RS/1
UNIT STOCKS OF SHRIMPS AND PRAWNS IN THE IPFC REGION AND UNIT FISHERIES EXPLOITING THEM

by

THAM AH KOW
Fisheries Biology Unit
University of Singapore
Republic of Singapore

Abstract

The author summarizes the existing knowledge of the distribution of shrimp and prawn species of economic value, and the main methods used for their capture and culture in the different countries of the Indo-Pacific Region.

Of the two main groups of species referred to, 51 belong to Penaeidea and 43 to Caridea. The largest species representation is from the genus Macrobrachium.

UNITES DE STOCKS DE CREVETTES DE LA REGION DU CIPP ET CATEGORIES DE PECHES LES EXPLOITANT

Résumé

L'auteur résume ce que l'on sait de la répartition des crevettes d'intérêt économique et des principales méthodes employées pour leur capture et leur élevage dans les divers pays de la région indo-pacifique.

Parmi les espèces des deux grandes catégories mentionnées, 51 appartiennent aux Penaeidea et 43 aux Caridea. C'est le genre Macrobrachium qui fournit le plus grand nombre d'espèces.

UNIDADES DE STOCKS DE CAMARONES Y GAMBAS EN LA REGION DEL INDO-PACIFICO Y UNIDADES DE PESQUERIAS QUE LOS EXPLOTAN

Extracto

El autor hace un sumario de los conocimientos actuales sobre la distribución de las especies de valor comercial de camarones y gambas, y de los principales métodos usados para su captura y cultivo en los diferentes países de la región del Indo-Pacífico.

De los dos grupos principales de especies a que se refiere, 51 son Penaeidea y 43 Caridea. La especie representada más ampliamente pertenece al Genus Macrobrachium.

1 INTRODUCTION

This paper has been prepared by the author at the request of the Indo-Pacific Fisheries Council at the 11th Session in Kuala Lumpur, Malaysia, in 1964, and is based on catalogues of unit fisheries and research project summaries sent to him by representatives of various Member Governments at the request of the Council. There was no response from a few countries and the information relating to these countries was obtained from the past proceedings of the Indo-Pacific Fisheries Council in order to complete the picture as far as possible.

2 SHRIMP RESOURCES OF THE REGION

The list of species of shrimps and prawns of economic value prepared by Holthuis and Rosa (1965) gives a very comprehensive picture of the commercially important species which have been reported from the region. The distribution of the Penaeidea and Caridea in the region is given in Table I. In preparing this table, the region is divided into six sectors as follows:

TABLE I

The total number of species listed by Holthuis and Rosa (1965) for the region is 94. The breakdown by genera is as follows:

The number of species of Caridea is only slightly lower than that of Penaeidea. In the section Penaeidea, two families, viz: Penaeidae and Sergestidae are represented. Among the Penaeidae, the genera Penaeus (14 species), Metapenaeus (13 species) and Parapenaeopsis (9 species) predominate. Among the Sergestidae, the genus Acetes predominates. In the section Caridea 5 families are represented. Most of the species are from the families Palaemonidae (29 species) and Atyidae (8 species). In the family Palaemonidae, most of the species are from the genus Macrobrachium (22 species).

3 DISTRIBUTION

The following table provides a picture of the distribution of the Penaeidea and Caridea by geographical sectors in the region.

TABLE II

The number of species recorded is highest in the South and Southeast Asian sectors. Whilst it may be that the small number of species recorded in sector I is due to the fact that the shrimp fauna has not perhaps been studied as thoroughly as in other sectors, the general picture is that the number of species in sectors II and III is higher than that in the other sectors. This is in part also due to the large number of species of Macrobrachium recorded, especially those in the southeast Asian sector.

