Cruise Report 69-S-2: Prawns

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Cruise Report 71-S-2: Prawns

(PDF contains 4 pages.)

Cruise Report 68-S-2 Prawns

(PDF contains 5 pages.)

Aquaculture potentials and investment opportunity in shrimps and prawns farming in Nigeria

Some aspects of the aquaculture potentials and investment opportunity in shrimps and prawn farming in Nigeria were overviewed. This paper presents the breeding pattern, spawner availability, culture water-type and properties, feeds and feeding regimes and other factors needed in practical shrimps and prawns culture. The culture systems, water management, larval management, stocking density, feeding strategies and diseases were fully discussed. The investment opportunity available as government plans to boost production of these resources from both artisanal and aquaculture sector was documented. Management strategies needed in practical practices of shrimps and prawns culture were enlisted. Effected efforts from the government were listed in this paper

The atyid prawns of Dominica

The family of primitive prawns, Atyidae, are freshwater animals with a circumtropical distribution, but additionally some have penetrated into temperate regions. An intriguing aspect of their distribution is that, although they are, and have long been, freshwater crustaceans, they have succeeded in colonizing many oceanic islands. The West Indies is an area of interest, as representatives of several genera sometimes occur on one island. For its size, Dominica is particularly rich in this respect. The fauna of the island includes the most primitive living atyid (a West Indian endemic, Xiphocaris elongata) and 2 representatives of the most advanced genus, Atya. Each of the other 3 spp belongs to a separate genus. The feeding behaviour of the Dominican atyids is discussed in this article.

The abiotic ecology of breeding ground of Palaemonid prawns in the Ilaje Estuary, Ondo State, Nigeria

In situ ecological assessment of the breeding grounds of palaemonid prawns was conducted in some selected locations around Ondo state coastal area between the months of April and September. Data obtained were subjected to both descriptive and inferential statistics. Three species of Palaemonid prawns were identified in four different locations within the study area with relative abundance ratio of 4:3:1. Macrobrachium macrobrachion, Nematopalaemon hastatus and Palaemon maculatus respectively. Sex ratio of 1 male to 5 females for M. macrobrachion, and 1 male to 2 females for N. hastatus and P. maculatus were observed with result showing significant relationships (P < 0.05) in distribution patterns across collection sites. Population distribution within the water column showed that palaemons are sub-lithoral prawns inhabiting maximum mean depth of 0.67m ± 0.025. Surface macro-phytes such as Eichhornia crassipies, Paspalum vaginatum, and Pistia stratiotes are common providing hiding spots for the prawn at the breeding ground. The mean soil pH across the sites stands at 6.67± 0.399 with the soil textural class that range from silty-loam to silty-clay. Also, the water quality parameters of study areas suggest that captive culture and rearing of Palaemons may be feasible outside the breeding areas.

Modified sorting technique to mitigate the collateral mortality of trawled school prawns (Metapenaeus macleayi)

The potential for changes to onboard handling practices in order to improve the fate of juvenile school prawns (Metapenaeus macleayi) discarded during trawling were investigated in two Australian rivers (Clarence and Hunter) by comparing a purpose-built, water-filled sorting tray against a conventional dry tray across various conditions, including the range of typical delays before the start of sorting the catch (2 min vs. 15 min). Juvenile school prawns (n= 5760), caught during 32 and 16 deployments in each river, were caged and sacrificed at four times: immediately (T0), and at 24 (T24), 72 (T72), and 120 (T12 0) hours after having been discarded. In both rivers, most mortalities occurred between T0 and T24 and, after adjusting for control deaths (<12%), were greatest for the 15-min conventional treatment (up to 41% at T120). Mixed-effects logistic models revealed that in addition to the sampling time, method of sorting, and delay in sorting, the weight of the catch, salinity, and percentage cloud cover were significant predictors of mortality. Although trawling caused some mortalities and comparable stress (measured as L -lactate) in all school prawns, use of the water tray lessened the negative impacts of some of the above factors across both the 2-min and 15-min delays in sorting so that the overall discard mortality was reduced by more than a third. When used in conjunction with selective trawls, widespread application of the water tray should help to improve the sustainability of trawling for school prawns.

Production of freshwater prawns in the Mekong Delta

Currently there are 2 sources of freshwater prawn Macrobrachium rosenbergii production in Vietnam - natural production from the rivers and canals and aquaculture production from ponds and ricefields. An account is given of the production of this prawn in the Mekong Delta. The prawns are harvested primarily by a common small scale method using shelter traps. The total annual freshwater prawn production in Vietnam during 1985-90 was reported to vary from 5000 to 8000 tons, most of it from natural fisheries; although there are no official statistics on the production of farmed prawns, the amount is believed to be very small. The grow-out system includes intensive monospecies pond culture, and semi-intensive or extensive integrated rice-prawn or vegetable-prawn culture.

