249
18. Assemblages, which generally have large
piscivores, are common in wetlands of
Northeast India, Myanmar, Thailand, China,
Lao PDR, Kampuchea, Philippines, etc. In
these wetlands, the zooplankton community
is generally dominated by rotifers, cladocerans, copepods, etc.
19. The single common feature of all fi sheries is
that they are basically ‘hunting’ operations.
The infl ow and outfl ow channels sometimes
reveal rich diversity and high yield of fi shes.
In addition to the above, many fi shes may
progress through a trophic ontogeny, in
which diets undergo changes as habitat shifts
occur and the relative sizes of predator and
prey change with growth dynamics. The
linkage between fi sh and other food web
components generally determines the food
web dynamics in the wetland ecosystem.
20. Fish yield had not been very high in different places and at different times. During
1976, 114 countries had landed 10,000 mt or
more of aquatic organisms. However, the
aggregated landings of six nations accounted
for more than one-half of the world’s total
harvest of 73.4 million mt. On perusal of
world’s conventional fi sheries with regard to
MSY, it could be revealed surprisingly that
most of them either nearing MSY or have
reached MSY.
21. Aquaculture has been growing since few
years to meet demands of aquatic food. Of
late, there has been a growing focus and
interest on controlled ‘fi sh farming’ or ‘aquaculture’. It is mainly because the world fi sh
catch seems to be approaching an upper
limit, at least for the foreseeable future. It
may be mentioned here that the total yield
for the year 1975 was calculated as 6.0 million mt (wet weight approx.). This was
<10 % of the estimated total world fi sh catch
for the same year. Nevertheless, it refl ected
>50 % increase since 1970. Further, it is
important to note here that >100 species of
plants and animals are cultured in aquaculture practices. But >60 % of the total aquaculture yield comes from pond culture of a
few species of fi nfi sh only. Approximately
75 % of the total world aquaculture yield is
obtained from the Indo-Pacifi c region. The
traditional ponds and fl ooded rice fi elds in
the Indian subcontinent including Bangladesh
account for a big share in the total global
aquaculture production. However, except
some, like the Japanese cultured pearl industry, almost all aquaculture products are meant
for direct human consumption. Further,
aquaculture usually provides higher yields
per unit area than agriculture in situations
where there is no supplementary feeding.
Annual fi sh yields to the tune of about
3,000 kg/ha/year could be obtained as compared to 500–700 kg of cattle fl esh/ha/year.
22. Contrary to the above, the development of
aquaculture in most of the western countries has been remaining little sluggish
since few years. It could be mainly due to
low market demands, intense competition,
high costs of potential sites for aquaculture
installations, and so on. Pillay had predicted that world aquaculture production
could probably double to 12 million metric
tonne (mmt) by 1985 as compared to the
yield in 1976.
Suggested Readings
Alversond L, Longhurst AR, Gulland JA (1970) How
much food from the sea. Science N Y 168:503–505
Angermeier PL, Karr JR (1983) Fish Communities along
environmental gradients in a system of tropical
streams. Environ Biol Fishes 9(2):117–135
Armontrout NB (1990) Aquatic inventory. Bureau of
Land Management, Eugene District, pp 32
Armstrong W (1980) Aeration in higher plants. Adv Bot
Res 7:225–332
Arunachalam M, Madhusudan Nair KC, Vijberg J,
Kortmulder K (1988) Food and habitat usage of cyprinid fi sh assemblage in stream pools of a South Indian
river. Report 19. Limnological Institute of Royal
Academy of Sciences, The Netherlands, pp 89
Barbhuiya AH, Kar D (2012) Treatise on mahseer fi shes.
Dominant Publishers, New Delhi, pp vii + 293
Bardach JE, Ryther JH, McLarney WO (1972)
Aquaculture: the farming and husbandry of freshwater and marine organisms. Wiley – Interscience,
New York
Battish SK (1992) Freshwater zooplankton of India.