Among the members of the genus Penaeus, certain species such as P. semisulcatus has been recorded in all sectors of the region, except Eastern Oceania and the islands of the Central Pacific, whilst others such as P. monodon and P. penicillatus have been recorded in all sectors except the extreme sectors, i.e. the western and eastern sectors of the region. On the other hand certain species are only found in certain sectors, e.g. P. plebejus only in the Australian sector, P. marginatus only in the central Pacific Islands, and P. orientalis only in the eastern sector (Japan). The distributional pattern of the other genera in the Penaeidea appears to be the same. In the section Caridea many of the species are common to two sectors, e.g. the south Asian and southeast Asian sectors. The number of species recorded for these two sectors is also comparatively high.

The members of the Penaeidea are all marine though quite often they are found in coastal and swampy areas where the water is usually of the high salinity brackish type. All the members of the Penaeidae, with one or two exceptions, e.g. in the case of the genus Metapenaeus, breed fairly far out at sea. The general picture is that the larval stages move towards the coastal areas to grow up and return to the offshore grounds on maturity to breed. The members of the Caridea, on the other hand, are predominantly freshwater, in particular the members of the genus Macrobrachium. There are exceptions, e.g. Macrobrachium equidens, M. rosenbergii, and Caridina propinqua, which according to Johnson (1962), may be found in brackish water. Palaemon styliferus and Palaemon tenuipes are also found in brackish water.

4 COMMERCIAL VALUE OF DIFFERENT SPECIES

The group which commands the highest prices in the markets are the members of the genus Penaeus as these species grow to a large size. This is so because of the world-wide great demand for these species. The members of the genus Metapenaeus come next in commercial value and they are in great demand by local consumers. To this group may also be included the larger members of the section Caridea, such as Macrobrachium rosenbergii. The other members of the section Penaeidea have a lower value and in South and Southeast Asia they are generally processed and sold as dried shrimps, or in the case of the Sergestidae, they are converted into shrimp paste. The majority of the members of the section Caridea are small and have fairly thick shells. Most of them are mature at a length of 40 to 60 mm. Their commercial value is very much lower.

5 UNIT STOCKS

Generally speaking, the unit stocks in the region may be placed in three categories, viz:

1. Stocks in the offshore region which consist mainly of the members of the genus Penaeus

2. Stocks in the coastal and estuarine region which consists mainly of the other members of the section Penaeidea and the brackish water members of the section Caridea

3. Stocks in the rivers and lakes which consist of the bulk of the members of the section Caridea

There is, however, no clear line of demarcation because many species of the genus Penaeus are caught by fishing methods employed in the coastal areas and this applies also to many Carideans which are also caught in the coastal and estuarine regions.

On the other hand, the unit stocks of different countries for each of the categories given above also differ in specific composition. Whilst there are many species which are common to the unit stocks of each category for several countries, e.g. Penaeus indicus which may be included in the unit stocks of India, Pakistan, Malaysia, Singapore, Philippines, there are other species which are specific for the unit stocks of particular countries, e.g. Penaeus plebejus, Metapenaeus endeavouri and M. macleayi for Australia, Penaeus orientalis, Metapenaeus burkenroadi, M. joyneri, M. acclivis for Japan, Pandalus borealis, Pandalus hypsinotus for Korea. The information available from the different countries are summarized in Table III.

6 UNIT FISHERIES

The main methods used for the capture and culture of shrimps in the different countries are as follows:

6.1 Shrimp trawls

These trawls are either otter trawls or beam trawls. In certain countries, such as Australia, fairly large powered boats, ranging from 20 to 75 ft (6 to 23 m) in length, with otter trawls are used and the unit stock exploited consists of species of Penaeus and Metapenaeus. In Korea otter trawls are also used but the unit stock exploited consists of species of Pandalus. The beam trawls are used in estuarine areas. The unit stock exploited by these beam trawls is similar, except that in certain countries, such as Australia, certain species such as Penaeus esculentus, P. plebejus and P. latisulcatus are apparently not caught. In certain countries they are operated throughout the year, whilst in others they are operated only during part of the year. Trawls are also used in Malaysia, Philippines, Cambodia and Korea.

