152 research outputs found
Relevance of the study of marine fish eggs and larvae in India
India is a tropical, peninsular country, situated
between about Lat. 3┬░ and 38┬о N and between about Long' 68'
and 80'' E. There is an extensive coastline of more than
6,500 Km, dotted with many estuaries, creeks, backwaters
bays, lagoons, etc. frequented by quite a few species
of fishes. According to Talwar and Kacker (1984)^ there
are about 1,400 marine and estuarine fish species in India,
Of these/ about 100 species belong to the group of sharks,
rays and skates (Esasmobranchii), which are mostly viviparous,
giving birth to their young ones and hence do not pose any
problems with regard to their identity in their young
stages
On the identification of the early developmental stages of clupeiform fishes from Indian waters
Among about 65 species of clupeiform fishes present in the seas around India, most are distributed along both the east and west coasts and have similar spawning seasons and spawning grounds. The most difficult problem experienced with regard to the identification of their early developmental stages is the overlapping sets of diagnostic features among many species within the same genus as well as among species belonging to two or more genera. From studies carried out recently, the present paper sites a few instances wherein certain subtle characters have been used for distinguishing the early developmental stages of a few allied species
Present status of work on marine fish eggs and larvae in India and outlook for the future
In India, interest on a study of marine fish eggs
and larvae is found to have begun only in the first
decade of the present century, when Bhattacharya (1916)
has identified the larvae of a few estuarine fishes.
Although there has, been a steady increase-in the output
of research thereafter, most of the publications till
the end of the thirties are on estuarine species only
An introduction to demersal finfish resources
An estimated 250 species of demersals form regular fisheries of
van.\ing magnitude in Indian coastal bottom, with greater diversity in
the east coast compared to the west coast and occupy all types of
habitats. They are exploited by a variety of traditional and mechanised
craft and gear. Their production has reached 7 lakh tonnes in 1994,
comprising of sciaenids (24 %), pink perch (12%), silverbellies (9%),
elasmobranchs (9%), large perches (8%), flatfishes (7%), catfishes and
powfrets (6% each), and lizard Jishes (5%). The paper overviews the
demersal fisheries research in India since the inception ofCMFRI
On judicious exploitation of marine fishery resources
The principal aim in marine fisheries
Tesearch is to find ways and means of
obtaining 'maximum sustained yield'
from year to year and to practise conservation
procedures for realizing such
an end. By 'maximum sustained yield'
is meant the maximum quantity of
fish th at can be harvested by man in
a given year, without adversely affecting
the regenerating or repleni shing
potentialities of the stock with reference
to future fisheries
Terminology of the early developmental stages of marine fishes
A perusal of literature shows that over the years
various authors have used different terminologies for the
various early developmental .stages or, phases of marine
fishes
A review of marine finfish culture experiments in India
Although India is blessed with many cultivable marine fin flshes, their
seeds and unpolluted coastal water bodies, commercial culture of this resource
has remained in a primitive condition all along. The traditional
methods practiced in West Bengal, Kerala, Goa, etc. fall short of the advanced
technology developed in countries such as Indonesia, Philippines
and Taiwan. Certain experiments undertaken have revealed that by resorting
to systematic and scientific steps of pond preparation, water management
and selective stocking, the growth and production of most of the
species could be enhanced considerably. However, certain drawbacks
observed in most of the experiments are: lack of published data on the
cost of cultivation, lack of technologies to grow ideal food for species such
as milk fish and to construct and maintain grow-out structures in relation
to the environmental and soil conditions, lack of adequate water supply
to culture facilities and lack of seeds. The paper examines these aspects
and presents suggestions for a more effective approach to solve the problems
as well as to ensure commercial culture of marine fin fishes as a
successful proposition
Development of eggs and larvae of marine fishes
For an individual fish, the beginning of development
is fertilisation of the egg by spermpatozoa. Most marine
teleosts have pelagic eggs which drift with the plankton
in a ll water layer between the surface and the bottom
However, fishes like the British herring
and Blennier and Gobier have demersal eggs, which attach
to substrata like stones, shells and weeds. Usually,
pelagic eggs are transparent and spherical, with the
exception of the eggs of certain engraulids t o l e v h o r u s
which are oblong. When the embryo is fully developed, '
&t hatches out as larva and undergoes further development,
Fertilisation end Embryonic developmen
Guidelines for the identification of marine fish eggs
Occurrence of early developmental stages in the
plankton and of spawners, spent, mature and/or recovering
stages in fish catches can be used to identify the former
as belonging to the latter only in a circumstantial manner,
Delsman (1922-1938) has made use of such a method for
assigning the early developmental stages; but, in addition
to this he has also assigned cogent reasons of taxonomic
nature in arriving/at his conclusion. -Thus, this circums
tantial evidence of coincident occurrence of the eggs in
the plankton and the spawning adults in the fishery can
be only of limited value
Notes on postlarval stages of the wWhite sardine, Kowala coval (Cuvier)
Kowala coval popularly called the ' white sardine', is one of the pelagic shoaling
clupeids occurring in the seas around India. It appears frequently in the catches
of the indigenous crafts and mechanised vessels operating in the coastal waters.
Also, it contributes a fishery of some magnitude along certain areas. (Chidambaram
and Venkataraman, 1946 ; Mookerjee and Bhattacharya, 1950 ; Nair, 1952), particularly
in the southwest region. Delsman (1926 b ; 1933) collected the plahktonic
eggs of this species from the Java Sea and gave descriptions of a few early larval
stages. Subsequently Devanesan and John (1941), Nair (1952) and Bapat (1955)
have dealt with certain aspects of its biology including maturity, spawning season,
eggs, early larvae etc
- тАж