Oxford and IBH Publishing Co., Ltd, New Delhi,
vi + 233
Suggested Readings
18. Assemblages, which generally have large
piscivores, are common in wetlands of
Northeast India, Myanmar, Thailand, China,
Lao PDR, Kampuchea, Philippines, etc. In
these wetlands, the zooplankton community
is generally dominated by rotifers, cladocerans, copepods, etc.
19. The single common feature of all fi sheries is
that they are basically ‘hunting’ operations.
The infl ow and outfl ow channels sometimes
reveal rich diversity and high yield of fi shes.
In addition to the above, many fi shes may
progress through a trophic ontogeny, in
which diets undergo changes as habitat shifts
occur and the relative sizes of predator and
prey change with growth dynamics. The
linkage between fi sh and other food web
components generally determines the food
web dynamics in the wetland ecosystem.
20. Fish yield had not been very high in different places and at different times. During
1976, 114 countries had landed 10,000 mt or
more of aquatic organisms. However, the
aggregated landings of six nations accounted
for more than one-half of the world’s total
harvest of 73.4 million mt. On perusal of
world’s conventional fi sheries with regard to
MSY, it could be revealed surprisingly that
most of them either nearing MSY or have
reached MSY.
21. Aquaculture has been growing since few
years to meet demands of aquatic food. Of
late, there has been a growing focus and
interest on controlled ‘fi sh farming’ or ‘aquaculture’. It is mainly because the world fi sh
catch seems to be approaching an upper
limit, at least for the foreseeable future. It
may be mentioned here that the total yield
for the year 1975 was calculated as 6.0 million mt (wet weight approx.). This was
<10 % of the estimated total world fi sh catch
for the same year. Nevertheless, it refl ected
>50 % increase since 1970. Further, it is
important to note here that >100 species of
plants and animals are cultured in aquaculture practices. But >60 % of the total aquaculture yield comes from pond culture of a
few species of fi nfi sh only. Approximately
75 % of the total world aquaculture yield is
obtained from the Indo-Pacifi c region. The
traditional ponds and fl ooded rice fi elds in
the Indian subcontinent including Bangladesh
account for a big share in the total global
aquaculture production. However, except
some, like the Japanese cultured pearl industry, almost all aquaculture products are meant
for direct human consumption. Further,
aquaculture usually provides higher yields
per unit area than agriculture in situations
where there is no supplementary feeding.
Annual fi sh yields to the tune of about
3,000 kg/ha/year could be obtained as compared to 500–700 kg of cattle fl esh/ha/year.
22. Contrary to the above, the development of
aquaculture in most of the western countries has been remaining little sluggish
since few years. It could be mainly due to
low market demands, intense competition,
high costs of potential sites for aquaculture
installations, and so on. Pillay had predicted that world aquaculture production
could probably double to 12 million metric
tonne (mmt) by 1985 as compared to the
yield in 1976.
Suggested Readings
Alversond L, Longhurst AR, Gulland JA (1970) How
much food from the sea. Science N Y 168:503–505
Angermeier PL, Karr JR (1983) Fish Communities along
environmental gradients in a system of tropical
streams. Environ Biol Fishes 9(2):117–135
Armontrout NB (1990) Aquatic inventory. Bureau of
Land Management, Eugene District, pp 32
Armstrong W (1980) Aeration in higher plants. Adv Bot
Res 7:225–332
Arunachalam M, Madhusudan Nair KC, Vijberg J,
Kortmulder K (1988) Food and habitat usage of cyprinid fi sh assemblage in stream pools of a South Indian
river. Report 19. Limnological Institute of Royal
Academy of Sciences, The Netherlands, pp 89
Barbhuiya AH, Kar D (2012) Treatise on mahseer fi shes.
Dominant Publishers, New Delhi, pp vii + 293
Bardach JE, Ryther JH, McLarney WO (1972)
Aquaculture: the farming and husbandry of freshwater and marine organisms. Wiley – Interscience,
New York
Battish SK (1992) Freshwater zooplankton of India.
Oxford and IBH Publishing Co., Ltd, New Delhi,
vi + 233
Suggested Readings