Ecosystem And Fisheries
#Milind B. Katare,
@Central Institute of Fisheries Education,
Seven Bunglows, Versova, Andheri (w.),
Mumbai-400061, Maharashtra, India
#KAFSU, College of Fisheries,
Manglore, Karnataka, India
*BSKKV, College of Fisheries,
Ratanagiri, Maharashtra, India
are one of the most productive ecosystems comparable to tropical
evergreen forests in the biosphere and play a significant role in the
ecological sustainability of a region. Wetlands form the transitional
zone between land and water, where saturation with water is the
dominant factor determining the nature of soil and the types of plant
and animals community's living in and on it. An immense variety of
species of micro-organism, plants, insects, amphibians, reptiles,
birds, fish and mammals are the part of a wetland ecosystem.
provide great volumes of food that attract many animal species. These
animals use wetlands for part of or all of their lifecycle. Dead
plants leaves and stems break down in the water to form small
particles of organic material called "detritus". This
enriched material is fed on by many small aquatic insects, shellfish
and small fish that are food for larger predatory fish, reptiles,
amphibians, birds and mammals. These zones would nowadays be classed
to Ramser Convention, the area of marsh, fen, peatland or water,
whether natural or artificial, permanent or temporary, with water
that is static or flowing, fresh, brackish or salt, including areas
of marine water the depth of which at low tide does not exceed 6
meters are considered as wetland system. Also consisting of peat bogs
like Ombrotrophic bogs, Soligenous bog and Maeshlands like Marshes,
Fens, Swamps, floodplains etc.
is an ecosystem which provides great volume of food that attracts
many animal species like shellfishes, small fishes and predatory
fishes. Capture and culture fisheries activities can be effectively
carried out in these type of water logged areas provided the system
is well managed.
naturally has its own biota where the capture fisheries can be
planned provided it is sufficiently deep enough. Carrying out the
fishing activities, capture fisheries is nothing but harvesting the
natural habitats from water by means of various verities of gears
such as cast net, gill net, traditional and advanced traps, trawl
gears, seiens etc. Further, land which is suitable for recreation,
mainly angling, sport fishing, and also tourism spot act as fishing
ground. We can develop ornamental capture fisheries with respect to
colorful fishes and ornamental plants.
major problem during operation of nets in wetlands area is
vegetation. Most of the time operations fail or various operational
problems occur like damage of net, arresting of net in vegetation.
Most aquatic vegetation problems are the result of elevated levels of
nutrients, primarily nitrogen and phosphorous, in the pond/lake's
water and sediments. These nutrients are always present in some
amounts and naturally build up over time.
the floodplains area, the gill net near the periphery of the wetland
area can be used. Pit or pond like structure near floodplains area in
which fish get entrapped during heavy rain-fall. Bamboo traps and
advance mechanized traps in this area can also be used for effective
capturing of the fishes. In the Marshes, fens and swamps, the traps
play a vary important role and these traps can easily be removed with
fish when placed in vary dense vegetative areas.
creeping habit of prawn and crabs at the bottom in the shore regions,
especially at night, are mostly caught by traps set in those areas.
In the deeper areas of the wetlands, mostly gill nets are operated.
In the shallow water which has less vegetation, mostly cast nets are
can be possible in the wetland area but before that the eradication
of aquatic weeds is pre-requisite. There are various methods which
are used for the eradication of aquatic weed; they are Mechanical
method, Chemical Method and Biological Method.
mechanical method for controlling aquatic weeds are very important
but followed on a limited scale.
are various types of cutters or mechanical equipment which are used
to eradicate aquatic weeds and fens and they are Water weed cutters
and Weed harvesters.
it is not only slow and expensive but also requires manuel labor to
complete the follow up operations,
the use of mechanical controls is usually only feasible for smaller
sized wetland areas or for spot treatments of smaller areas in larger
wetland bodies. Various methods include cutting or pulling out the
vegetation, raking and/or seining floating vegetation blown into
corners by the wind or wave action.
