Pen_Culture.pptx

pen culture details

1. Noakhali Science and Technology University Department of Fisheries and Marine Science Presentation on: Pen Culture: Types of Pens, advantages and disadvantages, site selection, design and construction, cultivable species, farming operation and management commercially important cultivable fin and shell fishes . Course Title : Advanced Coastal Aquaculture Course code: AQUA 5201 Presented to: Dr. Md. Mofizur Rahman Associate Professor Department of Fisheries and Marine Science, NSTU Presented by: Md. Juwel Rana Session: 2021-22 Year: 1 Term: 2

2. Content line: Introduction What is Pen? Meaning of Pen Culture Types of Pens Site Selection Design and Construction Cultivable Species Culture Operations Advantages of pen culture Disadvantage of pen culture Conclusion

3. What is Pen? The word ‘pen’ here is also used synonymous with ‘enclosure’ as it is used in enclosure culture. A Pen is defined as “a fixed enclosure in which the bottom is the bed of the water body ”. Fig: Pen Culture INTRODUCTION Meaning of Pen Culture Generally ‘enclosure culture’ is used to describe what more precisely could be defined as cage or pen culture . Both cage and pen culture are types of enclosure culture, i.e. holding culturable

4. aquatic organisms in captivity within an enclosed space whilst maintaining a free exchange of water . The two methods (cage and pen culture), however, are distinct from one another. A cage is totally enclosed on all sides by mesh or netting, whereas in pen culture the bottom of the enclosure is formed by the lake or sea bottom. Of the 6 possible zones: Shore Intertidal Sublittoral IV. Surface floating V. Mid-water and VI. Sea bed in the coastal waters

5. pen culture is possible only in the three zones, namely, intertidal, sublittoral and seabed -all having natural bottom as the limit of the lower side of the enclosure. Fig: 6 zones

6. Types of Pens The three types of pens earlier -i.e. A completely enclosed pen with net/rigid structures on all four sides in the middle of a bay/open water in lake without any foreshore; A shore enclosure with a foreshore extending to deep water surrounded by a net structure (island enclosure) and A bay or lock/fiord enclosure with an embankment or net barrier only at the entrance (of the bay ).

7. Fig: Types of Pens

8. Site Selection There are two separate aspects to be considered, one is the requirement of the species (biological) and the other is the structural requirements of the pen (physical). We have already referred to the inter-tidal and sub-littoral coastal areas (marine and brackish-water) and also the shallow freshwater bodies as suitable sites for pen culture. The site must have the following characteristics: Pollution free locate in a place where it can receive prevailing winds which will provide overall mixing and aeration. convenient for feeding and inspection Moderate water current Accessibility

9. Design and Construction Shape, size and design of the pens: On the basis of the pen culture it may be circular, square, and rectangular in shape depending upon the harvesting. The size of pens depends upon a number of physical factors such as location, water depth and biotic parameters. Large cages of 200m 3   or above may constructed for pen culture. The height of the pens depends upon the water level during entire culture period. The height also depends upon the jumping behaviour of cultured species. The height of pen may be at least 50cm. But about 30cm of the cages are fixed into the bottom to keep the pen wall secured.

10. Design and Construction Materials Used for Pens: The screen materials used for pen should be: Small meshed to prevent the escape of fry and fingerlings Resistant to long exposure in sun and water Steady enough to resist current, wind action and wave action Resists the attack of crabs and other animals Cheap and easily available, easy to handle The screens are usually made of split bamboo mats in eastern countries. Metal or metal coated with resin, nylon or HDPE, even rubber are used in western countries and Japan.

11. Design and Construction Supporting Structures : Matured and well seasoned bamboo are generally used as supporting materials, relatively in shallow waters. Other supporting materials like floats and heavy sinkers like stones are used as supporting materials.

12. Cultivable Species F ollowing criteria for selecting fish for use in enclosures: V alue of fish and market demand H ardiness (in terms of ability to adjust to high density culture, disease and handling). Ready availability of fish seed or juvenile fish for stocking Fast growth in confined waters Availability of suitable feeds

13. Cultivable Species Species of fishes and crustaceans cultivable in fresh-water, brackish-water and marine pens; selection of single species or combination of species for culture. Fresh Water Species milkfish, Chinese carps, Indian carps, mullets,  Tilapia mossambica,  T. nilotica,  puntius gonionotus , common carp, eals , catfish etc Brackish Water Species bays, coves, atolls etc.  Marine Species pompano, yellow-tail, tuna, grouper snapper, sea bass, sea bream, carangids, pomfret crustaceans, spiny lobsters

14. Culture Operations Seed Procurement Seeds of fish to be stocked in nurseries can be produced in a hatchery if sufficient control on the reproduction of the species is possible If the species to be stocked are not subject to breeding under controlled conditions, then the seeds or larvae have to be collected from the natural sources. Cleaning nursery and ‘fattening’ pens Before stocking the seeds/fry or fingerlings, the pen has to be cleared of all avoidable fauna and unwanted elements, especially predators and trash fishes

15. Culture Operations Stocking of nursery and grow out pens Fingerings after transport from source are kept in nursery pens for 5 – 6 hours or for as long as 2 – 3 weeks to prevent further environmental stress and reduce changes of predation. From the nursery pen, the fingerlings are stocked at 30,000/ha in the rearing pen where they are grown to a marketable size of 200g or more. The stocking density limits of any species are to be decided by the total biomass and its environmental requirements and also other biological and physicochemical characteristics of the water.

16. Culture Operations Fertilization and feeding In rich waters the natural productivity is sufficiently high that fertilization is not needed. Even in other cases, since the pen enclosures are open to flux of waters with the tide, fertilization if practiced, may not give full benefits. Fish are given dry or moist pellets, if relevant and costs reasonable. The feed can be offered either in feeding trays and/or with demand feeders. The recommended feeding rates for Yellow-tail are very high relatively i.e. r anging from 40-60 % of body w ight per day for 10-50g fish to 6-8 % in 100-1200g fish. The frequency of feeding would depend on the growth stage.

17. Culture Operations Maintenance of Pens Routine maintenance operations of sluices and gates and net barriers, rigid and non-rigid, are most important. Regular cleaning the nets Scrubbing operation Predator and weed control Regular checks and repairs/modifications Monitoring water quality especially D.O., salinity, temperature, pollution etc .

18. Culture Operations Harvesting P ens are convenient for cropping at any time because of the confined space and high density of fish stocked. Harvesting can be dependent on the size and shape of the pens .(see rounded and square angles earlier- square angles are easier to operate framed harvest nets). Seines and gill nets or framed nets, are often employed for catching fish.

19. ADVANTAGES OF PEN CULTURE The management cost in pen culture is low Relatively simple and cheap technique Construction cost of pens is very low. Intensive utilization of space Safety from predators Suitability for culturing many varied species Ease of harvest The flexibility of size and economy Availability of natural food and exchange of materials with the bottom

20. DISADVANTAGE OF PEN CULTURE High demand of oxygen and water flow Dependence on artificial feed Food losses Pollution Rapid spread of diseases Risk of theft Conflict with multiple use of natural waters

21. Enclosure culture is often viewed as desirable as it can generate employment, income and food to support the already available fishery activities. For adoption of these system, an integrated resource management or water shed perspective is essential Environmental, social and economic issues related to these systems will be taken care in this way. Among other things, adequate skills, good market and clear legal tenure of sites are prerequisites and this implies the full participation of resources users. Conclusion