The report covers a one-month mission for the UNDP/FAO Coastal Aquaculture Development Project to undertake site selection and make initial designs. for prawn hatcheries in India. It includes an overview of prawn capture and culture in India, objectives of the Project, summary of activities and observations of the four hatchery sites surveyed. It then gives general recommendations on hatchery production levels and future expansion, species to be reared, spawner and broodstock sources in relation to traditional fishing methods and seawater tests to be undertaken during dry and rainy seasons before final site selection. Details of hatchery layout and tank design based on underlying assumptions, and stocking, survival and water management are discussed in the text and outlined in various tables, figures and appendices. Specific recommendations and a proposed Work Plan are also included.
1.1 For the last 10 years, India has been the world's leading producer of prawns and shrimps with the bulk of producton coming from offshore landings (Table 1). With the stagnation in marine catches in recent years, however, the role of aquaculture in contributing to national prawn production cannot be over-emphasized.
1.2 At least 10% or 170,000 ha out of a total of 1.7 million ha of mangrove swamps, mud flats and other brackish water areas are suitable for prawn culture. At present, only 30,000 ha in Karnataka, Kerala and West Bengal are under traditional culture as pokhalis or bheris with another 3,500 ha farms existing or planned for 1986–87 (Table 1).
2.1 The development objective of the UNDP/FAO Development of Coastal Aquaculture Project (IND/85/059) is to develop 10,000 ha of. brackishwater areas to produce fish and prawns as envisaged in the Seventh Five Year Plan.
2.2 The immediate objective of the project is to develop coastal aquaculture by: i) carrying out possibility studies for selection of suitable sites and conducting site surveys; ii) developing suitable engineering designs for coastal aquaculture farms and shrimp hatcheries and operational procedures for the types of sites commonly found in the country; iii) testing the suitability of designs, their operational procedures and economic viability through the establishment of representative pilot projects; iv) establishing guidelines for designing and operation of small and large coastal farms and shrimp hatcheries in different types of sites; and v) training adequate-number of personnel to undertake feasibility studies, site surveys, preparation of farm designs, economic viability, establishment and operation of farms and hatcheries.
As Hatchery Specialist, my terms of reference are: a) to set up a shrimp hatchery near one of the pilot fish farms, b) design small-scale hatcheries as appropriate, and c) train local technicians in their operation, all under the guidance of the National Project Director.
4.1 The Institute (CICEF) had earlier identified a number of sites along the coastline of India that might be suitable for prawn hatcheries. National Project Director Mr. N.P. Bhakta and I reviewed these sites with the assistance of the CICEF staff and drew up a tentative list of sites to be visited as follows:
|Type||I||:||1) Madhavapur (near Mangrol)|
|Type||III||:||1) Mirya Bay/Ratnagiri Bay|
Standard criteria used in the selection of the above sites included hydrology, topography, spawner source and support services (Table 2). Figures 1 and 2a, 2b, 2c and 2d show the actual sites surveyed.
4.2 The remaining period (15–24 April) was devoted to field survey (Appendix 1) including monitoring of water quality. The Aquaculture Engineer Mr.R. Hechanova, joined Mr.Bhakta and I, starting 20th April for the sites in Andhra.
Pradesh and Orissa. Due to time constraints, survey of hatchery sites for Type III was postponed for the second visit in August/September during which rainy season seawater parameters (salinity, etc.) would also be monitored.
5.1 The following were direct observations or information povided in interviews with various officials we met (Appendix 2). A summary of the pertinent data for each site is found in Table 3.
Mangrol with a population of approximately 30,000 is 16 km away from Keshod airport. It is 42 km from Veraval, the nearest big town which has a newly-constructed fishing harbour. The proposed hatchery site itself is in Madhavapur, a small village with a population of 15,000.
