1. Pen culture as an aquaculture system
Evolution and history of pen or enclosure culture; advantages and disadvantages; pre-requisites for pen culture in inland, estuarine and marine waters; importance of suitable seabed conditions, availability of suitable species, water flow, salinity, temperature, and sheltered conditions.
2. Types of pens
(a) completely isolated enclosures surrounded by a net structure in the middle of a bay with no foreshore;
(b) shore enclosure with a portion of the foreshore extending into deep water surrounded by a net structure, and
(c) bay or lock enclosure with an embankment provided with sluices or net structure only at the entrance.
3. Design and construction
3.1 Selection of site (see Chapter II - Selection of Sites for Aquaculture)
3.2 Design
Concentric and contiguous pens; catwalks; boat locks; ancillary buildings and shelters.
3.3 Construction
(a) Rigid pens:
(i) Embanked pens - concrete, stone or earth embankments with sluices for water circulation.(ii) Net enclosures - framework or scaffolding and wall of mesh netting; materials used for framework (galvanized scaffolding, wooden or concrete piles, bamboo and/or mangrove stakes, etc.); criteria for the selection of netting material (reasonable life expectancy, resistance to fouling and corrosion, ease of handling and cleaning, etc); netting materials used; their physical properties; resistance to environmental and climatic factors and relative efficiencies; curved corners versus square corners; provision of collars (against jumping fish) and footings and surface covers (against predators); construction of catwalks, feeding platforms, and boat locks.
(b) Flexible pens:
Sinkers, chain-link footrope, headrope, flotation buoys, netting wall (vertical wall and horizontal floating net), strengthening lattice, catwalks and jetties.
(c) Outer barrier nets.
4. Shapes and dimensions of pens
Dimensions of nursery and fattening pens; effect of shape on the behaviour of fish and ease of harvesting.
5. 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; availability of stock.
6. Farming operations
Hatchery production or collection of seed; clearing nursery and fattening pens of unwanted fauna; stocking of nursery pens; transfer to fattening pens; stocking rates; fertilization and supplementary feeding; maintenance of pens (monitoring of water quality, cleaning, predator and weed control); cropping; selection of optimum size for harvesting.
7. Economics of pen culture
Average yield for different species and combinations of species; cost of construction and maintenance; amortization rate.
Practicals
Design of pen farms suited to selected areas; experiments in pen culture of local species.