Chemical Control Methods:
chemicals popularly known as herbicides can effectively control the
noxious aquatic weeds. A large number of chemicals have been used as
herbicides for the control and they are of six groups namely:
chemicals: ( Sodium arsenite)
chemicals: ( xylene)
iii) Auxin type
regulator: ( 2-4 Dichlorophenoxyacetate)
v) Algaecides: (
vi) Other growth
Biological Control of Aquatic Weeds
the biological control, a suitable organism is introduced. The
organism either feeds upon the aquatic weeds or otherwise damages it
severely and keeps it under check and spread to acceptable limits.The
organism used to check the spread of weeds is called bio control
agent or a bioagent which may be specific or non specific.
method of biological control of aquatic macrophytes has many
advantages over chemical control method. It is convenient, cheap,
free from pollution hazards and the fertility of the pond is not
examples of bio agents mainly herbivorous fishes are Grass carp
(Ctenopharyngodon idella), Puntius
javanicus, Common carp (Cyprinus carpio), Tilapia spp.,
Silver carp (Hypophthlmichthys molitrix),
Animals as Bio agents are Manatee(Sea cow), Ducks & Geese,
Aquatic Rats, Insects (like Water hyacinth weevil, Water hyacinth
moth, Water hyacinth mite) and Fresh water snails(Marisa
cornllarieties & Pomacea australis). In India Pillia
globosa is used for eradication of Salvinia molesta.
can develop the aquaculture in the wetland area, and altering and
eradication of aquatic weeds from the desirable depth of wetland area
thereby forcefully the aquaculture activities could be performed.
Pen is defined as "a fixed enclosure
in which the bottom is the bed of the water body". The word 'pen'
here is also used synonymous with 'enclosure' as it is used in
culture is a very important culture technique in the wetland area
since the wetland itself is a nutrient rich body. High primary
production, mostly found in wetland areas, and hence they are famous
for the food due to which it attracts various fishes towards it.
Particular area could be restricted with the help of net and
eradicate all vegetation with the help of mechanical, chemical or
biological methods and this water platform becomes a locked area for
aquaculture and thus it serves as pen culture.
of young stages of fin and shellfish in wetland pens represents a new
and relatively simple approach with potential to become an important
seed raising systems in near future for profitable resources
with potential for rearing pens are Indian and Chinese carp, eels,
catfishes, milkfishes, mullets, tilapia and both fresh water and
brackish water prawns.
culture may also be possible in wetland areas provided the depth is
sufficient to mount cages. However, removal of aquatic vegetation is
the prime duty before planning of cage culture practice. Cages are
made with a rigid bottom, the frame of the bottom pushes vegetation
of the wetland area and makes available water inside the cage and
this water can used for the aquaculture.
of cage culture is to rear spawn and fry to fingerling size within 2
to 3 months. High density rearing is restorted to in this phase, with
intensive high protein feeding. Due to availability of natural food
and by also providing supplementry feed results in faster growth rate
of the fishes. It is possible to rear Rohu, Catla, Mrigal, silver
carp grass carp and common carp fry or spawn in fresh water wetland
cage culture system.
of carp seed in wetland cages through appropriate technology reduces
pressure on land for fish nurseries.
of Pond near by the wetland area
the floodplain or in the lagoon side area the ponds automatically fed
by water due to increase and decrease of water level. Pumping to
fulfill the water demand of the pond can be the another option.
Pond near by the wetland area
AND STAKE CULTURE:
is also scope for the raft and stake culture in the wetland
area.Clams, Oyster etc. production from this type of aquaculture is
RAFT AND STAKE CULTURE
wetland area which is generally waste land can be used as integrated
fish farming with Makhana culture. This type of mixed culture will
offer greater efficiency in resource utilization, will reduce risk by
diversifying crops and will provide additional food and income. This
system will be of special significance as it will improve the
socio-economic status of weaker rural fisher community.
is mostly practiced near the coastal area especially where the water
level is lower to estuarine region.
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