6.2 Seine nets

These nets are hauled in on the beach or from the boat and their shrimp catches are incidental to the catch of fish. They are operated from small non-powered vessels in the inshore areas. They are operated in India, Pakistan, Malaysia, Philippines, Singapore and Korea. In Malaysia and Singapore they are operated throughout the year. The unit stock exploited consists of species of Penaeus and Metapenaeus.

6.3 Filter nets

These nets are fixed conical nets in the form of bags operated either with or without wings of netting or bamboo barriers on each side of the bag, anchored to the bottom with stakes and facing the tidal current so that the shrimps are filtered by the bag as they float with the current. They are known as conical nets or filter nets, or set pocket nets in different countries, and are operated in the coastal, estuarine or riverine areas in Ceylon, India, Pakistan, Philippines, Malaysia, Singapore and Australia. The unit stock exploited depends on the location. In the coastal areas it consists mainly of Penaeidae mixed with brackish water species of Carideans, and in the riverine areas it consists of freshwater Carideans. In Ceylon the nets are operated on dark nights and flares are placed above the mouth of the bags to attract the shrimps. In Malaysia they are operated throughout the year.

6.4 Barrier nets

These nets are fine-meshed and set at high tide parallel to the beach to enclose a certain area of sea and the shrimps are caught when the tide recedes. A certain amount of fish is caught at the same time. This net has been reported only from Malaysia. The unit stock exploited consists of Penaeids and fish. It is operated throughout the year.

TABLE III

Species commonly found in shrimp catches of different countries

¹ Most Australian records pertain to M. bennettae, and the Singapore records to M. burkenroadi

NOTE: (a) X indicates that the species has been reported in the commercial catches of the countries under which it is shown.

(b) This table is obviously not complete because only a few countries have sent returns to the author when requested by Mr. Rosa.

(c) The names of the species given in this table are those given by the reporting countries.

(d) + indicates that the name is not listed in the List of Species of Shrimps and Prawns of economic value prepared by Holthuis and Rosa. FAO Fisheries Technical Paper No. 52. 1965. Some of these species are listed under a different genus.

6.5 Push nets

These push nets are very common in the region. They have been reported from India, Philippines, Malaysia and Singapore. Generally it consists of a bag attached to two long poles and is operated by one person who pushes the net along the sea bottom in waist-deep water. In certain countries such as Philippines and Singapore it may be operated from boats with the operator standing in the front of the boat, which is propelled along slowly so that the operator can scoop up the surface shrimps. In Singapore this net is operated at the height of the Acetes season. The unit stock exploited consists of species of Penaeus, Metapenaeus, Acetes and some Carideans. They are operated throughout the year but the catch varies with the seasons. In Singapore the net is operated throughout the year but Acetes spp. dominate the catch from December to April and the Metapenaeids from May to November. In the Philippines they are operated on the western side from July to December, and on the eastern side from November to May.

6.6 Cast nets

These nets are universal in the region. They have been reported from Ceylon, India, Pakistan, Philippines, Malaysia and Singapore. It is operated by a single fisherman whilst standing on a rock on the beach, or standing in waist-deep water along the shore. In Singapore it is also operated from a rowing boat (sampan), with the fisherman standing in the front part of the boat. As soon as the cast net has gone down, the boatman reverses the boat and the fisherman hauls in the net. The shrimps are caught entangled in the meshes of the net. The unit stock exploited consists of the larger Penaeids. In Singapore the operation for shrimps is normally carried out just before dawn.

6.7 Pocketed scoop nets

This method is operated in the Peel Inlet, Murray River and Swan River in Australia. It is a hand scoop net, 2 ft 6 in (76 cm) in diameter, and is used from jetties with the aid of a light to catch the school prawn Metapenaeus mastersii (as M. ensis).

