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Sunday, January 1, 2023

Cage fishing ~ floating Cage pisciculture in Chingleput

Chennai often gets parched of water and that way you would find this lake brimming with water.  It is in nearby Chingleput, which one has to cross when travelling to Southern Districts by train or by road.   Can you imagine what these are ?

Chengalpattu was formerly a capital of the kings of Vijayanagara, after their defeat by the Deccan sultanates at Battle of Talikota in 1565. The fortress at Chengalpattu, built by the Vijayanagara kings in the 16th century, was of strategic importance, owing to its swampy surroundings and the lake that flanked its side. Chengalpattu was taken by the French in 1751 and was retaken in 1752 by Robert Clive, after which it proved of great strategic advantage to the British.  The Chingleput lake which was once big is known as ‘Kolavai lake’ now in Kancheepuram district.  The town of Chengalpattu is at the southern end of the lake.  It provides water to the city through tanker lorries.

Fish farming involves raising fish commercially in tanks or enclosures, usually for food.  In some countries, there is technique of cultivating rice and raising fish too in the same farm.   There, fish is introduced into flooded paddy fields – perhaps not in these parts.  Understand that type of carps are grown in this fashion. 

Elsewhere in Hongkong,  under eerie blue lights designed to simulate the ocean depths, hundreds of fish swim serenely through the bubbling waters of their circular tanks, 15 floors up in the sky. It is fish in sky as there are 11 plastic tanks in total, holding a combined 80,000 litres of salt water.  They are full of grouper, a white-fleshed fish, which are all destined to end up on the plates of restaurant-goers across Hong Kong.

In common parlance there is the ‘aquaculture’ – the breeding and harvesting of fish in ponds, lakes and other water bodies.   Marine aquaculture production includes oysters, clams, mussels, shrimp, and salmon, while freshwater aquaculture operations produce trout, catfish, and tilapia.   Fish farming is the principal form of aquaculture; in this  young (juvenile) fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. The most common fish species raised by fish farms are salmon, carp, tilapia, European seabass, catfish and cod. The reported output from global aquaculture operations would supply one half of the fish and shellfish that is directly consumed by humans.

The main problem with raising fish on land is that  of crowding fish into confined spaces that  increases the potential for devastating epidemics. At the same time, it creates demands for electricity and water that Asian infrastructures can't fulfill - a serious problem, given that an aeration or filter failure can kill an entire harvest in minutes.

Then there is cage fishing – which comprises of cages submerged in shallow, calm waters near shore, where they are protected from the weather and easily accessible for feeding and maintenance. Deepwater cages offer cleaner, more freely circulating ocean water and natural food, which can yield tastier fish.  In some places, there are aquapods, made of triangular panels covered with vinyl-coated, galvanized steel netting.  According to NIOT, in India, high-density polyethylene is used to build the cage and it will last for more than seven years.

In the State, Fisheries College and Research Institute (FCRI) developed a farmer-friendly and easy-to-follow technology in the open water aquaculture.  These are low cost cages made of iron frame with screen net ranging from one square metre to four square metre in size with feed pipes inserted in the middle of the cage.  Such cages are fixed in  bamboo rafts and 10 to 15 cages could be set up in one raft offering 25 to 50 cubic metre of rearing space for the fishes.  It is stated that fish variety ‘Cobia’ is being reared in these. 

Here are some photos of the floating cages seen on the lake, photos taken while travelling in train.

With regards – S. Sampathkumar

10th Feb 2015.

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