order to avoid losses.

M. macrobrachion:

It is a medium sized prawn (max. size 138mm) comparable to M. lar (Heller, 1862) and M. mammillodactylus (Thallwitz, 1891). Marioghae (1982) found the consumable portion (tail) of M. macrobrachion to be slightly larger than for M. vollenhovenii of a similar size. Usual habitat for this prawn is freshwater, and low salinity waters not exceeding 10 ppt (Powell, 1982). It may therefore be cultured safely in salinities within this range. From personal observation, M. macrobrachion is probably more hardy than M. vollenhovenii and can survive for over 20 munities out of water (Marioghae, 1982). Low oxygen and pH tolerance are similar to those for M. vollenhovenii.

M. macrobrachion is an omnivore with a slight preference for algae (Marioghae, 1982). It could thus do well in fertilised ponds. However, algal growth on the carapace might result, as has been observed in specimens picked up from non-tidal freshwater pools at Aluu - Port Harcourt. Also some Vorticella spp were observed to be living in commensal relationship attached to the coxae of the pleopods, otherwise no serious parasite or disease problems have been encountered.

M. macrobrachion breeds during the rainy season months, (May - November). Like the local members of the genus Palaemon M. macrobrachion has a fortnightly rhythm of breeding (Marioghae unpubl.) Clutch size varies from 3,000 – 12,000 depending on the size and age of the prawn. Ovigerous females constitute up to 30% of the entire population, (Miller, 1971 and Marioghae, 1982) or approximately 51% of the female population. Seed supply should therefore be adequate, although seasonal. Marioghae (1982) found that M. macrobrachion constituted up to 80% of the commercial Macrobrachium fishery catches in the Lagos lagoon during the rainy season. Similarly, Powell (1982) believed that the species was commercially more important than M. vollenhovenii in tidal areas of the Niger Delta where salinity was within its preferred range. Growth of the prawn to adulthood is estimated to be about 6 – 8 months. The market price is similar to that for M. vollenhovenii, because many fishermen and consumers cannot distinguish between the prawns which are usually sold mixed.

M. felicinum:

This prawn occurs along with M. vollenhovenii in non-tidal freshwater zones of white water rivers. Oxygen and pH tolerance will therefore be probably as for M. vollenhovenii. Not much is known about its feeding habits, but it is possibly mainly a detritus feeder like other local members of the genus. Fecundity appears to be adequate, and in addition adults and even juveniles engage in mass migration, a behaviour which Powell (1982) observed would allow for a cheap and reliable supply of seed for aquaculture purposes. However, maximum adult size (80mm), Powell (1982), is not good enough to recommend it for culture.

M. equidens:

Accidentally introduced into the Niger Delta from the Indo-West Pacific, Powell (pers comm.), this species is currently found in the high salinity zones of rivers in the Niger Delta (Powell, 1982).

With maximum adult size of 98mm, Holthuis (1980), it almost in the size range of M. macrobrachion with which it could be easily confused. Nothing definite can be said as at now for or againt its culture.

M. dux:

This is not a common species, and may be synonymous with M. raridens (Powell, 1982). It may be poorly adapted to situations with low dissolved oxygen, and low pH, since it occurs only in clear water rivers and streams. Consequently the culture of this species may require a greater degree of care. Besides, the maximum adult size of this species in the Niger Delta is rarely more than 80mm (Powell, 1982), although Holthuis (1980) reported a maximum carapace length of 50mm for the same species from elsewhere which would make it much larger than the Nigerian species. The small size of our local species certainly does not recommend it for culture.

RECOMMENDATIONS

In view of the foregoing, only two species (at least for now) may be whole-heartedly recommend for culture. They are M. vollenhovenii and M. macrobrachion in order of preference. They both meet the requriements in respect of size, growth adaptability and availability of seed.

From the attempt of Ville (1971), and my personal experience in lab-rearing of the larval stages of M. vollenhovenii and M. macrobrachion, it appears that hatchery production of fry should not be too difficult, especially as the process has been worked out for other members of the genus such as M. rosenbergii and M. americanum. Major feed ingredients such as soya beans, peanut cake, rice bran and wheat bran are locally available. Prawn meal (if it really becomes necessary) may be obtained by making use of the prawns discarded by coastal fish and shrimp trawlers. Little or no modification is needed on existing fish ponds before they can be used for prawn culture. Harvesting channels may need to be cut in the ponds, but these do not entail any heavy capital inputs. Similarly, pipes (bamboo, PVC, asbestos) may be laid in the ponds to provide refuge for moulting prawns, although it does not appear that these are absolutely necessary for reasons already adduced.

The greatest potential of these prawns may be in polyculture with Tilapia spp. which are notorious for excessive breeding within ponds. M. vollenhhovenii has been proved to be a good predator on tilapia fry Mwangi (1984). Its culture along with tilapia may prove to be a useful way of curbing the proliferation of tilapia fry in the pond which usually leads to stunting. It will also be a more scientific way of making full use of all the food niches in the pond, particularly on the benthos.

