FISHERIES IN VEMBANADU LAKE 

INTRODUCTION• Kerala offers extensive backwaters at the coast of Arabian sea.• The backwaters contribute productive ecosystem and the total fish

landing from Kerala backwaters vary from14,000 to 17000 tones/year. • Besides about 88,000 tones of live clams and 0.17 million tones of dead

mollusk shells are collected annually.• Vembanad Kol –wetland system ,one of the Ramsar sites in kerala• It is the largest estuarine system of the western coastal wetland system

and is spread over the districts of Alappuzha, Kottayam, Ernakulam, and Thrissur in kerala.

• The vembanadu wetland is a complex aquatic system of 96km long coastal backwaters, lagoons, marshes, mangroves and reclaimed lands, with intricate network of natural channels and manmade canals extending from Kuttanadu in the south to kol lands of thissur in north.

• The total area is around 1521.5km.

• Vembanad estuarine system is known to be abundantly enriched with diverse fishery resources, providing feeding, spawning and rearing areas for a very large proportion of commercial (fin) fish and shellfish.

• The health of the Vembanad wetlands is alarmingly declining due to a variety of reasons - obstruction of river courses, sand mining & habitat destruction, loss of riparian canopy cover, encroachment, pollution and unethical fishing practices.

• Reduced summer flow due to drying up of rivers and pollution hazards from agro-chemicals and sewage also lead to mass mortality of fishes.

• Depletion of fishery resources has changed this ‘inland fish basket’ to an ‘inland wastebasket’,

MAP

FISH DIVERSITY OF LAKE• On the basis of Vembanad Fish Count 2008 resulted in the

observation of 51 species of finshes representing 26 families and 35 genera, as well as 11 species of shell fish belonging to 7 families and 8 genera.

• The the occurrence of eight species of finfish and one crustacean of which six were commercially important.

• The drastic reduction of fishspecies in this area was noted to be a major area of concern as local knowledge indicated that catches of commercial species were going down with a potential to adversely affect the livelihoods of the fishers.

• Currently, a fisherman spending 10 hours of his effort gets only 1 -3 kg of fishes where as during earlier times they use to get more than 10kg which clearly indicates the decline of resources.

• But in Vembanadu fish count 2009 the resulted a total of 65 fin fish species were recorded where as only 51 species were recorded in 2008.

• The number of shell fish has also increased substantially from 11 species in 2008 to 14 in 2009.

• Two non native species viz. Catla catla and Oreochromis mossmbicus reported in 2008 was absent in the 2009 survey.

• In total the survey added 13 more native fish species and 3 shell fish species to the fish fauna of the lake.

• The survey also recorded two exotic species (Sucker catfish and Sutchi catfish) from the lake, for the first time.

• Anguilla bicolar(Eel), Anguilla bengalensis and Clarias dussumieri(Walking Catfish) which was vanishing eels from the southern sector of the lake is caused by stake net operation in the northern part of the lake and dams as both these obstruct the migratory pathway of eels.

FISHERY POTTENTIAL OF LAKE• A total of 104 species of fish ,9 species of shrimps and prawns, 5

species of mollusks were recorded from the lake.• Around 23 species of fishes were seen in the entire cruise which

includes many commercially important ones like channa and pearl spot with fishes like Pseudosphrone musdayi( paradise fish), Amblypharyngodon melettinus(carplet) and Wallago attu(fresh water shark) was found only at the riverinesector. Cat fish ,Chanos chanos( milk fish ), Mullets etc.are found only at the west bank.

• The total finfish landing from the lake are around 20 tonnes and freshwater prawn around 70 tonnes and that of shrimp from 110 tonnes.

• Among molluscs Meretrix costa and Villorita cyprinoids (Black clams) were the most dominant species.

• The production level of black clam was found to be 31,431 tonnes during 2000.

• During 1960s and 1970s, the average finfish and shell fish landing from the lake varied from 1200 to 8500 tonnes .

• The commercially important prawn and fish species on the lake are Metapenaeus dobsoni , M.monoceros , Penaeus indicus , Mugil cephalus, Valamugil cunnesius , M.parsia, Etroplus suratensis, Horobagrus brachysoma, Labeo dussumiery, Lates calcarifer , Chanos chanos, Anchovilla sp., catfishes, thredfins,silverbellies etc.

• The most abundend species are Metapenaeus dobsoni, and Mugil cephalus contributing 60% and 11% of the catch respectively.

• Etroplus suratensis is available in maximam numbers from June to September,Latescalcarifer from july to april,andChanoschanos from November to June.

• At present the water holding capacity of the lake is reduced due to siltation.

