993 research outputs found
Studies on the fishery of the penaeid prawn Metapenaeus affinis (Milne Edwards) Along the Mangalore coast
Tbe fishery anl certain features of the population structures of M. affiMs
caught by the trawlers fran 1962 through 1971 are reported. The fishery was
chiefly i^odal and was dominated by large size groups early in the season and
smaller size groups later. The maximum number of broods entering the fishery was
observed to be four. Age and growth studies indicated that tbe males attain a
length of about 95, 140 and 160 mm and females, lOO, 143 and 170 mm at the
end of one, two and three years, respectively. The miniminn size at first maturity
for males was found tp be 116 mm. The average annual instantaneous fishing
mwtality was found to be 3.76 for males and 2.50 for females between one and
two year olds
Prawn fishery of Alleppey coast during the S.W. monsoons of 1972-1976
The annual total catch of prawns showed wide fluctuations. The catch per
unit effort varied considerably from month to month of the same season and
also duting the corresponding months of different seasons. The prawn catch was
mainly constituted by Metapenaeus dobsoni (Miers). June-July months were
more productive on account of recruitment of more individuals belonging to
higher size groups. The monthly average mean sizes of M. dobsoni showed great
disparity, ranging between 75.2 mm and 91.5 mm for males and 81.3 mm and
103.4 mm for females. In the species, males were found in a higher proportion
than females in lower size groups, but females occurred in higher proportions
in higher size groups. The recruitment of mature females into the fishery was
quite irregular throughout the seasons of different years under study. The analysis
of stomac
On the prawn fishery by trawlers off Purakad, Sw coast, during 1972-76
The total catches indicated that the prawn fishery off Purakad was on a
steadily declining trend from 1972, except for 1974, the total catch of over 2000 t
in 1972 declining to less than 200 t in 1976. Though quantitatively all the species
were heavily suffering the decline, with the relative proportion more steeply declining,
from 29% in 72 to 6% in 76, P. indicus seems to be the species that was most
affected; and M. dobsoni, increasing from 52% in 72 to 72% in 76, the least
Tidal waves cause damages to coastal villages in Kerala
The article reports on the damages caused by giant tidal waves to coastal villages between Aarattupuzha (Alleppey District) in the south and Nattika (Trichur District) in the north for a distance of about 150 km along the Kerala coast. The giant tidal waves struck hard against the shore and rolled over into the low lying areas filling the sea water in the huts, wells, paddy fields etc. The damages were the minimum where ever the sea walls were present. But such calamities are unpredictable, hence the practical solution to such sudden natural calamities is to protect the coast line by constructing sea wall wherever the same is not present
Population characteristics and exploitation of the important marine prawns of Ambalapuzha, Kerala
The monthly landings of the different species and the effort expended show
wide fluctuations. However, the catch per unit of effort and the mean size of
the different speci(┬л do not show a regular declining trend. It has been found
that the successful spawning by the surviving spawners and the subsequent recruitment
of younger prawns into the fishable stock greatly influence the fluctuations
in the landings. Ecological changes brought out by the physico-chemical
distorbaiKes in the envirmunent and their influence on prawn landings are
dbcossed
Zooplankton abundance in the continental shelf waters of the northeast coast of India
Higher concentrations of zooplankton standing stock and population occurred
in the region off Chilka lake and Paradip (19┬░ 10'N-19┬░ 55'N and 85┬░09'E-86┬░ 50'E)
during January and off Visakhapatnam (17┬░30'N- 18┬░28'N and 83┬░14'E- 84┬░29*E)
during November and April. The most productive period along the northwestern part
of the Bay of Bengal was the northeast monsoon season (October-January) followed
by the premonsoon season (February-May). High abundance of copepods, chaetognaths,
siphonophores, cladocerans, fish larvae, planktonic molluscs, amphipods,
foraminifers and larval polychaetes constituted the northeast monsoon maximum.
Very low biomass values were recorded during the southwest monsoon season
(June-September). The neretic zone up to 50 m depth was rich in zooplankton
population during northeast monsoon and further to a lesser extent up to 100 m during
the premonsoon season. However, a steady decline was evident with increasing depth
zones. The less saline northern part exhibited remarkable differences in the abundance
of the population and standing stock in such a way that 63% of the total was
confined to the northern region. Fish eggs were predominant during February-May
and larvae in July and January-February. The peak period of the zooplankton
population coincided with the maximum landings of the pelagic and demersal fishery
resources of the northwestern coast of the Bay of Bengal
Resource assessment of the penaeid prawn Metapenaeus dobsoni (Miers) along the Mangalore coast
The fishery and certain aspects of the population characteristics of M.
dobxoni from 1962 through 1971 are reported. The fishery was generally bimodal
with peaks during March-April and September-October and showed wide annual
fluctuations. Th-; total catch showed a gradually diminishing increase when the
fishing effort reached a level of about 14,000 boat days. The catch per boat day
also showed a downward trend, in general. It would appear, therefore that any
additional increase in 'effort would be of little consequence in raising the yield.
The fishery was dominated by larger size groups (above 95 mm) during JiilyiNovember.
Recruitment of smaller size groups (60 mm onwards) was observed
duping DeC'imber-January. The maximum number of broods entering the fishery
was five. Age and growth studies indicated that the males and females attain a
length of 85 and 105 mm and 95 and 120 mm at the end of one and two years
respectively. Th-ereafter very little growth seems to take place. The late 'O' and
the one year class formed the mainstay of the fishery. The mean length showed
considerable annual fluctuations but these changes appear to be only due to natural
causes. Females preponderated in all the years except during 1965-66. They often
tended to exceed the males by more than 1.5 times during .April-May and November-
December which more or less coincided with periods of intense breeding activity.
The average annual instantaneous rate of mortality between one and two year olds
was found to be 4.18 and 4.61 for males and females respectively. The fluctuations
in the annual rainfall seem to bear a direct relation to the magnitude of the fishery.
No clear-cut relationship between the juvenile abundance in the estuary and the
marine fishery was discernible
Laboratory phenomics predicts field performance and identifies superior indica haplotypes for early seedling vigour in dry direct-seeded rice
Seedling vigour is an important agronomic trait and is gaining attention in Asian rice (Oryza sativa) as cultivation practices shift from transplanting to forms of direct seeding. To understand the genetic control of rice seedling vigour in dry direct seeded (aerobic) conditions we measured multiple seedling traits in 684 accessions from the 3000 Rice Genomes (3K-RG) population in both the laboratory and field at three planting depths. Our data show that phenotyping of mesocotyl length in laboratory conditions is a good predictor of field performance. By performing a genome wide association study, we found that the main QTL for mesocotyl length, percentage seedling emergence and shoot biomass are co-located on the short arm of chromosome 7. We show that haplotypes in the indica subgroup from this region can be used to predict the seedling vigour of 3K-RG accessions. The selected accessions may serve as potential donors in genomics-assisted breeding programs
Studies on Composite Extrudable Propellant with varied Burning Rate Pressure Index 'n'
This paper discusses the development of composite propellantextrusion technique and the study of burning rate pressure indices nwith respect to compositional variations. The n is found to vary from0.35 to plateau and plateau to mesa by suitable compositionalmodifications. Compositional influence on burning rate with specificreference to plateau and mesaburning additives is described. Detailsof the process parameters like fluidity of the slurry, extrusion pressure,extrusion rate and die-swell are presented. This propellant is based onISRO-CTPB binder using ISRO-AP as oxidizer. Ammonium perchlorate (AP) particle size variation and inclusion of additives likePVC, lead stearate, ammonium sulphate, lithium fluoride etc. are foundto influence the burning rate pressure index n
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