The Gujarat Fisheries and Aquatic Sciences Research Institute runs a prawn hatchery at Okha which produces around 1 × 106 fry/yr of P. merguiensis. Growth rates have been promising (25 g in 135 days) but survival was low at 40–55 ppt in the private ponds of the Singach saltworks and 20–25 g in 90 days at 25–33 ppt in government farms. Hatchery fry were transported in a temperature-controlled van over upto 17 hr periods with low mortality.
As with most of the Indian coastline, wind and wave action can be strong enough to cause storm surges and a constantly shifting sand substrate at the proposed hatchery site. Because it is very difficult if not impossible to lay an intake pipe directly to the sea bottom, an inshore well has been suggested by the Institute. Testing shall be done both below and above the high water level and a profile taken of salinity, concentration of heavy metals and rate of water flow at different depths, during dry and rainy seasons.
Prawn fishing gear consists of stern trawlers and traditional bottom gill nets. The fishing season is from September to May with the catch composition as follows: 90% Penaeus merguiensis (banana prawn), 1–2% Metapenaeus monoceros (brown prawn), 0.5% P. monodon (tiger prawn) and 10–12% Metapenaeus spp. For the proposed hatchery, P. monodon spawners will be obtained from bottom set gill net and hand net operators in Dwarka, Jakhau and other grounds and also from trawlers. During the off season from December to July, captive broodstock will be procured from the project farm or from private farms, most probably in the Bulsar area. Fry of P. merguiensis, the most abundant species, can be produced by the hatchery according to local demand.
Valinokkam is a small fishing village (pop. 5,000), a one and half hour ride from Ramanathapuram, the nearest town and 3 hr away from Madurai, the nearest airport. A fishery harbour is under construction and the state-run Tamil Nadu Salt Corp. produces approximately 2,000 tonnes/year of salt. m The Mandapam Fisheries Station is around 40 km from Valinokkam.
There are 50 ha of existing prawn monoculture ponds and another 200 ha planned for 1986–87, all pump-fed because of the renewed tidal amplitude. The farms are stocked with wild fry at 50, 000/ha/crop. Total wild fry stocked per year is 5 × 106 of which only 5% is P. monodon and the rest consists mainly of P. indicus (white prawn) and some Metapenaeus spp.
The proposed hatchery site is probably one of the very few places in India where an intake pipe can be laid on the sea bottom because of the absence of strong wave action. This natural protection is due to three factors, namely: a) location below 10 degrees latitude where cyclones seldom occur, b) presence of the island of Sri Lanka to the south, and c) bay formation of the site.
Prawn fishing gear consists of bottom set gill nets and mechanised fishing boats. The 40-m fishing boats trawl at 10–12 m depth and catch up to 10 pcs/night of P. monodon. The prawn fishing season is from April to September with sizes of 36–40 pcs/kg (25–40 g) for P. monodon and 40–60 pcs/kg (17–25 g) for P. indicus.
Visakhapatnam (Vizag) with a population of more than half a million is a major fishing port. The following data on the prawn capture fisheries are based on interviews with officials of the Visakhapatnam Fisheries Terminal Organization and the Andhra Pradesh Fish Freezing and Cold Storage-Cum-Ice Plant.
There are some 260 mechanised fishing boats, predominantly 10 m long, which trawl at 20–70 m depth and 86 trawlers at 50–100 m depth. The highest prawn landings in India is around the Vizag area with about 6,000 mt exports of headless prawns in 1985. The prawn fishing season is from September to February with a peak in October to November. Traditional fishing gear consists of bottom set gill nets. Prawn catch composition is 30–40% P. indicus, 20% P. monodon, 15–20% M. monoceros and 10–20% other species. Ten processing plants in Vizag have a total freezing capacity of 64 mt/day, mostly using plate freezers.
At present, there are 600 ha of existing prawn farms and another 1,000 ha planned for 1986–87. Stocking density of P. monodon is 25,000/ha/crop with 2 crops/yr with yields of 300 kg/ha/crop at average sizes of 30–35 g body weight. Because of the small harvest sizes, there is a growing trend among farmers to reduce stocking density to 15,000/ha and to increase stocking sizes of wild seed from 15–20 mm total length to attain 40–50 g sizes.