REFERENCES

Agnone, C. 1976. Shrimp farming in Tropics No. 93 pp 6–7

Borradaile, L.A. 1915. Notes on Carides - Ann. Mag. Nat. Hist. 8(15): 205 – 213.

Costello, T.J. 1971. Freshwater prawn culture developed. American Fish Farmer, World Aquaculture News, Jan. Issue, 27: 8 – 100.

Choudhury, P.C. 1979, Complete larval development of the palaemonid shrimp Macrobrachium acanthurus (Wiegman) reared in the laboratory. Crustaceana 18(2): 113 – 132.

Choudhury, P.C. 1971a, Complete larval development of the palaemonid shrimp Macrobrachium carcinus (L) reared in the laboratory. Crustaceana 20(1): 51 – 69.

Choudhury, P.C. 1971b. Responses of larval Macrobrachium carcinus to variations in salinity and diet. Crustaceana 20 (2) 113 – 120.

Choudhury, P.C. 1971c. Laboratory rearing of the palaemonid shrimp Macrobrachium acanthurus, Crustaceana 21 (2): 113 – 126

Fish Farming International. 1985 12(2) p. 18 and 12(3) p.1.

Fujimura, T. and H. Okamoto. 1972 Notes on progress made on developing a mass culturing technique for Macrobrachium rosennergii in Hawaii, in Coastal Aquaculture in the Indo, -“Pacific region” ed. T.V.R. Pillay, Fishing News/FAO pp 313 – 327.

Holthuis, L.B. 1980 FAO Species catalogue Vol. I - Shrimps and Prawns of the world. FIR/S.125 Vol.I, 271pp.

Kwon, C.S. and Y. Uno. 1968 The larval development of Palaemon mondestus (Heller), Bull. Soc. Franco. Jap. Oceanogr.

Kwon, C. S. and Y. Uno. 1969 The larval development of Macrobrachium nipponense (de Hann) reared in the laboratory. Bull. Soc. Franco. Jap. Oceanogr. 7(4): 278 – 294.

Ling, S.W. 1962. Studies on the rearing of larvae and juveniles and culturing of adults of Macrobrachium rosenbergii (de Hann), IPFC Tech. Pap. (57): 15pp.

Ling, S. W. & A B. C. Merican. 1961 Notes on the life and habits of the adults and larval stages of Macrobrachium rosenbergii, Proc. IPFC 9(2): 55 – 60.

Marioghae, I. E. 1980 The ecology and commercial fishery of Palaemon (Nematopalaemon) hastatus (Aurivillius, 1898) M.Sc. Thesis, University of Port Harcourt, Nigeria. 70pp.

Marioghae, I. E. 1982 Notes on the biology and distribution of Macrobrachium vollenhovenii and Macrobrachium macrobrachion in the Lagos lagoon. Rev. Zool. Afr. 96(3): 493 – 508.

Miller, G. C. 1971 Commercial fishery and biology of the freshwater shrimp Macrobrachium in the lower St. Paul River, Liberia (1952 – 1953) - Contr. 141 Nat. Mar. Fish. Sci. Rep. Fish. 626pp.

Mwangi, B. T. 1984 Macrobrachium vollenhovenii (Herklots, 1857) - Its availability, tolerance of salinity and low pH, and an assessment of its use as a predator in polyculture. M. Tech. Thesis. Rivers State University of Science and Technology/ African Regional Aquaculture Centre, Port Harcourt, Nigeria.

Powell, C. B. 1976 Two new freshwater shrimps from West Africa: the first euryrhnchinids (Decapoda, Palaemonidae) reported from the old world. Rev. Zool. Afr. 90: 883 – 902.

Powell, C. B. 1977 A revision of the African freshwater shrimp genus Demoscaris (Sollaud), with ecological notes and description of a new species. Rev. Zool. Afr. 91 (3): 649 – 674.

Powell, C. B. 1982 Fresh and brackish water shrimps of economic importance in the Niger Delta. Proc. 2nd. Ann. Conf. Fish. Soc. Nigeria, 254 – 285.

Sandiffer, P. I. 1976 Experimental aquaculture of the Malaysian prawn Macrobrachium rosenbergii (de Mann), in South Carolina, USA - FAO Tech. Conf. Aquacult. Contr. 47 South Carolina mar. res. centre. FIR: AQ/CONF/76/E.3.

Shokita, S. 1970 Studies on the multiplication of the freshwater prawn Macrobrachium formosense (Bate) 1. The larval development reared in the laboratory. Biol. Mag. Okinawa 6 (8): 1 – 12.

Ville, J. P. 1971a Ecologie des Macrobrachium de Cote d'Ivoire. I. Role de la temperature et de la salinite. Ann. Univ. Abidjan. Ser. E. Ecologie (1): 317 – 324.

Ville, J. P. 1971b Biologie de la reproduction des Macrobrachium de Cote d'Ivoire. III. Decription des premiers stades larvaires de Macrobrachium vollenhovenii (Herklots 1857), Ann. Univ. Abidjan, Ser. E. Ecologie, IV (1): 325 – 341.