6.8 Shrimp culture

Shrimp culture has been reported from four countries in the region, viz. India, Philippines, Malaysia and Singapore. An informative review on this subject has already been given by Kesteven and Job (1957). These methods have certain characteristics in common:

1. All the methods use an enclosed body of water in which the shrimps are impounded and grow up

2. The resources cultivated are all members of the Penaeidae

3. The shrimps do not breed in the ponds.

The details of culture method in the different countries, however, differ. The methods in Malaysia and Singapore are similar. In this method the young shrimps are not caught and placed in the pond by the culturists. The ponds are provided with sluice gates so that at high tide the sea water together with the young shrimps is allowed to flow into the ponds. When the tide recedes, part of the water is allowed to flow out through the sluice gates. The outflowing water is filtered by wire-mesh screens in the day and by filter nets in the night. Only sufficient water is retained in the ponds for the night catching operation which consists of allowing the water in the pond to pass out through fine mesh filter nets. It is presumed that the young shrimps stay in the ponds to feed and grow up because the catches consist of shrimps which are more than 2 to 2½ in. in length. Fishing is carried out once a day during spring tides throughout the year. The shrimps are not fed and no effective fertilization of the water is carried out. The unit stock exploited consists mainly of Penaeus indicus, P. merguiensis, Metapenaeus mastersii (as M. ensis). Other species such as Metapenaeus brevicornis and Penaeus semisulcatus occur in fairly large numbers during certain seasons. The yield varies from 0.15 to 0.35 ton per acre per annum. With careful management the yield of 0.30 to 0.35 ton per acre per annum can be obtained. Details of this fishing method are given in the Annual Report of the Fisheries Department, Federation of Malaya and Singapore, and by Hall (1962) and Tham (1955).

In India the cultivation, as described by Gopinath (1956), is carried out in the rice fields of Travancore-Cochin. During the rice cultivation period the water is fresh or very slightly brackish. Water from the tidal backwaters is permitted to flow freely in and out of the fields after the rice harvest. In August the salinity gradually increases, as a result of the cessation of water flow from the canals and the greater influence of the tides, until March - April when it reaches a maximum. In this method young shrimps also get into the ponds through the tidal flow. They grow up in the ponds and are harvested by means of filter nets. This method of fishing ends around April. Details of this method of culture are also given by Panikkar (1956) and Menon (1955).

In the Philippines the shrimps which are cultivated in the ponds are purchased by the shrimp culturists from fishermen who specialise in catching the young of Penaeus monodon. This is the Sugpo Fry Fishery. This type of shrimp culture is normally carried out together with Chanos culture. Some of the shrimps, both Penaeus monodon and Metapenaeus monoceros, also get into the pond through the tidal inflow. Details of this method are given by Delmendo and Rabanal (1956).

From the definition of a unit fishery as given by Kesteven (1964), it is a collection of fishing units which are identifiable as a distinct group because they fish the same stock or stocks, have some common features and operate under common circumstances. In line with this definition the fishing methods for shrimps in the region can conveniently be grouped into unit fisheries exploiting the resources classified within the following framework:

1. Freshwater

2. Brackish water

3. Marine

Certain fishing units such as cast nets and filter nets operate in all the three ecological divisions, particularly in the Southeast Asian sector. There is also an overlap between all these three ecological divisions in so far as distribution of shrimps are concerned. Many of the species of Penaeids are also found in both the Brackish Water and Marine divisions. In the case of Carideans some species such as Macrobrachium rosenbergii are found in both the Freshwater and Brackish Water divisions. The shrimp fauna is very mixed in each of these ecological divisions so that classification by “commodity produced” is even more unsatisfactory. The number of boat types used is also great, and many of these boat types are used even for the same fishing method so that classification by “boat types” is also unsatisfactory.