Total yearly wild fry collection is 100 × 106 P. monodon and another 100 × 106 P. indicus gathered from stagnant pools, creeks and estuaries by push nets or drag nets, particularly in the Kakinada area. Ten percent of wild fry collection is exported to Goa and Maharashtra with an average survival rate of 40% after a 72-hr transport by land to Maharashtra.
During the survey, three sites were visited: a) Lawson's Bay, b) Gudlavanipalem and c) Bimlipatam (Table 3). Gadlavanipalem is located close to a fishing village but 4 km away from Vizag.
Chandrabhaga is a small fishing village near the town of Konarak (pop. 10,000) and 60 km away from Bhubaneswar, the nearest airport.
Prawn fishing is by traditional gill nets and trawlers operating in Ramchandi and Puri. The season is from June to December with catch composition of 20–30% P. indicus/P. merguiensis, 20% P. monodon, 10% P. semisuloatus, 20% M. monoceros, 20% M. dobsoni, M. affinis and other species.
The state of Orissa has some 300 ha of existing prawn ponds in Chilka Lake and another 440 planned in Panaskapada, Binchinapalli and Jagatjore. Chilka Lake is the biggest brackishwater lake in South Asia with an area of 906 to 1,165 sq km, the depth of 60 to 120 m, and salinity ranging from 2 to 30 ppt, the extreme values representing the dry and monsoon seasons. Confined ponds of 0.2–0.5 ha are dug and enclosed by dikes during the dry season. After they fill up with the rising of the lake level during the monsoon, wild P. monodon juveniles are stocked at 10,000–15,000/ha. Harvest after 3 months is 400–500 kg/ha although ICAR-CMFRI has produced 3,000–5,000 kg/ha for the same period from experimental ponds wth pumped water. Only one P. monodon crop is possible due to increasing salinity as water evaporates from the ponds and in the absence of any water exchange. P. indicus has been tried as a second crop but growth rates have been poor.
Wild fry are collected by dip nets and push nets operating along river discharges and other estuaries. Species composition is 40% Metapenaeus spp., 30% P. monodon and 30% P. indicus/P. merguiensis. In Orissa, approximately 130 × 106 P. monodon and P. indicus seed are available yearly (Das and Mohanty, 1985). Around 36 × 106 or 9.6% of total prawn yearly prawn landings consist of juveniles of P. monodon and P. indicus in Chilka Lake, one of the richest brackishwater fishery and nursery areas.
The proposed site is next to the fishing village behind a stand of Casuarina planted to serve as storm buffer. If tests show that seawater from an inshore well (to avoid damage by storms) can support a prawn hatchery, the land can be obtained from the Department of Forestry. Road access and electrical lines will need to be extended by 1 km.
The Marine Products Export Development Authority (MPEDA) has tentatively identified a site in Gopalpur for a prawn hatchery of 50 × 106 PL/yr capacity. If the MPEDA plan pushes through, locating the UNDP project hatchery in Chandrabhaga would lead to a more even state-wise distribution of government hatcheries. Moreover, the Chandrabhaga hatchery is also intended to supply the farms in Type II areas. It is practically impossible to locate sites for prawn hatcheries in West Bengal (Type II) that do not experience lowering of salinity due to large river run-offs during the monsoon season.
6.1 It is recommended that hatchery production levels be set at 25 × 106 PL 20/yr of primarily P. monodon for two reasons. First, this target is easier to attain given the relatively low survival rates of P. monodon compared to other penaeid species, and constraints in spawner source and present level of technical manpower in India. Also, wild seed should remain the primary stocking material in order not to displace the thousands of traditional fry gatherers. Hatchery production should supplement and complement government efforts to improve wild fry collection, storage and transport methods.