Diseases and parasites of penaeid prawns of India: a short review

The diseases caused by bacteria, fungi, protozoa and metazoa as well as by other biotic and abiotic agents reported in the penaeid prawns of India are reviewed.

A study of the male reproductive organs of nine species of penaeid prawns (Crustacea: Penaeinae)

This paper deals with the male reproductive organs of nine species of penaeid prawns; Penaeus penicillatus Alcock, P. merguiensis De Man, P. semisulcatus De Haan, Metapenaeus affinis (H.Milne Edwards), M. monoceros (Fabricius), M. stebbingi Nobili, Parapenaeopsis hardwickii (Miers), P. sculptilis (Heller) and P. stylifera (H. Milne Edwards). The male reproductive organs exhibited structural variations, which were more pronounced at generic level. These variations are mainly due to the type of spermatophore they possess. One species of each genus, that is, P. merguiensis, M. affinis and P. sculptilis were also studied histologically to examine the internal structure of the male reproductive organs. Spermatophores of the six species belonging to the genera Penaeus and Parapenaeopsis are also described and illustrated.

A northern Indian Ocean record of a bopyrid, Parapenaeon japonica (Thielemann, 1910) parasitic on species of penaeid prawns (Penaeus)

A female of Penaeus merguiensis de Man collected from Karachi fish harbour (8 May, 1993) was with a large specimen of bopyrid in its right gill chamber. Since this was the second record (see Tirmizi and Bashir, 1973) of a bopyrid from a species other than Parapenauopsis stylifera H. Milne-Edwards the specimen was examined out of curiosity.

Sampling of frozen prawns for bacteriological estimation

Experiments were conducted to study the significance of difference between samples taken from the surface and interior of a frozen shrimps block, as well as to determine the size of sample necessary to represent the whole block, with respect to bacterial count determination. The results showed that the surface samples and interior samples did not differ significantly at 5% level of significance and that the minimum quantity representative of the block was 21-26 gms in the case of a block weighing about 1300 gms. The procedure adopted for taking the bacterial count was the normal standard plate count method.

Life history and behaviour of Indian prawns

Studies on life history and behaviour of prawns form an essential background for the understanding of the disposition of their fisheries and for the formulation of effective methods of exploitation and measures of conservation.

Life history of prawns: a review of recent studies with special reference to Indian species

The paper contains a brief review of the studies on the life histories of Indian species of prawns chiefly belonging to the family Penaeidae. References to similar work carried out outside India are furnished where significant variations have been observed. The three main larval stages viz., Nauplius, Protozoea and Zoea (Mysis) and their important characteristics, including modes of locomotion, are described. The post-larval development of one species that has been studied in detail (Metapenaeus dobsoni) is indicated in outline. Some aspects of the bionomics of these prawns, especially breeding and migration, are also briefly dealt with in view of their relevance in their life cycle. An outline of the life histories of some Palaemonid prawns of both fresh water and marine habitats is added at the end and the need for well- planned investigations in regard to species of such economic value as Palaemon carcinus (Macrobrachium rosenbergii) is indicated.

Deepwater prawns and lobsters off the Kerala coast

Majority of the prawn catch of the Kerala coast comes from the inshore regions within the 10 fathom line. A bottom deposit formed of fine mud rich in humus is found to be the ideal condition for the penaeid prawns. Similarly the lobster is observed in large numbers at localised areas very near the coast in the crevices of rocks. Though it has been observed that prawns and lobsters exist in deep water as well under different conditions, our knowledge about these forms along the Indian coasts is very scanty, being restricted to the works of Spence Bate, Alcock, De Man and Ramadan. Recently, during the cruises of the University Research Vessel Conch off the Kerala Coast (1958-1963) two species of deep water prawns and one species of lobster were collected from depths 100 - 180 fathoms. Of these, Penaeopsis philippi is found in large numbers occupying an almost continuous bed extending from Anjengo to Mangalore, while P. rectacutus has a restricted appearance between Cochin and Calicut. However, some sort of year to year variation has also been observed regarding the abundance of the species at various stations. Peurulus sewelli has a more restricted distribution, the maximum number being found between Puvar and Cochin. Attempt has been made to correlate the occurrence of the species with the hydrological conditions at the bottom and the nature of the substratum. It is observed that Peurulus sewelli occupies a more or less hard bed formed of sand with shell fragments or stones and small percentage of silt, the bottom temperature at the stations varying from 11°C to l4°C. P. sewelli is a more or less permanent inhabitant of the edge of the continental shell off the Kerala Coast worthy of attention for detailed investigation with a view to explore the possibilities of commercial exploitation.