In the circumstances it is deemed that for the IPFC region as a whole the classification of unit stocks into the following ecological framework is possibly the most convenient:

1. Freshwater

2. Brackish water and marine inshore

3. Marine offshore

The Shrimp Unit Fisheries of the Indo-Pacific Region may tentatively be grouped as follows:

1. Freshwater:

   Cast nets
   Filter nets
   Seine nets
   Pocketed scoop nets

2. Brackish water and marine inshore:

   Cast nets
   Filter nets
   Seine nets
   Push nets
   Barrier nets
   Beam trawls
   Shrimp culture

3. Marine offshore

   Otter trawls
   

7 RESEARCH PROJECTS

Information on research projects on shrimps are available only from the following countries:

8 REFERENCES

Ahmad, N., 1957 Prawns and prawn fishery of East Pakistan. Dacca, East Pakistan Govt. Press, 31 p.

Delmendo, M.N. and H.R. Rabanal, 1956 Cultivation of sugpo (Jumbo tiger shrimp) Penaeus monodon Fabricius in the Philippines. Proc.Indo-Pacif.Fish.Coun., 6(2–3):424–31

de Zylva, E.R.A., 1955 The prawn fisheries of Ceylon. Proc.Indo-Pacif.Fish.Coun., 6(2–3):324–7

Domantay, J.S., 1956 Prawn fisheries of the Philippines. Proc.Indo-Pacif.Fish.Coun., 6(2–3):359–66

Gopinath, K., 1956 Prawn culture in the rice fields of Travancore-Cochin, India. Proc. Indo-Pacif.Fish.Coun., 6(2–3):419–24

Hall, D.N.F., 1962 Observations on the taxonomy and biology of some Indo-West-Pacific Penaeidae (Crustacea, Decapoda). Fish.Publs colon.Off., (17):229 p.

Holthuis, L.B. and H. Rosa, Jr., 1965 List of species of shrimps and prawns of economic value. FAO Fish.tech.Pap., (52):21 p.

Johnson, D.S., 1962 A synopsis of the Decapoda, Caridea and Stenopodidea of Singapore with notes on their distribution and a key to the genera of Caridea occurring in Malayan waters. Bull.nath.Mus.St.Singapore, (30):44–79

Kesteven, G.L., (Ed.) 1964 Unit fisheries of Australia (2nd draft). Cronulla, CSIRO, Division of Fisheries and Oceanography

Kesteven, G.L. and T.J. Job, 1957 Shrimp culture in Asia and Far East. A preliminary review. Proc.Gulf Caribb.Fish.Inst., 10:49–68

Menon, M.K., 1955 On the paddy field prawn fishery of Travancore-Cochin, India and an experiment in prawn culture. Proc.Indo-Pacif.Fish.Coun., 5(2–3) 131–5

Panikkar, N.K. and M.K. Menon, 1956 Prawn fisheries of India. Proc.Indo-Pacif.Fish.Coun., 6(2–3):328–44

Tham, A.K., 1955 The shrimp industry of Singapore. Proc.Indo-Pacif.Fish.Coun., 5(2–3): 145–55

Acknowledgments

The author would like to express his thanks to Mr. H. Rosa, Jr., now Fishery Liaison Officer (International Organizations), FAO Department of Fisheries, for assistance in procuring reports on unit stocks, unit fisheries and project summaries from the various countries of the region. He would also like to thank Dr. G. L. Kesteven, Assistant Chief, Division of Fisheries and Oceanography, CSIRO, Australia; Mr. Soong Min Kong, Director of Fisheries, Malaysia; Mr. Arsenio N. Roldan, Jr., Commissioner of Fisheries, Philippines; Dr. Nazir Ahmad, Director of Fisheries, West Pakistan; Dr. Bae Dong Hwan, Chief, Deep-sea Fishing Section, Bureau of Fisheries, Korea; and Mr. Sao Leang, Director of Fisheries, Cambodia, for their prompt replies to Mr. Rosa's request for data, without which it would have been extremely difficult to prepare this summary.