6.2 Similarly, the primary source of spawners for the hatchery will be wild spawners or broodstock from trawlers and local fishing gear. Prawns caught by traditional methods are generally healthier and undergo less stress than those from trawlers which suffer mechanical injuries as the net is dragged. Income levels of whole coastal and estuarine fishing communities in the Philippines have improved as they have developed into collection centres for wild P. monodon spawners and broodstock to meet the demand of hatcheries in the area.
6.3 Although rated at 25 × 106 PL/yr, hatchery support facilities (seawater, blowers) could be duplicated to act as standby units in case of breakdown and to accommodate future expansion to 40 or even 50 million PL/yr.
6.4 The minimum harvest stage from the hatchery sturdy enough to be stocked in ponds (nursery or grow-out) is PL 20.
6.5 The hatchery tanks and other facilities should be designed to rear not only P. monodon out other penaeids (P. indicus, P. merguiensis) as well, depending on season and demand. In the future, the hatchery could even produce fry of grouper (Epinephelus spp.), seabass (Lates calcarifer), rabbitfish (Siganus spp.) and other marine finfish species following the examples of multispecies hatcheries in the Philippines and Thailand.
6.6 The Institute has proposed an inshore well for seawater intake in view of the strong wave action along most of the Indian coast, except for Valinokkam which enjoys natural protection (Table 3). One to two metre high waves can destroy the pipeline for seawater supply. Similarly, littoral drift (approx. 4–5 × 10 cu m /yr sand) can easily bury the intake pipes if laid directly on the sea bottom.
6.7 Ground seawater should be tested in the Madhavapur, Gudlavanipalem and Chandrabhaga sites for salinity, pH, alkalinity, heavy metals and yield of the well. Tests should be done below and above the high water level at regular 1 or 2-m depth, intervals during both dry and rainy seasons. Data obtained will determine suitability of seawater as to quality and quantity.
6.8 For Valinokkam, monthly salinity readings of coastal water should be taken during the dry and rainy seasons.
6.9 For all sites, monthly seawater temperature readings should be taken at mid-afternoon (maximum) and early morning (minimum).
6.10 Tables 4 and 5 give the details of stocking, survival and water management, and tank dimensions, respectively, for a 25 × 106 PL/yr P. monodon hatchery. Fig. 3 shows the proposed layout based on various underlying assumptions and guidelines for construction (Table 5). A list of required hatchery equipment is given in Appendix 4.
6.11 Considering purely biological and ecological factors, Valinokkam is an ideal site because of water quality, protected location and availability of spawners and broodstock. However, demand for fry is greater in Andhra Pradesh and Orissa so the first hatchery for construction can be Gudlavanipalem to supply to the existing and up-coming farms in Kakinada in the south and Chilka Lake in the north.
6.12 A plan for work has been prepared for hatchery site selection, design, construction and operation (Appendix 5).
7.1 It would greatly facilitate the work if the various experts - Coastal Aquaculturist, Hatchery Specialist and Aquaculture Engineer - could come at the same time, at least in the initial stages of site selection, planning and design. There could be clear agreement on basic concepts e.g. age and quantity of fry to be produced by the hatchery for the farm, extent of dependence of the hatchery on broodstock harvested from the farm and tank design and layout. This time, the engineer joined me halfway through my trip and the aquaculturist is to arrive the day after my departure.
7.2 A refractometer (to measure salinity), earlier ordered through FAO, had not arrived at the time of the field survey. Fortunately, we were able to take salinity readings of all seawater samples at the CMFRI prawn hatchery at Narakkal and the MPEDA branch office at Bhubaneshwar.
7.3 A local biologist should be assigned to the project to act as counterpart to the Hatchery Specialist by the time of the second visit. It is suggested that a scientist with some experience in prawn hatchery work (staff at the government hatcheries in CMFRI or CIFRI) be selected for such purpose.
The site survey activities were greatly facilitated by Director, Mr. Bhakta's excellent knowledge of the Indian coastline and familiarity with domestic travel arrangements.