• According to Planning commission Report, Government of India,2008 many euryhaline migratory species are unable to contribute the fishery of lake because of the construction of barrage and breeding migration of Macrobrachium rosenbergii and M.idella is also partly affected by the barrage.

FISHING METHODS AND GEARS• The important fishing gears of the Vembanadu lake are stake

net, Chinese net. The other nets, operational are drag nets, cast nets, boat seine etc.

• CHEENA VALAIt is a type stationary net used for fishing and it commonly used in all

backwaters of kerala.• STAKE NETThe stake net, known as ‘Oonni va1a' in the Malayalam language, is very

common in the backwaters of Kerala, especially in the Vembanad lake. They constitute the most important gear used for backwater fishing in the state. The stake conical bag net set in streams and tidal waters to small fish and prawns that are swept along its course fishing principle is filtering, it can be effectively where and when a strong current runs.

•  GILL NETSThe gill nets fishery is the typical fishing gear used in

Vembanadulake. The gill net is operated by very essay so the peoples are wildly used for the capture fishery in Kuttanad. The gill nets are usually set across the direction of the migrating fishes. Gill nets can be operated varieties of ways. Bottom setting gill nets were used to catch demersal fishes. Free drifting gill nets were used to catch surface fishes. Seven types of gill net are used in Kuttanadu inland water bodies.

• SEINESAmong the 5 types of seines were examined during the present study.

The main seines were used in kuttanad area Thelivanvala, Vallivala, Thirutavala, Kattuvala, Podovala.etc

• III. CAST NETS

Generally these are circular nets, they have to be thrown or cast with great skill in order to be fall flat upon the water's surface, and then quickly sinking by the reason of their edge, they fall over the fish that has been such or is supposed to be there. In contrast to the cover pots the cast nets can only be used in waters that have no obstacle or plants and they are also possible in water body have a smooth bottom

• IV. TRAPS• Generally in fishery trapping means that the prey enters a catching chamber

from which escaping is difficulty or even impossible. The fishes enters the trap voluntarily may be when searching for a shelter or lured by some bait or when frightened and guided by fisherman . The traps are varied from the types of behavior and species of the fishes to be captured. Commonly used traps are given bellow.

• 1. Tubular traps: Tubular traps are funnel shaped gear mostly closed at the smaller end and without any non-return device. They can make of split bamboo reeds or slender branches. They also made of plaited smooth blast or netting yarn. The fish creeps in to the gear get stuck tries to move back, but is prevented the backward angle ray of dorsal fins. Tubular traps are typically fishing gear for river with strong current. The main catch component of the tubular traps are channa sp, Clarias batrahcus, eels,etc.

• 2. Mechanical traps: These are similar to mouse traps where the victim itself release a mechanism which prevent the escape. In gravity trap, weight suspended which when released by the fish prevent its escape. The elastic power of a bent rod traps .In torsion traps, the strength of twisted used to close trap

• 3. Cover pots: Usually the cover pots are of wicker construction like behave with an opening at the top. The cover pot is clapped over the animal by the fisherman wading shallow water and the prey inside the pot is taken out through the top opening. This catching method will only be successful in turbid, especially in muddy water; otherwise the victims will escape. In capturing with cover pots the most of the fishes are air breathing

Fish trapbamboo trap for fishing

• VI. HOOKS AND LINES• The hooks are used to catch deep water fishes line fishing are done

with a light bamboo trapped to a then pointed serving as food The line is generally cotton but now a days it may be synthesized monofilament like nylon.

• 1. Hand line: Hand line is the simplest form of fishing line .Hand line can be operated with or without a pole or rod. A line with a few hooks is operated by a single man paying constant attention to the catch.

• 2. Set line: Several hooks are set in a fixed position in the case of set lines these consists of a main line to which snoods with baited or hooks are fixed at regular intervals.

• VII. HAND PICKING• The clams are picked with a collection basket known as undavala or

kilungam. A more effective method locally known as "varandi" or kolli using a toothed ion rake is employed for combing the bottom and hearing up there clams which are then recovered in the collection basket.

CONCLUSION• Vembanadu lake is one of the major backwater resource of kerala.• It is the largest kolesturine system of southern coastal wetland

system.• it have major role in the inland fishery and aquaculture fishery of

kerala. • The average annual finfish and shellfish landings from the lake

varied from 1200 to8500 tonnes in 1970s but in 2000, around 70 tonnes of fresh water prawns 110 tonnes of shrimp and about 20 tonnes of finfishes are gain per year. Among molluscs about 31431 tonnes of black clams also gain.

• From this data we know that the total fishery landing from the lake increases ,but the fishery potential of lake reduced.

• The use of modern fishery equipment increases the fish capturing ability but environmental and anthropogenic interventions reduce the fishery of the lake.

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